Diesel heater out or in?

[m_c]

It can be done but my concern again would be sooting up inside. Nobody shows the long term results. Whilst the heaters are so cheap they are almost disposable the amount of work required causes a lot of hassle.

We've got vehicles at work with 2.5m long exhausts, and there's no issues.
Having had a quick look at Eberspacher they say max exhaust length should be under 5m, and Webasto say a combined intake and exhaust length of 5.6m.

However ideally the heaters should be tuned once installed, to ensure optimum combustion.

The key thing to consider is where any condensation will go, as if you have a low point in the pipe, you risk water building up to the point flow gets restricted.

 

[Gragson]

the exhaust does not look to be a large diameter, perhaps someone can confirm the size.

On the generic PRC ones its about 25mm

The key thing to consider is where any condensation will go, as if you have a low point in the pipe, you risk water building up to the point flow gets restricted.

My exhaust is just a simple out and short drop down of about 1m end to end, but to be honest I had not considered condensation build up, so good point for straggling or convoluted exhausts.

I was not happy with the air intake protection provided so I stuck a hat on it to stop rain/snow getting into the provided air intake
https://www.ebay.co.uk/itm/324572896508?var=513620098453 2 of these stuck together in may case

 

[m_c]

On the generic PRC ones its about 25mm



My exhaust is just a simple out and short drop down of about 1m end to end, but to be honest I had not considered condensation build up, so good point for straggling or convoluted exhausts.

I was not happy with the air intake protection provided so I stuck a hat on it to stop rain/snow getting into the provided air intake
https://www.ebay.co.uk/itm/324572896508?var=513620098453 2 of these stuck together in may case

View attachment 525764

The intake pipe should point downwards, so any water that does get in, should just run back out.

 

[fizzy]

On the generic PRC ones its about 25mm



My exhaust is just a simple out and short drop down of about 1m end to end, but to be honest I had not considered condensation build up, so good point for straggling or convoluted exhausts.

I was not happy with the air intake protection provided so I stuck a hat on it to stop rain/snow getting into the provided air intake
https://www.ebay.co.uk/itm/324572896508?var=513620098453 2 of these stuck together in may case

View attachment 525764

Exhaust is fine but intake loads of work. Mine just dangles inside. Remember it is is purely air for combustion. It never gets near the circulating warm air.

 

[fizzy]

Some of my collection.

 

[indy4x]

Another diesel heater thread!!!!!

Inside IMO. Ensure the exhaust and Combustion Air inlet are both taken to outside.

(Work in progress but the concept of mine -)

I completely get having the exhaust piped outside but is there a need for the air inlet to be outside as well?

Edit: I have now read the whole thread and have seen the comments about the benefits of having the air intake external with the exhaust. Mine has been installed for 3yrs with the air intake inside, happy to take the risk

 

[fizzy]

I completely get having the exhaust piped outside but is there a need for the air inlet to be outside as well?

Asking for a friend

None at all!

 

[indy4x]

We have a Webasto in our camper, was fitted by the PO and on that the air intake into the heater was drawing air from outside the van, not just for combustion but a ruddy great hole for the main air intake into the heater

 

[Wedg1e]

Power supplies are now as little as £15 on Ebay. They all seem to be the same. Mine have lasted very well. Just be warned the terminals are semi exposed and need to be covered over or protected.
Get a 30amp one - they draw quite a lot on startup but only 1 or 2 amps running.

Pardon our interruption...

Watch out for those Chinese Amps.
I bought a '30A' switched mode from eBay to run my diesel heater (having first tried an ex-computer PSU (allegedly rated for 20A at 12V) that went into overload and shut itself down); it went through the warm-up routine but as soon as the igniter fired, the PSU shut down with a blown fuse. Changed fuse, wouldn't work.
Took it apart and found a blown MOSFET in a pair; close inspection revealed they were different and the soldering on one looked suspiciously different to the other.
Replaced them both as a pair; same thing happened - blew up as the igniter fired.
Replaced the FETs again and this time decided to load-test it using halogen headlamp bulbs (60W is about 5A at 12V).
It would run two bulbs, albeit the power devices were getting hot. Tried to add one of the low beam filaments (55W, so another 4A or so) and the PSU died again - this time all three filaments flashed a couple of times and then went off. Removing the load let it restart but it clearly can't run even a brief pulse of much more than 12A. So much for the 30A rating on the label
At the moment I've got the battery from the TVR wired to the heater and it's run for about 6 hours without issue.

 

[JOEPRO]

Exhaust is fine but intake loads of work. Mine just dangles inside. Remember it is is purely air for combustion. It never gets near the circulating warm air.

Post in thread 'Man-cave diesel heater 12V supply......' https://www.mig-welding.co.uk/forum/threads/man-cave-diesel-heater-12v-supply.132847/post-2339028



People can make up their own minds and install what they wish re air intake etc. Its been covered dozens of times on here

 

[fizzy]

Post in thread 'Man-cave diesel heater 12V supply......' https://www.mig-welding.co.uk/forum/threads/man-cave-diesel-heater-12v-supply.132847/post-2339028



People can make up their own minds and install what they wish re air intake etc. Its been covered dozens of times on here

That was 3 years ago. I was fairly new to them then. Now I have run several and dismantled them loads of times I know better
Oh and my kerosene inverter heater is still working brilliantly. Service it once a year.

 

[oldbikedavey]

I'm sticking with my Deville Poele de Campagne.......
The only thing that could be better would be another one .....

 

[Kayos]

This time of year you have no chance!
I have tried to keep car and boat batteries topped up but certainly in Wales it is too grim.
A mains 12v 30amp psu is only about £25. Why are people over complicating things? Power cuts in the UK are very rare and the odd power drop won't harm the heater - which only cost around £65 anyway!

Well put

We get the odd power outage, if the heater looses mains 1 out of 25 shutdowns, I'm sure it will be fine

 

[fizzy]

I'm sticking with my Deville Poele de Campagne.......
The only thing that could be better would be another one .....

Yes i would love one. I don't think my staff could cope with the starting procedure though

 

[zzr1200]

So no combustion intake supply to outside, all inside?

This has been a major debate on here and elsewhere for years. I used to go with intake inside but in this latest install in my front garage I put the intake supply from outside also.

Theory being that in normal operation the combustion process is seperated from the occupied space. If there was some form of running defect in the heater then hamful gases MAY expel from the combustion intake pipe. If they did and this intake pipe was inside then the gases will be too.

So if you have a gas fire in your living room the fire takes its oxygen from within the room, the exhaust fumes exit the room via the old chimney, the only modern adjustment is to make sure there is adequate air flow into the room.

Gas central heating boilers work with a balanced flue, but they are designed to shut down if the exhaust fume path should become blocked or restricted, as far as I'm aware these small diesel heater units, don't use a balanced flue technology mainly, because they aren't supplied with one, as part of the heater system. The installation instructions state exhaust exits on the outside of the building.

The heater units internal fan ensures a constant direction of airflow, so I can't see how/why any fumes could enter the working area via the burner intake, apart from a damaged exhaust pipe, if the exhaust becomes blocked the overheat circuit should shut down the heater unit.

If an air inlet is outside the building there is a possibly that it may become blocked by plant growth, birds nesting, mice or many other things, the unit is designed to have 2 air intakes one for the combustion chamber and one for the heat exchanger side.

Using this argument of air intake air paths, should both air intakes be outside???

Plus:----- Large space heater heaters suck, burn, and blow into the same space, but some use these in large area workshops....they aren't nice but they work sort of.....

 

[JOEPRO]

So if you have a gas fire in your living room the fire takes its oxygen from within the room, the exhaust fumes exit the room via the old chimney, the only modern adjustment is to make sure there is adequate air flow into the room.

Gas central heating boilers work with a balanced flue, but they are designed to shut down if the exhaust fume path should become blocked or restricted, as far as I'm aware these small diesel heater units, don't use a balanced flue technology mainly, because they aren't supplied with one, as part of the heater system. The installation instructions state exhaust exits on the outside of the building.

The heater units internal fan ensures a constant direction of airflow, so I can't see how/why any fumes could enter the working area via the burner intake, apart from a damaged exhaust pipe, if the exhaust becomes blocked the overheat circuit should shut down the heater unit.

If an air inlet is outside the building there is a possibly that it may become blocked by plant growth, birds nesting, mice or many other things, the unit is designed to have 2 air intakes one for the combustion chamber and one for the heat exchanger side.

Using this argument of air intake air paths, should both air intakes be outside???

Plus:----- Large space heater heaters suck, burn, and blow into the same space, but some use these in large area workshops....they aren't nice but they work sort of.....

Everyone has a different take on this - and that's OK.

Also with an understanding on differential pressures and how they may occur within a building its easy to see how the combustion intake could leak inside the space but alas, horse to water and all that. (My professional role gives me an unfair advantage / insight here let's say)

RE Heater Air intake from outside, I may do that with my large indirect heater actually. (Different system I know) Aka positive input ventilation had its own advantages such as conteracting cold draughts.

(Test run in the photo)

 

[JOEPRO]

So if you have a gas fire in your living room the fire takes its oxygen from within the room, the exhaust fumes exit the room via the old chimney, the only modern adjustment is to make sure there is adequate air flow into the room.

Gas central heating boilers work with a balanced flue, but they are designed to shut down if the exhaust fume path should become blocked or restricted, as far as I'm aware these small diesel heater units, don't use a balanced flue technology mainly, because they aren't supplied with one, as part of the heater system.

The use of balanced flues is ALL to do with the VOLUME of combustion air required for the given KW rating of the applicance itself. And if that air can be pulled from the space or requires to come from outside and room sealed.

Also stoves and gas fires can be impacted by things like cooker hoods in the same space which requires them to the room sealed and they cannot be legal or signed off without this.

Comparing apples to tomatoes here.

These little knock off china heaters are completely unregulated and installed by anyone.

The closest real instructions would be from Webasto etc from who china stole the design from. I'm certain if you therefore refer to correct / appropriate instructions they would say to route both intake and exhaust outside.

 

[JOEPRO]

Webasto extract from interwebs:

 

[Beanwood]

I am installing into a dusty work area so regardless of the combustion NEED would PREFER to run the pipe out through a timber shed wall. Does anyone have experience of suitable glands/grommets/whatever for making it a neat job!
I also want some type of filter for the heating input as I suspect large quantities of sawdust won’t do it any good. Again- thoughts please?

 

[JOEPRO]

Also with the air intake pipe inside a minor detail is that you are therefore losing that heated space air to outside. And depending on how well sealed the buiding fabric is, it could create a small negative pressure bringing in even more cold air.