"Mike Barnes" wrote in message
...
Our bathroom is soon to receive a new slate floor. SWMBO, after some bad
experiences with hotel bathroom floors, insists that it's heated. The
bathroom is upstairs in a traditional house with gas central heating,
fully pumped, and there will be a large heated towel rail in the same
room.

At this very early stage my questions a should I be looking at
running water pipes or electric cables under the floor? Issues are
height (raising the floor too much might result in the bath not fitting
under the windowsill), running costs, and control.

Would there normally be, or could there be, a thermostat *in* the floor,
as opposed to a thermostat in the room that would also be influenced by
the heated towel rail?

--
Mike Barnes

Hi Mike,

If you already have a water heating system, then that would be the way to
go.

Tee off from the flow pipe on the radiator above floor level, enough to
allow you to fit a thermo' valve (non directional) to this side of the
system. Drop from the valve through the floor to a snake of 8mm or 10mm
mini-bore pipe under the floor boards (8mm should be enough). The spacing
of the loops would roughly be about every foot (300mm). Try to keep as
close to the tops of the joists as possible, roughly again, would say about
30 mm down for your drill holes, and remember, when laying the boards down
again, to mark on the walls where the pipes are just in case. Try to stay
away from exteriors walls as much as you can, say about a foot (300mm) again
should be OK. Then it's just back to a tee connection in the return side of
the system, which can be under the floor if you want, and the jobs done.

No matter what type of covering you put down, you'll always have the heat
rising through it. It should keep the place lovely and cosy for your dainty
little feet. Under Floor Heating does the business.


---
BigWallop

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In uk.d-i-y, BigWallop wrote:

"Mike Barnes" wrote in message
...
Our bathroom is soon to receive a new slate floor. SWMBO, after some bad
experiences with hotel bathroom floors, insists that it's heated. The
bathroom is upstairs in a traditional house with gas central heating,
fully pumped, and there will be a large heated towel rail in the same
room.

At this very early stage my questions a should I be looking at
running water pipes or electric cables under the floor? Issues are
height (raising the floor too much might result in the bath not fitting
under the windowsill), running costs, and control.

Would there normally be, or could there be, a thermostat *in* the floor,
as opposed to a thermostat in the room that would also be influenced by
the heated towel rail?

--
Mike Barnes

Hi Mike,

If you already have a water heating system, then that would be the way to
go.

Tee off from the flow pipe on the radiator above floor level, enough to
allow you to fit a thermo' valve (non directional) to this side of the
system. Drop from the valve through the floor to a snake of 8mm or 10mm
mini-bore pipe under the floor boards (8mm should be enough). The spacing
of the loops would roughly be about every foot (300mm). Try to keep as
close to the tops of the joists as possible, roughly again, would say about
30 mm down for your drill holes, and remember, when laying the boards down
again, to mark on the walls where the pipes are just in case. Try to stay
away from exteriors walls as much as you can, say about a foot (300mm) again
should be OK. Then it's just back to a tee connection in the return side of
the system, which can be under the floor if you want, and the jobs done.

No matter what type of covering you put down, you'll always have the heat
rising through it. It should keep the place lovely and cosy for your dainty
little feet. Under Floor Heating does the business.

Thanks, that's useful stuff. It's actually going to be a *slate* floor
which makes a difference in detail - the slate will be on top of a
substantial new plywood base, and I assume that the heating snake goes
between that and the slates, along with the cement.

I was thinking that slate might feel cold even in summer, which is why I
was considering electric heating, or water heating teed into the DHW
primary. All I want is to take the chill off the stone, because the
towel rail should heat the air OK.

--
Mike Barnes

BigWallop wrote:

"Mike Barnes" wrote in message
...

Our bathroom is soon to receive a new slate floor. SWMBO, after some bad
experiences with hotel bathroom floors, insists that it's heated. The
bathroom is upstairs in a traditional house with gas central heating,
fully pumped, and there will be a large heated towel rail in the same
room.

At this very early stage my questions a should I be looking at
running water pipes or electric cables under the floor? Issues are
height (raising the floor too much might result in the bath not fitting
under the windowsill), running costs, and control.

Would there normally be, or could there be, a thermostat *in* the floor,
as opposed to a thermostat in the room that would also be influenced by
the heated towel rail?

--
Mike Barnes


Hi Mike,

If you already have a water heating system, then that would be the way to
go.

Tee off from the flow pipe on the radiator above floor level, enough to
allow you to fit a thermo' valve (non directional) to this side of the
system. Drop from the valve through the floor to a snake of 8mm or 10mm
mini-bore pipe under the floor boards (8mm should be enough). The spacing
of the loops would roughly be about every foot (300mm). Try to keep as
close to the tops of the joists as possible, roughly again, would say about
30 mm down for your drill holes, and remember, when laying the boards down
again, to mark on the walls where the pipes are just in case. Try to stay
away from exteriors walls as much as you can, say about a foot (300mm) again
should be OK. Then it's just back to a tee connection in the return side of
the system, which can be under the floor if you want, and the jobs done.

No matter what type of covering you put down, you'll always have the heat
rising through it. It should keep the place lovely and cosy for your dainty
little feet. Under Floor Heating does the business.



I wouldn't use microbore, as it desn't leak as much heat as 15mm, but
otherwise, I am with you on this.

You could even use proper UF heating (flexible butyl) pipe.



---
BigWallop

http://basecuritysystems.no-ip.com

Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
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Mike Barnes wrote:

In uk.d-i-y, BigWallop wrote:

"Mike Barnes" wrote in message
...

Our bathroom is soon to receive a new slate floor. SWMBO, after some bad
experiences with hotel bathroom floors, insists that it's heated. The
bathroom is upstairs in a traditional house with gas central heating,
fully pumped, and there will be a large heated towel rail in the same
room.

At this very early stage my questions a should I be looking at
running water pipes or electric cables under the floor? Issues are
height (raising the floor too much might result in the bath not fitting
under the windowsill), running costs, and control.

Would there normally be, or could there be, a thermostat *in* the floor,
as opposed to a thermostat in the room that would also be influenced by
the heated towel rail?

--
Mike Barnes

Hi Mike,

If you already have a water heating system, then that would be the way to
go.

Tee off from the flow pipe on the radiator above floor level, enough to
allow you to fit a thermo' valve (non directional) to this side of the
system. Drop from the valve through the floor to a snake of 8mm or 10mm
mini-bore pipe under the floor boards (8mm should be enough). The spacing
of the loops would roughly be about every foot (300mm). Try to keep as
close to the tops of the joists as possible, roughly again, would say about
30 mm down for your drill holes, and remember, when laying the boards down
again, to mark on the walls where the pipes are just in case. Try to stay
away from exteriors walls as much as you can, say about a foot (300mm) again
should be OK. Then it's just back to a tee connection in the return side of
the system, which can be under the floor if you want, and the jobs done.

No matter what type of covering you put down, you'll always have the heat
rising through it. It should keep the place lovely and cosy for your dainty
little feet. Under Floor Heating does the business.


Thanks, that's useful stuff. It's actually going to be a *slate* floor
which makes a difference in detail - the slate will be on top of a
substantial new plywood base, and I assume that the heating snake goes
between that and the slates, along with the cement.



No. Bung it under the ply. Its too mucgh faf to lay in the cement,
unless yoiu go electric.

You CAN get a bit sexy, and put insulation (probably foil backed
celotex) underneath to make sure the heat goes upwards, but essentuially
you are creating a warm space under the floor, which warms the floor.
Its such a large area the fact that wood and slate are not prefect
conductors merely means you get to walk on it with bare feet without
taking the skin off them :-) rather than making it so inefficient you
won't notice it.


I was thinking that slate might feel cold even in summer, which is why I
was considering electric heating, or water heating teed into the DHW
primary. All I want is to take the chill off the stone, because the
towel rail should heat the air OK.



Bleive me, a single pair of 15mm pipes under such a floor heats uit
wonderfully for about a foot either side, so going for that suggestion
of about 12" apart will be perfectly adequate. Its not the primary
heating for the room, so no need to get silly with it. Trust me and the
other responder. Snake the CH pipes around under the floor, lay the
timber and slates, and relax and have a toasty bathroom. You will be
utterly amazed at how nice it will be.

"The Natural Philosopher" wrote in message
...


I wouldn't use microbore, as it desn't leak as much heat as 15mm, but
otherwise, I am with you on this.

You could even use proper UF heating (flexible butyl) pipe.



I just don't trust that Butyl stuff under a finished floor NTP, I'd much
rather go with copper pipe and good joints for some funny reason.

The suggestion of using the mini-bore pipe was the same reason as your last
reply, i.e. it wont be the primary source of heating the room and will only
be used to keep your tootsies warm on a cold morning.

Also, your last reply talking about foil backed Celotex to reflect the heat
directly up toward the floor would probably work with this system too. I
know the Romans used animal dung covered with polished copper to reflect the
heat upward more efficiently on some of their UFH systems, so it is an idea
I am thinking about trying myself shortly.

Worth a few moments contemplation.

In uk.d-i-y, Mike Barnes wrote:
I was thinking that slate might feel cold even in summer, which is why I
was considering electric heating, or water heating teed into the DHW
primary. All I want is to take the chill off the stone, because the
towel rail should heat the air OK.

Can I take from the lack of response to this remark that everyone would
be quite happy with a heating system that only worked in winter when the
main house heating was on? The room underneath is the kitchen and is
normally pretty warm. If the bathroom floor feels cold to SWMBO's
tootsies in summer there will be hell to pay.

--
Mike Barnes

"Mike Barnes" wrote in message
...
Our bathroom is soon to receive a new slate floor. SWMBO, after some bad
experiences with hotel bathroom floors, insists that it's heated.


On thing to watch is that UFH is best carried out with temperature limited
water ... 38deg C or so as a maximum.
The water you are pumping in from your rad system might be too hot and cause
hot spots on the floor.

Perhaps a mixing valve teed across your F & R might be worth considering.

If you can't bury the pipes in a good thickness of screed under the slate
due to height limits - or on underside of the floor deck - then you may be
better off going for electric.


Rick

Can I take from the lack of response to this remark that everyone would
be quite happy with a heating system that only worked in winter when the
main house heating was on

Not sure how cold the floor will feel without any heat under it. My sister
has a slate kitchen floor onto screeded insulation, and right now this feels
refreshingly cool under bare feet. In an upstairs room it should be a whole
lot warmer. I can only suggest you get a couple of the slates out, let them
aclimatise and see how they feel.

On thing to watch is that UFH is best carried out with temperature
limited
water ... 38deg C or so as a maximum.
The water you are pumping in from your rad system might be too hot and
cause
hot spots on the floor.

Perhaps a mixing valve teed across your F & R might be worth
considering.

For small area like that it gets expensive to introduce separate zone
controls so combining with the CH is the economic option. If UFH is needed
in summer then a separate zone is the only option unless all radiators can
be shut off. A pro job would involve a separate pumped and mixed loop
controlled by a zone valve.
I see in the BES catalogue an "FJVR return temperature sensor" (p/n 15764)
plus valve body (p/n 15765). It looks just like a standard radiator TRV
except it measures the water temp and costs £25. This will restrict the
water exiting the UFH loop so that the water within the loop has the
opportunity to cool to the recommended 40deg or so. Of course a bit of
adjustment on the flow temperature will be needed, a warm floor in winter,
just take the chill off in summer.

Added to a digistat and zone valve this is the option I have selected for a
solid kitchen floor of 14m2.

If you decide you may only ever need the UFH infrequently the easier
installation of electric mat within the tile adhesive layer will win. You
should get about 125 w/m2 from the mat. I believe it's a close call for your
requirement.

Toby.

On Mon, 7 Jul 2003 09:30:44 +0100, Mike Barnes
wrote:



Not sure how cold the floor will feel without any heat under it. My sister
has a slate kitchen floor onto screeded insulation, and right now this feels
refreshingly cool under bare feet. In an upstairs room it should be a whole
lot warmer. I can only suggest you get a couple of the slates out, let them
aclimatise and see how they feel.

Now that's what I call a sensible suggestion... right, I've got a couple
of flooring slates from the shed, have placed them on the bathroom
floor, and have asked SWMBO to try them out from time to time.


I'd concur with this. I have slate floor on insulated concrete base
over most of the ground floor of the house. Typically I wander round
in bare feet and it never feels cold. I think it tends to acquire
the temperature of the surroundings and my impression is that compared
with ceramics or marble it is a lower conductor of heat anyway - hence
not feeling cold underfoot.

Another useful factor is that even if you use calibrated slate (i.e.
machined both sides), it is still not slippery when wet.


..andy

To email, substitute .nospam with .gl

BigWallop wrote:

"Mike Barnes" wrote in message
news .

Thanks, that's useful stuff. It's actually going to be a *slate* floor
which makes a difference in detail - the slate will be on top of a
substantial new plywood base, and I assume that the heating snake goes
between that and the slates, along with the cement.

I was thinking that slate might feel cold even in summer, which is why I
was considering electric heating, or water heating teed into the DHW
primary. All I want is to take the chill off the stone, because the
towel rail should heat the air OK.

--
Mike Barnes


A slate floor will make a big difference to the system I described Mike.
The pipework would definitely have to go either against, or very close to,
the slate for the heat to transferred up through enough to be viable. And
yet, on a ceramic tile floor, the pipes can be under the timber and it still
seems to allow the heat to radiate through OK.

Weird, but I know that for natural stone, it has to be in very close
proximity to the pipework for it to work with any great efficiency.



This is simply both not a big issue, and not entirely true.

ALL that matters is the relative heat conduction paths upwards through
the floor, and downwards through the ceiling, plus the total amount of
heat being pumped in - which is a function of teh water temp and how
much pipewprk you have.

IF this was a pukka 'in screed' system tou would already have had to
REDUCE water temp because of the dangers of screed cracking. In this
case here, the water temp an be left at CH normal (60-70C?) as teh
airgap between the pipe and the floor will develop a tempeature drop.

Transfer efficiency doesn't matter - in essence the heat is not lost -
it stays in the pipes for other radiators!!!

All you want is a bit of heat bleed from the hot underfloor space up
wards through the ply and slates. That WILL happen.

If that between fllor space heats up tp 60 C or so, do you really think
those slates won't feel warm to the touch?

Mike Barnes wrote:

In uk.d-i-y, Mike Barnes wrote:

I was thinking that slate might feel cold even in summer, which is why I
was considering electric heating, or water heating teed into the DHW
primary. All I want is to take the chill off the stone, because the
towel rail should heat the air OK.


Can I take from the lack of response to this remark that everyone would
be quite happy with a heating system that only worked in winter when the
main house heating was on? The room underneath is the kitchen and is
normally pretty warm. If the bathroom floor feels cold to SWMBO's
tootsies in summer there will be hell to pay.



You could run the hot water primary under there. However, I've got all
this, and no one has complained about cold tootsies in summer.

In fact, even on unheated screed floors in winter, the tiles are warm
from the room heating, in the one bathroom that is like this.

The 'dog shower' so called because its a wet room designed for
shampooing the mangy hound, has got UF heating, and SWMBO uses it more
than any other - maybe thats cos the other showers are not finished yet
tho :-)

"John Stumbles" ] wrote in message
...
"BigWallop" wrote in message
...

---8---

Also, your last reply talking about foil backed Celotex to reflect the
heat
directly up toward the floor would probably work with this system too.
I
know the Romans used animal dung covered with polished copper to
reflect
the
heat upward more efficiently on some of their UFH systems, so it is an
idea
I am thinking about trying myself shortly.

What sort of animal dung are you planning to use?


I can provide large quantities of Horse Manure at 50 pence a bag collected.
VBG

On Tue, 8 Jul 2003 17:20:33 +0000 (UTC), "John"
wrote:

I can provide large quantities of Horse Manure at 50 pence a bag collected.
VBG

Why not go down to parliament and load up? There are tons of bovine
excrement available every single day!

Andrew

Do you need a handyman service? Check out our
web site at http://www.handymac.co.uk

In uk.d-i-y, Mike Barnes wrote:
In uk.d-i-y, Toby wrote:
Can I take from the lack of response to this remark that everyone would
be quite happy with a heating system that only worked in winter when the
main house heating was on

Not sure how cold the floor will feel without any heat under it. My sister
has a slate kitchen floor onto screeded insulation, and right now this feels
refreshingly cool under bare feet. In an upstairs room it should be a whole
lot warmer. I can only suggest you get a couple of the slates out, let them
aclimatise and see how they feel.

Now that's what I call a sensible suggestion... right, I've got a couple
of flooring slates from the shed, have placed them on the bathroom
floor, and have asked SWMBO to try them out from time to time.

The experiment has run long enough to know that we definitely need some
sort of heating in summer.

For small area like that it gets expensive to introduce separate zone
controls so combining with the CH is the economic option. If UFH is needed
in summer then a separate zone is the only option unless all radiators can
be shut off. A pro job would involve a separate pumped and mixed loop
controlled by a zone valve.

I think that's where I'm going to end up. But for now the important
thing is to get the pipework under the floor. I can fiddle with the
controls in the airing cupboard later.

Thanks to everyone for their contributions.

--
Mike Barnes