Diesel heater installation and ducting

[Tenedos]

I have bought a Chinese diesel heater and am trying to make sure I install it right.

I bought one of these SS exhaust thru hulls. I have been reading that the exhaust is particularly important. Would this do the job?

Also I am somewhat confused about the ducting. This unit has 4 heat outlets and came with 2 hot air ducts which are pretty short. They don't appear to be a standard size, the outlets are 40mms. I need to carry the hot air a fair bit, at least 15 ft to the main cabin and around 8 ft to the master. I couldn't find any place selling 40mms hot air ducts. Any suggestions?

Thanks in advance.

[CaptTom]

I have a Planar diesel heater. It's a similar, Russian-made version.

You hit on two very important areas to consider. To answer your first question, yes, that's the right thru-hull. I bought the straight version, but if you can make it work with the angled one, that's even better to keep water out.

These units were built for trucks and RVs. They want to vent directly down below a metal chassis. The exhaust hose gets VERY hot, like 700-800F (375-400C). And if the exhaust hose is too long, the combustion chamber will overheat. How long is too long? Who knows. But remember it's designed to assume a very short run, maybe a foot or two. Likewise, the combustion air intake should be outside air, but again, any restriction from a hose can restrict the flow and cause overheating.

You will have similar issues with ducting. The fan for the cabin air is not designed to move it very far. And if the flow is too restricted, again, you'll overheat the unit.

One option might be to use a booster fan in the duct. I did that on my last boat for a long air conditioning duct and it worked pretty well. Since the air conditioner only ran on 120VAC, I used an off-the-shelf duct fan from a home supply store. A 12V version would probably require some searching.