Changing from copper to plastic

[dave1975]

I was about to change a few radiators using 10mm plastic sunk into the wall and had a crawl under the floor to check out the pipework. There must be 100 meters plus of 10mm copper piping not even clipped up so was thinking of changing it all to plastic and neatening it all up. There’s 22mm copper central to the house then 10mm shooting off to each radiator with some being 6 metres long. Is it ok for the 10mm to be that long or does the 22mm need to be closer to each radiator?

 

[Madrab]

All depends, 10mm pipe is restrictive and can struggle when it comes to older properties that have the need for larger radiators on longer runs. It works great in more modern houses with higher insulation values that then have smaller lower output rads with shorter runs though does need to be kept squeaky clean to ensure there's no circulation issues and rad sizes need to be limited as the pipework has a limit as to delivering enough flow.

Looking at your dwarf walls I'd suggest you are in an older brick/stone built property that uses med to large rads. If that's the case then if I'm being honest then you would really want to maximise your system by having 22mm to a centralised point then run 15mm out to the rads. That will shorten heat up time and allow the system to be balanced easier. You would be pleasantly surprised by the significant difference it would make.

If you are adamant that you want to stick with 10mm then the shorter you can make the 10mm runs the better, try to equalise the lengths of the runs as that will as that will encourage a level of self balancing and minimise the number of bends and fittings

 

[Notch7]

10mm copper piping not even clipped up so was thinking of changing it all to plastic and neatening it all up

I believe 10mm plastic has a much smaller bore size than 10mm copper

If you change to plastic you risk rodent damage -I certainly know the plumber I use has come across it when called out to deal with leaks in floor and loft spaces

I wonder how much heat is lost through all those pipes in the cold, ventilated to outside, floor void

 

[dave1975]

It’s a 1950s house which has had some major renovations with a new roof and dormers etc. it’s really well insulated upstairs so for the size of the house the radiator are quite small. Now I’m working on the downstairs where the radiators are huge so will be changing to modern ones. Yes you’re right that the copper is exposed to the elements so hoping plastic will be better insulated. I was wanting to connect the rads as it’s been done upstairs so I’d be happy to run 15mm to each rad then reduce to 10mm as done with the others. Does that sound feasible? I’m not a plumber by the way but more than capable of using push fit

 

[Notch7]

Now I’m working on the downstairs where the radiators are huge so will be changing to modern ones.

if you are changing the radiators, you might as well take the 15mm pipework up to the TRV, its only drilling a hole through the floor -and you will have less issue with problems in the future


what heating system do you have? -if you can fit large radiators you might be able to have a lower flow temp for greater heating efficiency -its worth thinking about it now and future proofing

if it was me Id replace with standard stelrads and not modern designer rads


I doubt whether plastic will be any different in heat loss than copper TBH -what you need is to set out your new runs to allow for pipe insulation -its cheap and will quickly pay for itself

 

[dave1975]

The pipes are coming through the floor anyway at the minute but will now chase it in centrally then out left and right so the pipework is hidden. I have an ideal logic + system S30 with a 250L water tank which is only 1 year old. Not that I know anything about boilers but it does a good job of heating the house. The rads upstairs are flowmasta so will use the same downstairs apart from vertical rads in the office and hall.

 

[trojanhawrs]

It might not look pretty under the floor but if it's not causing you any problems there's no reason to change it. Copper is superior to plastic in most ways, plastic is just easier and faster to throw in

 

[dave1975]

You’re probably right but It just pains me to see it in its current state. Maybe I should leave it as is but insulate it and clip it out of the way

 

[trojanhawrs]

I dunno, I'd say make it pretty where it's on show, otherwise put the floorboard back down and forget about it. Lagging wont hurt but under the floor is getting free heat at the moment, if pipes lagged it'll draw heat from the room above. Without insulating between the joists it won't make a great deal of difference

 

[Jurassicspark]

Without insulating between the joists it won't make a great deal of difference

 

[trojanhawrs]

I'm saying there's not a great deal of point in insulating your underfloor pipework if there's no insulation between room and void

 

[Jurassicspark]

I'm saying there's not a great deal of point in insulating your underfloor pipework if there's no insulation between room and void

It does help. In winter, do you bother wearing gloves when you're standing outside with the temperature of -2C?

Besides from heat loss, a suspended floor is always exchanging heat from the outside and with uninsulated hot pipes you're going to get condensation. Not a biggie but still worth adding insulation on it.

And lastly it does help the pipes from freezing to some degree.

With that said, hope your boilers condensate pipe is insulated too.