Member Since: 25 Aug 2018
Location: Lincoln
Posts: 386
FBH Exhaust extension or relocation?
I am surprised to find very few complaints about the exhaust fumes given from the FBH. I know recirculation somewhat solves the issue though not entirely.
I want to extend the exhaust to move it away from the air intake (seriously who put it there?).
Does anyone know what the maximum length the exhaust can be on one of these units? I would imagine if its too long, ie the back of the truck, it could create pressure build up etc. but maybe a few feet wouldnt be an issue?
Basically I just need it away from the cabin. My D3 is a camper and sometimes the engine is left running for a short while to provide some heat and charge to the batteries.
Any suggestions would be great, cheers.
6th Feb 2020 1:42 am
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5059
"I want to extend the exhaust to move it away from the air intake"
Err can you elaborate please? The exhaust runs down the inner n/s valence to just below the chassis leg, where it discharges below the engine cover! It shouldn't come near the cabin intake unless your exhaust is missing!yµ (idµ - eAµ) ψ=mψ
6th Feb 2020 2:04 am
Harry365
Member Since: 25 Aug 2018
Location: Lincoln
Posts: 386
ok fine not right next to it but within breathing distance (the exhaust is indeed present). The engine fan and convection do a fine job of carrying it towards the intake.
I might add that my use case is possibly unique rare in that the vehicle is stationary for long periods of time.
6th Feb 2020 2:28 am
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5059
OK I'm with you now, even though I have never known FBH fumes to be a cabin issue even during cold morning warm up whilst on the timer.
That said I see no reason why you couldn't add an extension to exhaust the fumes further down the underside of the body. That would reduce the possibility of fumes accessing the air intake, but would the exiting fumes now find another entry point perhaps making matters worse? Thinking of the D3 body structure I can't think of such an entry point other than the gear selector area, though much restricted by the shifter etc!
Motolab is a member on here who I think worked with the Webasto systems, and might be able to offer you some further insight.yµ (idµ - eAµ) ψ=mψ
6th Feb 2020 3:05 am
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14152
Hi
Don’t know if this helps but have put a picture and as prof G also mentions of where the FBH exhaust should terminate , can see it on the left hand side
Just thought , ref the air intake , do u also mean the intake where the pollen filter is fitted up by the scuttle panel ??
Think it would help if u can take some pics plse, will make it a lot easier to see where ur coming from
6th Feb 2020 3:06 am
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14152
PROFSR G wrote:
OK I'm with you now, even though I have never known FBH fumes to be a cabin issue even during cold morning warm up whilst on the timer.
That said I see no reason why you couldn't add an extension to exhaust the fumes further down the underside of the body. That would reduce the possibility of fumes accessing the air intake, but would the exiting fumes now find another entry point perhaps making matters worse? Thinking of the D3 body structure I can't think of such an entry point other than the gear selector area, though much restricted by the shifter etc!
Motolab is a member on here who I think worked with the Webasto systems, and might be able to offer you some further insight.
Hi mate
U explaining it like I think I know what u mean, ref the scuttle panel air intake point where the pollen filter is
But also must admit haven’t ever had an issue ref the FBH , even in traffic I just turn it to recirc
As u say maybe extend the FBH heater exhaust , think I saw some info about that k will see if I can find it
6th Feb 2020 3:14 am
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14152
Found some pipe but alas don’t know if it’s the right size
I would assume if it’s permissible to extend the exhaust that it may req it to be a larger internal bore ???
Click image to enlarge
Click image to enlarge
6th Feb 2020 3:18 am
Harry365
Member Since: 25 Aug 2018
Location: Lincoln
Posts: 386
PROFSR G wrote:
but would the exiting fumes now find another entry point perhaps making matters worse?
This is definitely a concern though as you say, there's not really anywhere else it could come in.
PROFSR G wrote:
Motolab is a member on here...
Thanks, I might get in touch.
gstuart wrote:
Just thought , ref the air intake , do u also mean the intake where the pollen filter is fitted up by the scuttle panel ?
Yeh, assuming that is the only way the air gets into the cabin via the CC?
gstuart wrote:
As u say maybe extend the FBH heater exhaust , think I saw some info about that k will see if I can find it
Essentially thats the plan; I just don't want to go to the effort of extending it to find it harms the FBH with the extra work it has to do to exhaust the erm exhaust... I fitted a Truma boiler recently and it was very specific about the maximum length of the flue. Slight different equipment but it got me thinking. Appreciate it!
The one reason im not too happy about just hitting the recirc button is that I then lose "positive pressure" in the vehicle and exhaust fumes from the engine find their way in. Vehicle positioning can help here but as you'll see per the requested pics below, I'm in a relatively good position to make some modifications at the moment and just thought, why not try and get it right for the few times a year it does bother me...
I heard diesel is bad to breath in
Click image to enlarge
6th Feb 2020 4:13 am
Harry365
Member Since: 25 Aug 2018
Location: Lincoln
Posts: 386
gstuart wrote:
Found some pipe but alas don’t know if it’s the right size
I would assume if it’s permissible to extend the exhaust that it may req it to be a larger internal bore ?
Oh yeh this stuff looks good. Maybe oversizing on the bore would deal with any concerns about back pressure. I'll measure the pipe tomorrow (oops today) and take a look. Thanks...
Just gotta figure where to run it now.
6th Feb 2020 4:27 am
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14152
Hi
Looks an awesome project ur doing and great pics
Have found some links for u which I hope may help , also wonder if an email direct to webasto could then indeed establish ref extending the exhaust pipe or if u need to convert it to a camper FBH ???
Here’s the links and hopefully someone will be along to assist u a lot more than I can, extremely knowledgeable members here
Will in the mean time see if I can find out any further infor for u
Hope that may help a little
Ps, if that’s ok, plse keep the piccies coming as we all adore pics of projects, thank u
6th Feb 2020 4:32 am
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14152
Harry365 wrote:
gstuart wrote:
Found some pipe but alas don’t know if it’s the right size
I would assume if it’s permissible to extend the exhaust that it may req it to be a larger internal bore ?
Oh yeh this stuff looks good. Maybe oversizing on the bore would deal with any concerns about back pressure. I'll measure the pipe tomorrow (oops today) and take a look. Thanks...
Just gotta figure where to run it now.
Indeed plus it’s just finding out if u can and what size
Had a thought its shame u can’t use something like a raised snorkel design to run the exhaust up and well out of the way so no chance of wind blowing fumes under the car / or via the pollen filter
Or if it was near the bottom of the car and a lot of snow come along
alas know it’s on the wrong side , as the normal snorkel is fitted on the drivers side
Then of course have the heat to contend with coming from the FBH exhaust
Unless maybe fitting a false snorkel on the passenger side, insulating the exhaust piping , then could exit out the dummy snorkel , also putting some form of non combustible sleeving Inside ????
Useto be a heating engineer and yeh i know need to get out more and just an off the wall idea
But indeed as mentioned all governed by what and if u can do anything with extending The exhaust
look forward to this project
6th Feb 2020 4:40 am
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14152
Also thought , if it was installed Into a false raised air Inlet I would wonder it may need a condenser drain trap to stop many going back into the heater ????
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
Rough rule of thumb used to be, both ex and inlet pipe should be the same lengths.
See the Webasto or Eberspacher websites.
But the one on my boat has about 2 mtrs of exhaust flex and no inlet pipe at all!
6th Feb 2020 7:14 am
Harry365
Member Since: 25 Aug 2018
Location: Lincoln
Posts: 386
Cheers for all the links. I'll have a look through.
I'll make some sort of post in the relevant section with more pics of the project. I took the body off for no one particular reason but lots of small ones combined. I'll send you a link when its posted.
I suspect that lengthening it a metre or so, especially with a larger diameter shouldn't be an issue.
6th Feb 2020 2:11 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14152
Glad it helped
Look forward to seeing the progress
Also just another idea, certainly wouldn’t hurt to place a carbon monoxide alarm inside the cabin
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