Looking to replace existing feed & vent arrangement by a combined 22mm feed and vent back to boiler. Is plastic ok, after a couple of metres of copper, given that vent is is there to take steam if boiler (oil fired) stat fails, boiler overheats and boils. Some pipe flexibility would greatly ease installation.
combined feed and vent pipe partly in plastic???
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Big No No, use copper. Only do it if your boiler has an overheat stat.
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W
wilhelm
put frekkin plastic in. aint gonna kill ya.
But it might someone else in the future 
And it aint gonna ****ing kill anyone to learn to fit copper.......if they look @ www.ukcopperboard.co.uk PS combined F+V are crap too...........but then I`m just a dinosaur
And it aint gonna ****ing kill anyone to learn to fit copper.......if they look @ www.ukcopperboard.co.uk PS combined F+V are crap too...........but then I`m just a dinosaur Why are they rubbish? It does away with the blocked cold feed problem. Also a vast amount of expansion takes place in the cold feed pipe anyway so Y not just use one?
I do have to say that I agree that PROPERLY INSTALLED a combined setup avoids many problems.
I always take the view that copper is the professional material. However I am willing to agree that plastic can be adequate when its charactistics are not exceeded.
Plastic will withstand SOME pressure up to about 130°.
A vent pipe being open to the atmosphere will not significantly exceed atnospheric pressure and as the system water will boil at about 99° then the maximum temperature rating is unlikely to be exceeded.
I do not consider that plastic pipe is suitable for sealed systems as double faults may cause it to fail if the temperature/pressure rating is exceeded.
Tony
I always take the view that copper is the professional material. However I am willing to agree that plastic can be adequate when its charactistics are not exceeded.
Plastic will withstand SOME pressure up to about 130°.
A vent pipe being open to the atmosphere will not significantly exceed atnospheric pressure and as the system water will boil at about 99° then the maximum temperature rating is unlikely to be exceeded.
I do not consider that plastic pipe is suitable for sealed systems as double faults may cause it to fail if the temperature/pressure rating is exceeded.
Tony
I agree Tony etc, a combined setup can save/sort problems. Problems that would not have been there had the system been installed correctly.
Combined cold feed/vent can also create as many problems as it cures and can make filling the system a nightmare.
To answer the plastic question, yes there are plastic that can be used for vent/cold feed, "Friatherm" for example is pushed together using a special glue
Combined cold feed/vent can also create as many problems as it cures and can make filling the system a nightmare.
To answer the plastic question, yes there are plastic that can be used for vent/cold feed, "Friatherm" for example is pushed together using a special glue
If the 22 mm vent rises as it should do then there should be no problem filing.
However, if its a converted back boiler system and there are 10 m of horizontal tube under the upstairs floor then obviously there will be problems with airlocking.
I sometimes use the combined feed as a simple ( and cheap ) solution to the blocked feed when the blockage is behind the cylinder and inaccessible.
Tony
However, if its a converted back boiler system and there are 10 m of horizontal tube under the upstairs floor then obviously there will be problems with airlocking.
I sometimes use the combined feed as a simple ( and cheap ) solution to the blocked feed when the blockage is behind the cylinder and inaccessible.
Tony
Nige F said:Why, because the ones I`ve tried to refill .......won`t or don`t without a lot of fiddling about....why save a few feet of 15mm copper.........Blocked cold feed .......not with a Myson airjec
I've had to unblock a 28mm blocked cold feed. So they all can block.
But none of mine haveChrisRoberts said:Nige F said:Why, because the ones I`ve tried to refill .......won`t or don`t without a lot of fiddling about....why save a few feet of 15mm copper.........Blocked cold feed .......not with a Myson airjec
I've had to unblock a 28mm blocked cold feed. So they all can block.
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