Troubleshooting Engine Waste Heat Calorifier Loop

[Dockhead]

My 50 liter hot water tank has, theoretically three sources of heat:

1. An electric immersion element running on 230v shorepower or generator
2. A loop to the Eberspaecher central heating system
3. A loop from the propulsion engine's fresh water cooling circuit.

I like heating with the immersion element because the water goes up to near boiling temperature and lasts much longer, since it is diluted before use.

But now that I am off shore power and on a midriver pontoon, I will have less opportunity to make a tank of nearly boiling water.

My hot water doesn't heat up from the main engine's cooling circuit. What could be the problem? Can anyone suggest a list of troubleshooting items?

Only thing I could think of was:

1. Airlock in the pipes -- bleed.

2. Faulty valve -- replace.

3. Faulty design -- hoses too long for the engine fresh water pump to provide enough flow. Install electric pump.


Anything else to check? The engine is a Yanmar 4JH3HTE. The calorifier is around the same level as the engine, about 4 or 5 meters away.

[Dockhead]

And while I'm at it, maybe install a fan coil unit into the loop, to get some cabin heat out of the engine waste heat? Or will that cool the engine down too much, do you think?

[donradcliffe]

The usual cause is an airlock. Feel the hoses where the water goes in and out of the engine block. If the outlet hose isn't getting warm, take off the top hose and pour water into it, then try again.

[djmarchand]

Dockhead:

Last question first. The coolant to the calorifier is controlled by the engine's thermostat so there is no risk of cooling it down too much.

If you have never really used the engine coolant circuit then it may be an installation problem, a stuck check valve or an air lock. Break the return connection for a few seconds and see what kind of flow you get with the engine warmed up so its thermostat is open. That may blow out the air lock as well.

David

[Dockhead]

Thanks, guys! I will give that a shot before trying more radical measures like installing a circulation pump.