hot water heater

hello, i have a 6 gallon hot water system that uses the starboard engine to heat it, it is only luke warm after and hour and a half of running the engine at 80 c, the motor is fresh water cooled. the engines that i removed were raw water cooled mercruisers, is it possible that the heater coils would salt up and cause this problem or are these heaters just very slow to heat water, i have never had one before to compare it.

 

It should heat up faster than that.

You say you removed a raw water cooled engine and put in a fresh water cooled engine?

Did you ever try the water heater with the raw water engine running to compare before you changed to the fresh water engine?

In short, yes... it is quite possible for calcification to have narrowed the flow through the heating element if salt water was flowing through it for many years prior to the engine change.

 

Are you heating the tank with fresh water or sea water.

 

Working properly the heater connected to a freshwater cooled engine will scald you unless it is one the newer types with a mixing valve attached.

 

where are the 2 pipes connected to the engine?

 

If the heater is mounted above the outlet from the engine I would check for air in the heater. I use full pressure from water hose to get the air out and then I connect it to the engine.

 

thanks for all the replys, i tried it again today and the water was scalding after running the engine 30 minutes. it may have been an airlock as iceboater says, the top of the heater is higher than the engine. it is fresh now frosty but the old engines were raw water. i never tried it with the old engines cat. the pipes run off the water pump and bypass outlet. once again thanks for the replys, i was over the moon when i had hot water today, never had a luxury like that on a boat before.

 

cold beer and Ice cream are next!!