Diesel air heater

[lewisericeric]

Hi All

 

Looking to install a diesel air/fan heater and wondering where to put the unit. My boat is a cruiser stern, but limited space on the bulkhead walls in the engine bay now, plus as the heaters have their own little 10l diesel tank, could be fiddly/irritating having to go in engine bay to refill.

 

My boat will be trad layout with bedroom at the back, but unlike most boats, I'll have a separate utility room after the bedroom.... this room is NOT accessible from the bedroom (i.e. no door to it) so I'm wondering if the heater could be mounted in there.... It's no different to if I had an engine room on a trad stern and there's also going to be no door between it and the bedroom for any potential leaks? Are there any issue around BSS does anyone know? 

[Alan de Enfield]

3 minutes ago, lewisericeric said:

Looking to install a diesel air/fan heater and wondering where to put the unit. My boat is a cruiser stern, but limited space on the bulkhead walls in the engine bay now, plus as the heaters have their own little 10l diesel tank, could be fiddly/irritating having to go in engine bay to refill.

 

Is this one of the 'cheap' Chinese heaters ?

There are a number of components that are not compatible with the BSS so you will need to change the exhaust and fuel hose as a minimum otherwise you will have a BSS fail.

 

There are one of two folks on the forum that have fitted them so will be able to tell you everything that needs replacing.

[lewisericeric]

Thanks Alan - yes it's not a Webasto or similar, a cheap Chinese one! So good if anyone does have any info on what needs changing and if this could be mounted in my separate-to-main-cabin "utility room"

[cheesegas]

I’ve fitted an Lf Bros heater (a Czech-made one, a bit more expensive than the Chinese ones) in my cruiser stern. It’ll be fine fitted inside as long as you make sure all the exhaust joints are gas tight. 
 

You need to bin the following items in the kit - exhaust silencer, fuel tank, fuel filter, jubilee clips (they’re usually crap)
 

And buy this, it’ll cost around £150 - brass or rubber ISO7840 compliant fuel hose and fittings, metal fuel filter, sealed marine type exhaust silencer, insulated skin fitting, exhaust condensate trap.

 

Some crap kits come with a 1.5mm2 power cable which is about 3m long, the voltage drop on startup is too much, if your batteries are less than fully charged it will fail to start. You’ll need to cut it and splice in a 10mm2 or larger cable as your run to the batteries will be quite long. It will pull about 10 amps for 1-2 minutes on startup and shutdown. 

The plastic fuel tank in the kit can’t be used in the engine space, and whilst I’m not sure if the BSS forbids it in the living space, it’s not a great idea. You’ll need to tap off the main tank - run a long brass/copper fuel line from a spare outlet on the water separator (most boats have one) to the heaters dosing pump. It doesn’t have good suction, so it will need to be lower than the fuel tank, and I have no idea if it can deal with the long fuel line, you may need another lift pump after the water separator. The dosing pump is designed to be gravity fed. Note that the fuel line from the pump to the heater can’t be ISO7840 rubber as it expands too much with each pulse of the pump - you need to use the included hard nylon tube, I sheathed it in rubber hose for some sort of flame resistance, passes BSS too. Not the most elegant of solutions, I know!

 

The exhaust needs to be lagged to avoid the fumes condensing as much as possible, and the skin fitting fitted as high as you can get whilst being below the heater, check how far it is from the waterline! You need a U bend and a condensate trap if it’s not a straight run down from heater to skin fitting. 

 

Combustion air can be drawn from the cabin space, but consider where the heater intake takes its air from. If it’s from the cabin, you’ll have maximum efficiency but also condensation inside the boat as the air is never renewed. If it’s from outside, you lose efficiency but you don’t get condensation issues. I installed a 2 way valve (about £8 on eBay) on the intake so it pulls in a mix of outside and inside air, about 70/30 outdoor/indoor air works well. 

[Jen-in-Wellies]

43 minutes ago, cheesegas said:

The dosing pump is designed to be gravity fed. Note that the fuel line from the pump to the heater can’t be ISO7840 rubber as it expands too much with each pulse of the pump - you need to use the included hard nylon tube, I sheathed it in rubber hose for some sort of flame resistance, passes BSS too. Not the most elegant of solutions, I know!

An alternative is to use copper brake pipe. This is 3/16" outside diameter (around 5mm), but has a small bore similar to the hard nylon tubing. Designed for hydraulic pressures, so well able to handle the pulses from the pump. This pipe can also be flared at the ends, so helps secure the shortest possible lengths of 5mm ID ISO 7840 hose at the ends for joining it to the pump and heater. A local car repair garage should be able to sort you out with suitable lengths and flare them for you as replacing MOT failed brake pipes is a common job.

Jen

[Alan de Enfield]

10 hours ago, lewisericeric said:

Thanks Alan - yes it's not a Webasto or similar, a cheap Chinese one! So good if anyone does have any info on what needs changing and if this could be mounted in my separate-to-main-cabin "utility room"

 

 

I have found when talking to folks about their choices that the 'cheap' heater actually works out to be more expensive (when correctly installed with new parts) than it would have been to have used a 'quality' Webasto or Eberspacher, and, cannot be actually fitted easily due to being designed for a gravity feed fuel line and the exhaust outlet needing to be lower than the heater.

 

We had a Propex LPG blown air heater in our Horse box, which was a superb bit of kit, but required the exhaust to exit thru the floor - which would not be ideal in a boat !

 

We have a marine Eberspacher blown air heater in the cruiser - super bit of kit - simply press the button and the boat is warm within minutes, although we tend to leave it on permanently and use the thermostat. Warning - they are 'hungry' for leccy tho.

[MtB]

12 minutes ago, Alan de Enfield said:

I have found when talking to folks about their choices that the 'cheap' heater actually works out to be more expensive (when correctly installed with new parts) than it would have been to have used a 'quality' Webasto or Eberspacher, and, cannot be actually fitted easily due to being designed for a gravity feed fuel line and the exhaust outlet needing to be lower than the heater.

 

 

I've connected mine to the day tanks which works fine. And I've fitted the exhaust outlets higher than the heaters with no detectable adverse effects so far...

 

 

But of course those of you without a proper engine won't have a day tank....

 

[Tony Brooks]

30 minutes ago, MtB said:

But of course those of you without a proper engine won't have a day tank....

 

 

But they could have if they installed one for the heater. Back in the day we fitted all our hire boats Webastos with their own tank so they used Kerosene. (they were a totally different design to today's offering). I suspect that the engine leak off could be fed via such a tank so it would not need topping up very often when cruising.

[cheesegas]

52 minutes ago, Alan de Enfield said:

I have found when talking to folks about their choices that the 'cheap' heater actually works out to be more expensive (when correctly installed with new parts) than it would have been to have used a 'quality' Webasto or Eberspacher, and, cannot be actually fitted easily due to being designed for a gravity feed fuel line and the exhaust outlet needing to be lower than the heater.

 

We have a marine Eberspacher blown air heater in the cruiser - super bit of kit - simply press the button and the boat is warm within minutes, although we tend to leave it on permanently and use the thermostat. Warning - they are 'hungry' for leccy tho.

I've found that my Czech heater, whilst being a lot cheaper than the Eber/Webastos, is actually a lot better on power consumption. On the lowest 1.4kw setting, it uses 800mA, and on 2kw it's only 1.2A. Not very hungry at all if you have decent batteries. An Air Top pulls almost double that on its 1kw setting... I remember when I shopped around, an Air Top was about £600 and that didn't include the marine specific bits like the silencer and skin fitting, whereas the LF Bros was just under half that.

The expensive heaters may last for longer in durability, but after a couple of winters with the cheaper one, it's great so far. I opened it up just before this winter to check for coking as I usually run it on the 2kw setting (out of a max. 5kw) for long periods, but it was clean inside. As you probably know, it's a good idea to run it on full blast once a while to clear out carbon deposits.

[Tom and Bex]

I've fitted 2 of these heaters to our current boat, and I can assure @Alan de Enfield that the total cost of both heaters and extra fittings was considerably less than the cost of a single eberspacher or webasto heater on its own!

 

BSS are currently reviewing requirements for these heaters, and will currently allow installation using supplied fittings, tank, pipes etc (see attached pdf from them). 

 

Our rear heater was installed in engine bay, and takes diesel from existing eberspacher feed from main tank. It was installed without silencer, and pipework is copper brake pipe throughout, with short iso compliant rubber hoses for connecting up, as per standard marine kits with the expensive heaters. Brake pipe was flared using automotive flaring tool. Combustion air intake is from within engine compartment (standard cruiser stern). I use this heater for heating back deck (ideal for drying laundry with pram hood up!) and rear bedroom/dining room. Don't find it particularly noisy without silencer either inside or outside the boat. 

 

Our front heater is installed using supplied tank, and supplied hose from tank to pump, both fitted in outside front locker. I then used copper brake pipe to bring the feed inside to the heater which is installed in a front cupboard next to the door. For this heater I used a marine silencer. Combustion air is drawn from near water tank, and heater air from behind paneling (due to space!).

 

Both heaters have recently passed the BSS, and it was an examiner that pointed me to the current BSS guidance on diesel heaters. Front heater is installed with the exhaust outlet noticeably higher than the heater with no problems. Both have the exhaust lagged, and beware the exhaust gets VERY hot during use. Can't see the need for an insulated skin fitting for a steel boat though, and both ours use a standard brass skin fitting. 

 

It's often cheaper to buy the all-in-one heater unless you need the separate tank, and the heaters and control panel inside the casing are identical. I'd suggest shortening supplied power cables and replacing with thicker cables direct to battery (via fuse). I just about got away with using supplied cabling, but only due to the higher voltage of lithiums.  Both heaters cost less than £80ea, and I just went for cheapest I could find on ebay with UK stock. Rear heater now been in use for 2 years, and front for 1 year, both have been 100% reliable during that time. 

Marine silencer (£37.50) and mounting bracket (£15) for front heater came from southernmarineproducts.uk  which is considerably cheaper than i could find elsewhere, and seem very sturdy and well made. 

 

Happy to answer any further questions on our setup. I'd strongly advise CO and smoke alarms for peace of mind. BSS guidance pdf attached. 

 

ETA - Fuel pump for rear heater is mounted at deck height (12" above top of tank) and has to draw fuel through around 2m of copper pipe. Although standard advice is to mount pump below tank, this setup hasn't caused any problem in 2 years, and heater actually primes much easier and faster than eberspacher that is mounted close to, and below diesel tank.

bss-interim-position-on-diesel-appliance-fuel-supply-arrangements-dec-2021-final-v10-modified-on-211208.pdf

Edited November 9, 2022 by Tom and Bex
Added bit about fuel pump

[lewisericeric]

Thanks so much everyone for all the helpful information.

 

Tom/Bex, do you know if the actual unit and tank could be installed (For ease) in my utility room - similar to an engine bay, it's at the back of the boat, not accessible by door from the bedroom only via the back deck doors. 

 

Or do these units HAVE to be in the engine bay themselves? 

[Tom and Bex]

18 minutes ago, lewisericeric said:

Thanks so much everyone for all the helpful information.

 

Tom/Bex, do you know if the actual unit and tank could be installed (For ease) in my utility room - similar to an engine bay, it's at the back of the boat, not accessible by door from the bedroom only via the back deck doors. 

 

Or do these units HAVE to be in the engine bay themselves? 

One of ours is installed in an open cupboard in the lounge, but diesel tank installed in outside locker. Would be wary about having diesel tank inside due to smell and possible spillage when topping up, but nothing to stop you having it in your utility room. Just ensure the exhaust is well lagged due to heat, and obviously exhaust exits through hull (and don't use supplied silencer!).

[Crewcut]

If I was replacing the Mikuni on my boat I'd go with Planar, see here. Good quality, reasonable price...

Eberspacher & Webasto are price riggers & very overpriced...

[jonathanA]

54 minutes ago, Crewcut said:

If I was replacing the Mikuni on my boat I'd go with Planar, see here. Good quality, reasonable price...

Eberspacher & Webasto are price riggers & very overpriced...

What a weird website ? Every price followed by this :

(Please note that we do not retail or sell heaters on their own. This price is for the appliance only, if we fit it. This price does not include labour)

 

Based on their web site these people come across to me as, idiots and I'd avoid....

[Tom and Bex]

2 hours ago, Crewcut said:

If I was replacing the Mikuni on my boat I'd go with Planar, see here. Good quality, reasonable price...

10x the price I paid! Think I'll stick to my cheap Chinese heaters and take a chance!

[Crewcut]

16 hours ago, jonathanA said:

What a weird website ? Every price followed by this :

(Please note that we do not retail or sell heaters on their own. This price is for the appliance only, if we fit it. This price does not include labour)

 

Based on their web site these people come across to me as, idiots and I'd avoid....

 

Apologies I got the wrong website, here's where I intended to point to...

[George and Dragon]

We just had our Webby Thermotop C refurbished: this involved replacing the blower motor, burner tube and heat exchanger none of which had apparently been touched since the heater was installed in 2008. Hardly surprising given the location of the heater.

Total cost excluding replacing the damaged skin fitting which had caused the unit to stop working was almost £900 +VAT.

 

[MtB]

My cheapo Chinese one expired yesterday after about three years of use. It started making a crackling noise then went out. On restarting it, it tripped the circuit breaker.

 

Rather than fix it I'm probably gonna shell out another eighty quid on a new one! 

[rusty69]

On 09/11/2022 at 09:53, MtB said:

 

I've connected mine to the day tanks which works fine. And I've fitted the exhaust outlets higher than the heaters with no detectable adverse effects so far...

 

 

But of course those of you without a proper engine won't have a day tank....

 

 

I too have done this.

 

 

 

19 hours ago, MtB said:

My cheapo Chinese one expired yesterday after about three years of use. It started making a crackling noise then went out. On restarting it, it tripped the circuit breaker.

 

Rather than fix it I'm probably gonna shell out another eighty quid on a new one! 

 

Do you think the death of your heater could be related in some way to the above? Build up of gunk in the combustion chamber, or is it likely to be entirely electrically related? I will be interested to read about the post-mortem.

 

Waddya mean your not gonna find out what killed it?

[MtB]

24 minutes ago, rusty69 said:

 

Do you think the death of your heater could be related in some way to the above? Build up of gunk in the combustion chamber, or is it likely to be entirely electrically related? I will be interested to read about the post-mortem.

 

Waddya mean your not gonna find out what killed it?

 

 

It seems unlikely as after removal the exhaust is clear, if rather sooted on the inside surface. I have the unit back here in the workshops in my hovel and I'll be dismantling it over the next few days. What  suspect has happened is the heater plug has expired and shorted out. 

 

It has spent many a long hour running apparently happily on minimum tickover output, but the soot suggests otherwise!

 

I've bought a whole new one (£97, ouch!) to fit in the interim. 

 

 

Edited November 22, 2022 by MtB

[MtB]

One thing I DON'T like about these cheapo Chinese heaters is there is no direct flame monitoring, so if combustion fails the electronics only realise when the output temperature falls unexpectedly and it shut the thing down. This takes several minutes during which time the dosing pump continues to pump fuel into the combustion chamber. Just so you are aware of this 'feature'! 

 

I'm expecting this one to have an eggcupful of fuel sloshing about inside when I dismantle it....

 

 

[rusty69]

5 minutes ago, MtB said:

 

 

It seems unlikely as after removal the exhaust is clear, if rather sooted on the inside surface. I have the unit back here in the workshops in my hovel and I'll be dismantling it over the next few days. What  suspect has happened is the heater plug has expired and shorted out. 

 

It has spent many a long hour running apparently happily on minimum tickover output, but the soot suggests otherwise!

 

I've bought a whole new one (£97, ouch!) to fit in the interim. 

 

 

Yes, they do appear to have gone up a bit. I got one in March for 80 quid delivered after my last one died. I will be interested in the state of yours when you dismantle it, especially the gauze screen, if you can get it out. Glow plugs are quite cheap iirc, but there are more than one size (don't ask me how i know).

[MtB]

1 minute ago, rusty69 said:

Yes, they do appear to have gone up a bit. I got one in March for 80 quid delivered after my last one died. I will be interested in the state of yours when you dismantle it, especially the gauze screen, if you can get it out. Glow plugs are quite cheap iirc, but there are more than one size (don't ask me how i know).

 

Yes annoyingly, although they all look the same there are at least two different manufacturers and one works much nicer than the other. DMHIK either! 

 

The model number of this dead one is XMZ-1 and it runs (or ran) beautifully. Could not find the same model number again anywhere so I've no idea how similar the new one will be, when it arrives. 

 

 

 

 

5 minutes ago, rusty69 said:

Yes, they do appear to have gone up a bit.

 

I'm pretty sure this is very recent. Even a couple of weeks ago ISTR seeing them at £80, which seemed crazily low. Then they all jumped up £20! 

 

 

[rusty69]

9 minutes ago, MtB said:

 

 

I'm pretty sure this is very recent. Even a couple of weeks ago ISTR seeing them at £80, which seemed crazily low. Then they all jumped up £20! 

 

 

Even at 100 quid they are a bargain. The burner itself seems like a decent bit of engineering to me, as long as all the ancillaries are put in the nearest bin.

[MtB]

11 minutes ago, rusty69 said:

Even at 100 quid they are a bargain. The burner itself seems like a decent bit of engineering to me, as long as all the ancillaries are put in the nearest bin.

 

Yes I completely stripped down the first one I ever bought to see if it was a bad mistake and I too was very impressed with it (other than the absence of flame monitoring). 

 

Agree about the ancillaries except the dosing pump needs to be kept. I also searched high and low for a bare unit with no ancillaries as they must add £20 to the price! But no cigar...