Skip to main content

Ready to hire?

Post your job in minutes, browse real reviews and choose who to speak to.Post a job

Need some tips or advice?

Ask a question
Gas Works

Changing conventional gas boiler and gravity fed system to combi - do I need to replace gas pipe?

Anonymous user 28/02/2024 - 3.02 PM

I want to change my conventional gas boiler and gravity fed system for a combi. I am looking at the Worcester 29CDI. I have had 4 Gas Safe installers come and look at the job. 2 have said that I will need to have the gas supply from the meter to the boiler upgraded to 22mm pipes as the 15mm pipes that are there at present are not suitable. But the other 2 didn't mention it at all. I'm worried that if the installation isn't done correctly, the warranty on the boiler will be invalid, but likewise I don't want to pay over the odds. Any advice please?

Are you a tradesperson and able to answer this question?

Log in

3 Answers

Boiler Homecare

Rating: 5 out of 5
Honiton
The first 2 who stated that the existing 15mm gas supply is not adequate are correct, give the other 2 a wide birth. All good gas engineers know by experience if your existing gas appliances running at full rate have the correct sized gas pipe and the combined kilowatt rating does not exceed capacity of your gas meter. There is a formula to calculate the correct pipe size(s) but normally as stated, good knowledge and experience is sufficient enough.
Answered14 March 2014
1

Anonymous user

A 'combi boiler' would draw off more gas in a shorter period of time as the hot water is instantaneously heated, as opposed to a 'heat only' or 'system boiler' where they would heat a HW cylinder over a period up to an hour. Little behold to upsize a 15mm gas pipe to 22mm or even a 28mm pipe is not a difficult job. A registered gas engineer should work out with calculations the exact pipe size needed, although many other factors are to be included such as gas hob size, gas fire etc. Hope this helps. DC Plumbing & Heating.
Answered28 December 2014
1

McEwan plumbing

Rating: 4.8 out of 5
Sunbury On Thames
I would certainly not even consider the 2 who did not mention the gas pipe size upgrade
Answered11 September 2022
0