Gas flue in catio

cathymaker

WIAWSNB said:

FreeBear said

From the WB document I linked to earlier -

The exhaust terminal [of a plume management kit] can also be routed through the roof of the carport providing 25mm clearance is provided around the flue pipe to any flammable material and that it extends at least 300mm above the roof.

Thanks for the details.
I'm going to speculate, then, that the GS was effectively saying there was nothing to attach a plume flue to from within the catio. He didn't have - didn't want - the option of getting access to above the roof for this. If he had, then I think the bargeboard would be suitable for mounting a bracket(s).
I'm also going to speculate that, since the catio isn't a permanent construction, any 'plume' solution will have to effectively avoid contact with it. Ie, it cannot be set up so that anyone dismantling the structure - as is bound to occur at some point - could disturb the flue. That part may come down to the judgement of individual GS's, but I wouldn't blame them if they made that call. So, a solution that allows the roof to completely avoid the flue - eg an open-ended cutout with plenty clearance, and no flashing that joins them, is I think more likely to be acceptable.
That would mean a small amount of rain will get through, but I'm guessing that this wouldn't be a problem?
Cathy, can you recall how the builder managed to get access to the roof to attach it down? Were they up on top?

I really appreciate how much thought you're putting into this as my head is spinning, especially as I passed on your suggestions to my GE yesterday and he sent a msg back saying I can't have a plume cos there is nothing to attach it to and the bargeboard a no go because of guttering being in the way. He's now said I can get a 'deflector', which is something I can buy myself allegedly. I decided to park it for a day after that reply as I think I'd need to call Baxi again to see what they think of that idea as I dont know why it's not been mentioned sooner. I'm afraid I didn't see how the builder attached the roof but he was a one man band and it didn't take him very long to install the whole thing.  Think it came pretty much ready made and then slotted together on the premises. 

WIAWSNB

cathymaker said:

I really appreciate how much thought you're putting into this as my head is spinning, especially as I passed on your suggestions to my GE yesterday and he sent a msg back saying I can't have a plume cos there is nothing to attach it to and the bargeboard a no go because of guttering being in the way. He's now said I can get a 'deflector', which is something I can buy myself allegedly. I decided to park it for a day after that reply as I think I'd need to call Baxi again to see what they think of that idea as I dont know why it's not been mentioned sooner. I'm afraid I didn't see how the builder attached the roof but he was a one man band and it didn't take him very long to install the whole thing.  Think it came pretty much ready made and then slotted together on the premises. 

You are welcome.

I have to emphasise that I'm not a GS, and not 'qualified', but am just generally 'informed'. And, based on this, I cannot understand your GS's reasoning. 

I suspect - but suspect only - that he doesn't want the job, as he presumes it'll entail him climbing onto a weak-looking roof, and I can't blame him.

If, however, that roofing panel were first removed, then I think fitting a plume kit would be dead easy, and the guttering of no issue at all - I have a plume kit fitted to my flue, and it's far more convoluted than that, and does also go past the gutter.

I have to say, I'm a bit surprised that the GS didn't condemn the current setup, as the exhaust does appear to be partially restricted by the timber beam, and I'd imagine that would spread out the flue gas, with an amount then being drawn back in through the 'intake' - the grill on the underside of the flue. And, of course, the possibility of an exhaust gas build up under that roof. BUT, I don't know.

In your position, I would see if I could get that roofing panel removed, and then call up either the same GS, or a different fellow.

jefaz07

FreeBear said:

Lorian said:

I am not a gas safe engineer but I'm almost certain you cannot fit a plume management kit and leave the intake below that roof and the exhaust above it.

From the WB document I linked to earlier -

The exhaust terminal [of a plume management kit] can also be routed through the roof of the carport providing 25mm clearance is provided around the flue pipe to any flammable material and that it extends at least 300mm above the roof.

If the exhaust terminates within the footprint of the carport then the carport must have at least two sides completely open.

Looking at the images, the exhaust terminal is too close to the polycarb roof (min 75mm clearance) and the window (1200mm min).

I don’t think that’s a Worcester though. Most likely a Baxi. 

I’d be concerned about the flue being in different pressure zones if a plume kit was used. Not sure how you haven’t been given a warning notice either if I’m honest. 

cathymaker

WIAWSNB said:

cathymaker said:

I really appreciate how much thought you're putting into this as my head is spinning, especially as I passed on your suggestions to my GE yesterday and he sent a msg back saying I can't have a plume cos there is nothing to attach it to and the bargeboard a no go because of guttering being in the way. He's now said I can get a 'deflector', which is something I can buy myself allegedly. I decided to park it for a day after that reply as I think I'd need to call Baxi again to see what they think of that idea as I dont know why it's not been mentioned sooner. I'm afraid I didn't see how the builder attached the roof but he was a one man band and it didn't take him very long to install the whole thing.  Think it came pretty much ready made and then slotted together on the premises. 

You are welcome.

I have to emphasise that I'm not a GS, and not 'qualified', but am just generally 'informed'. And, based on this, I cannot understand your GS's reasoning. 

I suspect - but suspect only - that he doesn't want the job, as he presumes it'll entail him climbing onto a weak-looking roof, and I can't blame him.

If, however, that roofing panel were first removed, then I think fitting a plume kit would be dead easy, and the guttering of no issue at all - I have a plume kit fitted to my flue, and it's far more convoluted than that, and does also go past the gutter.

I have to say, I'm a bit surprised that the GS didn't condemn the current setup, as the exhaust does appear to be partially restricted by the timber beam, and I'd imagine that would spread out the flue gas, with an amount then being drawn back in through the 'intake' - the grill on the underside of the flue. And, of course, the possibility of an exhaust gas build up under that roof. BUT, I don't know.

In your position, I would see if I could get that roofing panel removed, and then call up either the same GS, or a different fellow.

Thank you. I got the impression on the day that he was struggling to think how he could do the job, and not that it couldn't be done because at the time he said that was the solution, and it's been at the back of my mind to see if another gas engineer could give a second opinion on the practicalities. The roof is coming off now, solution or no solution, as it's clearly not going to be a quick fix.  I'm really appreciative of your help. 

Brackenfield

We have the same issue of a flue in our recently built catio.  My husband said we needed an open air catio due to this and some kind or upward vent (the flume you take about maybe?) 

We have a wooden framework including a baton on the wall of the house and have used mesh as a ceiling.  It's strong garden mesh from Knowlenets (they took about 15 days to deliver but we can't pull it apart so figure the 3 cats can't either!) and it's stapled onto the wooden frame and baton.  The mesh has only been up since Sunday so hopefully it's secure and they won't escape!!  An option perhaps?   

cathymaker

Brackenfield said:

We have the same issue of a flue in our recently built catio.  My husband said we needed an open air catio due to this and some kind or upward vent (the flume you take about maybe?) 

We have a wooden framework including a baton on the wall of the house and have used mesh as a ceiling.  It's strong garden mesh from Knowlenets (they took about 15 days to deliver but we can't pull it apart so figure the 3 cats can't either!) and it's stapled onto the wooden frame and baton.  The mesh has only been up since Sunday so hopefully it's secure and they won't escape!!  An option perhaps?   

Thank you. I did suggest mesh to replace the polycarb to the engineer but he said the fumes would rot it and Baxi also said that mesh wasn't a solution. BUT please bear in mind the man at Baxi I spoke to had no idea what a catio is and just quoted me the carport dimensions for distance of roof - mesh or otherwise - to flue required. I didn't pursue a plume conversation with him while it seemed a non starter, according to engineer.  If a flume is possible and avoids the mesh, I cant see why it would be a problem. Have you got a photo I could see please? Maybe a different engineer would be willing to take on the job. Obviously it will let in rain but maybe that's the compromise I'd have to make. 

Brackenfield

the mesh is up but not tidied yet, cant reach it all, need my taller hubby... but hope it gives you an idea.  Ours is a diy catio, not a professional one like yours x

WIAWSNB

cathymaker said:

Brackenfield said:

We have the same issue of a flue in our recently built catio.  My husband said we needed an open air catio due to this and some kind or upward vent (the flume you take about maybe?) 

We have a wooden framework including a baton on the wall of the house and have used mesh as a ceiling.  It's strong garden mesh from Knowlenets (they took about 15 days to deliver but we can't pull it apart so figure the 3 cats can't either!) and it's stapled onto the wooden frame and baton.  The mesh has only been up since Sunday so hopefully it's secure and they won't escape!!  An option perhaps?   

Thank you. I did suggest mesh to replace the polycarb to the engineer but he said the fumes would rot it and Baxi also said that mesh wasn't a solution. BUT please bear in mind the man at Baxi I spoke to had no idea what a catio is and just quoted me the carport dimensions for distance of roof - mesh or otherwise - to flue required. I didn't pursue a plume conversation with him while it seemed a non starter, according to engineer.  If a flume is possible and avoids the mesh, I cant see why it would be a problem. Have you got a photo I could see please? Maybe a different engineer would be willing to take on the job. Obviously it will let in rain but maybe that's the compromise I'd have to make. 

Hmm, I don't think these folk understand the situation. But tbf to the Baxi guy, the two construction types are very similar, and have 'solid' roofs.
The flue exhaust is slightly acidic, and the materials at direct risk from this are some metals, and masonry. The mesh will likely be polypropylene or similar, and I cannot see it being bothered at all. So, replacing the polycarb with mesh as in Bracken's fine example would almost certainly sort the 'exhaust' issue, if you wished to go that way.
However, my main concern with your current setup is the timber joist in front of the nozzle. 
There are ways around this, whilst keeping your current roof. I suggest first asking another GS to visit and discuss solutions - Ie, a plume kit. Make it clear that you will arrange to have that sheet removed - time to sweet-talk your niece - and will replace it afterwards only with a sizeable clearance slot cut it in to avoid the pipe. See if they'll agree to plume this.
Yes, a wee bit of rain will get through there, but I guess that ain't a big deal?
Your cheeky catio installer - if your GS had slapped a 'Danger -  do not use' warning on your boiler due to that joist, you'd have been able to force them to reposition it, or your money back. Hey-ho :-)
Exact model of Baxi?

cathymaker

Brackenfield said:

the mesh is up but not tidied yet, cant reach it all, need my taller hubby... but hope it gives you an idea.  Ours is a diy catio, not a professional one like yours x

Thank you!! Looks great btw.

cathymaker

WIAWSNB said:

cathymaker said:

Brackenfield said:

We have the same issue of a flue in our recently built catio.  My husband said we needed an open air catio due to this and some kind or upward vent (the flume you take about maybe?) 

We have a wooden framework including a baton on the wall of the house and have used mesh as a ceiling.  It's strong garden mesh from Knowlenets (they took about 15 days to deliver but we can't pull it apart so figure the 3 cats can't either!) and it's stapled onto the wooden frame and baton.  The mesh has only been up since Sunday so hopefully it's secure and they won't escape!!  An option perhaps?   

Thank you. I did suggest mesh to replace the polycarb to the engineer but he said the fumes would rot it and Baxi also said that mesh wasn't a solution. BUT please bear in mind the man at Baxi I spoke to had no idea what a catio is and just quoted me the carport dimensions for distance of roof - mesh or otherwise - to flue required. I didn't pursue a plume conversation with him while it seemed a non starter, according to engineer.  If a flume is possible and avoids the mesh, I cant see why it would be a problem. Have you got a photo I could see please? Maybe a different engineer would be willing to take on the job. Obviously it will let in rain but maybe that's the compromise I'd have to make. 

Hmm, I don't think these folk understand the situation. But tbf to the Baxi guy, the two construction types are very similar, and have 'solid' roofs.
The flue exhaust is slightly acidic, and the materials at direct risk from this are some metals, and masonry. The mesh will likely be polypropylene or similar, and I cannot see it being bothered at all. So, replacing the polycarb with mesh as in Bracken's fine example would almost certainly sort the 'exhaust' issue, if you wished to go that way.
However, my main concern with your current setup is the timber joist in front of the nozzle. 
There are ways around this, whilst keeping your current roof. I suggest first asking another GS to visit and discuss solutions - Ie, a plume kit. Make it clear that you will arrange to have that sheet removed - time to sweet-talk your niece - and will replace it afterwards only with a sizeable clearance slot cut it in to avoid the pipe. See if they'll agree to plume this.
Yes, a wee bit of rain will get through there, but I guess that ain't a big deal?
Your cheeky catio installer - if your GS had slapped a 'Danger -  do not use' warning on your boiler due to that joist, you'd have been able to force them to reposition it, or your money back. Hey-ho :-)
Exact model of Baxi?

It's a BAXI 800. I shall keep you posted as I've got a gas engineer coming out tomorrow for a second opinion and will discuss ideas. Yours mainly - you've been brilliant!