E32-2 Universal M3-20B coolant takeoff for bus heater

[Pacific Spirit Marine]

I'm looking to install a bus heater into my 1974 E32-200. It has a Universal M3-20B inside. Has anybody done this before? I'm looking for the correct location to port the engine coolant to the heater.

The coolant pump has no extra ports, other than a hose for the coolant bypass circuit. The M3-20B has an external heat exchanger, so I figure that may be the likely spot, but I had a mechanic friend on board the other day, and neither of us could really determine the best spot to pull the coolant. The only likely spot I noted was a hose that exits the exhaust elbow area and goes to the heat exchanger. Does anybody have any experience pulling hot engine coolant for a bus heater or hot water tank installation?

 

[Christian Williams]

I think that plumbing to a water heater is usually either from the heat exchanger or thermostat bypass.
I recently re-plumbed from the thermostat, simply because it made for a neater world at the back of the engine.
I'm not familiar with cabin heaters that use coolant, but the thermostat alternative is described in this thread:

Marine Diesel Cooling System Upgrade 2020

Symptoms: Apparent decrease in water volume at exhaust. Temperature RPM limitation at Wide Open Throttle. Steam from exhaust at idle. Solution: clean heat exchanger, optional general upgrade. When I took over Thelonious II four years ago, the boat would run at near seven knots all day at...

ericsonyachts.org

 

[Loren Beach]

There are several threads discussing adding a cabin heater (works off of the engine coolant, like your vehicle heater). As you might guess, it works only when the engine is operating.
Here is one with pix of ours -- still works wonderfully. A few years ago when motoring up the WA coast, it put out copious amounts of heat thru the cold night, on the lowest fan setting. I would guess that the cabin temp was about 80 degrees with the hatch open to the cockpit. The guy sleeping on a settee, on the off watch, loved it.
Ours is routed in series with the coolant hose line to the hot water heater coil. If the engine in the OP's boat does not have a coolant hose going to and returning from a hot water tank, best to ask the folks at Universal/Westerbeke for the answer.

Engine coolant cabin heater-install ideas ?

I have it in my head I want to install an Red Dot brand cabin heater in our 1986 E32-3 that uses engine coolant for the heat source. We motor a lot here in the Pacific NW and capturing some of that waste heat just seems like a good idea in these cold winter months. I have kind of looked at where...

ericsonyachts.org

ps: I edited the thread title to make searching easier.

 

[Pacific Spirit Marine]

I think that plumbing to a water heater is usually either from the heat exchanger or thermostat bypass.
I recently re-plumbed from the thermostat, simply because it made for a neater world at the back of the engine.
I'm not familiar with cabin heaters that use coolant, but the thermostat alternative is described in this thread:

Marine Diesel Cooling System Upgrade 2020

Symptoms: Apparent decrease in water volume at exhaust. Temperature RPM limitation at Wide Open Throttle. Steam from exhaust at idle. Solution: clean heat exchanger, optional general upgrade. When I took over Thelonious II four years ago, the boat would run at near seven knots all day at...

ericsonyachts.org

I saw your write up about plumbing from the bypass a while back, but seeing as my bypass hose is roughly 3/8" hose, I figured there's a good chance I wouldn't get enough heat for a coolant heater/water tank circuit. Do you find yours heats up adequately? I wonder if the bypass circuit may get less flow once the thermostat opens up. Like will have to talk to the dealer for more info.

 

[Christian Williams]

Heats better than previously.