Radiator distribtion systems

What a lovely old fashioned radiator

There are a whole load of things to be considered when installing a new central heating system and I’ll be writing a load of blogs over the next few weeks to discuss some of these. But I am going to start, probably not where you might expect me to-with the heat source, i.e. boiler type, but with the heat distrubution-i.e. the radiators.

This is my starting point because this is what is most important to you. Unless you’re a heating obsessive you probably don’t want to spend your time worrying about where your heating is coming from-you just want to enjoy ¬†being warm. Therefore the mode through which you ‘feel the heat’ is the most important.

If you’re looking for the most straightforward system to retrofit to your property, then you are looking at a wet radiator system. I would say about 95% of central heating systems in the UK are of this kind and this is for a reason-its effective, its reasonably priced and its not massively disruptive to install.

Some people love radiators. They look at them¬†and just feel warm. I once installed an underfloor system (more on that on next blog!) to an old lady who insisted that I put in a radiator as well…not connect it up, just put it in so that she could look at it and feel warm. Madness! (I eventually talked her out of it and she now loves her underfloor system).

But people like radiators because they know where their heat is coming from, can put their hand on it and know its working. And to be fair, they are a great way to distribute high grade heat around a building. Beware though-they are deceptively complex and more thought goes into a well designed radiator system than you might imagine.

First of all, distribution. The pipes need to get from your heat source to your radiators. There is a flow and a return which each radiator connects to. A bit like this lovely diagram.


So, where are the pipes going to go? Easiest and neatest way is under the floor. But this will only work if you have a cavity (preferably more than 2′ deep-working on your back installing a heating network isn’t that much fun, believe me!) or floorboards that can be lifted and set back down again. If you have a concrete floor (presumably with tiles/carpets laid down) then this is going to be a major job best avoided.

If taking the pipes down is not an option then they must either go horizontally between the radiators or vertically. A vertical system means having the distribution in the loft and then dropping down for each individual radiator. Either way, this is going to mean that pipes are exposed UNLESS you want them integrated into the wall. This is possible although again will mean some mess. A plasterboard wall is easier as the plasterboard can be cut away, the pipework ran and then replaced and replastered. A stone/brick wall must be ‘chased out’. This is the soul-destroying process of chipping away at the brick until there is a space big enough for the pipes to go in. Once everything is in the pipes are plastered back in.

In my opinion, both of these options are totally unnecessary. The pipes should be boxed in or even made a feature of in an industrial uber-cafe, hipster kind of way. Either way, you won’t notice them after a while and the poor plumber will still have the will to live.

Thought should be given to the sizing of the distribution pipework. i.e. if many radiators are being taken off a single branch then the branch needs to be a bigger diameter pipe (i.e. 22mm or even 28mm) than if one radiator being taken off it. However, a heating engineer should probably be consulted for sizing of pipework as it can be a little tricky.

Sizing of radiators is the next job. You have probably noticed that big rooms tend to have big radiators and little rooms have little radiators. I am not going to patronise you with the reason for this. Radiator sizing is done by matching the heat loss of a room with the radiator’s btu or power rating. Now, this is pretty complicated and I know very few heating engineers who actually do it. They usually just go on experience. This will probably be fine but you may get unlucky. Always ask the heating engineer if he or she knows the heat loss of the room and if the radiator is sized to match. If they try to fob you off then they haven’t done it!

One of the problems with radiators is it really limits the room layout. If a radiator is on the wall then you can’t really put furniture in front of it or it won’t do its job. Ideally the radiator should be made as small as possible. This can be done with double, or even triple radiators. These kind of radiators have more depth and give out more heat for the wall space taken up. These are more expensive but really make a big difference. I would always recommend at least doubles in everything except the smallest of rooms. Another little trick that I see more and more is aluminium foil being placed behind the radiators. This basically stops the heat from being absorbed into the wall and reflects it back into the room. Great for making the most of your radiator but doesn’t look too pretty!

People often ask if copper or plastic should be used. To be honest, either is absolutely fine. Copper is obviously the traditional choice and many plumbers refuse to use plastic. But to be honest, they both do the job perfectly well. Some early plastic fittings sprang leaks fairly easily but you shouldn’t get this problem now. Hep-my plastic pipe of choice-offer a 50 year guarantee on pipe and fittings-you won’t go wrong.

One last little thing which is a bit of a bugbear of mine is the tails to the radiator. I hate to see an exposed plastic fitting underneath a radiator. They just look clunky and horrible. As I said above, plastic is fine but a plastic fitting on the tails? No way! Make sure its copper.

Plastic fittings on radiator tails…ugh!

So that’s a few thoughts on radiator networks. Of course, its not comprehensive and I’d love to hear any questions or comments you have on this. If so, please comment below.

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