Any boilers that can still use 15mm gas supply?

[jamesinturvey]

My boiler is over ten years old now and last time I had it checked I asked the engineer about getting it replaced. He initially said no problem, but then discovered that the supply pipe is 15mm and apparently modern boilers need 22mm?

Unfortunately the gas pipe enters my house at the front, and is buried throughout in the floor under concrete which is now covered with a stone floor and a built-in kitchen, then it emerges right at the back of the house where the boiler is. Digging it all up is just not an option, neither is routing it elsewhere because of the quirks of my old house - the only possible route crosses doorways, requires going through 18" thick stone walls and would need to be partly outside :-(

So, my question is, are there any boilers left that can still cope with a 15mm supply?

Thanks.

 

[Harvest Fields]

Yes Vaillant. But if the boiler isn’t getting enough gas the gas pipe will need upgrading anyway.

 

[Scott_D]

Plenty of boilers have a 15mm connection at the boiler
That is irrelevant though as the supply pipe must be suitably sized

Are you changing to a combi?

 

[jamesinturvey]

Thanks both for the advice so far. I have a Vaillant combi boiler at the moment, it's basically fine but it would be good to get a more efficient model before it inevitably starts going downhill.

 

[gmartine]

Any other gas appliances share the same supply...cooker, heater etc?

 

[Riley]

Could it be re-sited??

 

[jamesinturvey]

There's a four-ring hob using the same supply. I don't think the boiler could be resited as it's a pretty small house and there's nowhere else it could go on an exterior wall.

 

[jamesinturvey]

Don't think the loft is an option either as the only 'walls' are plasterboard dividers to my neighbours' lofts on either side, plus it's a listed building so I doubt I'd be allowed to have the exhaust pipe through the tiled roof. It's all pretty impossible :-(

 

[Riley]

Ask the question mate. You can easily build a frame in a loft to support a boiler. Maybe ask your neighbours where their boilers are?? Also no respectable gas engineer will install on undersized pipe

 

[Scott_D]

If yours is working then it can be tested to see if a like for like replacement will be ok.
Your boiler may have been fitted to an undersized gas pipe all those years ago.

 

[hammers4spanner]

I installed an ideal vogue not that long ago gas rate was bang on but pressure was a bit low but in tolerance for the manufacturer instructions. Phoned them up and they said yes it will work but suggest an upgrade of gas supply.
That was on a 15 mm gas supply so i assume although they could work in with MIs just upgrade it anyway.

 

[fixitflav]

I installed an ideal vogue not that long ago gas rate was bang on but pressure was a bit low but in tolerance for the manufacturer instructions. Phoned them up and they said yes it will work but suggest an upgrade of gas supply.
That was on a 15 mm gas supply so i assume although they could work in with MIs just upgrade it anyway.

What do you think about maximum 1mb pressure drop between meter and boiler inlet? There seems to be uncertainty among GSRs about whether that's mandatory, advisory, or unimportant provided the pressure at the boiler meets manufacture's spec.

 

[BYP]

22mm is generally the standard at least.

 

[king of pipes]

Come on guys 15 mm won't do a boiler and 4 ring gas hob op has already stated the supply is buried under a floor, 1 mbar drop from meter to appliance inlet is the regs , light the gas hob 3 rings minimum and boiler on maximum rate is a guaranteed fail if it can't be upgraded internally then do it externally pain I know but that's the rule . Cheers kop

 

[hammers4spanner]

What do you think about maximum 1mb pressure drop between meter and boiler inlet? There seems to be uncertainty among GSRs about whether that's mandatory, advisory, or unimportant provided the pressure at the boiler meets manufacture's spec.

Its in my post what and why uncertain ?
You upgrade the pipe even the manufacturer says ok it works but do the right thing and upgrade.
Not difficult to be honest

 

[fixitflav]

Its in my post what and why uncertain ?
You upgrade the pipe even the manufacturer says ok it works but do the right thing and upgrade.
Not difficult to be honest

I was asking about the 1mb pressure drop, and I didn't see anything about that in your #11. If "in the regs" in kop's #14 means it's mandatory, that's it. But I can understand the OP wanting to avoid upping the pipe size if he can. The existing set-up most likely doesn't meet the 1mb but it's apparently been OK for 10 years. Depending on the pressure requirement of the new boiler vs the old, and whether the output is higher, it could be OK, if the 1mb is advisory only. That's why I was asking.

 

[sammathias]

1mb drop from meter to appliance as kop said. Although some manufacturers tolerate an even bigger drop through gas valve and even the external test point built into the gas isolation valve. No brainer to upgrade pipe tho.

 

[hammers4spanner]

I was asking about the 1mb pressure drop, and I didn't see anything about that in your #11. If "in the regs" in kop's #14 means it's mandatory, that's it. But I can understand the OP wanting to avoid upping the pipe size if he can. The existing set-up most likely doesn't meet the 1mb but it's apparently been OK for 10 years. Depending on the pressure requirement of the new boiler vs the old, and whether the output is higher, it could be OK, if the 1mb is advisory only. That's why I was asking.

Self explanatory

 

[ShaunCorbs]

The range manufacturers list is for winter eg everyone turning there boiler on the main supply can drop below the recommended pressures

 

[dan_the_plumber]

You just need to re-run pipe in 22mm. A skilled GSR will be able to work out a viable pipe route

 

[Sunnylotus]

This may be a basic question for many of you, but I do need good advice. I want to replace my 16 year old 15kw heat only boiler with a more powerful one since we are building an extension onto our small 30yr old house. With the extension completed we will then have 17 small rads, plus the existing hot water cylinder and gas hob. The existing gas feed into the boiler is 15mm. What size boiler can I go up to please?

 

[ShaunCorbs]

Upgrade the gas pipe ?

 

[Ric2013]

This may be a basic question for many of you, but I do need good advice. I want to replace my 16 year old 15kw heat only boiler with a more powerful one since we are building an extension onto our small 30yr old house. With the extension completed we will then have 17 small rads, plus the existing hot water cylinder and gas hob. The existing gas feed into the boiler is 15mm. What size boiler can I go up to please?

How far from the meter? How many bends? How is the existing gas pipe sized over its entire length? How well have the internal cuts inside the joints been deburred? Any other appliances served by that pipe? Then it depends on how the proposed boiler is designed. If you want to keep your existing gas run, then to get a decent answer you need a gas installer on site to comment.

There are people on here (not me) who could probably easily comment on an installer's specific proposal, but very hard to give you a list of what boilers you could have, even with the above information. It isn't a basic question, I'm afraid.

 

[king of pipes]

Definitely a upgrade 😉 I'm afraid . Kop

 

[fixitflav]

This may be a basic question for many of you, but I do need good advice. I want to replace my 16 year old 15kw heat only boiler with a more powerful one since we are building an extension onto our small 30yr old house. With the extension completed we will then have 17 small rads, plus the existing hot water cylinder and gas hob. The existing gas feed into the boiler is 15mm. What size boiler can I go up to please?

It depends on the existing pipe - length, dia. and fittings. There are standard calculations an installer should be able to do. Alternatively, he could measure the pressure at the meter and at the existing boiler, and estimate from that the maximum gas flow to meet the regs.