Which pipe should i use for a combi system

[cal]

Hope someone can help me. I am intending/ need to replace the heating system in my 2 bed bungalow and want to try and keep the cost down by replacing the pipework for the heating myself.

Would the use of plastic pipe and push fit connectors be suitable to cope with the pressure of a combi system and would 15mm be ok.

Thanks

 

[BOB.DOLE]

Hope someone can help me. I am intending/ need to replace the heating system in my 2 bed bungalow and want to try and keep the cost down by replacing the pipework for the heating myself.

Would the use of plastic pipe and push fit connectors be suitable to cope with the pressure of a combi system and would 15mm be ok.

Thanks

22mm for first 3 meter with and 15mm for rest flow and return

 

[cal]

thanks for that. i assume that the plastic pipe option would also be ok?

 

[ChrisR]

Not near the boiler it wouldn't.
Don't do the boiler/gas yourself, and get a corgi on board before you start. Otherwise you'll make simple mistakes.

 

[Agile]

You should not normally use plastic within a metre or two of the boiler.

Be aware that plastic is not as durable under fault conditions and will burst at about 130°C whereas copper will remain intact up to about 300°C and retain a much higher pressure.

It is generally seen as a lower standard job and might affect the value of the property.

Since plastic is more expensive my advice is to use copper as its cheaper and better as well as looking much nicer!

Tony

 

[Gasman1015]

Hope someone can help me. I am intending/ need to replace the heating system in my 2 bed bungalow and want to try and keep the cost down by replacing the pipework for the heating myself.

Would the use of plastic pipe and push fit connectors be suitable to cope with the pressure of a combi system and would 15mm be ok.

Thanks

Yes, make sure you use barrier pipe and sleeves on all joints and use copper where pipework will be seen.

 

[cal]

thanks for all your advice. its just that the existing system is piped in 15mm then reduces to 8mm microbore to the rads and i was told in the past that 8mm is ok for a conventional system but not if you install a combi

 

[ChrisR]

i was told in the past that 8mm is ok for a conventional system but not if you install a combi

borrocks!

 

[chrishutt]

What's actually wrong with the existing system? 8mm is fine, so why replace it?

 

[Softus]

You should not normally use plastic within a metre or two of the boiler.

Not so - you should never put plastic pipe, or pushfit fittings, within 1 metre of the heating appliance.

Be aware that plastic is not as durable under fault conditions and will burst at about 130°C whereas copper will remain intact up to about 300°C and retain a much higher pressure.

Quite so. Be aware also that copper is not as durable as plastic under non-fault conditions.

It is generally seen as a lower standard job and might affect the value of the property.

This is opinion only, and is moot.

Since plastic is more expensive my advice is to use copper as its cheaper and better as well as looking much nicer!

Solid and accurate advice. IMHO.