Adding diesel heat to Cruzair Heatpump System

Has anyone successfully added diesel heat to their boat without removing the AC heat pumps? The heat pumps are great for summer or when the Genset is on so don’t want to get rid of them but would love retrofitting with diesel heat as well.

Thoughts/Advice appreciated.

Arthur

How is the current system ducted?

I have 3 units, each with simple ducting (Salon under the couch, pilothouse under the dash which also outputs into the master stateroom and forward stateroom under the bed) , I was thinking about maybe putting those small self contained webastos either inline or in parallel with a Y right before the output vent. If inline I’m assuming I would need to wire the fan of the webasto into the AC system fan so it runs when the Heatpump is on.

Drawback would be running fuel and exhaust. Other option is hydronic in the ER.

IT will be far easier to add a stand alone diesel system for true winter operation..


If only a bit of heat is needed perhaps adding 120V heat elements as done on RV would be enough heat.

I put Heatercraft hot water surface mount heaters in the forward stateroom, saloon, and pilothouse. The loop runs off the engine cooling system and produces adequate heat down to about 32 degrees outside temperature while the engine is burning 2 GPH. Forward stateroom heat is a little marginal as it's the last heater in the loop and the room is surrounded by cold water. For each heater I installed a thermostat that controls the blower motor for room temperature control. I also added a 12 VDC circulator pump to increase flow rate around the loop. The system would probably work much better in cold temperatures if I was burning 3 to 4 GPH. I believe the engine thermostat is probably closed when all 3 heaters are running.

With a little engineering, a system like that should be able to run off your engine or a diesel boiler.

Ted

I have two in wall electric cabin heaters which draw 7 amps of AC power each.
And a reverse cycle heat pump, 12-13 amps, which seems to work well for me.

I wonder how expensive burning diesel versus electric power, the comparison is. I would think electric is cheaper, definitely if dockside.

Running engines creates much waste heat, but they have to be running.

It’s more to not run the Genset at night, I like the self designed option with a mini boiler and engine heat exchange.

sdowney717 said:

I have two in wall electric cabin heaters which draw 7 amps of AC power each.
And a reverse cycle heat pump, 12-13 amps, which seems to work well for me.

I wonder how expensive burning diesel versus electric power, the comparison is. I would think electric is cheaper, definitely if dockside.

Running engines creates much waste heat, but they have to be running.

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There is something like 135,000 BTUs to a gallon of diesel. Converting it to heat though a boiler and circulating it through a hot water heating system will be multiple times more efficient than running a generator to run electric heaters. A side from the heat lost through the engine cooling system and exhaust, the boiler cycles on and off based on need, where the generator must run continuously regardless of demand.

The real issue is whether the infrastructure cost is justifiable. In my case, the savings from utilizing heat off the engine versus "all in cost" for running the generator, paid for itself in the first year.

Ted

Agreed Ted, there is also just the operational pain of running a Genset that I have a hard time justifying just for heat, despite being super quiet it’s still a large running motor that I don’t need to put all those hours on, I can charge my batteries in a little over 4 hours. Not to mention, I’ve been in Roche the past 2 days and already had 2 plugged strainers from eelgrass.

So thoughts on the best boilers?

AC
Thousands of vessels in the PNW have diesel fired hydronic heating. Hurricane, Olympic or Kubola seem a good choice.

It is all in the install though. In Seattle there are several experienced groups to do this whether Emerald Harbor Marine, Sure or etc. Ask to see a typical install. I was on a reasonably new KK 44 recently and that install was top notch.

Personally I don’t like direct hooking into the water heater due to potential for cross contamination - unless system is valved to bypass the water heater. Yes to a valved engine heat exchanger loop though,, easy to do.

If you place one of the large hydronic heat exchangers in your helm area AC air return flow you’ll get a lot of heat into the ducts without heat pump running, only the fan powered by the inverter. Great for clearing windows on those misty days when cruising.

We have a diesel boiler system that runs on 12VDC with a hot water loop going through the boat to several blowers. the burner kicks on as needed to keep the water at 190*. Will keep the boat warm when it get down to 20*. We haven't been anywhere colder than that.

Thanks, I’ve heard great things about Sure. I’m going back in for a few months to take on some other upgrades so will likely have this done at the same time. I will say the foam cored hull on KK is amazing at retaining heat.

Our North Pacific 52 came with both air conditioning and diesel hydronic heat. The diesel fired system is a Kabola while the AC is Cruisair. They do not share vents or ducting.