Is UFH for bathrooms worth it?

[MortarThePoint]

It's interesting to calculate how well coupled different areas within the insulated envelope are connected. In the extreme, I think I have worked out that if we had no first floor heating, it would only sit lower in temperature than the ground floor by 20% of the difference between the inside and outside temperatures. So that's an unheated first floor temperature of 16C when the ground floor is 20C and outside is 0C. It's a lot of effort to go to really for the benefit since all our living space is downstairs. It feels too brave to omit it completely though.

 

Considering just the bathrooms however. Each has only 25% of its walls as external and the ceiling u-value is obviously massively better than that of the floor. If the bathroom was unheated, it would be less than 1C below the rest of the house when the outside temperature is 8C or higher. Below is the calculation where I have considered the heat flow*  based on each surface of the bathroom 'cube':

 

 

This begs the question of whether it's worth the effort. I estimate the cost of adding UFH to each bathroom to cost around £300.

 

If you want the warm feet feeling, a 1.5m2 electric UFH mat just in front of the bath/shower could cost around £35. It could come one when the light turns on and draw 225W whilst running and cost £12/year based on 1hour per day which is a lot of bathroom time. That's a 22 year payback time which is pretty rubbish and the electric solution would be more immediate. Alternatively, just a heated towel rail adds some room warmth and warm towels.

 

Is this the sort of thing that ends up a "Specification point" in that without it the perceived value is lower even if the reality isn't the case. It being hard to add later we add it now to satisfy the possible future purchaser.

 

* Note: Q = Direction * U-value * Area * dT

Edited April 5, 2021 by MortarThePoint

[ProDave]

We have UFH downstairs and upstairs only in the bathrooms.

 

Here in the Highlands where -10 is normal and a daytime high 0 still below 0, it performs well.  Bedrooms not usually below 17 usually 18 or more.

 

Bathrooms are heated with spreader plates, chipboard then tiles.  That does not seem to give as much heat to the room as downstairs with UFH in biscuit mix and wood floors.  So in the bathrooms it is more to prevent complaints of a "cold floor" rather than much in the way of significant heat input.

[MortarThePoint]

2 minutes ago, ProDave said:

We have UFH downstairs and upstairs only in the bathrooms.

 

Here in the Highlands where -10 is normal and a daytime high 0 still below 0, it performs well.  Bedrooms not usually below 17 usually 18 or more.

 

Bathrooms are heated with spreader plates, chipboard then tiles.  That does not seem to give as much heat to the room as downstairs with UFH in biscuit mix and wood floors.  So in the bathrooms it is more to prevent complaints of a "cold floor" rather than much in the way of significant heat input.

 

Interesting, so the opposite of my thought process. You are obviously braver than me but it makes sense since cooler bedrooms are nicer anyway. 

Edited April 5, 2021 by MortarThePoint

[MortarThePoint]

4 minutes ago, ProDave said:

We have UFH downstairs and upstairs only in the bathrooms.

 

Is that a wet system or electric heat mat in the bathrooms?

[ProDave]

Just now, MortarThePoint said:

 

Is that a wet system or electric heat mat in the bathrooms?

Wet both upstairs and down.

 

 

I did what several have done, installed dedicated heater points in each bedroom so a small electric panel heater could be fitted if the bedrooms were found to be too cold.

 

And like others that have done that, they remain unused.

[joe90]

I have electric UFH in our ensuite on a timer, one hour before rising and one hour before bedtime with LVT (which is warmer than tiles anyway) only used in winter and worth every penny when you have removed your clothes ?.

rather than dedicated point for heaters they all come with three pin plugs so plenty of sockets (yet to use one in the bedroom but er indoors occasionally uses one in the upstairs office when working).

Edited April 5, 2021 by joe90

[MortarThePoint]

11 minutes ago, ProDave said:

I did what several have done, installed dedicated heater points in each bedroom so a small electric panel heater could be fitted if the bedrooms were found to be too cold.

 

And like others that have done that, they remain unused.

 

Would be painful to have to install the electric panel heater and not have then benefit of the heat pump COP as well as hidden heating provided by UFH

[ProDave]

3 minutes ago, MortarThePoint said:

 

Would be painful to have to install the electric panel heater and not have then benefit of the heat pump COP as well as hidden heating provided by UFH

I believed others on here who said heating in bedrooms was unecessary.  The heater points were only fitted for the benefit of other house members who did not share the faith and needed convincing there would be some form of heating if needed.

[nod]

If you really eat it in your bathrooms I would go with wet UFH 

We had electric matting at our previous house A total waste of time We hardly ever used it It took that long to heat up 

 

Though-it was handy for drying the floor after our messy young adults had been in Though they never switched it off when they had finished ?

Edited April 5, 2021 by nod

[Bored Shopper]

For me, UFH in bathrooms is perfect. We have walk-in wetrooms, so for me it is essential to step on a warm floor, and also for the floor to dry quickly afterwards to prevent mould / wet smells (yes, MVHR is in residence, but UFH helps). Now got used to it and won't have it any other way.

[Bitpipe]

Yes - we have wet UFH on GF and wet towel rads in bathrooms but used electric mats in bathrooms as it was a bit of a last minute decision. They work really well - just got cheap 150W single wire mats from Warmstar.

 

 

[MortarThePoint]

32 minutes ago, Bitpipe said:

Yes - we have wet UFH on GF and wet towel rads in bathrooms but used electric mats in bathrooms as it was a bit of a last minute decision. They work really well - just got cheap 150W single wire mats from Warmstar.

 

What did you do by way of thermostats? Do you have them both on timers?

[joe90]

52 minutes ago, MortarThePoint said:

 

What did you do by way of thermostats? Do you have them both on timers?

I did, UFH came with timer and built in stat, just timer fir towel rad ?

[MortarThePoint]

4 hours ago, Bitpipe said:

Yes - we have wet UFH on GF and wet towel rads in bathrooms but used electric mats in bathrooms as it was a bit of a last minute decision. They work really well - just got cheap 150W single wire mats from Warmstar.

 

Is this the sort of thing:

https://www.ebay.co.uk/itm/321589962068

 

Very low price (e.g. £40/£53 for 1.5m2 with a manual/digital thermostat, £57/£71 for 3m2). Did you use that digital thermostat?

 

[Temp]

We have wet UFH in the main bathroom which has a stone floor. Means bare feet are comfortable in the winter and summer.

[joe90]

32 minutes ago, MortarThePoint said:

Is this the sort of thing:

Exactly what I used ?

[Gus Potter]

I'm puting wet UF in our bathroom refurb. As..

 

I does get cold up here, I don't want a shock in the morning..ideally the bathroom should just be as warm as the bed you just got out of. 

 

I can leave a towel on the floor and it will dry.. if it's too hot I can open the window. I think it dries out the shower tray too so it gets less mouldy so don't need to clean it "that way", also it's really good to step into a warm shower tray, I have delicate feet.

 

Practically UF in the bathroom avoids condensation, keeps the water vapour as a gas and you can vent this via a fan or window.. for me it keeps my talc dry which I like to keep on the bottom shelf of my "vanity unit" near the floor.

 

Lastly if you feel that your heating bills are a bit high then you can just turn that UF circiut off.

[Bitpipe]

10 hours ago, MortarThePoint said:

 

Is this the sort of thing:

https://www.ebay.co.uk/itm/321589962068

 

Very low price (e.g. £40/£53 for 1.5m2 with a manual/digital thermostat, £57/£71 for 3m2). Did you use that digital thermostat?

 

 

I upgraded the stat to some fancier ones from the UFHSS but used everything else. Also worth buying a digital multimeter to note resistance readings and mat alarm which detects shorts when the mat is being laid.

 

Tiler used 6mm insulated boards below and covered with two part laytex before tiling over. 

 

Work great and stat has a timer so just have them come on an hour before we get up.

[MortarThePoint]

56 minutes ago, Bitpipe said:

I upgraded the stat to some fancier ones from the UFHSS

If you have a link or picture that would be cool as I'm considering options. The most likely approach will be linking it to the home automation system that I am cooking up. I can then use a simple analogue thermostat that has its power turned on/off by a smart switch relay (e.g. something like Sonoff TH16).

 

59 minutes ago, Bitpipe said:

Also worth buying a digital multimeter

I'd be embarrassed to admit how many of these I have already as that's part of the day job ?

[Bitpipe]

Just now, MortarThePoint said:

If you have a link or picture that would be cool as I'm considering options. The most likely approach will be linking it to the home automation system that I am cooking up. I can then use a simple analogue thermostat that has its power turned on/off by a smart switch relay (e.g. something like Sonoff TH16).

 

 

I got Harmoni ones but they don't seem to to them anymore. The Heatmiser range look to have ones that can be integrated.

 

Ultimately, the system comprises of an in floor stat that is laid alongside the mat and something to turn the mat on and off so you could create your own if you're going down that path.

 

[MortarThePoint]

2 hours ago, Bitpipe said:

The Heatmiser range

 

It's a good name from the bill payer's perspective, but sets the tone with the family. Is there a KindDad range instead

Edited April 6, 2021 by MortarThePoint

[Bitpipe]

19 minutes ago, MortarThePoint said:

 

It's a good name from the bill payer's perspective, but sets the tone with the family. Is there a KindDad range instead

 

I cant imagine they cost much to run, they only cover the areas of bathroom you walk in (so not under bath, shower or WC) but don't forget to extend under the sink. Come on for a few hours a day to take the chill off but as the house is usually 20^o year round not needed much.

[epsilonGreedy]

My thinking is that if the principal bathroom is 10% lower than the prevailing internal house temperature then I will have to overheat the whole house to mitigate the complaints. That will rise the total heating bill more than the cost of bathroom UFH. I also hope that a warm bathroom will allow me to shut down the main house heating earlier in the Spring.

 

Don't under estimate the value of a dry floor and dry warm towels when doing your raw thermal calcs.

 

 

 

 

[ToughButterCup]

23 hours ago, MortarThePoint said:

...

If you want the warm feet feeling, a 1.5m2 electric UFH mat just in front of the bath/shower could cost around £35. It could come one when the light turns on and draw 225W whilst running and cost £12/year based on 1hour per day

...

 

Is what worth it? 

What are you measuring? Money? Comfort? The smile on your partner's face? The non-slipiness of the dry patch?  The cat's comfort?

Yes, you guessed correctly: The bath mat is over an unheated area, Sid (never heard him hiss yet) is on the warm area. This is our downstairs wet room. Upstairs exactly the same arrangement

 

23 hours ago, MortarThePoint said:

...

It's a lot of effort to go to really for the benefit since all our living space is downstairs. It feels too brave to omit it completely though.

...

 

Exactly right. The psychological effect of warmth in a wet room is greater there  than anywhere else because most of us shower with no clothes on.

It takes a day for ther floor to heat up fully: switch it on for just an hour as you suggest, and we would feel nearly no benefit. You can feel a slight temperature difference where the mat ends ( or begins)

I'm willing to pay a lot more for the comfort glow that a really warm wetroom floor gives. It's not just about money.

 

Edited April 6, 2021 by ToughButterCup

[markc]

Got to agree with the above, if you want to experience pure bliss, watch a cat sprawl out on heated tiles, also feels really nice under foot