Webasto thermotop C Installation Instructions Manual - Plumbing Options
Webasto Part Number : 4110310A
Issue No: 02 : 10th November 2010
Matthew Millard
In the interests of continued development, we reserve the right to change
specifications without prior notice
© Webasto Product UK Limited
Marine Comfort
PLUMBING OPTIONS
WATER (Hints & Tips)
In order for the heater to work effectively a few simple rules need to be adhered to.
The heating circuit the Webasto is connected to is very similar to a domestic
installation with a hot water cylinder and radiators but with a few subtle differences.
Supplied Water Pump.
The water circulation pump is physically small compared to a domestic pump such as
those made by Grundfoss or Wilo and consequently the flow rates are smaller also. It
is not permitted to fit a larger capacity pump, the supplied pump must be used. The
supplied pumps flow characteristics are matched to the heaters thermal transfer
properties.
Do not use Thermostatic Radiator Valves.
Only use standard lock shields on the radiators. TRV's will cause differential pressure
problems that will effect the balance of the water flow and consequently have an
effect on the heater with regards short cycling.
Correctly load the heater.
If the heater has a maximum output of 5.2Kw, (Thermotop C) then it is advisable to
have a load 10% greater than the heater output. In the case of the Thermotop C the
desired loading should be approximately 5.7Kw. This will ensure that the heater will
fire at full load for longer and the amount of time idling will be conversely less.
Operating the heater in this manner will yield a greater lifespan of the burner and
increase the interval between services.
Blower boxes.
Try to avoid installing blower boxes as they are not really suitable for use with these
types of heater. The problem is that nobody manufactures a blower box specifically
for hot water applications. The technology is derived from air-conditioning where it is
desirable to have a long winding flow across the matrix to evaporate all the gas and to
dehumidify the cabin. To use this same technology for heating will never work
effectively as we need a buffer of water at each end of the matrix so there is parallel
flow across the whole of the matrix and therefore a small
∆
t, (delta t, the temperature
difference between the flow & return). With the standard air-conditioning derived units
the
∆
t will be unacceptably large by the time the liquid has exited the matrix because
of the distance the liquid has to travel.
Balance the system
Balance the radiators with the lockshields and remember to fit a lock shield /
balancing valve to the Calorifier coil outlet pipe. Also, do not pipe the Calorifier in
series with the spine.
Visit www.butlertechnik.com for more technical information and downloads.
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