Adding extra radiators. Help!

[Raif]

We have a small one bedroomed house heated by a combi-boiler and, at th

moment, four radiators. Basically I want to add a couple of extr radiators in the small hallways (if thats the right term, they AR small) at the front and rear of the house. My plumbing experience so far consists of moving and replacing tw radiators and I'm reasonably confident with pipework. I have trie reading up as much as possible and know a little about flow and retur pipes and not connecting radiators in series. What I'm not sure abou is how I connect up the two extra radiators as there is no acces (without major work) to the flow and return pipes coming from/to th boiler. I do have access (from the cellar) to the 15mm pipes feedin the living room radiator though. Can I tap into these? As far as I ca tell, the flow/return pipes from the boiler simply run vertically dow the wall (boxed in and behind work surface)from the boiler in th bathroom and come to an end below floor level in the corner of th kitchen directly below with 15mm pipes coming off feeding each of th four radiators. Hope I've made myself clear and not waffled too much - first post! Any advice greatly appreciated

-- Raif

[John Rumm]

The short answer is yes.

As long as the living room radiator is not huge (and hence using all the capacity of the 15mm pipework) you should be fine. Even then it sounds like you only need to add small extra rads so its unlikely to be a problem either way.

[Raif]

Thought/hoped that might be the case. Not sure if the two curren radiators on each floor are connected independently to the flow an return pipes from the boiler or whether one feed covers two radiators if you see what I mean?! When you say huge, how huge is huge? ie what is the capacity of th

15mm pipework

-- Raif

[Christian McArdle]

It is quite likely that you can just use those pipes. 15mm pipework is good for 6kW, IIRC, which easily runs 1 large and 2 small radiators. My 3 bed house was plumbed with each floor sharing one 15mm run, joined together by

22mm runs to the boiler, although I've modified it so that each 15mm run is off its own zone valve, with a new 22mm to the loft where the boiler is.

Your main problem is if the main trunk of your system is run in 15mm, which could be quite marginal to run a 1 bedroom house from. You may need to turn the pump up in this case and it might get noisy in some circumstances. If so, consider replacing the pump with a Grundfos Alpha model. This would be cheaper than replacing the congested sections with 22mm, although, perhaps not quite as effective.

Christian.