Fri, 16 Oct 2026 14:44:02 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=12993#Comment_12993 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=12993#Comment_12993 Mon, 21 Jan 2008 17:19:50 +0000 scandibrit Please read them and Tunas entries if you haven't made up your mind yet.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=12994#Comment_12994 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=12994#Comment_12994 Mon, 21 Jan 2008 17:44:49 +0000 jamesingram
They generally seem to know what there on about and as said ,have a longer history of effiecently heated house than we do,

I think the first answer to my question , seems the best
" under the floor "

I've first fixed the job , that the orginal question was for
some of the rads are under windows , some are on external walls , some on internal walls
We tried to put them on internal walls, I do like the idea of a low steady heat, heating up the thermal mass, ( whether this is the most effiecent I'm unsure)
, but really , use of space was the deciding factor in positioning

Any expert heating engineers or scientists that can give a view?

thanks jim]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13002#Comment_13002 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13002#Comment_13002 Mon, 21 Jan 2008 18:36:30 +0000 krishna
[quote]James, I take my low thermal mass / fast response goal even to include the UFH. All my UFH is without screed. On the ground floor I lay OSB over 100mm of Kingspan. I fit 50x25 battens to this at 400mm centres and Foil Tec the lot. Two rows of pipe are nailed to this between the battens and floorboards to suit are fitted over. The Foil Tec spreads the heat all over and it is remarkably quick to warm up / cool down. I run with the flow at 40 degrees. I once tried 50 degrees and nearly cooked everyone. I never use spreader plates they are much much too expensive. I use the same basic idea upstairs except that the OSB is fitted between the joists, set down 25mm and no battens used.[/quote]

1. I assume the ground floor construction here is solid.
2. Is the Foiltec laid over the battens and down into the spaces between? How is it fixed in position?
3. How are the pipes nailed to the FoilTec? Are the pipes nailed to the OSB and is that the reason for having it, or does it serve another purpose?
4. UFH suppliers I've spoken to say the problem with laying the pipes like this is the air gap will act as an insulator and reduce heating efficiency by upto 20%. They say that is why they recommend filling this void with a screed. Is there any logic in this?
5. I spoke to the guys at invisibleheating.co.uk, as mentioned in another thread and they say if you leave an air gap it will then be necessary to run the water at temps as high as 60deg! Surely if you put enough pipework in, there should be no need for such high temperatures?

FInally, we have only 4" joists downstairs and up. I'm thinking of installing UFH on both levels. On ground floor (suspended timber floor), by the time I allow for the 25mm gap under floorboards and the OSB (or pos 9mm ply?), that only leaves me 65mm to bottom of joists. How much Kingspan do I need and is there a way around this limitation. I suppose I could raise the floor level on ground floor by 35-40mm, which would then enable me to use 100mm Kingspan.

All help appreciated.
Thanks
Krishna]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13008#Comment_13008 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13008#Comment_13008 Mon, 21 Jan 2008 19:32:24 +0000 biffvernon https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13018#Comment_13018 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13018#Comment_13018 Mon, 21 Jan 2008 20:24:21 +0000 chrisc https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13021#Comment_13021 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13021#Comment_13021 Mon, 21 Jan 2008 21:19:48 +0000 jamesingram the suppliers should know there product, but I guess they play it safe
heres a guess at the answers to your questions, if I was to try that method
1. yes, the insulation could on a slab with dpm or maybe blinded hardcore with dpm ?
2.yes, staple gun, imagine the supplier usual 1st floor method ,it sthe same but the foil tech replaces the spreader plates(which are dear)
3.nail down pipe clips into the OSB , like cable clips but 15mm
4.they dont on the first floor solution they offer , but do they decrease the spacing, more pipe m2 ?
5.my rads in my house run at about 45-50 deg heats fine, there design temperature is higher
6. can you get below the joist and suspend quilt, could you increase the joist size downwards , more room for PIR board
have a look at the last Greenbuilding mag there a article on floor renovation p46, very similiar

I like 'workoholics' solution for a low thermal mass ufh floor , cheap and simple,
but I think i'm with screed, heavy weight loby still, just seems to make more sense to me
something to take advantage and hold the low temperature heat, spreading it slowly and evenly]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13091#Comment_13091 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13091#Comment_13091 Tue, 22 Jan 2008 17:56:57 +0000 scandibrit
Good point Chris! You're solution is spot-on. Scandinavians mount a shelf/internal sill behind curtains with a gap between base of window frame and shelf/sill so that some heat rises in front of the window stemming cold and humid penetration of the room (essential) and some heat raises the room temperature. Full-length curtains can be pulled back below the internal sill or preferably shortened.
Heavy lined curtains prove the point that we all want to stop cold air plunges penetrating the room (and giving distant radiators a massive job to do! -which they can't efficiently because their heat rises up the internal wall and across the ceiling instead of stemming the cold air crossing the floor and filling the lower half of the room).]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13135#Comment_13135 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13135#Comment_13135 Tue, 22 Jan 2008 23:25:43 +0000 chrisc Posted By: scandibritScandinavians mount a shelf/internal sill behind curtains with a gap between base of window frame and shelf/sill so that some heat rises in front of the window stemming cold and humid penetration of the room (essential) and some heat raises the room temperature.

Ahh, interesting, I didn't know about the gap to allow some heat to go up behind the curtain, how big should this gap be, 5mm or so?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13146#Comment_13146 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13146#Comment_13146 Wed, 23 Jan 2008 00:51:23 +0000 Paul in Montreal
http://www.esim.ca/2001/documents/proceedings/Session7-2.pdf

All that said, energy efficiency and perceived comfort are often at odds so the most energy efficient solution may not be the most comfortable - which leads to human factors changing the thermostat for comfort at the expense of efficiency. Air that is at less than blood temperature feels cool when moving over the body which is why a drafty room at 21C feels much cooler than one with perfectly still air at 18C. This is part of the reason UFH systems use less energy than conventional systems - not because they actually use less, but because they give the perception of warmth at lower air temperatures than either forced air or radiator systems.

Paul in Montreal.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13164#Comment_13164 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13164#Comment_13164 Wed, 23 Jan 2008 12:25:11 +0000 tony https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13165#Comment_13165 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13165#Comment_13165 Wed, 23 Jan 2008 12:36:09 +0000 Chris Wardle ]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13187#Comment_13187 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13187#Comment_13187 Wed, 23 Jan 2008 17:13:54 +0000 Ian Ashton
After spending time in Trondheim, I noticed that not many Norwegians close their curtains.

This makes sense that with highly insulated windows, you are warming the area around the window, and limiting condensation of cold air trapped behind the curtains.

This also stops the windows condensing externally or even icing over in the coldest temperature, due to heat loss through the glass.

When we are talking about windows with centre panes of 0.5w/m2k, then unless you have massive glazed areas, the losses are not that great. Obviously the worse the windows perform, the worse the cold air problem becomes, and the greater need for curtains, greater condensation problem.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13409#Comment_13409 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=13409#Comment_13409 Sun, 27 Jan 2008 23:34:41 +0000 scandibrit
Ian, that's right. Most Scandinavians don't even bother to draw their curtains. But it's not to prevent ice building on the outside. The cold air lowers humidity and condensation doesn't form externally because the outside of the glass is practically the same temp as the air itself, esp with double glazing or more. (On the other hand ice forms on your car windscreen in the morning if your car's colder than the damp air. At stable low temps of -10 or -30 celsius, your car actually ices up less. Excuse the digression!) You're right to bring humidity and condensation into the equation however!
As Paul's link proves the science of this is very complex and not just a matter of simple arithmetic.
I still find this link helpful: http://energysavingnow.com/comfort/ for a Swedish view.

I fully agree with Paul -perceived airflows and humidity certainly make us turn up the themostat whatever the actual temp. That's why ventilation should probably also be discussed here.......at least, where to place it........]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=23793#Comment_23793 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=23793#Comment_23793 Mon, 16 Jun 2008 17:18:38 +0100 davidHarris As we are only intermittently in our house, it seems to me we want a fast response (small thermal mass). Standard advice is that 50mm+ of screed is needed or it will crack. If we use a solid wood floor (reclaimed sleepers etc) which would take the load of people's weight etc, could we get away with only just covering the PEX pipes? If it cracks, does it matter? If I understand you correctly, you have no screed at all and presumably the 40mm battens take the weight from the floor?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=23812#Comment_23812 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=23812#Comment_23812 Mon, 16 Jun 2008 20:23:36 +0100 philedge https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27081#Comment_27081 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27081#Comment_27081 Tue, 15 Jul 2008 17:15:50 +0100 TheDoctor
Boiler comes on Monday - cant wait 'til winter?!!

its just the complicated / duel control nature of running the old half of the house on radiators. Bedrooms only though, so no need to heat above 16 degrees]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27088#Comment_27088 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27088#Comment_27088 Tue, 15 Jul 2008 17:55:30 +0100 mrswhitecat https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27341#Comment_27341 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27341#Comment_27341 Wed, 16 Jul 2008 23:49:23 +0100 craigindav this eliminated the higher level of heat loss from "hot spots" where areqas of much colder were close by
ie. rads under windows
so that you felt warmer with a lower avarage temp.
This is what they are pushing now with underfloor heating
What goes around comes around.
whatever happened to Fin-rad?
I googled finrad & only got a marine floor rad or an investment bank]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27342#Comment_27342 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27342#Comment_27342 Thu, 17 Jul 2008 00:07:26 +0100 hotelRefurber
By the way I would have been better to spend that £500 on something far more worthwhile like additional glazing on the window..

I have serious doubts about underfloor heating - expansion and contraction in the floor - probably a long term maintenance nightmare, imagine if you get a leak too. Furthermore it means the thing has to be on most of the time as it takes longer to get the heat you want.

The great thing about underfloor heating is you can operate a lower temperature,why not have larger wall based rads or maybe an air based heating systems make the most sense - but I dont know much about the nitty gritty - possible complex mechanical issues.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27344#Comment_27344 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27344#Comment_27344 Thu, 17 Jul 2008 07:09:13 +0100 joe.e https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27346#Comment_27346 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27346#Comment_27346 Thu, 17 Jul 2008 08:17:02 +0100 jon
If that happened you would probably be living in an older house and so would need the radiators under the windows?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27351#Comment_27351 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27351#Comment_27351 Thu, 17 Jul 2008 09:10:11 +0100 joe.e https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27352#Comment_27352 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27352#Comment_27352 Thu, 17 Jul 2008 09:17:33 +0100 agu https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27353#Comment_27353 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27353#Comment_27353 Thu, 17 Jul 2008 09:21:14 +0100 Chris Wardle
If I had to fit another house out with radiators I'd put them under the window for less restrictions on furniture positioning and the avoidance of cold sinking air next the window due to heat losses through the window. I would fit a cover to the radiator and insulate behind it, thereby reducing heat loss into the wall and directing heat out into the room and not up behind the curtains. The worst thing to have in a room is a cold spot or a draft as the individual experiencing it walks directly to the TRV or the room stat and turns it up.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27796#Comment_27796 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27796#Comment_27796 Mon, 21 Jul 2008 12:46:43 +0100 craigindav reduce the number of hotspots with even levels of insulation means fewer cold spots in the room.
then the rads can be sited wherever suits the room layout.
If that is against an internal wall then all the outer walls are still at an even temperature.
I have a client who wanted skirting rads but all I can find online is "discrete heat" any body seen anything of "fin-rad" lately (other than boatbuilders or merchant banks).]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27797#Comment_27797 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27797#Comment_27797 Mon, 21 Jul 2008 12:48:43 +0100 agu https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27799#Comment_27799 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27799#Comment_27799 Mon, 21 Jul 2008 13:34:26 +0100 Graham T
Have a look at http://www.hekos.com/UK/index.php and http://www.radgone.co.uk/index.htm and the thread titled "radiators or ufh" in Housing - Renovation.

I am almost certainly going for DiscreteHeat's Thermaskirt - Rapid response times of rads, even heat of ufh, frees wallspace, looks good, does what it says in the blurb, good reports from installers and users, can be fitted by a competent DIYer, can support installation of towel rads. More expensive than wall rads but cheaper and less disruption than ufh.
I am also insulating my walls and solid conc floor.

Graham]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27806#Comment_27806 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=27806#Comment_27806 Mon, 21 Jul 2008 14:56:27 +0100 davidHarris https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=29645#Comment_29645 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=29645#Comment_29645 Sat, 09 Aug 2008 09:02:12 +0100 nandos
If you require a bay window radiator visit

www.shivradiators.com


The company custom builds radiators to fit bay windows.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=29655#Comment_29655 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=924&Focus=29655#Comment_29655 Sat, 09 Aug 2008 11:45:37 +0100 tony
Best place to site a radiator is to leave it at the merchants -- then you dont have to pay for it or the heating system, bills etc. ---

I you must have them then on internal walls or in the floor are both better places in terms of saving energy and resources.]]>