Upstairs heating options for passivehaus - electric or wet systems; looking for advice

[Great_scot_selfbuild]

Looking for advice on electric UFH pads/loose wire laid to a plan. We don’t believe we’ll need it much if at all, but we’ve not met or spoken to anyone who has used it - effectiveness, cost, installation. Here’s our situation and some questions.

 

Our build will have a passivehaus level of thermal and airtightness. I’ve visited a similar size/build where they have wet UFH downstairs and only towel radiators in the bathroom upstairs; they have no issues with warmth upstairs.

 

(Numbers for ease of reference / comment)

 

Current thinking / starting point:

1. Wet UFH downstairs
2. Towel rails upstairs (electric)
3. Electric UFH pads in bathrooms (electric) 
4. The back-up: Install electric UFH pads in the bedrooms (not covering the whole floor area) as a reserve for cold snaps and the ability to apply some heat to the bedrooms that could be relatively effective (i.e. you’d be walking on it and so the impact of turning it on would have some relative immediacy of effect).

 

Alternatives we’re considering:

5. Install wet radiators (2 bathrooms) connected to the ASHP.

6. Would prefer not to install wet heating to the bedrooms (space, cost, don’t believe we’ll need it).

 

Question about electric UFH:

7. I’ve had slightly confusing explanation from a UFH supply company (clearly in sales, not technical). They described the electric pad installs (for both under tile and under carpet) as:

a) Tile backers required (are they essential).

b) Electric heating pad, or loose heating wire that can be laid to one of their designs, which allows it to fit around items (beds/baths) easier.

c) Self-levelling compound is mixed up to lay over the wire (as shallow as 10mm). We have a timber frame and timber first floor (Caberdek) and so I asked about this needing to be waterproofed - he didn’t have an answer.

 

I appreciate that’s quite a download, any comments/sanity checks appreciated.

[Bornagain]

Our self build is heading towards passiv haus, wall u value=0.15, roof=0.1, windows/doors=1.0, MVHR etc etc.

 

We heat the house with UFH downstairs into a very thick slab, we have no heating whatsoever upstairs.

 

if we built again, we would do the same, there is absolutely no need unless you want a very warm bathroom - we don’t.

 

[JohnMo]

With it being upstairs and if doors are open you are likely to have warmer bedrooms, like it not, I would keep it simple. Just install panel heaters in bedrooms or the provision for them, keep the electric UFH in bathrooms. But if you are going for a grant (I just wouldn't bother) they will require all heating by ASHP.

 

But to mess your head up more, are you likely to need cooling upstairs? If so just do fan coils for heating and cooling in bedrooms and bathrooms. Cool Energy do bathroom fan coil towel rails. Do mild cooling keep the water flow above dew point then no need for drains to be added.

[Great_scot_selfbuild]

4 minutes ago, Bornagain said:

Our self build is heading towards passiv haus, wall u value=0.15, roof=0.1, windows/doors=1.0, MVHR etc etc.

 

We heat the house with UFH downstairs into a very thick slab, we have no heating whatsoever upstairs.

 

if we built again, we would do the same, there is absolutely no need unless you want a very warm bathroom - we don’t.

 

Thank you!

[Great_scot_selfbuild]

3 minutes ago, JohnMo said:

But to mess your head up more, are you likely to need cooling upstairs? If so just do fan coils for heating and cooling in bedrooms and bathrooms. Cool Energy do bathroom fan coil towel rails. Do mild cooling keep the water flow above dew point then no need for drains to be added.

We did do a lot of thinking around this early on (pre-detailed SAP and modelled part O calcs). I think we’re good, but I’m going to look into this as what you’ve described is new to me - can you point to a couple of links of what you’re describing please?

[JohnMo]

https://coolenergyshop.com/collections/radiators-fan-coils?srsltid=AfmBOoo2Jwpa28-xTPSwQCmxyskK6onq3GBoEW004T_AV7JvfWtJQvZo

 

Here are a couple of photos of ours which heats a summer house (a Myson unit). First is the unit without the cover installed, controller is on the right, a finned radiator panel behind the sheet metal and a linear fan below it. It basically modulates the fan speed to maintain a a set room temp. Way smaller than an equivalent radiator.

 

[Thorfun]

We have wet ufh downstairs and electric towel rads and electric ufh in the bathrooms. 
 

our heating backup is our AC. Not needed it to heat yet at all. 
 

BUT…..we use the AC all the time in the summer. We have external blinds to keep the heat of the sun out but it’s nice to be able to look out of the windows so AC is essential. Plus as we use it in the summer it’s run off the solar so is effectively free to run. 
 

obviously, @JohnMo’s suggestion of fan coils would work but we decided to keep our systems separate which has advantages in my opinion. Plus a ducted AC system is extremely quiet and unobtrusive. Only thing I’d do differently if I was doing it again is install ducted AC everywhere rather than having wall units downstairs. 
 

Give serious consideration to keeping the house cool. 

[ProDave]

We have wet UFH downstairs and wet UFH upstairs only in the bathrooms.

 

We like a cool bedroom 17-18C is fine.  Most of the year to keep the bedroom that cool we need to keep the door shut.  In the cold weather we have been having for the last few weeks, we occasionally have to open the bedroom door to let a bit of heat up the stairwell in.

 

I fitted an electric point on the wall of each bedroom to fit an electric panel heater should it be required.  None have ever been needed.

[Bornagain]

43 minutes ago, Great_scot_selfbuild said:

Thank you!

As an afterthought, our stairwell is very open and this allows heat from downstairs to make its way into the upstairs rooms, we have to keep the bedroom doors closed  to keep them cool.

If your stairwell is very narrow then there is a possibility that the heat from downstairs won’t be able to make its way upstairs, it’s worth thinking about.

[FarmerN]

We are in a bungalow so not comparable.

 

I would recommend electric towel rails on a timer . Ours are on 3 hours a day, at cheap rate, hour and a half morning and night. Towels always dry.

Our towel rails have timer built in to element , but wish we had put the timer in the wiring circuit, probably back in plant room.

 

We have wet UFH which is on 9 months of the year but we have 90mm screed and tiles, with a different, warmer surface, might not need it. The floor and stone effect shower tray do dry quickly after a shower. Not had any heat on in bedrooms through the two winters we have been here.

We put a high level wire connection to take an infrared heater or similar if required but not needed it yet, but its there for when I am 90 if needed.

 

Both our neighbours in new builds, both with heat pumps and MVHR,  talk about over heating far more than heating, but both have a lot of glass. Overheating not been an issue for us but we have a lot less glass, and high level Velux windows we can leave open at night when warm.

[Nestor]

Recommend in bathrooms, electric UFH and electric towel radiators with accessible timers.

We have wet UFH elsewhere but not used in the first floor bedrooms since moving in. 

Cooling must be considered. I plumbed for independent AC (Not implemented yet).

As above keep it simple.