Diesel warm air heating

Lightwave395

Lightwave395

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My just acquired new boat has an Eberspacher warm air heating system, it has 5 outlets and it seems to work well.

I've never previously had the luxury of this but I'm a bit concerned that the ducting (black flexible aluminium) runs around the boat through the lockers and under the saloon seating completely exposed.

There's a lot of potential storage space around the ducting but I can't help thinking it should be either boxed in somehow and / or insulated as anything stored around it - plastic crates, toolbag, spares etc is going to get hot and / or damage it.

Any insight welcomed - I've seen webasto / eberspacher wrap round insulation advertised which I guess would keep the heat in but it wouldn't protect it from damage I suspect ?
 
Definitely needs to be insulated, the wrap around stiff is expensive, but very good and easy to fit to existing ducting. It offers no appreciable protection from damage though.
 
Hi
The heating is lovely on a chilly morning and does make life a lot more pleasant.
Unfortunately the sucking does take up space, and can get crushed if you are not careful.
We have our ducting boxed off in lockers were we store items that may damage it. In other locations it is just securely held in place and clear of any bilge area.
We did consider insulating the ducting but have not felt the need so far.
We do make sure we don't store certain items near the ducting. Chocolate does not do well near it for example...
 
elenya said:
Hi
The heating is lovely on a chilly morning and does make life a lot more pleasant.
Unfortunately the sucking does take up space, and can get crushed if you are not careful.
We have our ducting boxed off in lockers were we store items that may damage it. In other locations it is just securely held in place and clear of any bilge area.
We did consider insulating the ducting but have not felt the need so far.
We do make sure we don't store certain items near the ducting. Chocolate does not do well near it for example...
Click to expand...
Without ducting you waste something like 40% of your heat. Our current boat came with no insulation so i fitted some, the difference was surprising.
 
That does sound like it is worth doing. Did you use a foam wrap around insulation or the type of lagging wrapped around dry exhaust pipes?
Thanks
 
I insulated my ducting with the wrap stuff, and encased it with some of this fairly tough extractor fan ducting from Wickes to help protect it from impact. It’s not perfect, but it’s cheap and it helps. You still can’t throw bricks on top and not expect damage, but general stowage rolling around won’t do too much.
Manrose Aluminium Duct - 100mm x 3m | Wickes.co.uk

I found that the warm air in the lockers from imperfect duct insulation encouraged airflow behind the saloon cladding, which reduced the amount of condensation forming and running down the hull into the bilge on that side of the boat.
 
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We have two outlets in the saloon and one each in the two cabins, not thought about lagging it though, the ducting runs under the deck on the port side and the heater is mounted on a shelf under and behind the the saloon seat, the hull is insulated in that area and the boat does get toasty warm with it, the heater has it's own 10 gallon fuel tank that gets fed off the excess diesel from the engines until it is full then the top is skimmed off back into the main tank.
 
My current boat came with an Eberspacher, the first time had such a luxury, and all the ducting was uninsulated. It still worked absolutely fine, the additional fuel cost was negligible in the overall cost of boat ownership, and insulating it was nowhere near the top of the queue of jobs needing doing.

Tackling it was further delayed while I dithered about the surprisingly steep cost of the typical insulation offered for such use, and trying to make sense of the seeming gap between the maximum temperature capability of the insulation offered and the temperature which the heater literature suggests the ducting can reach. It was only reading those things, too, when it dawned on me I had tins of paint and bottles of white spirit etc. next to the ducting in one cockpit locker - not such a great idea!

I am currently replacing the heater, and have bought insulation for the 'external' sections of duct - two bits open to the air under the aft deck and in an open sided locker, and another in an enclosed cockpit locker (mentioned above) - plus a short internal section behind the fridge. I have one tubular section which I can slide on the accessible end as I'm changing the heater unit, and the others are the type one can wrap round mid-sections of duct between bulkheads in situ.

The sections of duct running in internal lockers and under berths I'm less concerned about, and might or might not do later. The heat loss is much less, and they help keep the interior warm, including after the heating is switched off.

p.s. I also want to box in a couple of sections of ducting in lockers, so things can be stored on top of it. (Ideally , the ducting would be under the tops of the lockers, rather than laid along their bottoms, but moving it would be too complicated.
 
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Ours is a 5kW unit with 6 outlets and worked very well in Scotland. Even visits to the yard were fine in winter with temp. down to -5C overnight. No problem with the ducting as the runs are actually in areas that aren't easy to access. There are a couple of spots where the ducting is visible inside a front opening locker but never had any problem with damage. No problem with lack of insulation as most of the runs are well enclosed and behind panels that act like low temperature radiators anyway.

Not so useful here in Greece but we fire it up once each year to use some fresh fuel and check it works. It was fired up today as it was a relatively cool day, only 33C in the shade. Worked perfectly but needed to put the thermostat close to maximum to make certain it would start. I had outside jobs to do during the test, otherwise I'd have been verging on homicidal during the test run. :D
 
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PaulRainbow said:
Without ducting you waste something like 40% of your heat. Our current boat came with no insulation so i fitted some, the difference was surprising.
Click to expand...
i presume you meant without insulation! I’m not sure it’s “lost” it just gets absorbed into the fabric of the boat quicker, and the atmosphere on the boat slower - eventually with insulation the air heats the berths/lockers etc anyway and without insulation the warmer lockers slowly add background heat. The only way to really “lose” heat is if the ducting is directly in contact with the hull and you are heating the sea. Undoubtedly though, with insulation you will get hotter air out the vents and so feel warmer, quicker. Given the heaters actually prefer a good hard run - it may be no bad thing for them to have to work harder to get the boat up to temp.
 
ylop said:
. . . Undoubtedly though, with insulation you will get hotter air out the vents and so feel warmer, quicker. . . .
Click to expand...

I wouldn't want the air coming out of the vents to be hotter. In the boat I mentioned above, even with a long run of uninsulated ducting from the stern the length of the cockpit (several feet of the duct there is exposed to the open air), then through the wheelhouse and a hanging locker, you have to be careful when sitting in the saloon not to have your leg in front of the duct there as it'll burn your ankle! (Ask me how I know.) It's just as hot coming out of the vents in the wheelhouse and the forecabin, but you don't tend to be stationary in the direct blast of hot air there.
 
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ylop said:
i presume you meant without insulation!
Click to expand...
Yes, without ducting you lose lot more o_O
ylop said:
I’m not sure it’s “lost” it just gets absorbed into the fabric of the boat quicker, and the atmosphere on the boat slower - eventually with insulation the air heats the berths/lockers etc anyway and without insulation the warmer lockers slowly add background heat. The only way to really “lose” heat is if the ducting is directly in contact with the hull and you are heating the sea. Undoubtedly though, with insulation you will get hotter air out the vents and so feel warmer, quicker. Given the heaters actually prefer a good hard run - it may be no bad thing for them to have to work harder to get the boat up to temp.
Click to expand...
The loss depends on where the uninsulated ducting runs are. If it's in a wardrobe, for instance, it wouldn't be much of a loss and would help with keeping your clothes dry. If it's in a cockpit locker and spaces next to the hull etc then you're paying to heat those spaces and they soon lose that heat to the outside World.
 
ylop said:
i presume you meant without insulation! I’m not sure it’s “lost” it just gets absorbed into the fabric of the boat quicker, and the atmosphere on the boat slower - eventually with insulation the air heats the berths/lockers etc anyway and without insulation the warmer lockers slowly add background heat. The only way to really “lose” heat is if the ducting is directly in contact with the hull and you are heating the sea. Undoubtedly though, with insulation you will get hotter air out the vents and so feel warmer, quicker. Given the heaters actually prefer a good hard run - it may be no bad thing for them to have to work harder to get the boat up to temp.
Click to expand...
That’s our take on it. Our duct is quite exposed in the heads, and without an actual air outlet the heads (and the seat) get pleasantly warm after a while with the heating on. The run through the lockers is under a ply shelf, so no direct contact, it doesn’t get anywhere near hot enough to be a fire risk. We’re perfectly happy to leave ours uninsulated.
 
Like Little Sister we have a long run from Ebi in the stern, then under cockpit deck, through hanging locker and then under starboard berth in saloon. As we only needed 70mm duct I stuck it inside some old 100mm duct under the cockpit for insulation and only boxed it in in the hanging locker where there is a whole pother of immersion suits spare LJs and similar heavy and possibly vulnerable stuff. As the saloon locker only contains dry goods such as kitchen towel loo roll, rice and oats plus charts for less frequently visited areas, I dont mind if they get kept warm as much off the heat will leak upwards through the cushions to warm my seat - and they also provide insulation of the hull as duct above them.

Chocolate wine and beer are in the cooler port locker
 
Similar applications in caravans; same ducting, different heat source. The walls and floors are insulated though, but ducts under wardrobes, beds, etc, usually have holes pierced to allow trickle heating. I had a ‘van with one run going under the floor, that needed simple wrap foil insulation from Wickes to vastly improve heat.
 
There best insulation I've used on boat hot air ducting is Thinsulate. Lots of different versions available, but ready cut strips with press studs is the easiest to fit to an existing installation. Very good but expensive.
I've also used a form of bubble wrap coated in aluminium. Cut into straps and spiraled round the duct, held in place by tie wraps. It works surprisingly well. However, I've only ever used it on a hydronic system, where the maximum temperature of the air is 100C. I think that it would probably melt is placed close a hot air heater.
I found insulation really speeded up heating the cabin on cold mornings in NW Scotland. Very worth while.
 
I have a system still to be installed .. and I find such threads interesting.

Of course like everyone - we all make plans of how to install - where pipe runs etc ... which inevitably get amended ..

But considering under bunk / in locker runs - it has been my mind to insulate the ducting ... to preserve max heat to outlets ... but to protect any content I may place in locker / underbunks - I propose boxing in .. with sheet that has multiple air-holes for circulation ... this way - I keep all dry in the locker / underbunk - but also keep any items from contact with insulation / ducting. First I thought metal grills - but they will heat up over time and defeat their primary purpose. So it comes down a fire-proof composite material or plywood with fire-proof insulation on one side.
 
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