Central heating question

[Norman Verona]

Someone has suggested that I install underfloor heating in the barn conversion. However, one end of the open plan ground floor will have huge slate slabs as the floor. They're at least 50mm - 75 mm thick.

I doubt the heat will get through that thickness and if it does it'll take 2 or 3 days to warm up.

If there's any doubt can I fit trad rads at one end and the underfloor pipes under the oak florr going at the other end?

I'm also concerned about the capacity of the heating system needed.

The main barn is 10.5m x 6.85m with the walls at 4.0m and pitch of the roof at 7.26m. The single floor "offshot" (kitchen) is 4.0m x 6.85 and 2.5m high.

The interior of the main barn is fully open  plan with 1/3 of the upper level being the bedroom & bathroom all (well not the bathroom!) open with a balustrade. The other 2/3rds are open to the full height of the roof.

Pictures on these pages

many thanks.

ps, this project was put on hold for a year whilst HM had a wobbly. Wobbly over it's now back on.  We have 2 houses to sell (on the farm) before we can complete the whole conversion but I'll be getting on with the "easy" (and cheap) bit over the winter.

[blankczechbook]

if you do consider this then don't scrimp on the insulating layer under the heating - the heat will otherwise be lost downwards.

heating the big slabs just a little would have a great effect - and big thermal heatsinks are all the rage at the moment - add a few water solar panels to heat a pool in summer - and the floor in winter - maybe a big water tank to store hot water from summer panels - when this loses heat then swop back to the central heating boiler...

is this one going to be lived in - or just rented out occasionally ?

lived in? - i'd go for the underfloor heating - maybe with a woodburning stove to give a boost at peak cold periods.

rented out? - you'd probably need a quicker blast of heat to warm up from unoccupied periods - and the investment of underfloor heating you wouldn't feel the benefits of yourself - stick to rads - with antifrost settings on the rad valves :-)

[Norman Verona]

Adrian, It's going to be our main house so lived in all the time.

I am planning to have an open fire in the middle but more for effect than heat.

OK, so, lay a 100mm insulation under the pipe panel then a weak mix then the slate slabs.

Easy!

Thanks.

[blankczechbook]

open fires are nice but do suck out room heat too..  

- the chimney takes ages to warm through to get the nice warm effect in our main house.

in our chalets we have wood burners which only suck up the burnt waste gases, these are great as the hot air around the wood burner can be channeled through the house too if you want that option - worth deciding at the building stage.

these can be on full power for heating - or damped down for warming - something hard to do with an open fire!

do consider these - they can be left full when you go to bed - and with the air inlet almost closed down the fire burns slowly all night - to just be topped up in the morning - and they hardly make much ash as they recirculate the heat!

warm floors are nice - do consider the edges of the room to be warmed too - so the walls get slight air circulation - no damp patches on your old walls!

[SteveH]

You've got to use UFH on the stone floor!  

It does take a while to heat that kind of floor up but the heat then lasts for hours after you've stopped supplying it.  We've got slate floors with UFH and it's just superb, a gentle warmth throughout and very very nice underfoot.  There's just no other option that you should consider!

Might want to think twice about putting it under the oak though as it can cause movement or shrinkage and it doesn't transmit the heat as well as stone.

[carpetstu]

Might want to think twice about putting it under the oak though as it can cause movement or shrinkage and it doesn't transmit the heat as well as stone.

If you do put UFH with an oak floor you need to heat very slowly and avoid shocking the floor with massive sudden heat differences.

It will be a pain in the   and as already said you may well experience shrinkage or cupping (where the floor expands and pushes up at the board edges) if it expands.

Cracking and joint creaking (the floor not you) may also be an issue.

IMHO insulate the floor well and stay with traditional above floor heating if you are installing real wood floors!

If you do go with UFH be careful with tog ratings of any floor you install and adhesives etc used in the instillation.

[Nick Algar - Competition Secretary]

I'll let the technical guys tell you how to do it Norman, but it is great, my brother in law did nearly all his downstairs a couple of years ago with an electric system and so nice to live with as just makes the place feel warm, without going stupid hot, which you can sometimes get with wood burners etc.

So can recommend it

[BigRuss]

We've got underfloor heating, and are having real problems with it.

It was put in about 7 years ago and has stopped working and we can't get anyone to come and look at it for love nor money. The attitude seems to be if they didn't install it they don't want to know.

[Dave]

I put an electric system under the ceramic tiles in me kitchen it was brilliant for the first year  

Then the thermostat probe stopped working and as its buried under the tiles in the middle of the floor it will be a b****r to replace    

I’m having to look at a infrared temp system linked into the timer control which may or may not work

Given the choice again I would get the kango out and go for a water fed system

Dave

[SteveH]

Water is much better and it's pretty simple to fit and run  

[Norman Verona]

Thanks all.

The plan is coming together.

If we say that 1/3rd is the heavy slate slabs I'm going to lay 100mm of polystyrene then the water pipes then a weak mix then the slate.

The other 2/3rd will have a 1m border of tomats (red clay hand made (old) tiles. So under floor water laid as above.

The oak floor in the centre will not have underfloor heating.

Then we'll put some rads around the wall as well and a 14kw wood burner at the 1/3rd - 2/3d division line

Phew.

Then there's the roof....

[SteveH]

Sounds spot on!

When you say a weak mix, what exactly are you thinking of?  For ufh we've used a fibre screed, not sure what type of fibre it is but it's supposed to give it some extra stability for the heat.  Probably wouldn't matter so much under the slabs but might help to avoid movement and cracks for the tiles.

[Jonah]

Norman, As you have quite a lot of ground around the property, have you considered a heat pump for heating the water and central heating. Plenty of info on the net.

[carpetstu]

Found this on the fibre additives

fibre for concrete screed

Also tried to have a loom at www.F.Ball .co.uk which are main suppliers to the UK flooring industry but their site appears to be down.

I realise they are both UK suppliers but they may be able to point you in a direction if you need a starter.

[SteveH]

A ground source heat pump (GSHP) will only reach about 40-50 degrees output at it's most efficient setting so you'd still need an emersion or other heat method to ensure the hot water is pasturised but it's perfect for UFH and fine for rads so long as they are big enough.