Gas Piping - Is this normal?

[Chris_J]

After reading a recent thread about undersized gas pipework and the dangers of it, I decided to inspect my system - which was installed by the previous owner of my house about 3 years ago (who was an RGI, but still a bit of a cowboy.)

First thing I noticed was all the gas piping is in 15mm. My boiler is a 24kW combi that is located in a cupboard right next to the gas meter. The pipework from the meter to the boiler is less than 1m in length, and there is a t-piece half way along, leading under the floor to the gas hobs (oven is electric.)

I thought I'd do a little bit of an acid test last night to see what would happen if I had all the hobs running at full, and I fired the boiler up on full DWH demand. So I tried it and what I saw was the flames on the hobs 'blip' a little bit as the gas valve opened, then very slightly blip again as the boiler goes off.

Could anyone tell me whether this behaviour is normal? The manual states the boiler only needs a 15mm connection, but I'm thinking what should have been done is 22mm piping from the meter and to the hobs, then a t-piece with 15mm reducer to the boiler. The reason I'm asking you guys is I'm wanting to install a small gas fire in the front room, and want to prepare myself with the additional money if the pipework needs upgrading.

I understand that the gas pressure will have to be checked anyway, but I just wonder whether the blipping is a sure sign that the pressure drop is too high.

 

[EliteHeat]

No one will be able to answer this without attending site with a manometer and a stopwatch and access to the MIs.

 

[doitall]

Existing should be fine without looking. its certainly with range from the information you provided

From the meter your RGI can change the pipe to 22mm then tee off in 15mm to the fire.

 

[Anybody]

Here are my answers to some rather crucial questions you may have.

Gas Piping - Is this normal?

More normal than it should be. For years cowboys and even some who are now RGI's have been undersizing pipework.

Is it right?

Probably not. It should be checked and put right.
Occasionally the combi is within 3 metres of the gas supply. Quite often this is actually within the constraints of a safe job for a 24 KW combi.

Am I going to die?

Probably not. If you said that the flame dropped considerably I would be concerned. A blip in the pressure as you describe although not recommended will be unlikely to kill you.

 

[Chris_J]

Thanks for the help, guys.

Sounds like I should be okay. Although that all may change when installing the gas fire.

I've got a feeling that without him even testing the pressure, the RGI would want to change the lot to 22mm.

 

[doitall]

Here are my answers to some rather crucial questions you may have.

Gas Piping - Is this normal?

More normal than it should be. For years cowboys and even some who are now RGI's have been undersizing pipework.

Is it right?

Probably not. It should be checked and put right.
Occasionally the combi is within 3 metres of the gas supply. Quite often this is actually within the constraints of a safe job for a 24 KW combi.

Am I going to die?

Probably not. If you said that the flame dropped considerably I would be concerned. A blip in the pressure as you describe although not recommended will be unlikely to kill you.

Anybody.

Your post suggest the RGI that did the work is an cowboy, quite wrongly in this case, in fact in my opinion I don't think you know what you're talking about.

1M and a couple of bends is sufficient to feed an 24kw boiler and the hob.

So the OP wants to have an gas fire fitted and the pipe will have to be changed, thats not the original RGIs problem, and it sure as hell doesn't make him a cowboy.

 

[doitall]

Thanks for the help, guys.

Sounds like I should be okay. Although that all may change when installing the gas fire.

I've got a feeling that without him even testing the pressure, the RGI would want to change the lot to 22mm.

He will need to change the pipe from the meter to where he tees off for the fire, that could be a couple of hundred mm if you run the pipe for the fire back to the meter.

 

[Anybody]

The pipework from the meter to the boiler is less than 1m in length,

You are dead right DIA! I missed the bit above when I read the original post.
What I meant was that in general there are still a lot of undersized pipework situations about but at least I am more sure now that the OP wont die.

 

[Chris_J]

Whoo!

 

[Alanka]

You can check the pipe sizing yourself (at least approximately) by looking at the nomogram at

http://www.slumberlands.freeserve.co.uk/gasflow.htm

Hope this helps

Cheers

Big Al