On 28/05/2016 09:49, The Natural Philosopher wrote:
On 28/05/16 09:36, Pet @ www.gymratz.co.uk ;¬) wrote:
Most important thing is having insulation up to spec. That way the
heating will never need to heat from cold and you'll never need to worry
about switching off the heating is you go away for a week.

And that is the issue.

If you have poor insulation sticking the heat next to the cold hard
ground will waste huge amounts of it.

In a reasonably well insulated setup I found 50W/square meter adequate,
100W/sq meter capable of fast warm up to insane temperatures (if not
controlled).

You have to remember that a thick insulated fitted carpet is fine as an
insulator over a concrete floor slab with radiators, but its not usable
over UFH.

Indeed.
Our bedrooms are on the ground floor and the "insulation" consists
of.... nothing. Which is brilliant as bedrooms are lovely and cool in
the summer and the one with carpet/underlay heats up with ease by the
radiators and the under-foot feel is still warm. The one with laminate
in feels colder as the floor is colder underfoot even though the room
it's self is the same temp as the carpeted room.

IN all cases you have to understand the house design in totality.

There is no 'UFH is good/bad/fast/slow' etc etc.

Id definitely use it again, but I'd be even MORE careful about
insulation design this time.

Absolutely.
And I have it in our new extension although unfortunately at time of
planning her ladyship wanted radiators so no allowance was made for
insualtion on top of the slab which is on top of the 100mm cellotex so
I've had to put down a multi-foli in the "new" rooms. Old garage was
better as the insualtion went on top of the garage floor so job's a
good-un in there but I've run 150mm spacing on all pipes which should
still give ample output to the all-new slab-on-insualtion floors.

Just waiting for the screeding to be done at the moment.

On 27/05/2016 18:07, Bert Coules wrote:
Tim Lamb wrote:.

It is normally controlled by local roomstats for each separate heated
area. A large lounge might require 2 or more lengths of piping but
controlled from one stat.

Thanks for that. The overall footprint of the bungalow is a simple
rectangle. The ground floor - currently the only floor - is completely
open plan except for the bathroom, which cuts into one side of the
space: broadly speaking the living area is in the shape of a very thick
capital letter E with the central horizontal line missing. If it's
practical, I suppose that could constitute two zones, one for the living
area, another for the bathroom.

The new first floor will be essentially similar, so another two zones,
perhaps.

What is the absolute minimum thickness required by UFH? As planned, the
headroom on the new first floor is not generous: 2060mm on the drawings.

If bedrooms are upstairs Go for radiators.
That way you can have a nice warmth (22 degrees) to get up to and not
worry about obscuring most of the radiant surface with beds, cupboards
etc. as you'd be doing with UFH, and you can have thick luxurious carpet
on the floos. UFH in bedrooms is in my mind a complete waste of money
and a sub-optimal way of heating bedrooms in which you spend little time
awake and should be much cooler during the night anyway.

If the ground floor is joists over a void as I think you mentioned then
the floor surface will remain the same height after UFH.

And of course... don't forget you'll still want heated towel radiator
things in bathrooms even if you have UFH in them. You absolutely need
such items to not only dry damp towels but to hang wet coats/clothes on
if you get caught in a shower etc.
I have mine spurred off the boiler feed before the 2 way
(upstairs/downstairs/both) zone valve. That way it's heated all the time
the boiler is running unless both upstairs and downstairs zones are
fully satisfied so the boiler is off.


Cheers - Pete

polygonum Wrote in message:
On 26/05/2016 19:22, RJH wrote:
On 26/05/2016 19:06, polygonum wrote:
On 26/05/2016 18:49, The Natural Philosopher wrote:
It remains my favourite heating system of all time. Hot air second

I have experienced underfloor heating in a few places. For myself,
maybe, but with a partner who suffers, then absolutely no way.

We now see "disabled" facilities everywhere, such as flat access, WCs
large enough for wheelchairs, etc. Some people are effectively barred
from places with underfloor heating. The thought of it becoming more
widespread is not pleasant.


In what way does your partner (and other users) suffer with underfloor
heating?


Severe pain in feet and legs. Seems to be moving up and also affecting
hands a bit. There are quite a number of videos - mostly poorly
presented/filmed or very individual. This is better than many:

https://www.youtube.com/watch?v=m7CTUjoHnOU


"this video is not available "

--
Jim K


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

On 28/05/2016 13:37, jim wrote:
polygonum Wrote in message:
On 26/05/2016 19:22, RJH wrote:
On 26/05/2016 19:06, polygonum wrote:
On 26/05/2016 18:49, The Natural Philosopher wrote:
It remains my favourite heating system of all time. Hot air second

I have experienced underfloor heating in a few places. For myself,
maybe, but with a partner who suffers, then absolutely no way.

We now see "disabled" facilities everywhere, such as flat access, WCs
large enough for wheelchairs, etc. Some people are effectively barred
from places with underfloor heating. The thought of it becoming more
widespread is not pleasant.


In what way does your partner (and other users) suffer with underfloor
heating?


Severe pain in feet and legs. Seems to be moving up and also affecting
hands a bit. There are quite a number of videos - mostly poorly
presented/filmed or very individual. This is better than many:

https://www.youtube.com/watch?v=m7CTUjoHnOU


"this video is not available "

Just checked it - working fine for me.

--
Rod

Tim Lamb wrote:

Otherwise, the fix from top system goes
between the joists prior to laying the floor
and does not raise the floor.

Tim, I didn't know about this type: I'll investigate. Many thanks.

Belated thanks for the new replies: all much appreciated, contrary views and
advice and all.

It's clear that proper insulation is the key to success with UFH, but am I
right in thinking that however good that insulation is, a large expanse of
glass - as with a run of patio doors - is still potentially a localised cold
area however successful the heating is overall?

If so (and assuming that it's practical to do so) would running
separately-controlled trench radiators along the length of the doors be an
effective remedy?

Many thanks.

In message , Bert
Coules writes
Belated thanks for the new replies: all much appreciated, contrary
views and advice and all.

Free advice is always worth what you pay...:-)

It's clear that proper insulation is the key to success with UFH, but
am I right in thinking that however good that insulation is, a large
expanse of glass - as with a run of patio doors - is still potentially
a localised cold area however successful the heating is overall?

Bigger problem is likely to be solar gain. Particularly with pipes in
screed and big areas of unshaded glass.

If so (and assuming that it's practical to do so) would running
separately-controlled trench radiators along the length of the doors be
an effective remedy?

Many thanks.


--
Tim Lamb

On 01/06/16 00:13, Bert Coules wrote:
Belated thanks for the new replies: all much appreciated, contrary views
and advice and all.

It's clear that proper insulation is the key to success with UFH, but am
I right in thinking that however good that insulation is, a large
expanse of glass - as with a run of patio doors - is still potentially a
localised cold area however successful the heating is overall?

Yes, but also be aware o9f just how much heat UFH can put out with the
pipes laid real close. I had a run of about 12 pipes going down a 900mm
corridor to various zones. It was like an oven there., Used to have to
kick the cats out of the way.


If to have bare tiles or laminate by the window and lay the pipes at
something like 100-150 mm centres in a strip along there, you will get a
really hot pieces of floor.

BUT my experience of UFH is that is actually reduces draughts hugely.
There are normally no hotspots or coldspots so there is little
convection and little lateral air movement. And because te floor is warm
cold ankle level air is non existent. I used to run the rooms about 1-2
degrees colder than radiators for the same subjective feelings of warmth.





If so (and assuming that it's practical to do so) would running
separately-controlled trench radiators along the length of the doors be
an effective remedy?


You don't need to do that. Simple increase the pipe density of the UFH
in that area.


A low density UFH is around 50W/sq meter with water temps around 50-60C.
That's at around 800mm centers. 200W/sq meter is easy, at 200mm centres
IIRC and 400W /sq me easily possible. So 2x1 area of floor might be
crackling out 800W.


Thats is more than an Aga.

You will find some sites say you shouldnt exceed 100W/sq meter. I say
that is utter bull****. My corridoor was about 5 times that an it didn't
crack.


Many thanks.



--
Karl Marx said religion is the opium of the people.
But Marxism is the crack cocaine.

Thanks for those. What I'm slightly concerned about is installing UFH and
then discovering that the patio door run still does get appreciably colder
than the rest of the open-plan space (perhaps because of heat loss through
the framing?)

I was wondering if a belt-and-braces approach installed during construction
might be worthwhile insurance.

Tim Lamb wrote:

Bigger problem is likely to be solar gain.

Is solar gain the result of direct sunlight? The run of doors only receives
that in the late afternoon, and even in the hottest weather never becomes
noticeably warmer than the rest of the space. But the drop in temperature
relative to the rest, even with the current heating system set pretty high,
is very marked.

Pete,

Thanks for that: you're the first person to suggest radiators for upstairs
and UFH for the ground floor. Your reasoning makes sense for separate
bedrooms though perhaps lass so for a single large open-plan space (bathroom
apart) containing just one bed, which is what I'm planning. But I take the
point about heating under large items of furniture being redundant and
perhaps wasteful.

On 01/06/16 11:25, Bert Coules wrote:
Pete,

Thanks for that: you're the first person to suggest radiators for
upstairs and UFH for the ground floor. Your reasoning makes sense for
separate bedrooms though perhaps lass so for a single large open-plan
space (bathroom apart) containing just one bed, which is what I'm
planning. But I take the point about heating under large items of
furniture being redundant and perhaps wasteful.


no, its isn't altogether as bad as it appears. What happens is that
locally the floor there doesn't lose heat, but that means it doesn't
actually 'steal' the heat from the hot water.

The danger is to be understood more simply. What determines the
efficiency is the insulation above to the insulation below ratio.

BUT even if that is bad, the *overall* heat loss is low from that place,
and what happens is that the heat transfer to the room (or loss through
the floor to underneath is dominated by sections that CAN cool the water
BECAUSE they are NOT under furniture.

Or to put it another way, you will only increase unwanted heatloss to
the ground underneath, if the actual pipe temperature and screed
temperature is increased in that area, and then only by an amount
dependent on the insulation under it.


As I said before, have huge amounts of insulation under any screed.



My way of doing the thing was as follows. A concrete slab floor was
sanded, then a DPM laid on it, then in my case 50mm of high density
polystyrene. Today Id be thinking of 100mm+ and that shuld be laid up
the walls as well.

Then we cut reinforcing mesh to fit over that. It's very cheap and helps
stop screed cracking.

The UFH pipes were tie wrapped to that. Again, simple and cheaper than
the 'custom system', and allows some very tight spacings - IIRC the
reinforcing grid was around 100mm grid extent.

The zones were brought back to a manifold, connected and filled with
water, then I pressurised the whole thing with a hired pump, top about 3
bar IIRC, and watched for leaks. The pressure was left in for the two
days it took to screed the whole ground floor.

Then the wall bits of foam were cut off flush with the screed. After
that it was tiling slating and laminate laying time. After a bit of
levelling on the screed which was shoddily done as it happened.

Much to my surprise the whole thing performed to spec, and the only
mistake I made was sizing the boiler and pipes just big enough to cope
with -5C. That left nothing over to get it UP top temperature when it
was -5C :except the open fires and the wood burner. But they worked
splendidly. Peak output from the main fir probably around 20KW :-)


I'd lay more pipe next time 50W/sq ft is OK for a modern well insulated
room if you leave it on all the time, which I ended up doing, but isn't
enough for a rapid warm up.







--
"Women actually are capable of being far more than the feminists will
let them."

On 01/06/2016 11:25, Bert Coules wrote:
Pete,

Thanks for that: you're the first person to suggest radiators for
upstairs and UFH for the ground floor. Your reasoning makes sense for
separate bedrooms though perhaps lass so for a single large open-plan
space (bathroom apart) containing just one bed, which is what I'm
planning. But I take the point about heating under large items of
furniture being redundant and perhaps wasteful.

Our bedrooms are all pretty small so single finned radiators still heat
up the spaces nicely and eliminate cold zones caused by old double
glazed windows whilst running UFH temperatures but for a large open plan
type area built to modern spec. I'd go for UFH.

Our between-joists rooms cool quickly enough that I have the heating on
right up to around 23:30 at night.

I was also slightly side tracked by the fact our bedrooms are down
stairs so UFH would be an in-screed install which would give long
warm-up and cool-down times which again in our house, heating bedrooms
by radiators is a far better solution to achieve warm go-to-bed and
wake-up periods without having a hot bedroom during sleep hours.