Any boilers that can still use 15mm gas supply?

[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.

 

[Timmy D]

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?

Is your boiler more than a couple of meters away from your meter? If so, you’re already undersized.

 

[Knappers]

Just to make it really clear.
I'm not a jobsworth and am happy to push the limits when appropriate but...
A 1mb drop is the maximum drop allowed, there's no tolerance and no exceptions!
Even if boiler manufacturer permits it (and they dont) there's a world of difference between safe operation and the requirement for a new install to be compliant.

 

[Riley]

You would mark undersized pipework on a landlords check you cannot install a boiler not to requirements. If it’s that close I’d either insist on upgrade or walk away