Feeding a cabin heater from an I/O

[big zeke]

I have a 4.3 merc with closed cooling. Recently I got ahold of a cabin heater for the cuddy, a fairly simple unit with a 2 speed fan and a rating of ~8000BTU, the coils are copper with 3/4" copper connectors brazed to them, the coils are stamped as MAWP of 40 psi. Since the boat is closed loop cooling I can feed it from the glycol system or I can feed it from the hot water side of the exchanger and then just dump the water back into the manifolds...

Any input on which (if any) is better. I'm leaning towards cutting into the water side as a leak can easily be shut off with a manual valve without hurting anything. Feeding it from the glycol system will alleviate any corrosion issues but I'm not sure where to send the cold glycol return from the heater.

Don't get me worng, I was given this heater and I am not sold that I even will use it. Certainly if adding it into the system will cause reliability issues it will be ditched.

Thx
Zeke

 

[Don S]

Re: Feeding a cabin heater from an I/O

There are specific places, but it wouls sure help to know what vintage V6 you have. Year might help, Serial number would be a sure thing.

 

[big zeke]

Re: Feeding a cabin heater from an I/O

Sorry Don, missed that...it's a '93, the serial is unknown as there is no markings on the block (recent rebuild), believe me, we have looked everywhere and there is no numbers on this engine.

 

[jimbo_jwc]

Re: Feeding a cabin heater from an I/O

I thought of the same but smaller heater core with fan plumbed to plug that I loosen to drain motor at thermostat housing and dump out side of cuddy . Thermostat housing when opened has about 3/8-1/2 hole bypassing it why ? 145-150 degree air will feel good but don't know about lose of flow in motor loop .

 

[Scott Danforth]

Re: Feeding a cabin heater from an I/O

put it in parallel with the hx. use a tee, come off the t-stat housing, then return to the waterpump inlet.

 

[Don S]

Re: Feeding a cabin heater from an I/O

You should have a 1/2" pipe plug in the intake manifold, on either side of your thermostat housing. Put a hose barb fitting in the open one, this will be hot water to the heater, then the return will go to the circulation pump. Look for another pipe plug in the pump, port side just above the large hose.