10mm or not 10mm that is the question...

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I have bought a new house (old house - new to me!) and am going to replace the central heating piping on the ground floor.
I want to chase my new pipe work into the walls but the plaster is only 20mm thick. Will I be ok to have a 15mm ring upstairs under the floor boards and then tee off using 10mm pipe 2.5 meters down to each radiator?
I was thinking of lagging the pipes in denso tape and then plastering over, or should I use some plastic conduit? :confused:
 
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15mm ring and tee down to 10mm drops? I wouldn't go there.Get your pipe sizing right from the start and save a lot of heartache.
 
45yearsagasman - I'm struggling to see why a 15mm ring with 10mm tee'd off to each rad individually would be an issue? I know that there would be a (approx) 2500w limit to the radiators used but other than that... Is there anyone else that can contribute with a more "constructive" comment?... :unsure:
 
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That would be better, but I would still use 15mm for the drops and plan the pipework so as to make it less obvious. Do it right first time. There are many things to consider when pipe sizing a system.
 
I'm sorry that my comments were not what you wanted.With so little info from you regarding existing system size/rad size distance of pipe runs what do you expect. Hope you find that more constructive :rolleyes: I'm out.
 
45yearsagasman - judging by your responses you were never in! :LOL: There will be 6 radiators each averaging 1500w, the total flow and return of the system will be circa 50m - distance between radiators approx 3m. There are 4 radiators upstairs all running 15mm, again 3m apart. Can anyone see any obvious issues with the above :?: cheers
 
There's nothing inherently wrong with 10mm. You may or may not be able to get the required output with 15mm pipework, this can be calculated, or you can make a guesstimate.
 
my central heating piping goes 22mm out of the boiler flow/return up to 1st couple of rads then down to 15mm in the 15mm pvc piping flow/return to every rad up and down..is this correct or should it run in 22mm copper piping throughout then tee off in 15mm..what are todays new installs done in ? sure ive seen new houses just done in 15mm plastic throughout ? if it were to be incorrect whats the worst that could happen..rads take longer to heat ur..etc
 
in my opinoin u should never go lower than 15mm on heating pipes.

to much resistance,slow heat up,,and long term,they block easy,i.e debri ect. sometimes they block so hard u cant clear it,so it gets re-piped.
 
The worst that could happen is that the rads never get warm enough to heat the rooms effectively...
 
In my own house all the droppers are in 8mm,the system has been in 30 years although i swopped the boiler last year.I cleansed and treated ,no problems what so ever.
 
Thanks for the responses people - so the worst that can happen if I run 15mm and drop down in 10mm will be that the rads don't heat up effectively?
 
45yearsagasman - judging by your responses you were never in! :LOL:

I think he was.

15mm ring and tee down to 10mm drops? I wouldn't go there.Get your pipe sizing right from the start and save a lot of heartache.

15mm ring, 50m length, 6 rads, 9kW? I'd do some careful calculating. But then he told you that and you didn't want to be told. Reverse return? Maybe not.

Good luck with it. I'd ensure there was nothing left to luck.
 
45yearsagasman - I'm struggling to see why a 15mm ring with 10mm tee'd off to each rad individually would be an issue? I know that there would be a (approx) 2500w limit to the radiators used but other than that... Is there anyone else that can contribute with a more "constructive" comment?... :unsure:

Unfortunately when somebody gives you information you dont want to hear it !

I appreciate that there is a perception that plumbers are all thick and left school at 16 with only three GSCEs but nowadays many have degrees.

In choosing pipe sizes there are many issues to take into account. One of the most relevant is the temp differential and that depends on the boiler model. You have not bothered to tell us what boiler you have or the delta T at which you are operating it.

The reality is that it will work but with restricted pipework sizes may be slow to heat up and might not reach the maximum output. Then the rad sizes compared with the heat loss has to be taken in to account.

Another important point is to ensure there is an expansion adsorbing medium round the pipes to be buried in plaster.

Tony Glazier
 

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