Size of gas feed pipe for a regular condensing boiler?

[Agile]

2face, you seem to have become out of touch with current regulations!

Dont you think that rather than a complete reassessment every five years it would be better to have an annual ONE day update training and short reassessment?

That would spread the cost, keep you updated and only use up a day a year!

Tony

 

[albag]

Guys just reading some of these post trying to find out if i need larger than 22mm gas supply to my new boiler, apart from a few feet of pipe
and a couple of bends to get the pipe in to the floor space the run from gas supply to boiler is 43 feet, i assume its a given that i will need bigger than 22mm copper!!
if so is there a way finding out or calculation i can do to workout pipe size required, boiler being fitted is WORCESTER BOSCH GREENSTAR 42CDI
WHICH IS 42KW

al

 

[powell30]

Albag, yes there is a calculation but it would be pointless you doing it. It is based on gas rate of the boiler and the length and pipe size of the gas run. It is also critical that it is calculated correctly to ensure the boiler is burning 'clean'......leave it to the RGI there is no reason why the gas run can't be re-routed (even outside) as long as regs are followed

 

[DP]

Typical response from 'fitters' who think all boilers only need 15mm gas line (also feeding cookers and fires). Often these are the guys who think they are competent and do not need to be qualified as they are very good DIYers.

OP, ask the installer for calculations for the selected bore of pipe. Do brace yourself as 28mm if that is what is needed, will cost a few bob. Have a stiff drink nearby if size is next one up.

Select undersize pipe at your own peril. For starters undersize pipe and large combis do not go together. You might not even get output a 20kw combi gives (despite your boiler being twice the output) if your boiler does not get the gas it needs.

Often end users and fitter fail to comprehend these boilers are very gas hungry. Heating water needs lots of power.

 

[Agile]

If you already have a 22 mm supply to the boiler location then that could be retained and a new supply added in parallel, possibly outside.

It might be possible to only use 22 mm for all or part of the additional supply but the CORGI doing the job would calculate whats required.

Tony

 

[doitall]

If you already have a 22 mm supply to the boiler location then that could be retained and a new supply added in parallel, possibly outside.

It might be possible to only use 22 mm for all or part of the additional supply but the CORGI doing the job would calculate whats required.

Tony

It's stupid and dangerous to feed two supplies to one appliance.

A rough calculation says that if the first half of the pipes was changed to 28mm it would be ok, possible less it the RGI worked it our on site.

 

[kirkgas]

domestic engineers can now work 70kw net Heat input applainces and on 35mm pipe as long as the internal volume of the whole installation including meter does not exceed 0.035m3, which is a pain in the butt as you have to calculate the IV then advise the customer you can't work on it, ( i think rule of thumb, using a U16 meter you can have approx 10m of 35mm pipe and be under 0.035m3,)

 

[Deleted member 105431]

If you already have a 22 mm supply to the boiler location then that could be retained and a new supply added in parallel, possibly outside.

It might be possible to only use 22 mm for all or part of the additional supply but the CORGI doing the job would calculate whats required.

Tony

It's stupid and dangerous to feed two supplies to one appliance.

A rough calculation says that if the first half of the pipes was changed to 28mm it would be ok, possible less it the RGI worked it our on site.

I have never seen it done myself. Why would it be dangerous though?

 

[doitall]

Because sections of pipe will be fed from two directions.

Bit like have two electric supplies to a boiler.

 

[Deleted member 105431]

Because sections of pipe will be fed from two directions.

Bit like have two electric supplies to a boiler.

Ah i see. I'm not aware of any regs against it though.

 

[doitall]

Neither an I

 

[Corgigrouch]

Because sections of pipe will be fed from two directions.

Bit like have two electric supplies to a boiler.

That's called a ring main..

I asked about running two pipes last time I renewed my ACS and as far as anyone can see, there is nothing to say it cannot be done. True it would not be ideal but could get you out of a tricky spot

 

[Deleted member 105431]

Because sections of pipe will be fed from two directions.

Bit like have two electric supplies to a boiler.

That's called a ring main..

I asked about running two pipes last time I renewed my ACS and as far as anyone can see, there is nothing to say it cannot be done. True it would not be ideal but could get you out of a tricky spot

while its not illegal it still seems like a bodge to me. I've never seen it done anywhere but I can see the benefit to do on a boiler replacement where there are mulitple appliances (and a very awkard pipe run).

 

[WDIK]

ring mains? very common commercially, many an MOD base has them at 6bar
and quite common at 21mb

oh and 70kw and 35mm is now dommestic,

gawd knows why

 

[Deleted member 105431]

ring mains? very common commercially, many an MOD base has them at 6bar
and quite common at 21mb

oh and 70kw and 35mm is now dommestic,

gawd knows why

6bar gas ringmain? that could do some serious damage.