LPG - Calculating minimum pipe size required to supply a gas fire

[Pete]

Hi.

I am interesting in installing an open gas fire.

I already have a half-inch gas pipe which supplies LPG to a gas heating stove in an adjacent room. So I was thinking that a T-junction in this pipe, enabling the addition of a second pipe through the wall to the neighbouring room, might do the trick. The question is, how do I calculate whether the gas flow will be sufficient to run both the existing gas stove and the new open fire?

The specs. are;

Gas supply source - 2 tonne cylindricat gas tank Existing supply pipe - 1/2 inch copper pipe Existing gas stove - maximum of 4.5 kilowatts input New open gas fire - maximum of 32 kilowatts input

The input figure (32 kilowatts) for the new open gas fire may seem excessive, but it is correct - manufacturer's figures.

Can anyone tell me if the existing 1/2 inch supply pipe is large enough? If so, can you advise the method of calculation so that I can rework the figures for alternative fires or stoves?

Thanks for any advice.

[Pete C]

Bonkers!!!

Do they quote the efficiency too...?

cheers, Pete.

[Alistair Riddell]

What size of gas fire is it?! Are you heating the great hall in a castle or something?

I seem to remember that the copper development agency

has online tables for sizing pipes.

HTH

[Donwill]

I suspect they've left out the decimal point? Maybe it should be 3.2 Kw unless there is a very large boiler behind it :-).

Some figures from and old catalogue which may help :-

15mm pipe dia. pipe length- 10ft 20ft 30ft 40ft gas flow, 108 76 62 -- cu ft/hr & for 22mm pipe 225 160 130 110 cu ft/hr

Hope this helps Donwill

[Pete]

I know, the consumption is quite astonishing isn't it? However, the maximum heat input is definitely 32 kw; specs. can be viewed at

entry for a large Swan's Nest fire in the table near the bottom of the document).

I have also spoken to Gazco's technical department, and they confirm that the figure is correct. (Incidentally, I understand that the heat input and output are quoted at the same figures for these fires.) The efficiency rate is between 15% and 25%, depending on the setitng - most of the heat disappears up the chimney, as with open wood fires. So even the large fire version may only produce 4.8 kw of heating.

I will actually probably be looking to install the medium sized fire, which has a (still apalling) maximum input of 21.9 kw. However, my query mentioned the consumption figure for the large fire as installing this size is a remote possibility.

I am looking at these fires as they match the existing wood burning grate. A smaller fire would be lost in the seven foot wide, three foot deep inset fireplace (it's an early 17th century farmhouse). The high gas consumption isn't a major concern for reasons which I won't go into here (but it's not because I'm mega-wealthy!).

Anyway, thanks for the information and the quick replies; I will look into your suggestions this evening.

Cheers.

[Pete C]

Hmmm....

Why not a wood burning grate or stove for a _real_ fire? If you're in a rural area there's always plenty of wood around...

Go on ;)

cheers, Pete.