gas supply to combi

[div69]

I am thinking of changing my 'glow-warm' back boiler with more efficient condensing combi. The problem I have is the gas pipe that is terminated in my kitchen is 1/2 inch and not 22mm. If I was to connect Baxi 105 HE (which should normaly give me flow rate of 12 litres per minute) to a gas supply comming from 1/2 inch pipe, what should be the impact on flow rate. Does it depend on the gas pressure, i.e if there is enough gas pressure will it still deliver 12 l/min or I need to go for a less powerful model (e.g. 9 l/min)?
Thanks for you advise.

 

[kevplumb]

gas pipe size wont affect the water flow
it will affect the temp rise
it needs replacing with 22mm

 

[div69]

Thanks kevplumb,
based on what you said, to test my understanding, the flow rate will not be affected, but the effective water temperature of 12 l/min flow rate will be lower than if using boiler with 9 l/min flow rate.
I am still currious to know what the impact will be if supplying a combi from a 1/2" (12mm) gas pipe rather than 22mm. A dealer told me that CH will not be affected, only the HW.

Thanks again kevplumb for sharing your knowledge.

 

[kevplumb]

both will be affected as the heat input of the boiler is based on the amount of gas it can burn
you wont notice it as much on heating as the water is being recurculated and will just take longer to heat

the hot water is heating from cold all the time so if the boiler cant reach the temp its more noticable

 

[corgiman]

FYI Ideal say they are happy with upto 15mts of 15mm pipe for the 30-80 Isar (dont forget this includes elbows)

 

[PEDANTICVINDICTIVEMAN]

Cowboys fit 15mm pipe from the meter across whole of house and feed a gas fire, cooker and combi, still works, if you use an eletric shower no worries, just dont expect a hot bath.
I have reported to corgi someone fitting a double oven triple hob and 50,000btu boiler all from 15mm pipe, corgi not interested so why should you or I be, do what you like.

 

[corgiman]

Cowboys fit 15mm pipe from the meter across whole of house and feed a gas fire, cooker and combi, still works, if you use an eletric shower no worries, just dont expect a hot bath.
I have reported to corgi someone fitting a double oven triple hob and 50,000btu boiler all from 15mm pipe, corgi not interested so why should you or I be, do what you like.

OMG




What a bunch of ****s they are?

 

[Noraslad]

Whose the ****s?


The cowboys?


CORGI ?



Or should it be who are the biggest

 

[kevplumb]

fair comment corgi man but i wouldnt try it with a baxi

fitted a few isar/icos you can run them in 15 up to 17m calc

ive never gone further than 6

 

[div69]

Thank you all for your replies. I'll give it a try and use 15mm, its about 8m from the gas meter. I'll let you know how it goes in a few days time.
Thanks again

 

[kevplumb]

no way will you get the gas rate

 

[div69]

... on a second thought, I really think I shouldn't waste my time and do it properly. I was tempted as the 15mm pipe was 1m from my combi and I was rushing to get it done for the new year. The combi has 12 l/min flow rate and I really want to get rid of my electric shower. I am realising now that only 22mm gas supply will be good to keep its efficiency to 87% (it is low for a condensing combi as it is).
Cheers kevplumb!

p.s. bl**dy cowboys, I was so close to becoming one.

 

[kevplumb]

thats what i like to hear

 

[PEDANTICVINDICTIVEMAN]

87%, what a pile of c**p, all that aggro of pluming and condensate to get 87%, shant be fitting one of them then in the new year.

 

[corgiman]

... on a second thought, I really think I shouldn't waste my time and do it properly. I was tempted as the 15mm pipe was 1m from my combi and I was rushing to get it done for the new year. The combi has 12 l/min flow rate and I really want to get rid of my electric shower. I am realising now that only 22mm gas supply will be good to keep its efficiency to 87% (it is low for a condensing combi as it is).
Cheers kevplumb!

p.s. bl**dy cowboys, I was so close to becoming one.

Are you doing this yourself? I take it you are CORGI'd up?