Extending Heating Into Ground Floor Extension

[Joseph Cefai]

Just had a new ground floor extension built and the plumber has taken a feed from the main heating circuit from the boiler that runs under our easily accessible ground floor void, run 15 speed fit pipes back up into the roof of the extension, and then fed back down to each radiator. We have four radiators in total being fed this way. Does this make any sense to anyone else? I was expecting the heating supply to get put into the floor of the new extension (since the screed had not been laid at the point of first fix for plumbing, a 22mm pipe extension from the existing circuit stepped down to 15 mm for each radiator; with each radiator being fed upwards from the floor.

 

[Harry Bloomfield]

No sense, I would expect it buried in the floor, why has he not done that?

 

[Exedon]

Try looking at wras 2.7 no fittings buried in screed floors.

 

[Joseph Cefai]

"WRAS 2.7 covers where and how you should run pipes in any building with a mains water supply".
This is a closed circuit heating system.

 

[oldbutnotdead]

Your builder is lazy. Or forgot to put the pipework in the screed. 4 rads on a 15mm Speedfit feed may be pushing the thermal capacity of the tube at quiet water speed (1 m/sec), especially if you're using a condensing boiler properly (so lowish flow temps and big radiators). Up and down sections like that are an invitation for airlocks as well

 

[Exedon]

"WRAS 2.7 covers where and how you should run pipes in any building with a mains water supply".
This is a closed circuit heating system.

I'm afraid your wrong please read carefully the only heating pipework what can be installed without access to any joints is continuous pipework ie underfloor heating .

 

[Joseph Cefai]

Thanks. Was not aware of this. However, Im not sure it justifies his choice of installation. In meeting this regulation Ive still ended up with 4 radiators being fed from 15mm speedfit (so effectively it's going down to about 10mm at the joints). The consequence is that they often don't even see any hot water before the heating knocks off.

 

[Harry Bloomfield]

Thanks. Was not aware of this. However, Im not sure it justifies his choice of installation. In meeting this regulation Ive still ended up with 4 radiators being fed from 15mm speedfit (so effectively it's going down to about 10mm at the joints). The consequence is that they often don't even see any hot water before the heating knocks off.

You need it properly sorted out now, before the screed goes down, rather than later when the screed will need to be lifted to do it.

 

[Madrab]

If you want this done properly then the 22mm backbone should be extended out and then branched out in 15mm to each rad. If you are going to screed then one way would be to lay ducting for the pipes to run in, or a channel with a removable cover at each joint. There is also nothing stopping the plumber from running 22mm down to a manifold outwith the screed and then running continuous 15mm pipe out to each rad from there, balancing then becomes key but that should be an installers bread and butter. Many ways to do this properly. As an addition to this, as long as copper is used and that copper is soldered properly and pressure tested then it for all intents and purposes it is then considered to be a single pipe for these purposes and can be encased in screed. Before the pipe is then covered in screed it must be protected, either wrapped or sleeved.

Any reason you aren't putting in UFH? It seems like a bit of a no brainer?

As far as WRAS 2.7 is concerned, then that specifically covers mechanical fittings that become inaccessible - looking at the scope of the The Water Supply (Water Fittings) Regulations 1999 - specifically section 1.3 the regs seem to state that they are only applicable to pipework that is or could be connected to water supplied to the undertaker/transporter (mains water). Obviously CH pipework isn't connected to the mains. I think the jury is still out on this and how it is to be properly interpreted as some read it as any pipework in a property that has mains water. Does that mean if I install a rainwater recovery system and run it to all my toilets on a complete closed circuit then the regs apply, I don't think they would care about that TBH. That's the problem with regs, they can be really woolly sometimes.