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This got me thinking...does a product exist that simply adds fans to the top of standard radiators to perform this function. Indeed, quite a few seem to exist, although they all seem to be cheapish and a bit of a hash-job. E.g. https://radiatorfan.co.uk/radiator-fans/ I did find a very interesting report on experiments that were carried out on radiator fans... https://www.sciencedirect.com/science/article/pii/S2214157X23007384?ssrnid=4513816&dgcid=SSRN_redirect_SD They found that the 337W of a std convector radiator at 40degC was increased to 616W at normal fan speed and 1173W at higher fan speed. Good empirical proof that they work as you would expect. It states that the effect is greater at lower flow temperatures, so lends itself well to ASHP heating and I wonder if these are a good way around fitting bigger rads. It would also be easily removed if it was found that the MCS heat demand estimates were overdone. Anyone have any experience of these?

I may be adding confusion. If I was going for UFH then I would be digging out and installing thicker insulation. The 30mm was just to be laid on top of existing slab. I'll need to recalculate the room demand based on the extra insulation to see if the rads need upgrading.

I was assuming that you need special insulation for the compressive strength, but I guess the battens get around that. Thinking further about this though...the battens will likely create thermal bridging points in the insulation so am I possibly better off with XPS or PIR that has greater rigidity and doesn't require battens? Also easier to install and cheaper. I see Kingspan Thermafloor comes in 30mm.

The realisation that I probably can't lower the flow temperature as I still have rads in other rooms has got me thinking again about UFH. I would still love to put some insulation in though - and this may help bring the room demand down such that I don't need a massive radiator (or multiple plinth heaters!). Is there good insulation that can go directly under wood flooring? There is a slight step down to the living area so I could install to 30mm without a massive impact.

For reference it's a stone walled, detached house. Built about 1880 I think. Walls are about 50-55cm thick, I assume rubble filled. My point was that the walls were there long before a cement floor was laid, so it should be in no way structural. If I was digging out then I would intend to taper in (45 deg?) at the edges and ensure that I am in no way compromising the wall foundations.

I think the floor was relayed in 2006 when the house was reconfigured. The stone walls have been standing for 120 years before that so I think will be fine as long as I don't undercut the founds. Although I guess given the age it was probably built straight on the ground.

Ah, ok sorry. Had a look at the SS5 and at 45degC ASHP temps it only puts out 0.6kW at the 'normal' setting (or 1.1kW at 70degC). The existing double convector in my living area is rated at 2kW. So I guess I would need at least 2. I assume the heat from them is better distributed, given that it is blown rather than convected?...what are people's experience of this? Or do they create a 'wind-chill' effect?

Direct electric? I prefer the idea of a 4+ COP over the next 25 years. 🙂

I had quotes for exactly this a year or two ago. Since then my oil-fired boiler has had numerous issues (to the point of needing replacement asap) and I've also realised that I can get a £9000 grant for a full ASHP (sadly no grant for air to air)! The thinking behind the UFH was that it's also a chance to stick in 100-150mm insulation. The heat demand survey shows a huge loss through the floor.

Ah, I was wondering that and have already asked the installer this question. My assumption was that the flow temperature could somehow be reduced for an UFH loop. I guess it just reduces the flow instead?

I've just arranged for quotes for installing an ASHP to replace our ageing oil-fired boiler. I highly suspect they are going to come back and say that our radiators in the living space are too small and would need replaced. For that reason, and for general comfort/insulation, I am considering retrofitting UFH for the living space. The floor is currently wood on concrete, redone in 2006 and I assume uninsulated. I would do an 'exploratory hole' to check this before proceeding! The room is 5m x 4m. My first thoughts are to lift the wood flooring, dig out the concrete to required depth (up to edges but not affecting founds), flatten with hardcore, lay insulation (100mm or 150mm PIR/PUR?) + DPM, lay UFH pipework and encapsulate in a 60-75mm concrete slab, re-lay wood floor. I'm not sure that I would be able to have insulated upstands at the edges so I guess I would keep the UFH pipework inbound a bit more (500mm?) to reduce the thermal bridging. Anything I'm missing or need to be aware of before speaking with installers/builders? E.g. is it a good idea to be mixing UFH with radiators (in all other rooms)?

Yes, Iceverge you are spot on. I should have dug into the numbers. I thought aerogel was supposed to be some wonder material but once manufactured into the blanket form a K value of 0.02 vs 0.034 is Rockwool is not exactly groundbreaking. I now see why aerogel has not taken off! Thanks.

This doesn't make sense to me. The U-value of aerogel blanket far exceeds that of rockwool.

Lost the thread on this when xmas took over. Does anyone know if Spacetherm (aerogel blanket) is suitable for this purpose? By the specs it looks ok for temperature and is fire rated.

10mm 'Spacetherm' aerogel blanket is about £150 for the area I need. Not cheap, but if it makes the room warmer I'm willing to stomach the price

I'm changing out a wood burner and I want to insulate to the stone wall behind while I have access. I only have about 60-70mm from wall to flue. Can anyone advise on best fire board and insulation combo to give best insulation? Is aerogel fit for this purpose? Only 1m2 so cost is not an issue.