Barry1965

Thanks for the plinths heaters idea. These look to be cheap and effective https://kitchenheaters.co.uk/product-category/heat-pumps/ but does anyone have any experience of these or other models? Is the noise excessive? I can only find a couple of videos online that suggest they might be noisy...

No plinths and food will be stored elsewhere, so there shouldn't be an issue heating these areas.

Yes, heat pump is already installed and house is now mostly well insulated too. Although it's the kitchen, because we are going for free standing units we were planning on installing UFH to all areas. We hadn't thought of plinth heaters before but they do look a good option for an occasional boost, thanks.

I completely agree! But it's this or rethink the kitchen layout to fit in some massive radiators...

Thanks for your replies @ProDave@SteamyTea@JohnMo, @Nickfromwales We were looking at the overlay systems because we want to avoid any digging up if possible, and as we have ASHP we would be looking at running it continuously with flow temps of max 35C. Having done a bit more reading around yesterday, I went back to our original heat loss report and calculated the following: For the areas we are looking to install UFH, floor heat loss is currently ~500W or about 6% of total house heat loss, so assuming a doubling in floor heat loss in these areas due to hotter UFH heated floors (and ignoring any insulating effect of overlay panels) would give an overall increase in heat loss of ~6%. Our heat loss report gave a figure of ~5000KWH for annual heat pump energy use for space heating (in reality this has been much lower), which at ~20p/KWh would mean an additional cost of ~£60 per year if we used UFH in these areas... which seems very low. Or have I missed something or made any daft assumptions? In conclusion, as we are only proposing to install UFH to ~28% of floors and because downward heat loss is only a minor part of total heat loss in these areas, then the additional heating cost shouldn't be too extreme. Thanks again for your help, Baz

Thanks for your replies. We don't have any insulation below the proposed overlay system. The floor is currently concrete slab and we don't really want to start digging down, and existing doors and fittings limit us to about 40mm build up. If we were to put down an overlay system on the concrete slab then pour a thin layer of liquid screed over the top, what sort of outputs could we expect if we topped it with 10mm tiles. (assuming 20mm XPS boards, 16mm pipe at 120 spacings) Thanks again for your help, Baz

Thanks John, We're using a heat pump so want to keep flow temperatures as low as possible. Do you think the OSB had an impact on the poor performance of your system? Thanks, Baz

Thanks John, What was the overlay system that you used? Was it rubbish in terms of outputs or were there other issues too? We are restricted to a build up of 40mm max so are unable to use a screed system unfortunately. Are there similar output charts to the one you included for overlay systems? Presumably this output also depends on the insulation below the installed system? Thanks, Baz

Hello all, There are several overlay panel systems that we are looking at (Wunda, Ambiente, Nu-Heat etc) that give expected heat outputs per m2 for their systems. For example, Ambiente claim that their AmbiDeck 20 Pro gives out 70W/m2 at 35C MWT with a 150mm pipe spacing and a 0 tog floor tile finish in a 20C heated room. How realistic are these claims and are there any important assumptions behind these figures that we should be aware of. Our system is to be installed on concrete slab (no insulation below) and running 24 hours a day at flow temperatures between 30-40C. Many thanks, Baz