hot water underfloor heating

[tom patton]

Hi all. Im just about to install the floor in my new ensuite 2.5x2.5 square metres. The floor is suspended and part of it will be a shower area. I am going to tile it. I read some info on underfloor plastic heating pipe[HEP 20 underfloor]. Looks a reasonably cheap system £50 for 70 metres approx. My big reservation is---- I am told anything less than two layers of 18 mil exterior ply under floor tiles in a bathroom is asking for tile cracks. Can underfloor hot water heating work 36mil below the tiles.

[The3rd Earl Of Derby]

Why would anyone want underfloor heating in a bathroom? The conventional rad in a BR sports less problems.

-- Sir Benjamin Middlethwaite

[tom patton]

"

The bathroom is on a south facing wall 600 feet above sea level in Scotland. The tiles could be very cold in winter. I was raised in a house where ice formed inside the windows in winter--this has made me yearn for the soft life--. Surely if the Romans had heated tile floors its possible for us---although they did have slaves to keep the system supplied with fuel--.

[Rick]

The slave trade is banned, but many people are effectivly still slaves. I am sure many slave trading compaines from the empire days still exist doing something entirley different, and may be persuaded to go back to their old ways.

I will have UFH in my batroom, but as its so small, I am not going to use water to heat it.

Rick

[The3rd Earl Of Derby]

I don't have tiles in my bathroom, so don't know about the tiles being cold as I would of thought it would be a disaster zone the tiles being slippy as you get out the shower/bath? plus a nightmare should you have problems with the electrics and any piping that would be underneath the floor?

-- Sir Benjamin Middlethwaite

[Andy Hall]

That is a matter of choosing suitable tiles that do not present a slippery surface when wet. Alternatives such as vinyl are generally rather yukky and the UK is about the only country I know where people still put carpets in bathrooms.

That is why a piped system is probably a safer bet than an electric one. Barring mechanical damamge to the pipe, it is unlikely to fail.

[John Rumm]

As long as the correct (slightly flexible) adhesive is used you can get away with a little less - a total floor thickness of 25mm or so ought to be ok (3/4" floor boards with 9mm ply over for example)

Should do.

[John Rumm]

You have the (often simpler) solution of going up through the ceiling below.

[DJC]

The floor of my wetroom has tiles on 40mm wedi board on 18mm ply. No undefloor heating but the tiles seem well insulated by the styrofoam core of the Wedi board and get quite warm when the shower is running.

[zaax]

Hypocaust

the Romans knew how to build a bath room

[Andy Hall]

They still do...

[tom patton]

Many thanks for all your suggestions. The most interesting was the roman design with the incentive that I could easily get the twigs needed to provide the heat for free. There are two downsides to this---

1 my wife would object to taking her turn to feed the underfloor fire when it was my turn for a shower---jolly unsporting. 2 the 2 foot height requirement needed for the underfloor ducting is beyond the available space in my 1974 bungalow.

[andrewd909]

Do you intend to insulate under the heating pipes? if you fix the heating pipes to foil backed insulation this should reflect the heat upwards. When ufh is fitted on a solid floor a 50mm screed is applied over the top and then a floor covering etc over that, it seems to work ok although some earlier postings suggested that ufh can be slow to react. How are you going to control the ufh? it may be an idea to have it on its own programmer /thermostat so the bathroom could be heated earlier / later than the rest of the house.

[Mike Tomlinson]

In article , tom patton writes

My bathroom has one sheet of 18mm ply (and floorboards) below the tiles. It's not actually underfloor heating as such, but the flow and return pipes from the boiler (28mm) run under the bathroom floor, and do a good job of taking the shriek factor out of walking on them in bare feet in winter.

[Huge]

Why would anyone want it anywhere else? Bathrooms are *the* place you want warm tooties.

The conventional

[Christian McArdle]

The bathroom is the room that most benefits from underfloor heating. This is because:

(a) cold tiles barefoot feel uncomfortable. (b) spills evaporate off more quickly. (c) the large warm surface area provides radiant heat that is particularly effective when naked and wet.

Christian.

[The3rd Earl Of Derby]

I'm sorry but a normal rad will heat the BR in no time, as for cold feet wear flipflops till you get in&out of the bath/shower.

I can only see problems... Warpage of the wood underneath tiles resulting in tiles coming away from cement fixer?

-- Sir Benjamin Middlethwaite

[John Rumm]

No one was suggesting it would not...

The whole point of UFH in this situation is to create a more comfortable environment for users of the bathroom - without needing to tit about with flip flops. The fact that spils evaporate faster also imrpoves the safety of the basthroom as slips are less likely.

Its not rocket science - UFH is pretty tried and tested technology and is very frequently used in just these circumstances without any problems.

[Christian McArdle]

Yes, but it will provide much less radiant heat, so will be less effective at heating a wet person, even when heating to the same air temperature.

I would do no such thing. That would be a major inconvenience.

Use a good flexible tile adhesive such as Ardex Ardu-Flex 7001 Timber System. Ensure that the pipe temperature is nice and low to avoid excessive expansion/contraction. Don't use anywhere near the maximum mixing temperature.

Christian.

[J B]

Why not keep your dressing gown on as well, then there's no need for heating at all!

;-)