Replacing some gas piping with 28mm pipe

[Sparkgap]

Thank you - its the pipe issue that really concerns me and its knowing who to believe. Its a very costly exercise to rip up my hallway (and if thats not enough to rip up my tiled kitchen floor with under floor heating).

*gets out *** packet* 32kW boiler, about 3.5 cu.m/h so about 0.97 l/s for 22mm copper drops about 6.2Pa/m so about 136Pa total for 22m straight run or 1.36 mB which is a tad higher than recommended. 28mm copper drops about 2Pa/m so 44Pa/0.44mB which is okay.
That's not to say the boiler won't work on the smaller pipe. I know plenty installations where the pressure off the meter is actually a bit above the recommended and most boilers won't suddenly curl their toes up if the pressure drops a smidgen below 20mB. Could be your existing boiler is also more tolerant of lower pressures.
If it's that much hassle to do it you could go with the existing pipe and see what happens and look for other routes that avoid digging up the floors if possible.

 

[dfish]

Thank you. Scottish gas seems to think only a partial replacement is necessary and the independant guy doesn't know if that is enough! The latter I don't find satisfactory. Safe Gas registry said I have to ask the right questions, only go with the company that guarantees to complete the task at the price (and then if it doesn't work they have to pay for further work) and finally trust my gut instinct!!! Seriously that's what they said.

 

[dfish]

Cheers Sparkgap. Thanks for such a detailed reply. How sensible you are. I will take this view on board and use this to be more forceful with suppliers. Thanks have a good week.

 

[Scott_D]

Those figures don't allow for any bends, fittings or other gas appliances

 

[dfish]

Ok I understand. There needs to be a degree of flexibility depending on bends and boiler.
Thank you. Such a minefield.

 

[Sparkgap]

Those figures don't allow for any bends, fittings or other gas appliances

Quite agree. I did say straight pipe as I don't know the details of the pipe route. I would be inclined to put in a larger pipe but if it's the hassle the OP says it might be worth waiting to see if the boiler works on the original pipe, bearing in mind the existing one did. Other option would be to suss out another route that doesn't involve digging up floors if possible.

 

[dfish]

Can the pipe route go through bedrooms and outside before reaching the boiler (above ground level).

 

[ShaunCorbs]

Can the pipe route go through bedrooms and outside before reaching the boiler (above ground level).

as long as in trunking i dont see a problem (some nice talon)

http://www.talon.co.uk/images/stories/products/pipe-cover/Talon_Pipe_Cover.pdf

 

[Sparkgap]

Can the pipe route go through bedrooms and outside before reaching the boiler (above ground level).

No probs provided the pipe is in a ventilated space. Looking at some flats at the moment with the gas pipes rising on the outside and internals done in tracpipe through the floor.

 

[dfish]

Thank you

 

[dfish]

Ok thank you

 

[jonnyswamp]

Use a smaller output boiler, may take a bit longer to fill a bath, but may save you shelling out on unnecessary building works
Providing existing gas pipe will be adequate

 

[dfish]

thanks yes I think that is what I am going to attempt to do.

 

[Ric2013]

I would say because the blokes are qualified and competent.

Then why do they have different opinions on this - can it really be a grey area, or are some of them more competent than others? Or have made a mistake?

 

[newcastle phill]

The mistake was probably some being complacent and not bothering to calculate.
I havent read the whole post but i would go with the one who has calculated - as they have taken the time to assess the installation and subsequent gas demands

 

[Scott_D]

It's not grey, it needs upgrading based on the information available.
Those who didn't quote to upgrade are either going to leave a non compliant install or have to ask for additional £££ at the end

 

[dfish]

Thanks Phill - good advice. I have gone with the ones who initially mentioned replacing some of the piping and have come back to explain it all to me properly.
Thanks for your time.
Dorothy

 

[Stu Davis]

That length of pipe run sounds like part should be 28mm or any wont get enough inlet pressure, baxi's are a right pain for being noisy if inlet pressure isnt right due to under sized gas pipe

 

[dfish]

Thanks for the info - yes I am going to get at least half of the pipe replaced with 28mm. Hopefully that will be enough.
thanks D

 

[ShaunCorbs]

Thanks for the info - yes I am going to get at least half of the pipe replaced with 28mm. Hopefully that will be enough.
thanks D

dont hope get him/them to work it out

 

[dfish]

I have never met such a bunch of vague people using the words HOPE and SHOULD BE. I have a guaranteed price. The problem they say is that they don't know how many bends are in the pipe!
I guess half of them shouldn't be in business. Thanks for your help.

 

[Ric2013]

Yeah, shouldn't be.

I hope it's not contagious.

 

[dfish]

I hope not - have a good week.
Cheers D

 

[ShaunCorbs]

I have never met such a bunch of vague people using the words HOPE and SHOULD BE. I have a guaranteed price. The problem they say is that they don't know how many bends are in the pipe!
I guess half of them shouldn't be in business. Thanks for your help.

worst case then

 

[Sparkgap]

I have never met such a bunch of vague people using the words HOPE and SHOULD BE. I have a guaranteed price. The problem they say is that they don't know how many bends are in the pipe!
I guess half of them shouldn't be in business. Thanks for your help.

It's called CYA! :wink5:
I've got a £300k project at the moment to replace underground heating and water pipework in a school with new pipework running over the roofs. Our quote is liberally sprinkled with caveats as short of digging up the floors or smashing out wall panels we don't know exactly where the existing pipes are that we need to connect onto, so for the purposes of issuing a quote we have made a number of assumptions with a few quid on top to cover Sod's Law and the client knows this, as well as the fact that if we find things are completely different once we start, then we will be coming back to them for a variation. Minor differences I expect we'd just deal with anyway as they would be covered by the padding in the quote.
In your case I expect some have looked at the existing boiler and pipework and assumed that the new one being the same-ish output SHOULD be okay. Others have decided to cover their backsides and point out that the gas pipe may be undersized. If you go with the former and the new boiler doesn't work you MAY have a claim against them depending on how they worded their quote. If you go with the others and don't change the pipework and it doesn't work it's your problem not theirs.