Replace 15mm gas or not?

[trumansparks]

Hi,

1st fix central heating been put in but had someone round to help with another job (complete renovation) who said the gas should be 22mm.

2 up 2 down stone terrace house with single story extension. gas pipe is from entry;
up front wall 22
straight across 1st ceilings 22
then changes to 15mm through backroom out into extension then 22 mm for last 1.5 metres.

Now is this likely to be ok or not? there is the option now to replace the backroom 15 with 22 leaving approx 3-4 metres of 15mm while ceiling is down. i could also have more of the 15 in kitchen replaced leaving approx 1 metre of 15mm in total.

I could have everything 15 replaced but i believe its not going to be easy and probably expensive to get through the thick stone walls into the extension.

so really after advise as to what is reasonable course of action as dont want to be low pressure and ruin a new boiler or have a sub standared unsafe job.

thanks
truman

 

[stevw451]

unfortunately you need to increase the lot to 22mm

 

[Gasman77]

haha how do you know that? he might be running a 12kw boiler??

 

[stevw451]

and if he isnt but finds out later his WP is too low
change it while the chance is there

 

[boilerdoktor]

In the case of gas you need someone who can size the pipework using a calculation. What size boiler is going in? If it is a fair run and the boiler is 35kw say you may even need 28mm pipe! Best left to a competent heating engineer! Every elbow etc affects the flow! A conventional boiler is the only exception I can think of!

 

[Morris40]

it really does matter what you are going to be running off the supply, how long the pipe run is and how many elbows T's and bends there are if it's a combi you are going to run then i'd bet a pound to a penny you'll need to go to 28mm for the vast majority of the run and as a min it would need to be 22mm, will you also be running a hob or/and a gas fire ?

 

[trumansparks]

thanks for the help so far,

to answer a few questions, its a potterton gold 28 he combi (25kw) and nothing else is running off the gas supply. its relatively straight with approx 7-8 corners in total possibly 12-14 meters pipework

would be happy enough to have all but the bit through the wall replaced if sufficient.

but if safety issue the whole lot will have to be done, is their a gas safety register rule/law that apply's?

truman.

 

[Morris40]

that boiler is around 2.4 m3 per hour so you will not need 28mm but you will need 22 mm copper, which over that distance with that many bends will give you around 2.9 m3 per hour so you may get away with a short length of 15mm, up to you if you take the chance,

 

[trumansparks]

thanks morris for the calcs,

not really sure now, would like to do the lot but might not be possible, is this a safety issue at all?

you say its my choice, but is it and should it be?

cheers

truman

 

[Morris40]

what i mean is that you can risk it however if you have the boiler installed and the gas rate does not meet required standards as quoted on data plate and in manufacturer instructions then you'll have to change all to 22mm, sorry but thats the best info i can give, sorry it's not more concrete, get your local Gas Safe registered engineer out to quote for install and he can do a more exact calc without to much trouble,infact he should do this anyway as part of the install inspection, I would

 

[trumansparks]

thanks again morris ,

i understand where your coming from, yes it needs to be right and the calc needs doing accurately on my pipes so i will ask for this to be done, what annoys me is why have a gas registered person come to fit new central heating system and leave this pipework in place. If i hadnt had someone else in i would never of found all this out and ignorance wouldent be bliss for long!

will post back to update.

cheers
truman

 

[trumansparks]

Well the plot thickens..........


Been having a good dig around and can see the blow off valve is plumbed in (via a T) to another pipe coming from boiler draining out through wall.

Also have seen a small sticker inside boiler saying 24he not as i would expect 28he as i asked for a potterton gold 28 and which was agreed as a higher water output.

WTF is going on???? fearing a horse riding big hat wearing job? not sure how to proceed as struggling to get in touch with plumber.

truman

 

[Gasman77]

I Think you've been had!

 

[trumansparks]

possibly, but only half had if that... paid out half the money so far and so about evens if job ends now, all be it with a lower output boiler.

 

[Morris40]

do you have his Gas Safe number ? if so you can report him to Gas Safe call 0800 4085577 his number should be on the benchmark form he would have filled in for the boiler and given to you