Solid exhaust tube for eber/webasto/etc?

Kelpie

Kelpie

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I'm looking into installing a blown air diesel heater, and one of the more worrying aspects of them is the integrity of the exhaust tubing. Mine would have to run through the lazarette, so could be at risk of being bashed about by fenders etc. I'm sure this is not an uncommon situation.

The standard flexible stainless tubing would obviously be the easiest to install, but would there be any disadvantages to using solid tubing instead? I gather than the lifespan of the flexi tube is limited and any leaks in the system are potentially lethal, so you would need to replace it every few years.

I happen to have a 2m length of 25mm od stainless tube, and was wondering if this would make a more robust exhaust option for at least part of the run. The other option would be to do it in copper, but I'd need to make sure that any fittings were capable of handling the heat involved.
 
Anything is possible but be certain welds, joints, etc are absolutely spot on. The pipe gets friggin hot too so watch for sheets, fenders, ropes, etc as they'll not last too long when put up against the exhaust. Finally the exit point through fibreglass(?), had a few in since I've been at Southwold where the fibreglass has discoloured, not necessarily melted but you could see the heat damage.

They are more often than no lagged heavily to stop direct burns but even close to the lagging is still more than warm enough!
 
Thanks, I'm aware that I'll need the correct marine skin fitting and silencer for this- not the vehicle stuff. Also aware of the need to lag the exhaust and keep it out of contact with everything.
My biggest concern about using solid tubing is, as you say, making sure the joints are secure. Perhaps it would be more practical to simply substitute solid pipe for the main straight run, and use the normal flexi tubing at either end. Will likely come down to how good the fit is between the different types of tubing.
 
I've considered fitting a stainless mesh tunnel around the exhaust, something like 10mm mesh and using some kind of insulation as support. I think solid tube is great idea but will be more difficult to fabricate.
 
You'll have to have flexi tails at each end as the whole system will want to move a little bit. Solid all the way would give the system a chance to crack or stress as things naturally flex, expand, contract, etc.

The perforated guards that go over commercial tube heaters in restrooms but in stainless would be a good cover.

Kelpie said:
Thanks, I'm aware that I'll need the correct marine skin fitting and silencer for this- not the vehicle stuff. Also aware of the need to lag the exhaust and keep it out of contact with everything.
My biggest concern about using solid tubing is, as you say, making sure the joints are secure. Perhaps it would be more practical to simply substitute solid pipe for the main straight run, and use the normal flexi tubing at either end. Will likely come down to how good the fit is between the different types of tubing.
Click to expand...
 
Kelpie said:
I'm looking into installing a blown air diesel heater, and one of the more worrying aspects of them is the integrity of the exhaust tubing. Mine would have to run through the lazarette, so could be at risk of being bashed about by fenders etc. I'm sure this is not an uncommon situation.

The standard flexible stainless tubing would obviously be the easiest to install, but would there be any disadvantages to using solid tubing instead? I gather than the lifespan of the flexi tube is limited and any leaks in the system are potentially lethal, so you would need to replace it every few years.

I happen to have a 2m length of 25mm od stainless tube, and was wondering if this would make a more robust exhaust option for at least part of the run. The other option would be to do it in copper, but I'd need to make sure that any fittings were capable of handling the heat involved.
Click to expand...

The BT vans I used to get the D2s off had solid SS exhausts, 24mm by the way! Ive got a pile in the garage, they are bent to suit transit vans!
Stu
 
skipper_stu said:
The BT vans I used to get the D2s off had solid SS exhausts, 24mm by the way! Ive got a pile in the garage, they are bent to suit transit vans!
Stu
Click to expand...

So in principle, there may be nothing wrong with the idea.
What's going to be more reliable- a flexi tube, or some welds? I guess that depends on who's doing the welding.

At a minimum I'm thinking the exhaust will need some sort of guard where it passes through the locker. I'd be curious to know what other people have used for this. I guess you want it to easily removable so that you can inspect the exhaust?
 
The thing some people do not realise about eberbasto exhausts on boats is that they generally need insulating.
The exhaust gases must not condense or the exhaust will fill up with a fairly nasty corrosive solution.
That must work on the lowest power setting.
On a van, there is normally a silencer with a drain hole.
Straight 'solid' tubing will make a noisier exhaust than standard flex hose.

I understand that some people have made condensing, silenced exhaust systems, comlete with a pump to get rid of the condensate.
 
On my boat the heater exhaust also runs through the lazarette (on the floor) and I keep all manner of heavy stuff there; think spare anchors.

It uses a solid 28mm tube (welded St steel) for the first few inches because some bends and a condensation drain are needed, then it enters a flexible tube which is wrapped by insulation, which in turn runs inside a fairly solid but corrugated aluminium conduit, of ~ 45mm OD. The outer tube provides the crush resistance needed and yet allows the insulation to do its job. It has has been working well for a good few years now. Not my doing but what Rustler installed from new btw.
 
jdc said:
On my boat the heater exhaust also runs through the lazarette (on the floor) and I keep all manner of heavy stuff there; think spare anchors.

It uses a solid 28mm tube (welded St steel) for the first few inches because some bends and a condensation drain are needed, then it enters a flexible tube which is wrapped by insulation, which in turn runs inside a fairly solid but corrugated aluminium conduit, of ~ 45mm OD. The outer tube provides the crush resistance needed and yet allows the insulation to do its job. It has has been working well for a good few years now. Not my doing but what Rustler installed from new btw.
Click to expand...

I have a very similar system. Its a D4 Uber with a silenced exhaust (actually a Webasto part but compatible), this is wrapped in insulation then enclosed in something like 50mm duct (similar to the Uber vent duct), works very well, and nice and quiet:-)
Angus
 
Kelpie said:
The standard flexible stainless tubing would obviously be the easiest to install, but would there be any disadvantages to using solid tubing instead? I gather than the lifespan of the flexi tube is limited and any leaks in the system are potentially lethal, so you would need to replace it every few years.

I happen to have a 2m length of 25mm od stainless tube, and was wondering if this would make a more robust exhaust option for at least part of the run. The other option would be to do it in copper, but I'd need to make sure that any fittings were capable of handling the heat involved.
Click to expand...

If you use solid tube, you'll still need a flexible section at each end, so you'll be doubling the number of joints with the potential to leak gases. Far more reliable to stick with a properly insulated flexible exhaust. I don't think good quality flexible tubing needs replacing "every few years" either!
 
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