gas supply to boiler

[PP]

Hi

I'm having a central heating boiler replaced to a Baxi condensing one but my installer called this morning to tell me that the Baxi he was going to install has been discontinued (Baxi 80 HE Plus) and a newer model will now be installed that doesn't require the gas supply pipe to be 22mm. The boiler he said will now be installed is a Baxi Duoheat ( I think that's what it was called) with a built in filling loop. I have been on the Baxi website but cannot find that boiler. What I want to know is has anyone else heard of that boiler and is it right that it doesn't need a 22mm supply?

TIA

[Phil Anthropist]

Did you hear him wrong? There is a Dimplex Duoheat electric radiator but no trace of Baxi using this name.

[PP]

Hi

I've found the one he was referring to ... Baxi Duo-tec 24HE. Can't find out about the inlet pipe on the gas though.

P

[EricP]

It doesn't really matter. The size of pipe to the boiler will depend on the site conditions prevailing and the installers opinion on what is necessary.

[ARWadsworth]

Yes, the boiler may only need 15mm but the supply pipe may need to be 22mm to cope with length and bends. Any CORGI installer will do the calculations before an install

Adam

[PP]

Cheers. I'll check with the installer.

[fred]

In article , PP writes

When I did the calcs for my own installation with a boiler of similar size

15mm was a no-no by a long way. Like you I couldn't see a Duo-tec 24HE but the installation manual for the Platinum 24HE shows a 22mm inlet pipe and the standard minimum inlet pressure of 20mbar. Note also that having a 15mm inlet pipe on a boiler is no indication that a run of 15mm is adequate, my own is 15mm but is increased to 22mm within a foot of the case to avoid excessive pressure drop on the pipe run.

If you can get a look at the installer manual look for the Gas Inlet pressure quoted in the Specification section, if it's the standard 20mbar then I'd suggest that 15mm is a no-no.

[Roger Hersee]

The size of pipe required will depend on the distance from the meter to the boiler and any bends or other off-takes along that route. I don't know the formula but you'd need around 22mm pipework for boiler providing 30kW at up to 30m overall. I think15mm could only be used for something like 10m overall. To determine the overall/effective length, you need to add about half a meter for each bend along the way. I've no idea what effect a tee off to a fire or gas cooker would have, but I'd assume another meter. You've got to allow enough gas to flow to the boiler. The more heat the more gas is required, otherwise the boiler will be starved of gas and not reach full potential (and may not even work at all). I'd expect all boilers to require 22m pipework (or larger). It doesn't need to be that size throughout, so long as the required flow rate at the boiler can be achieved. Roger

[Roger Hersee]

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