Centra heating - radiators or under-floor?

[AL_n]

Woo-hoo! It's my lucky day! ...Or is it??

I picked up a whole set of second-hand radiators today, for the princely sum of £5! I thought this was fantastic, because my house needs a central heating system, and I have to somehow install one on a shoestring due to a long-term income aqueeze due to a long-term disability.

I hauled the things home and then I started thinking... I wonder if radiators are the best option... Would underfloor heating be a better choice? At least for the upstairs, (the ground floor floors are solid comcrete). The house was built in 1991, with chipboard floors upstairs. The pipework for central heating is already in place, with stubs sticking up where radiators could be sited.

I can see the attraction of underfloor heating, namely that one doesn't have unsightly radiators limiting one's furniture-siting options, but is the alternative (underfloor heating) easy for the DIY-er to install? How much does it cost to do the upstairs of a 3-bed semi? How about if I did the whole house (concrete floors and all)? Does anyone know any crafty tricks that enable one to install an underfloor heating circuit cheaply?

Thank you!

Al

[The Natural Philosopher]

Its certainly worth thinking about BUT UFH suits lots of warmish water rather than a little hot, and often requires a step down auxiliary circuit to drop temperatures below acceptable for a floor sytem

Its almost impossible to do retrospectively on solid floors without digging them up and relaying them. You MUST habe LOTS of insulation between them and the cold ground.

Its very ineffective with fitted carpets as well.

If you haven't got the time or money to do it well, use radiators.

Or you will be disapppointed.

[John Rumm]

Make sure if using s/h rads that once installed you flush the system very thoroughly and treat with the correct concentration of inhibitor.

Well it seems that if you want UFH, you don't want to start from where you are!

Its certainly not the cheap option, and is potentially hard work to retrofit. (its fairly easy if designed in during the build). Hence Given you have pipework already, I would go with rads.

The crafty "tricks" that pros use to do it cheaply include things like running all the pipework clipped to walls rather than under floors etc. However if you are doing the work its really down to how you cost your time, since these tricks will not save you any material costs. Since you say you have pipework, it all sounds a bit academic anyway - the hard bit is done.

[Jules Richardson]

Presumably it's possible to seal them at one end and hook them up to a compressor to see if they're leaky? Maybe they came out of a house that was being converted to some other form of heating system, so they're not necessarily junk.

cheers

Jules

[Peter Parry]

As mentioned above retrofit is very difficult. Even for the upstairs it would involve removing most of the floor to get the pipes and heat spreader plates in.

Works perfectly well here with fitted carpets.

I'd agree with that, especially if you have the pipe work for radiators already in position.

[John Rumm]

Agreed, the rads may be fine - even if a bit rusty, if they hold water once flushed and treated with inhibitor, then there is no reason to expect them to fail at an accelerated rate after that.

However, I would caution against pressure testing any unknown container with compressed air as this is highly dangerous and will result in an explosion if a failure were to occur. Pressure testing is usually done with water for this reason - its inelastic and hence can't store masses of energy in compression.

[The Natural Philosopher]

the two statements are not mutually incompatible: where I have carpeting, the floor gets pretty hot underneath, showing the rug makes a decent insulator. Now if that is upstairs, then more heat is lost to downstairs..if its on the ground floor, more heat is lost to the ground or air. Not good.

You get less watts per square meter out of a carpeted floor than a tiled one for sure. That means you need more pipes and a hotter running floor. And increase risk of heat loss downwards rather than upwards. It can work perfectly effectively, in the same way you can perfectly effectively heat an uninsulated house with 20KW of fan blown convectors. It just may not be the most efficient way to do things.

[The Natural Philosopher]

greed. a 5 bar test on CH systems with water, is a damned good idea anyway. Will find any weeping joints and pinholes quickly.

[AL_n]

John Rumm wrote in news:9dadnQEU1bNk [e-mail]:

Thanks to all for the advice thus far. OK then, it looks as though I'll be using the radiators after all. They appear to be in serviceable condition. There may be a little rust on the inside. I will flush thoroughly, etc.

Al

[Jules Richardson]

Yes, good point! (although I would expect any rad that's likely to catastrophically fail under pressure to be obviously junk - and most will just pop and hiss if they're going to do anything at all. But better safe than impaled by chunks of steel, as they say :-)

[John MacLeod]

On Sep 17, 3:55=A0am, "AL_n" wrote:

The answer in your case is simple and you've already reached the conclusion that you'll use the rads. In which case, make the most of the available heat by ensuring that the wall behind is insulated and that you have reflective foil behind each of the rads. And, most important, a shelf above, to keep the heat from going straight up to the ceiling.

Existing concrete floors downstairs make life rather difficult when it comes to installing underfloor heating. Depending on how thick it is, you might be able to use a Stihl saw -- perhaps in two bites -- to cut it into squares just inside the walls of each room and remove it, excavate down far enough to install insulating board and then lay a snake of PEX pipe below -- or actually just within -- a new concrete floor. We did a simple snake of PEX pipe in two rooms here about fifteen years ago when the 150 year old suspended floors were being replaced -- and our only regret is that we didn't do it over the whole ground floor of the house. As has been pointed out, you need to ensure that the temperature of the circulating water is within the temperature rating of the PEX pipe. You also need to note, as has again been pointed out, the need to run it rather hotter if there are any carpeted areas. However, there's an overlap between the range of temperatures suitable for rads and those suitable for PEX pipe, so by playing around with valves to control the flow rate to different areas it is possible to mix UFL and rads. Not ideal. But possible. UFL is great -- but only if you're in the house most of the time. It's going to take a day to change the temperature in a big way, so it's no use for people who are out all day -- they're not getting the good of it. It makes for a very draught-free house, though -- a much more even temperature.

John

[Spamlet]

I visited a campus office where they had underfllor heating. It was awful and I had to take my shoes off and keep my feet up on a chair to survive a meeting.

On the other hand, under bathroom or kitchen floor tiles, a little heating is good for the early morning bare feet.

S

[Alan Braggins]

When the old Nu-Heat underfloor heating in my house failed upstairs, we decided taking down all the downstairs ceilings off would be a lot easier than taking up the floors upstairs (large T+G chipboard panels, with the walls built on top of them). And putting new heating on top of the existing floor then a new floor on top of that even easier, but still a pain in the neck. So now there are radiators.

And here - or at least when it didn't work, the carpets had nothing to do with it. But the more insulation on top of it, the more important the insulation underneath is, and the slower the response to the pipes heating is, so really thick carpets might be unwise.

[Alan Braggins]

Much of the strength of the legs on this was just to hold it up when filled with water for initial pressure testing:

(Largest pressure vessel in Europe at the time, so I was told. Unless that was the 9x13, not the 8x8.)

[The Natural Philosopher]

Public sector heating is always at someone else's expense..

[Spamlet]

One has to wonder why we have no heated carpets. We have heating mat under our bathroom tiles that was just cut to shape: they could do the same with carpet underlay.

S

[Doctor Drivel]

Don't use second hand rads, they are full of corrosion.

In your case fit new rads as the pipes are there. Also fit a high flow combi as well. Look at the Avantplus 39C combi.

[Heliotrope Smith]

"Doctor Drivel" wrote in news:if7pd5$vs1$ [e-mail]:

Look at the Avantplus 39C combi.

Only one combi??

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