15mm gas feed for new boiler ??

[Chri5]

Have had a decent quote for a new condensing boiler to replace the traditional (old) style Pot profile 80E.

The plumbers has highlighted the need for a 22mm feed, and of course it's 15mm !!

Part of the route back for a 22mm is near impossible due to a flooring system.

Are there any makers of condensing boilers that can run on a 15mm feed or is a 22mm absolutely essential ?

Thank you

 

[petit_pablo]

Its not so much the size of pipe to the boiler, but the volume of gas the pipe can carry.

 

[Elkato531]

It depends on the power rating of the new boiler. What boiler is being proposed and has it been correctly sized for the property? Once this has been done, the gas supply pipe sizing can be worked out. If your installer is not doing this, get another quote from someone will.

 

[gas4you]

Are you confusing condensing with combination?

A lot of home owners do.

If it is a combi you are having, then realistically anything more than about 3m of gas pipe and it will have to be at least 22mm.

You cannot however just assume 22mm will be ok, it has to be calculated properly.

 

[PEDANTICVINDICTIVEMAN]

An ideal Logic 24Kw "may" do it if the run isn't ridiculously long as it has a 1:1 ratio gas valve, BUT as others have said, it needs working out.

 

[ChrisR]

The Requirement is to satisfy the law, not just to get a boiler going. That's where the 1mbar pressure drop is stipulated.

I find 22mm is almost never big enough.

 

[muggles]

An ideal Logic 24Kw "may" do it if the run isn't ridiculously long as it has a 1:1 ratio gas valve, BUT as others have said, it needs working out.

And also, you'd be installing an Ideal, which generally isn't

 

[Chri5]

It's a modern London supply.

The roads were dug up 2009 and all the gas is on new mains. In to the house it's 22mm from a semi submersed meter and case.

Quite where is converts down to 15mm that feeds the kitchen (gas oven and existing boiler) will need some investigating.

There's a couple of things that run on from the valued answers you peeps have given, so:-

If I managed to get a route- is there a flexible pipe that is acceptable for gas supply ?

What is the special calcs you all talk about- could an accurate assessment be achieved with a lay persons skills ?

If a modern boiler is designed to use less energy, then surely that means lowering the gas use and hence replacing a 80k btu with a modern unit would work on the existing supply ?


I curious, please don't think I'm being contrary or trying to avoid issues- I'm not.

The boiler quoted for is a Vaillant Eco Tec 428 and all I'm trying to do is factor in costs for items likely to be outside the current quote.

Thanks again for previous answers.

 

[petit_pablo]

If I managed to get a route- is there a flexible pipe that is acceptable for gas supply ?
Tracpipe can be used be used but cost is prohibitive comapred to copper.

What is the special calcs you all talk about- could an accurate assessment be achieved with a lay persons skills ?
Nothing black magic. If you have a planned pipe run, measure the distance and number of turns it will need and posted it up here. Im sure someone will advise.

If a modern boiler is designed to use less energy, then surely that means lowering the gas use and hence replacing a 80k btu with a modern unit would work on the existing supply ?
Its gains its efficiency from the way it uses the gas not the volume it uses in. The boilers will use less gas long term as they wont be on as long as older units. Steamers reuse the flue gas heat to transfer more heat into the water. This cools the fluee gases rapidly, hence the formation of condensation.

 

[ChrisR]

The pressure loss tables are at the COpper Development Assocn site. YOu have to factor in all the bends and whatnot and then add a considerable fudge factor, cos the loss is always more than the calculations predict.

I have run 28mm Tracpipe in concrete from the front to the back of a deep terraced house, materials and lobour was something like £500 - £600. All over in a day, which was quick for the length.

The thing at the back of everyone's mind is that if Gas Safe Register man comes along and inspects, he can order the engineer to rectify if the pipe's too small. Free of course, whatever it takes.

 

[f42]

We have just fitted a Worcester Bosch Greenstar 30cdi and a 28mm gas supply, around a 10m run