Central Heating Install advice

[zanwan]

I've been asked to install a brand new central heating system at a friends house. He wants 7 Rads installed, 3 downstairs, 4 upstairs.

I wont be installing the boiler as i'm not corgi, havent done any boilers before so dont wanna mess around with this. I will simply install the rads and pipework all the way to the boiler location and a gas engineer will instal boiler and make final connections.

I've done a bit on rad installs when i was at college, measuring up, installing etc. However i'm a bit unsure on a few things based on what i have seen in some houses and was hoping someone here could advise.

My parents house has 7 rads, however the pipework is all 15mm all the way around the system, flow and return (sealed system). Its only just as the pipes leave the boiler that they are 22mm. After about 2 metres they reduce down to 15mm.

Now i always assumed the pipework was 15mm for flow, and 22mm for return?

Could i do my friends install as my parents house is, 15mm all the way and then 22mm just as the pipework reaches the boiler?

thanks in advance and merry christmas!!!

 

[Bahco]

Could i do my friends install ....... 15mm all the way and then 22mm just as the pipework reaches the boiler?

Can't see why not. The more 22mm you use the easier to balance.

 

[dextrous]

Personally, I'd go for 22mm flow and returns and tee off to the rads in 15.

Depends on your pipe runs really.

 

[zanwan]

what would be the potential downside of 15mm all the way round?

 

[dextrous]

Probably fine for a small system. Just thinking long term sludging up, which isn't so bad nowadays with chemicals and magnacleans etc.

 

[squarenut9]

Probably fine for a small system. Just thinking long term sludging up, which isn't so bad nowadays with chemicals and magnacleans etc.

I used 22mm all round, teeing off with 22-15-22 Tees per rad and the last on line I used 15mm immediately from the second from last rad. A 22-15-15 Tee was used here. I also, because I have wooden floors, fitted drain off cocks enabling me to drain off ther system from outside, not messing about inside under a radiator and staining the carpet. Also make sure you get good quality pump isolator valves. The cheepes are a waste of time, they seize up after a few months even with inhibitor

I used to work along side heating engineers in the past and has no end of useful advice.

 

[dextrous]

IronNaz,

You may want to suggest to the owners that they have an independently controlled bathroom heating circuit (towel rad plus small standard rad for heat) to enable tham to have heat in there in the summer all year round (towel drying facility!)

This entails two -2port valves situated near the boiler(one for the main house and one for the bathroom), a 2-channel programmer and an RF thermostat (for the bathroom - no electricity in there, you see) in addition to the main house thermostat. Works well for us! Couple of hundred more in materials, but worth it in my opinion.

 

[londonboy]

Dextrous would it not be cheaper to take bathroom rad(s) off primaries and stick a trv on it? I dont know the regs as I'm no plumber

 

[dextrous]

Dextrous would it not be cheaper to take bathroom rad(s) off primaries and stick a trv on it? I dont know the regs as I'm no plumber

Possibly. In my case we had a combi installed, so your method didn't apply.