I want to overboard a draughty, uneven floor.
And as I could do with raising it about an inch I was thinking about a
thick insulation inbetween.
Then I started thinking about UFH and there are pre-grooved polystyrene
panels that would be ideal.
So just wondering if anyone has any experience of DIY UFH or any
opinions of UFH in general.
The system we have in the conservatory is embedded in the screed, but
could have been used as you mention.
Our add-on system runs off the normal central heating, via a motorised
valve and unvalved return (like a radiator), but that is far too hot, so
there is a blending valve and a separate pump.
Water is circulated by the dedicated pump, from the floor, through the
blending valve and back to the floor. If the water is too cool, the
blending valve mixes it with some from the main central heating and the
excess naturally exits to the main system.
It works well, but there is about 4" of screed, so warm-up and cool down
are slow. You need to have the heating on well before you need the room
and off well before you finish using it.
Cats love it though!
We had a conservatory put up about 5 years ago. Floating floor with
concrete beams and breeze block, covered with screed and 75 or 100 mm of
Celotex (I can't remember the actual thickness). Then laminate.
The UF heating was by electric film - 1.8kW. At the time, we considered
hot water - either UFH or radiators, but connecting it up to the current
HW system required approval, and the boiler was running pretty near to
capacity anyway. But we find the UFH is not sufficient to keep the
conservatory warm in winter, and is very expensive to run. Really, there
aren't enough decent days in winter to merit using the conservatory
anyway, and when it is sunny that will supply a useful amount of heat,
and it can be supplemented with a fan heater. I'm not sure that any type
of UFH in a conservatory is justified unless the conservatory is triple
or quadruple glazed.
When you have a house with a hall, kitchen (small and only for cooking,
not eating) and a through living room, plus three children, you want
another downstairs space! Self-building a conservatory was the cheapest
option and, at the time, the only financially practical one. Insulated
cavity walls, partial solid roof, double glazing, triple-wall roofing,
blinds all round and under-floor heating, make it practical to use for
almost all the year - hot summer days are the only problem.
As the rules have changed, we may change the roof to keep some of the
I'm an avid plant grower, so it's more of a greenhouse attached to the
house than a conservatory! And, having one side of it as a house wall,
means it's a bit cheaper to heat than a greenhouse, and it keeps one
wall of the house a little warmer.
But it's somewhat true what you say. As a "room" it is usually too cold
in winter and too hot in summer. Nice in spring and autumn, though.
The pipes are plastic and able to cope with a little flexing and do it
silently, even with minor misalignment at a slight crack. The screed as
a whole sits on insulation and stops just short (25mm or so) of the
walls due to insulation being placed around the edges before laying the
screed. That gives some space to expand and contract slightly without
significant forces being generated.
As to how likely things are to fail. It has been done that way for
decades and there doesn't seem to be big fuss about failures, so it must
work. Certainly ours does.
As for the type that is laid within insulation panels, perhaps with
spreader plates to distribute the heat. I would assume that the
insulation flex stops creaking noises and the floor on top is a floating
floor, so that can freely move too and is little different to the
expansion and contraction of a laminate floor.
Ah. You didn't mention it was a suspended floor.
Lift it, and put 6" celotex between the joists, tape over, and then lay
your pipes on top
No need for poly ,poulding. Just use big plastic staples to located them
to the celotex If the joists are stable you can screed/tile or else
overboard with ply and engineered wood.
Aim for a spacing of around 4" between pipes to get best output.
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Umm.. you have to slot the joists for the pipe return. An alternative is
to use the pre-formed 22mm slotted flooring chip plus your choice of
overboard. If you fancy ceramic floor tiles there are cement based
boards for this.
Have a look in here or one of their many competitors
If you can only raise the level by 1", your options are very limited.
There's nowhere near enough room for a wet system, so it would have to
be electrical - which would be very expensive to run. Even then, there's
insufficient headroom for a decent amount of insulation.
When we converted an integral garage into a kitchen, we needed to raise
the floor level by 6". We installed a wet system but even 6" was tight
and only allowed for about 3" of insulation in order to make space for a
couple of inches of screed on top of the pipes.
You don't have to use screed. There are systems that use thin, grooved
insulation on top of the existing floor, with the pipes in it and metal
spreader plates to spread the heat. With a few mm of laminate floor
underlay on top and then laminate. 1" might be more than a bit tight
though. Further insulation can be put between the floor joists.
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