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Central Heating

Plastic pipe into condensing pipe for pressure relief (combi boiler)

Anonymous user 23/02/2024 - 3.12 PM

Hello, My plumber fitted a plastic pipe(with a tundish) for the pressure relieve pipework. He attached it to the condensing pipe, as there is no easy access to an outside wall. Another plumber came over for another unrelated job and said the plastic pipe would not cope with the heat in case of a boiler issue and therefore should be replaced with copper. I looked at the boiler installation guide and it says it should be copper. I have 2 concerns: * Is it okay to use a plastic pipe for the Discharge pipe? * Is it okay to put the discharge pipe to the condensing pipe (T) rather than outside? Thank you!

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2 Answers

Boiler Homecare

Rating: 5 out of 5

Honiton

I disagree with the previous posters comments, in rare instances we have no choice but to run the PRV discharge pipe into the boiler condense pipe. I have discussed this matter with Worcester Bosch's own lead technicians and as long as there is sufficient fall on the condense pipe from the boiler at the point at which the PRV pipe tee's into the condense pipe and it is as far enough away from the boiler as practically possible thus preventing any back-fill into the boiler condense trap and more importantly at the point the PRV pipe terminates into the condense it is a tight mechanical seal which can be archived with the right fittings, which prevents spillage W-B see no problem with this method. To test the installation method above, I have operated the boiler to a point where it is running at maximum heat rate and manually opened the PRV to test for safe discharge, the heating water drained away perfectly and no heat damage to the condense pipe either. After all how many times have we tipped boiling hot water from a kettle down the sink without any detrimental effect to either the sink trap or waste pipe, and we are certainly not talking about boiling hot discharge water from the boiler here!

Answered25 October 2017

K&M Browning

Rating: 4.6 out of 5

Bridgend, Mid Glamorgan

Plastic pipework is not allowed on the pr side, it will have to be replaced by copper. The condensate can be terminated into the the condensate so long as there is no danger of burning (only when the plastic pipe has been replaced by copper.

Answered28 June 2018