Officially confused about first floor wet UFH

[Tadpole]

We are building a pretty conventional Potton SIPS house with ground floor wet UFH, heat pump, insulated raft, triple glazed, MVHR.....  Most of the time there will be just two of us in a 3 bedroom, 3 bathroom house; so only one bedroom & bathroom in regular use.

 

For the first floor our plumber and project manager both want to install wet UFH. It will be in some sort of grooved or clipped panels as it will go in after the first floor flooring is down.

 

Here's my question. I've read quite a few times on here of people who installed it but don't ever turn it on, people who didn't install and don't regret it. I haven't seen any examples where someone chose not to install it, but wishes they had.

 

So, are you out there?  

 

thanks in advance

 

[Ronan 1]

Interested in this thread too as I'm in the same boat except my plumber and architect reckons I don't need anything just a few towel rads in upstairs en suits and bathroom, but I just feel if I didn't put it in now and needed it later I'd regret it big time and don't think the saving will be that big and I could always leave it turned off BUT I currently flip flopping on the subject

[SteamyTea]

Do a room by room heat loss calculation and that will tell you. It is why it is done, room by room.

[JohnMo]

I would do wet or even electric UFH in bathroom/ en-suites and electric towel rads (for towel drying, not heating 300 to 400W).  And provision for an electric panel heater in bedrooms.

 

UFH in bedrooms has no real place, we have it and its a complete waste.  Very slow to heat up and even slower to cool down.  You need (possibly) a warm hour in the morning and evening.  But cool when you go to bed. 

 

I would keep the cash in your pocket.

[Faz]

I have wet ufh downstairs and rads upstairs with electric ufh to the bathrooms.

 

Since moving in early this year I have turned to upstairs rads off and no-one has ever used the ufh in the bathrooms.  The ground floor heat loops are so effective it sorts the entire house. I used Prowarm electric mats which were fairly cheap and easy to install but you then have the faffing about with laytex screed and the like.

 

I wouldn't bother if I were you.

[CharlieKLP]

I think UFH on the ground floor and radiators upstairs (towel rails in bathrooms too) is really quite pleasant. I do know some people with UFH on both floors who like it too, that’s struck me as unecessary and I like UFH to be combined with tiles so it radiates heat slowly. 
 

I don’t really see the need for SIPs and triple glazing, I think it’s too expensive for what you get. There’s a good chance your spec is so high it’s going to roast you. Ask Potton for a SAP and overheating calc.

[LA3222]

I have wet UFH upstairs and down. I turn it on in the colder months, the way I see it is that 280m2 of UFH vs 140m2 is a better way to warm the house. Also I wanted to be able.to heat all the ensuite tiled floors. I have them set to a temperature probe in the floor rather than air temp so the floors are nice and warm when showering etc.

 

The other reason I wanted both is when I turn the ASHP to cooling mode. My logic is again, that 280m2 of loops will cool more effectively than half that.

 

 

[ProDave]

Our last house, built nearly 20 years ago to ordinary standards of the time had wet UFH upstairs and down and it needed it and it generally worked very well.

 

The present house we finished lat year is built to much higher standards, close to passive house, nice and air tight and well insulated.  This one we did not fit any heating upstairs apart from UFH in the bathrooms to take the chill off a tiled floor.  This had proved entirely satisfactory even up here in a cold Highland winter, the bedrooms are always warm enough.

 

In fact at times I get the complaint that the bathroom floors are cold and "it is not working"  That is because the bathrooms are up to temperature and the UFH has shut off and the floor cooled down.

[LA3222]

This is one of those topics where 'in my opinion' folk like to say how their house is so good they don't need it - bit of a look how big my schlong is statement. 

 

Yes, in a passive house the first floor will generally be warm enough without, but the outlay is minimal and the benefits worth it imo.

 

We talk about oversizing ASHPs to make them work less hard etc, why wouldn't you over size the 'emitting' surface within the house so it is easier to warm up/cool down.

 

When folks are insulating their houses to the hilt and making them airtight and sticking loads of glazing in, keeping cool is a far bigger issue than warm. The use of an ASHP in cooling mode seems a go to approach on here to help in that sense, surely having twice the surface area when using the ASHP in this manner is one of the key points in favour of installing UFH upstairs.

 

For context, my own build is 0.1 U Value for walls, floor, ceiling, triple glazing and 0.2ACH. Keeping warm is not an issue and was never going to be, I put the UFH in upstairs for other reasons, keeping tiled floors 'feeling' warm and helping to cool in the warmer months.

Edited May 17, 2022 by LA3222

[SuperJohnG]

I've not installed it on the first floor...purely based on what I read here. Mostly on a hope and prayer.. but with some degree of calcs that my heat input would be low...6kW for the whole on a minus 20 day. 

 

I'm.going to do electric UFH mats in bathrooms and worst case know I can add wall mounted electric heaters for a quick blast if I have gotten it wrong. 

 

SIPS build pretty much as you described with 300sqm. 

[Tadpole]

Thanks to all who contributed. 

 

Our (likely) plumber gave me one of -those- looks when I suggested not bothering upstairs. 

 

I've now settled on wet ufh upstairs on the basis that the incremental cost is not significant; and one day when we want to sell, we won't have to explain or justify.

 

thanks again - now for my next topic (pending).

 

[Temp]

We have wet UFH on both floors. It gets used upstairs. Great with stone floor in bathroom. 

[Nickfromwales]

On 19/05/2022 at 20:15, Tadpole said:

I've now settled on wet ufh upstairs on the basis that the incremental cost is not significant; and one day when we want to sell, we won't have to explain or justify.

Just advised one client to do exactly the same. Negates ever having to fit / temporarily install a panel heater for 'whenever'. Cost uplift is negligible when view as a % on build costs, and North facing bedrooms will be colder on PHPP, regardless. 

[joth]

I wish we'd installed it upstairs, for increased cooling capacity, not for heating!

Like others we currently have no heating upstairs and it still runs 2-4ºC warmer than downstairs. Stack venting cools downstairs a treat, but the house stratifies the warmth very well and retains it upstairs.

For a new build I guess the cost is negligible but we were a retrofit and installing upstairs would have been quite a lot of expense, so still glad we didn't, but I now have a never ending project getting the upstairs FCU installed and effective.