Diesel heater - heated air intake location

[SimonA]

I've got a diesel heater installed in my engine bay and have a choice of fitting the heated air intake in the cockpit or the cabin. The intake is noisy so I was intending to install it in the cockpit which has a canopy over it and a closable outlet for the heater, but I've been told I'm better off installing the inlet in the cabin to recirculate the heat for more effective heating. Do diesel heaters work better with recirculated air? I'm not keen on having it in the cabin as the intake makes a lot of noise as it sucks the air in.

 

[Boathook]

Having the inlet in the cabin is more efficient as the air is already warm, once the heater has been working for a while. The downside is that you are recirculating stale and possibly damp air, so difficult to get rid of condensation. I would think that having the inlet in the cockpit is a good compromise as if cold you are more likely to have the canopy up and closed so the air will be slightly warm.

 

[Plum]

If you recirculate the cabin air the cabin wil heat up quicker and you will use less fuel BUT this will not reduce the inevitable condensation which makes the cabin unpleasant. Far better, in my experience, is to suck in fresh air and ensure the damp air can escape through a small vent (or badly fitting doors), particularly if you are going to sleep on board.

Edit: i see Boathook, above, was typing the same message at the same time as me!

www.solocoastalsailing.co.uk

 

[simonfraser]

the air in the cabin will be warm due to the heater
that means the air can hold more water
once the air gets onto the cold windows it can not hold the water any more and you get condensation

some of the water in the inside air will come from the humans inside, cooking and any leaks the boat may have

fresh air will help, but with single glazing and a smallish space you'll get condensation whatever you do with the intake
i have my intake from the inside, the exhaust is obviously to the outside, so some air is being expelled, recon that is a good compromise

 

[PeterBoater]

the air in the cabin will be warm due to the heater
that means the air can hold more water
once the air gets onto the cold windows it can not hold the water any more and you get condensation

some of the water in the inside air will come from the humans inside, cooking and any leaks the boat may have

fresh air will help, but with single glazing and a smallish space you'll get condensation whatever you do with the intake
i have my intake from the inside, the exhaust is obviously to the outside, so some air is being expelled, recon that is a good compromise

I believe that most/all heaters have different air intakes for combustion air and air to be heated and circulated, so exhaust air being expelled has nothing to do with the air to be heated and circulated. Additionally, if the intake for air to be heated and circulated is within the cabin area (recirculated), if there is a fault in the heater resulting in CO leaking into the cabin air supply, then the CO will build up rapidly.

 

[jon and michie]

Here's something to consider :
The cost of running a diesel heater is pennies.
Cleaning up damp/condensation takes time.
Ok it may take longer to heat the cabin up but you'll be getting fresh air not recirculated air carrying moisture.

Go for your cockpit idea

Jon

 

[LittleSister]

I have, would have again, and strongly recommend air intake of fresh air, not recirculated, to reduce condensation and make it more pleasant.

 

[Antony Collis]

I would draw it in from the cabin. If there is an issue with damp you need to let it out with an open vent. If you draw air in from the cockpit this will also be cool damp air. I can't imaging that you would only be running your heater on a hot sunny afternoon!
Cabin air will make your heater work properly, deal with any damp as a separate issue.

 

[NormanB]

Rig up an intake from the cabin with a fresh air make up from the cockpit, should be aiming for approx 10% fresh and you could achieve that by appropriately sized hose (s) by internal cross sectional area.

 

[AndieMac]

My Eber is set up in the engine room, air intake is near the ER vents.

 

[lynallbel]

Two boats, both had intake in cockpit, I assumed some eber/webby requirement as well as the noise in the cabin.

 

[lynallbel]

Just checked webby manual, and it appears either is okay

 

[penberth3]

I've got a diesel heater installed in my engine bay and have a choice of fitting the heated air intake in the cockpit or the cabin. The intake is noisy so I was intending to install it in the cockpit which has a canopy over it and a closable outlet for the heater, but I've been told I'm better off installing the inlet in the cabin to recirculate the heat for more effective heating. Do diesel heaters work better with recirculated air? I'm not keen on having it in the cabin as the intake makes a lot of noise as it sucks the air in.

Did you see this in another thread?
https://assets.publishing.service.gov.uk/media/5f85ac6c8fa8f561ce5417d7/2020-SB2-Diversion.pdf