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' Sigmar: Test Baatmagasinet Marine Boiler Test /comparison'



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TEST water heaters in the 20-litre class




Wet heat         home comfort on board
This test of Water Heaters for Yachts has   There are wide differences bet-
been carried out by the independent
Norwegian Boating Magazine                  ween water heaters. In the best
BÅTMAGASINET, the leading motor-            one, the temperature of the hot
boat magazine in Scandinavia. The
article is written and photographed by      water fell by only 3,9 degrees
Jan Harry Svendsen and reported in          over 12 hours of cooling.
 issue nr. 7 of BÅTMAGASINET,
June/July 2004. This article is reprinted   The worst of them lost more than
without any changes or comments by
Indel Marine Italy, producer of Isotemp
                                            20 degrees and cost the most.
Water Heaters. The translation from
Norwegian language to English has
been made by authorised translator
Sprakservice, Member of Swedish
Association of Professional Translators.
TEST water heaters in the 20-litre class




T
       he difference between a warm, pleas-             COOLANT AS HEAT SOURCE                       drawback of this solution is that the tank is
       ant shower and a cold shower that               Most of the water heaters in the test have    heavy. It weighs as much as 23 kilograms.
       makes you shiver is no more than 1,35       the same basic design idea. An insulated tank
degrees an hour. While the Isotemp Basic has       is connected to the boat's freshwater system                ISOTEMP GOOD,
a heat loss of only 0,33 degrees an hour over      and the engine cooling system. The engine               WEBASTO DISAPPOINTING
12 hours, the Sigmar Thermoinox loses as           coolant is conveyed through a heat exchang-           The ATI BB 2212 had the highest tem-
much as 1,68 degrees. However, the Sigmar          er inside the tank and heats up the water.        perature after one hour of heating using the
is not the overall loser in the test. It redeems   Most of the tanks are additionally supplied       heat exchanger, 68,8 degrees. That's more
itself by having a slightly higher tempera-        with a heating element which makes it possi-      than 20 degrees warmer than the Mobitherm
ture after the heating cycle has ended than        ble to heat up water from the shore power         MWH-020 and the QL Water-Heater, with
the Webasto, which does not manage to sup-         supply.                                           48,2 and 48,5 degrees respectively. The pic-
ply a drop of water over 40 degrees after a            Vetus has chosen a different solution,        ture changes when we have left the water
cooling period of 12 hours.                        with two tanks one inside the other. The          heaters standing for twelve hours without
                                                   freshwater is in the inner tank,, while the en-   heating. Then the Vetus provides the hottest
                                                   gine coolant circulates in the outer tank. The    water at 55,2 degrees, while the Webasto
TO ENSURE THAT the test results were repeatable, and that the tanks operated in identical
conditions, they were tested on the bench. Here the tank of the Vetus is connected.




20L does not manage to supply water              a valve it is possible to choose to add cold
warmer than 39,9 degrees. The limit for a        water to the hot water drained from the
comfortable shower temperature is around         heater. Better use is made of the hot water
40 degrees.                                      in this way.
     What is of greatest interest, however, is       Another advantage is that using this
how many litres of water over 40 degrees         valve it is possible to adjust how hot water
the heaters manage to supply after 12 hours      the heater is to deliver. This reduces the dan-
of cooling.                                      ger of burns, particularly if there are young
Here the Isotemp Basic is in a class of its      children on board.
own. From its 24 litre tank it supplies as
much as 23 litres of water at a temperature                   CHECK OUTPUT
above 40 degrees. The Vetus is also good             All the water heaters in the test, with the
                                                                                                   THE TANKS were taken apart so that we
with 17 litres from a 20 litre tank. The         exception of the Vetus, were equipped with a      could study their construction.
Isotemp Slim 20 and Quick Nautic Boiler          heating element as standard. Connecting the
deliver 15 litres. The Sigmar Thermionox         hot-water tank to the boat's shore power sys-
and the ATI BB 2212 are disappointing,           tem ensures that there is also hot water when         SAFETY THERMOSTAT FAILED
with nine and eight litres respectively. Both    the boat is moored. With a built-in thermostat,   All the heating elements are equipped with a
have a capacity of 22 litres. By far the worst   the efficiency of the hot-water tank is like at   thermostat, and in the vast majority of cases
is the Webasto. It does not manage to deliv-     home. Most of the tanks in the test have heat-    these are adjustable. The exception is the
er so much as a drop of water above 40 de-       ing elements that deliver around 800 Watts.       Isotemp, which has a thermostat fixed at 75
grees after 12 hours.                            The exception is the ATI, which has a 1,500       degrees. For the water heaters from Sigmar,
                                                 Watt element. It is basically a good one, but     Mobitherm, QL and Webasto the temperature
       MIXER VALVE IS USEFUL                     the drawback is that most shore power sys-        was a few degrees above the value at which
    Part of the secret behind the good re-       tems have many users connected to the same        the thermostat was set, while the rest of the
sults achieved by the Isotemp is the mixer       outlet. Too high a wattage in the element may     tanks were a few degrees below the set tem-
valve. Both the Isotemp Slim 20 and the          therefore lead to the fuse in the shore power     perature.
Isotemp Basic have this as standard. Using       system blowing.                                       All the thermostats are additionally
                                                    DRAIN: The tank of the Vetus is drained        SMALL SLEEVE COUPLING: The tank is drained
                                                    by unscrewing a plastic lid. This solution     via the small sleeve coupling. Not only does this
                                                    will result in waste-water when the tank       take a long time, it is also difficult to attach a hose
                                                    has to be drained.                             to the sleeve coupling.




SAFETY THERMOSTAT: The Isotemp is
the only water heater in the test with a
safety thermostat that works on boiling
dry. The blue "box" is the safety ther-
mostat, while the operating thermostat              THERMOSTAT: All the water heaters in           MIXER VALVE: The tanks from Isotemp have a mi-
is the white "box".                                 the test with the exception of the             xer valve as standard. The temperature of the wa-
                                                    Isotemp have an adjustable thermostat.         ter to be supplied by the heater is set here. Cold
                                                    However, the safety thermostat failed on       water is mixed in with the hot water to attain the
                                                    all the thermostats.                           correct temperature.


equipped with a safety thermostat. This is in-        six bar. The deviations between specified         and heavy. Vetus charge no less than NOK
tended to trip if the water heater is switched on     opening pressure and actual opening pres-         3.855 for their tank and if you want a heating
and there is no water in the tank (boiling dry)       sure were minimal for these tanks.                element the price rises to NOK 4.617. The
or if the ordinary operating thermostat fails.                                                          Quick Nautic Boiler offers a lot for the mon-
Only the Isotemp had a system that worked the                        SAME MAKE                          ey. With a guide price of NOK 2.350 it is the
way it was meant to. After just under five min-       We have brought together nine different           most inexpensive tank in the test. The 20-litre
utes the safety thermostat tripped on both the        tanks in this test. But four of these tanks are   tank nevertheless delivers 15 litres of hot wa-
Slim 20 and Basic. The element in the Vetus           of the same make. Sigmar has produced the         ter, and in material selection it is superior to
and ATI short-circuited and blew the fuse on          tanks for Mobitherm, QL and Webasto.              the other tanks in the test. Stainless steel
the shore power side. On the other water              However, there are some differences be-           (AISI 316) is used in the tank, heating coil
heaters the operating thermostat took over the        tween the tanks. The Thermionox has a tank        and in the casing around the tank. Despite
job of the safety thermostat and switched on          capacity of 22 litres, while the Webasto, QL      low price, good performance and quality ma-
and off with an empty tank.                           and Mobitherm have 20-litre tanks.                terials, the tank of the Quick comes third be-
                                                      Webasto for its part has its own heat ex-         cause the safety thermostat did not trip in the
     POOR CONNECTING OPTIONS                          changer for the connection of external heat,      boiling-dry test. The Quick is therefore beat-
A combined one-way valve and safety                   for example a Webasto heater.                     en by the Isotemp Slim 20. Its performance is
valve is fitted on all the tanks. This valve              The QL and Mobitherm, on the other            the same as that of the Quick with regard to
has several functions, including preventing           hand, are completely identical tanks, which       hot water, but the Slim 20 has a mixer ther-
hot water from running out of the tank. In            our test results also show to be the case.        mostat as standard and has a safety thermo-
addition, the valve is used when the water            They track each other with regard to both         stat that works. The drawback is the price.
heater is to be drained. The drawback with            the number of litres above 40 degrees the         The Isotemp costs nearly NOK 1.000 more
most of the valves is that the diameter of the        tank can deliver and the temperature after        than the Quick.
drain coupling is too small. This makes it            heating has ended. The heat loss is also               Modest performance and a high price
difficult to attach a hose to the valve, and at       identical for the two tanks. It might be          should make the tanks from both QL and
the same time it takes too long to drain the          thought that identical tanks would cost the       Mobitherm uninteresting. The Isotemp
tank. A welcome exception is the Vetus,               same. They do not. The QL costs NOK               Slim 20, for example, is cheaper to buy than
which has a valve with a decent connection            3.125, while the Mobitherm carries a price        the Mobitherm MWH-20.
for a hose on the safety valve. The draw-             tag of NOK 3.750. Mobitherm thus charges               Both the Sigmar Thermoinox and the
back with the Vetus solution is that they             NOK 600 more than QL for exactly the              ATI BB2212 have a capacity of 22 litres.
have chosen to have a separate unit to drain          same tank (1   8,5 NOK).                          However, they do not manage to deliver
the tank. This is done by unscrewing a                                                                  more than nine and eight litres of water re-
small plastic lid. This solution is not ideal,                      ISOTEMP BEST                        spectively at a temperature above
and will cause waste-water in the boat.               This test provides ample proof that expensive     40 degrees. The only tank worse than these
    All the tanks with the exception of the           is not always best. The Webasto 20 L is the       is the Webasto 20 L, which does not pro-
Isotemp and Quick have safety valves that             most expensive and worst tank in the test.        vide a drop of water warmer than
open at a pressure of four bar. The manufac-          The Isotemp Basic is the best. With its tank      40 degrees. The price is also very high, so
turer's information was in good agreement             capacity of 24 litres, it delivers 23 litres of   you need to have a very good reason to
with our test results during our pressure             water at a temperature above 40 degrees after     choose the Webasto tank.
test. However, it is poor when the ATI and            a cooling period of 12 hours. The Basic costs
Webasto valves already start to ooze at               NOK 3.350, but a mixer valve comes as stan-
three bar.                                            dard. Vetus is also a tank with good perfor-
    Both the Isotemp and the Quick have               mance. No less than 17 litres from its 20-litre
valves that do not open until a pressure of           tank is good, but the tank is both expensive
                                                                                                                                                 Tes
                                                                                                                                                    tw
                                           Isotemp Basic 24                                               Price: NOK 3.350                            inn
                                           The ISOTEMP BASIC has good la-
                                                               belling to
                                                                                                                                     CONCLUSION          er
                                                                                                                                     The Isotemp Basic is the
                                                               show                                                                  winner in the test. It supplies
                                                               where the
                                                               various                                                               a lot of hot water in relation to
                                                               hoses are                                                             its size and has low heat loss.
                                                               to be con-                                                            The water heater is well put
                                                               nected.                                                               together in all its details, and
                                                                                                                                     has a high level of equipment.
                                                                                                                                     A mixer valve, for example, is
                                                                                                                                     standard.

The Isotemp Basic has a tank capa-         acid-proof steel (AISI 316). A casing,      THE CONSTRUCTION makes no                   temperature at 55.8 degrees. This is
city of 24 litres. It can be mounted ho-   made of non-magnetic stainless steel        compromises. The heat exchanger             relatively modest, when the tempera-
rizontally and vertically, but in that     (AISI 304) protects the tank's insulati-    goes in several loops, and the hea-         ture of the water that circulated
                                                                                       ting element is angled downwards
case with the connection points fa-        on. The insulation is of polyurethane       for optimum output.
                                                                                                                                   through the heat exchanger had a
cing down. The water heater has very       foam.                                                                                   temperature of
strong feet that are spot-welded to a         The thermostat of the heating ele-          The Isotemp Basic has low heat           70 degrees. However, the capacity of
strap that goes round the tank. Mixer      ment is not adjustable, but is pro-         loss. After 12 hours the total heat loss    the water heater is impressive. After
thermostat and heating element are         grammed to trip at 75 degrees. The          was only 3.9 degrees. That gives an         12 hours of cooling, the tank delivers
standard.                                  safety thermostat works as intended         average heat loss per hour of only          as much as 23 litres of water at a
   Both the tank and the heat ex-          on boiling dry, and trips quickly. It has   0.33 degrees. After one hour of engi-       temperature above 40 degrees.
changer are made of high-grade             to be reset manually.                       ne running we measured the water
                                                                                                                                     CONCLUSION
                                                                                                                                     The Isotemp Slim 20 is a good
                                           Isotemp Slim 20                                         Price: NOK 3.265
                                                                                                                                     hot-water tank. Its modest di-
                                                                                                                                     mensions mean that it also
                                           CONNECTION is straightforward,                                                            fits into tight spaces.
                                           thanks to good labelling of the va-                                                       The water heater has a high
                                                                   rious con-                                                        level of equipment and has
                                                                   nection
                                                                                                                                     useful capacity.
                                                                   points.
                                                                                                                                    THE CONSTRUCTION of the
                                                                                                                                   Slim 20 L is identical to the
                                                                                                                                   Basic. Here too the heating ele-
                                                                                                                                   ment is angled down, but be-
                                                                                                                                   cause the tank is smaller the
                                                                                                                                   heating coil has fewer loops.

The Isotemp Slim 20 has a tank ca-            Both the tank and heat exchanger         on boiling dry, and trips quickly. It       capacity of the water heater is ap-
pacity of 20 litres. It can be mounted     are made of high-quality acid-proof         has to be reset manually.                   proved. After 12 hours of cooling,
horizontally and vertically, but in that   steel (AISI 316). A casing protects            The Isotemp Slim 20 has an ave-          the tank delivers 15 litres of water at
case with the connection points fa-        the insulation. The insulation is of        rage heat loss; after 12 hours the to-      a temperature above 40 degrees.
cing down. The water heater has            polyurethane foam.                          tal heat loss was 12.1 degrees. It
strong feet that are spot-welded to a         The thermostat of the heating ele-       provides an average heat loss of
strap that goes round the tank. Mixer      ment is not adjustable, but is pro-         one degree per hour. After running
thermostat and heating element are         grammed to trip at 75 degrees. The          for one hour we measured the water
standard.                                  safety thermostat works as intended         temperature at 62.7 degrees. The
                                                                                                                                     CONCLUSION
                                                                                                                                     The Quick Nautic Boiler is a
                                                                                                                                     good hot-water tank.

                                           Quick Nautic Boiler                                            Price: NOK 2.350
                                                                                                                                     The tank is reasonably pri-
                                                                                                                                     ced, but is costly in choice
                                                                                                                                     of material. It has useful ca-
                                                                                                                                     pacity and an efficient heat
                                                                                                                                     exchanger. A disappoint-
                                                                                                                                     ment is the safety thermos-
                                                                                                                                     tat, which does not work as
                                                                                                                                     intended.

                                                                                                                                    THE HEATING COIL is strong
                                                                                                                                   and well dimensioned. The wa-
                                                                                                                                   ter heater ought to have had
                                                                                                                                   rather better insulation.

The Quick Nautic Boiler has a tank         The QUICK has a clear front, with good         The safety thermostat is integrated         The Quick Nautic Boiler has relati-
capacity of 20 litres and can be           labelling. The fact that the text is cast   into the thermostat housing which sits      vely high heat loss; after 12 hours the
mounted horizontally and vertically.       into the plate means that problems          on the outside the tank. This works po-     total heat loss was 15,6 degrees. This
                                           with glued-on slips are avoided.
The water heater has simple feet                                                       orly because the sensor is too far          gives an average heat loss per hour of
welded to a strap that goes round the      of steel (AISI 316), protects the tan-      away from the heating element.              1,3 degrees. After one hour of engine
tank. Heating element is standard          k's insulation, which is made of poly-      During our test the water heater knoc-      running, we measured the water tem-
equipment.                                 urethane foam.                              ked against the operating thermostat        perature at 64,3 degrees. The capaci-
   Both the tank and the heat ex-             The thermostat of the heating ele-       on boiling dry. In other words, the safe-   ty of the water heater is approved.
changer are made of acid-proof steel       ment is adjustable in the                   ty thermostat did not work as inten-        After 12 hours of cooling the tank deli-
(AISI 316). A casing, also of acid-pro-    20-80 degree range.                         ded.                                        vers 15 litres of water at a temperature
                                                                                                                                   above 40 degrees.
                                         Vetus WH20A
                                         THE LABELLING of the connecti-
                                                                                       Price: NOK 3.855
                                                                                                                              CONCLUSION
                                                                                                                              Vetus supplies a tank with
                                                                                                                              solid performance. Its capa-
                                                                                                                              city is very good and it has
                                         on points is useful. However, the
                                                                 distinctive                                                  low heat loss. However, the
                                                                 design of                                                    tank is too expensive; with
                                                                 the tank                                                     an electric heating element it
                                                                 makes                                                        costs NOK 4.617. Its design
                                                                 correct                                                      also makes the tank heavy.
                                                                 fitting
                                                                 very im-
                                                                 portant.
                                                                                                                              DOUBLE: The Vetus has an
                                                                                                                             inner and an outer tank, with
                                                                                                                             the engine coolant circulating
The Vetus has a tank capacity of         outer tank in which the engine coo-      in safety thermostat is intended to        in the outer tank. Its design
20 litres and can be mounted hori-       lant circulates. The inner tank is       protect against boiling dry, but the       makes the tank heavy.
zontally and vertically. The water he-   made of non-magnetic stainless steel     element short-circuited before the
ater has strong feet screwed into the    (AISI 304). The outer tank is made of    thermostat tripped.                        perature at 63 degrees. The capacity
tank itself. A heating element is not    steel. The design of the tank makes it      The Vetus has a low water loss; af-     of the water heater is very good. After
standard, despite the high price of      very heavy. The insulation is poly-      ter twelve hours the total water loss      12 hours of cooling the tank delivers
the water heater.                        urethane foam with a casing of vinyl,    was 7.8 degrees. This results in an        17 litres of water at a temperature
   The design of the Vetus differs ra-   but there is polystyrene at each end.    average water loss per hour of             above 40 degrees.
dically from the other tanks in the         The heating element is adjustable     0.65 degrees. After an hour of engine
test. There is an inner tank and an      in the 40 to 80 degree range. A built-   running we measured the water tem-



                                         QL Water Heater                                         Price: NOK 3.125              CONCLUSION
                                                                                                                               The QL Water Heater is a
                                         THE CONNECTION POINTS are                                                             simple hot-water tank. The
                                                            usefully la-
                                                            belled.                                                            heating loop is U-shaped
                                                            The insu-                                                          and therefore makes poor
                                                            lation is                                                          use of the coolant. Only
                                                            un-protec-                                                         12 litres of hot water above
                                                            ted.                                                               40 degrees is also on the
                                                                                                                               low side. The tank is identi-
                                                                                                                               cal to the Mobitherm MWH-
                                                                                                                               020.

The QL Water Heater has a tank ca-       with any protective casing.              THE CONSTRUCTION of the tank is            butes to the water in the water heater
pacity of 20 litres and can be moun-        The thermostat of the heating ele-    simple, and the material is acid-pro-      having the lowest temperature, toget-
ted horizontally and vertically. The     ment is adjustable; the temperature      of steel (AISI 316). The heat ex-          her with the Mobitherm, after one
water heater has simple feet that are    range is from 30 to                      changer is very rudimentary, as the        hour of engine running. The tempera-
                                                                                  test results also show.
spot-welded to a strap that goes         80 degrees. The safety mechanism                                                    ture is only
round the tank.                          does not work as intended on boiling        The QL Water Heater has low wa-         48.5 degrees. After 12 hours of coo-
   Both the tank and the heat ex-        dry; the sensor is located too far       ter loss; after 12 hours the total water   ling the tank delivered 12 litres of wa-
changer are made of acid-proof steel     away from the heating element. The       loss was 5.9 degrees. This gives a         ter at a temperature above
(AISI 316). The insulation is of poly-   result is that the water heater knocks   total heat loss per hour of 0.49 degre-    40 degrees.
urethane foam, but is not equipped       against the operating thermostat.        es. An inefficient heating coil contri-




                                         Mobitherm MWH-020                                                       Price: NOK 3.750

                                                                                                                              CONCLUSION
                                                                                                                              The QL Water Heater is a
                                                                                                                              simple hot-water tank. The
                                                                                                                              heat coil is U-shaped and
                                                                                                                              thus makes poor use of the
                                                                                                                              coolant. Only 12 litres of hot
                                                                                                                              water above 40 degrees is
                                                                                                                              on the low side. The tank is
                                                                                                                              identical to the QL Water
                                                                                                                              Heater.

The Mobitherm has a capacity of          USEFUL labelling of the connection       SIMPLE CONSTRUCTION, and the               ves an average heat loss per hour of
20 litres, and can be mounted hori-      points on the tank.                      material is acid-proof AISI 316 steel.     0,44 degrees. An inefficient heat coil
                                         The insulation is unprotected.           The test shows that the heat ex-           contributes to the water in the water
zontally and vertically. The water he-
                                                                                  changer is rudimentary. The tank is
ater has simple feet spot-welded to a       The thermostat of the heating ele-                                               heater having the lowest temperatu-
                                                                                  identical to the QL.
strap that goes round the tank.          ment is adjustable; the temperature                                                 re, together with the QL, after one
Both the tank and heat exchanger                                                                                             hour of engine running. The tempe-
                                         range is from 30 to 80 degrees.          that the water heater knocks against
are made of high-quality acid-proof                                                                                          rature is only 48,2 degrees. After 12
                                            The safety thermostat does not        the operating thermostat.
steel (AISI 316). The insulation is of                                                                                       hours of cooling the tank delivered
                                         work as intended on boiling dry; the        The Mobitherm Cal 020 has low
                                                                                                                             12 litres of water at a temperature
polyurethane foam, but is not equip-     sensor is located too far away from      heat loss; after 12 hours the total
                                                                                                                             above 40 degrees.
ped with any protective casing.          the heating element. The result is       heat loss was 5,3 degrees. This gi-
                                                                                                                               CONCLUSION
                                                                                                                               The Sigmar Thermoinox is a
                                          Sigmar Thermoinox                                                 Price: 2.575
                                                                                                                               simple water heater. The
                                                                                                                               choice of material is good,
                                                                                                                               but the insulation can be
                                                                                                                               improved. A heat loss of
                                                                                                                               more than 20 degrees over
                                                                                                                               12 hours is scandalous.
                                                                                                                               Its capacity is also very
                                                                                                                               poor. The water heater only
                                                                                                                               managed to deliver nine li-
                                                                                                                               tres of hot water from its
                                                                                                                               tank of 22 litres.


The Sigmar Thermoinox has capa-           POOR insulation on the Sigmar             SIMPLE TANK. The heat coil is a sim-      20,1 degrees. This gives an average
city of 22 litres, and can be mounted     Thermoinox, but the connection            ple U, and the water heater has high      heat loss per hour of 1,68 degrees.
horizontally and vertically. The water    points are well labelled.                 heat loss.                                After one hour of engine running the
heater has simple feet that are spot-     not equipped with any protective ca-      the operating thermostat. Here too        water heater delivers water at a tem-
welded to a strap that goes round the     sing.                                     the sensor for the thermostat is loca-    perature of 60,6 degrees. The capa-
tank.                                        The thermostat of the heating ele-     ted too far away from the heating ele-    city is, however, lamentable.
   Both the tank and the heat ex-         ment is adjustable from 30 to             ment.                                     The water heater only manages to
changer are made of acid-proof steel      80 degrees. The safety thermostat            The Sigmar Thermoinox has the          deliver nine litres of water above
(AISI 316). The insulation is polyuret-   does not work as intended on boiling      highest heat loss in the test. After      40 degrees.
hane foam, but the water heater is        dry. The water heater knocks against      12 hours the total heat loss was
                                                                                                                                CONCLUSION

                                          ATI BB 2212                               Price: NOK 2.530
                                                                                                                                The ATI BB 2212 is a hot-wa-
                                                                                                                                ter tank with an unusual
                                                                                                                                choice of materials. Instead
                                                                                                                                of acid-proof steel, the insi-
                                                                                                                                de of the steel tank has been
                                                                                                                                enamelled. A plus point for a
                                                                                                                                powerful heat exchanger,
                                                                                                                                but the capacity of the tank
                                                                                                                                is inadequate.
                                                                                                                               OVER-DIMENSIONED heat
                                                                                                                              exchanger for optimum utili-
                                                                                                                              sation of the engine coolant.
                                                                                                                              Unfortunately the tank has
The ATI has capacity of 22 litres and     THE CONNECTIONS on the tank of the        ling dry, because the heating ele-        high heat loss and poor capa-
                                          ATI ought to have been labelled better.                                             city.
can be mounted horizontally and ver-                                                ment short-circuits. The ATI is the
tically. The water heater has simple      The ATI is the only tank in the test to   only tank in the test to have a zinc      one hour of heating. We measured
                                          use 3/8 inch couplings on the inlet and
feet that must be screwed onto the        outlet of the fresh-water side.
                                                                                    anode fitted as standard on the hea-      the temperature as being as high as
straps that go round the tank.                                                      ting element.                             68.8 degrees. A decent heat ex-
   The tank is made of steel, but the     sistant aluminium protects the insula-       The ATI has high heat loss. After      changer with as many as 16 loops is
surface is enamelled and heat-tre-        tion.                                     12 hours the total heat loss was          responsible for the good result.
ated at 860 degrees. The heat ex-            The thermostat of the heating ele-     19.2 degrees. This gives an average       Unfortunately the capacity of the tank
changer is made of copper and the         ment is adjustable in the range from      heat loss of 1.6 degrees per hour. On     is not good. It only manages to deli-
insulation is made of polyurethane.       0 to 70 degrees. The safety thermos-      the other hand, the water heater has      ver eight litres of water above
A casing of anodised, sea-water-re-       tat does not work as intended on boi-     the highest water temperature after       40 degrees.



                                          Webasto 20 L                                   Price: NOK 4.340
                                                                                                                               CONCLUSION
                                                                                                                               The Webasto 20 L is the big
                                                                                                                               surprise in the test. It might
                                          THE WEBASTO'S tank has many
                                                              connection                                                       be thought that the name
                                                              points                                                           would oblige. It evidently
                                                              with good                                                        does not do so in this case.
                                                              labelling.                                                       The capacity of the tank is
                                                                                                                               below criticism; it does not
                                                                                                                               manage to deliver a drop of
                                                                                                                               water above 40 degrees. In
                                                                                                                               addition, its price is far too
                                                                                                                               high.

The Webasto has a capacity of             In addition to the heat exchanger         OWN HEAT COIL for use together               The Webasto 20 L has relatively
20 litres and can be mounted hori-        which is connected to the engine co-      with boat heaters. The high location      high heat loss. After 12 hours the to-
zontally and vertically. The water he-    oling system, the water heater has        of the heat exchanger that circulates     tal heat loss is 17,3 degrees. This gi-
                                                                                    the engine coolant contributes to
ater has simple feet spot-welded to       its own heat exchanger for the con-       the poor test result.                     ves an average heat loss per hour of
straps that go round the tank.            nection of external heat, for example                                               1,44 degrees. The water temperatu-
   Both the tank and the heat ex-         Webasto boat heaters.                     as intended on boiling dry. The water     re after one hour of engine running
changer are made of acid-proof ste-          The thermostat of the heating ele-     heater knocks against the operating       is 57,2 degrees. It is disappointing
el (AISI 316). The insulation is made     ment is adjustable; the temperature       thermostat. This happens because          that the tank does not deliver water
of polyurethane foam, but it is not       range is from 30 to 80 degrees.           the sensor of the thermostat is located   above 40 degrees after 12 hours of
equipped with any protective casing.         The safety thermostat does not work    too far away from the element.            cooling.
  TEST water heaters in the 20-litre class
                                                   simulates a natural cycle as found on a board         with a pressure increase of 0.1 bar.
   How we performed                                leisure craft. The temperature was measured.            Measurements were performed when the
       the test                                    The circulation of the engine coolant was then
                                                   started up again to equalise the temperature
                                                                                                         valve started to ooze water and when there
                                                                                                         was full opening.


 T
        he test was performed in the heavy lab-    drop which the one litre of cold water had              The test was performed in March and
        oratory of the Department of Maritime      brought about. The circulation this time was          April 2004.
        Sciences at Vestfold University College    interrupted after half an hour. The tank was
 (HIVE) in Horten. A Fluke 54 II temperature       then left standing for 12 hours to simulate a
 gauge was used as measuring equipment. The        night on board. Cold water was added to the
 instrument was calibrated in a liquid bath at     tank after 12 hours with a flow rate of four
 IKM Laboratorier in Tananger. In addition, a      litres a minute. The temperature was mea-
 pressure gauge was used during the pressure       sured for each 15 seconds, or for each litre
 testing of the tanks. The pressure gauge is ac-   drained from the tank.
 curate to +/- 5 per cent.                            The test on the heating elements of the tanks
    A test bench was used during the test. A hot   was carried out by setting the thermostat to
 water tank with a 3.000 Watt heating element      max. The tank was then filled with water at a
 delivers "coolant" at a temperature of 70 de-     temperature of 20 degrees and then it was
 grees. A circulating pump was used to circu-      plugged in. The temperature as measured when
 late the coolant through the heat exchanger in    the thermostat tripped for the first time. The
 the water heaters. The speed of the pumps         test on the safety thermostat was carried out by
 could be regulated, and they could be adjusted    the tank being connected to the power source
 so that the flow through the heat exchanger of    WITHOUT there being water in the water
 the tank was 3 litres a minute. The tanks were    heater. The time before the safety thermostat
 fitted and connected before each test. They       tripped was then measured. Several of the tanks
 were then filled with freshwater at a tempera-    did not pass the test, and for these the test was
 ture of 20 degrees before circulation of          terminated after 30 minutes.
 "coolant" was started. The circulation was in-        The pressure test on the safety valve was
 terrupted after an hour, when precisely one       undertaken by filling the tanks with water and
 litre of cold water (20 degrees) was added        then adding compressed air. The compressed
 through the freshwater inlet of the tank. This    air was let into the tank by means of a valve,



MEASUREMENTS WATER HEATERS IN THE                          20-LITRE CLASS
Water heater:           Isotemp       Isotemp         Quick             Vetus           QL          Mobitherm Sigmar   ATI                        Webasto
                        Basic         Slim 20         Nautic Boiler     WH20A           Water       MWH-020 Thermoinox BB 2212                    20L
                                                                                        Heater
Temp after
1 hour engine running: 55,8°          62,7°           64,3°             63°             48,5°       48,2°        60,6°            68,6°           57,2°
Temp after
12 h cooling:          51,9°          50,6°           48,7°             55,2°           42,6°       42,9°        40,5°            49,6°           39,9°
Heat loss:             3,9°           12,1°           15,6°             7,8°            5,9°        5,3°         20,1°            19,2°           17,3°
Heat loss
degrees per hour:      0,33°          1°              1,3°              0,65°           0,49°       0,44°        1,68°            1,6°            1,44°
No, litres water
above 40 degrees:      23 litres      15 litres       15 litres         17 litres       12 litres   12 litres    9 litres         8 litres        0 litres
Temp, with heating
element:               69,6°          67,2°           78,3°             66,2°           82,3°       82,8°        83,9°            62,5°           81,1°
Time before safety
thermostat trips:      4 min 50 sec   4 min 01 sec     ­       Element short-circuits    ­           ­            ­      Element short-circuits    ­
Residual water
after draining:        0,2 litres     0,4 litres      0,78 litres       2,65 litres     0,76 litres 0,1 litres   0,92 litres      3,65 litres     0,68 litres
TECHNICAL DATA
Volume:                 24 litres     20 litres       20 litres         20 litres       20 litres   20 litres    22 litres        22 litres       20 litres
Length:                 480 mm        660 mm          505 mm            540 mm          387 mm      391 mm       538 mm           492 mm          401 mm
Width:                  395 mm        287 mm          327 mm            406 mm          352 mm      351 mm       299 mm           318 mm          347 mm
Height:                 400 mm        302 mm          313 mm            430 mm          395 mm      374 mm       299 mm           326 mm          384 mm
Weight:                 11 kg         11,5 kg         10,9 kg           23 kg           9 kg        8 kg         11 kg            14 kg           9 kg
Heating element output: 750 watt       750 watt       500 watt          1.000 watt      800 watt    800 watt     800 watt         1,200 watt      800 watt
Opening of safety valve:
Oozing:                 6 bar         5,6 bar         5,6 bar           4,2 bar         3,9 bar     3,6 bar      3,7 bar          3 bar           3,1 bar
Full opening: >         6 bar         6 bar           5,8 bar           4,4 bar         4,3 bar     4,4 bar      4,2 bar          4 bar           3,7 bar
Diameter of couplings:
                            ,,            ,,              ,,                ,,              ,,          ,,           ,,               ,,              ,,
Heat exchanger:         1/2           1/2             1/2               1/2             1/2         1/2          1/2              1/2             1/2
                            ,,            ,,              ,,                ,,              ,,          ,,           ,,               ,,              ,,
Inlet cold water:       1/2           1/2             1/2               1/2             1/2         1/2          1/2              3/8             1/2
                            ,,            ,,              ,,                ,,              ,,          ,,           ,,               ,,              ,,
Outlet hot water:       1/2           1/2             1/2               1/2             1/2         1/2          1/2              3/8             1/2
Price (1  8,5 NOK): 3,350             3,265           2,350             3,855           3,125       3,750        2,575            2,530           4,340
                           Indel Marine, I - 61019 S. Agata Feltria (PU) Italy - Phone +39 0541 848030 - www.indelmarine.com


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