Air heater installation on Hunter 336

[Tabare]

Hi sailors, I am planning to install a diesel air heater and I wonder if there are any fellow H336 owners that have installed one? I am thinking to install the heating unit on the cockpit lazarette (starboard side) and I wonder what’s the best route to run the ducting (ideally 6” wide duct) to the V berth. Really appreciate your help, if you can share pictures of similar installations would be fantastic. Thank you!

 

[Ken Cross]

Our Hunter 30 was set up that way when we got her. In our case the heat was noisy in our berth (under the cockpit).
It easily could have been just a poor installation. In our case we always turned off the heat and fridge (same issue as the compressor was near our heads while sleeping). I'm not sure if there really is a practical alternative.

 

[jssailem]

QUOTE="Tabare, post: 1804032, member: 163706"]
ducting (ideally 6” wide duct) to the V berth
[/QUOTE]
WOW>.. You have that much free space to run air duct the length of the boat? Likely not.
I installed ( and continue to adjust) the duct work for my boat.

The typical duct used it 60mm or 75mm ducting.

When I want to limit heat radiating from the duct tube, I wrap it in insulation. In some space the duct is not insulated allowing some parasitic heat loss to radiate.

I have found that boat ducting is not cheap.

 

[Tabare]

Thanks for your comment, that’s useful. I may have to use different duct diameter in some areas where the space is restricted. Specifically to get from the cockpit lazarette to the aft berth there’s no issue but to get from the aft berth to the saloon and V berth is very tight. I am currently trying to understand (before drilling holes) if there is a pre-defined/recommended path for the ducts on my Hunter 336.

 

[jssailem]

trying to understand (before drilling holes) if there is a pre-defined/recommended path for the ducts

I’m sorry I can not help you with that detail Hopefully someone here can. I would not go with less than 60mm ducts. The longer you go the less effective the fan performance pushing the air gets. Your heater manufacturer should be able to provide some specific information about the air movement demands.

I’m not an HVAC guy. There is a science and art form to their system designs. I do know that you want to limit the number of bends you put in the ducts.

 

[Ralph Johnstone]

I can only say my complete set of drawings on my boat does not show a heater. I think that most heaters are after market installation which means give it your best shot.

This shows the 4" dia. ducting to the V-berth after two previous take-offs. The heater outlet is 4" dia. hence the choice. After two take-offs, the dia. could be dropped to 3" dia. for space saving if required.

 

[Tabare]

Thanks, that’s useful….which route did the ducts follow to get from the aft berth to that point?

 

[mermike]

There's a company called Bobil Vans in the UK that makes a hydronic heater attachment for an air diesel heater. I considered this in order to run a heat exchanger up to the v-berth. There is no way to run ducting of any size. A couple of small PEX lines however...in the end I did without heat in the v-berth and it hasn't been an issue.

 

[Ralph Johnstone]

Thanks, that’s useful….which route did the ducts follow to get from the aft berth to that point?

For our '99 H-310, ours runs along in the starboard catch all (for lack of a better name) out through the bulkhead, under the range and under the starboard seats with take-offs. You'd have to be there to understand.

I would encourage you to do your own design as others who have had theirs installed by an aftermarket installer may not have a good design or even a crappy design. I know that I could have done a better job on a few of the aftermarket installs when the boat was new.