Anyone have underfloor heating under wood?

[Archie_tect]

With underfloor heating you want the layer below the heating pipes to be as highly insulated as possible but it has to be rigid and resistant to deflection and crushing.
The underfloor pipes ideally should be fully encased in screed so they are in direct contact with the floor finish [often using metal spreader plates touching the floor finish [if screed is not used] which ideally should be uninsulating, ie to transfer as much heat as possible. Tiles, sheet vinyl/ 'engineered' wood [ie dense as possible] or stone flags are ideal for heat transference.

However dense materials feel colder because they 'absorb' heat from your feet so wood gives a much warmer touch when the heating's turned off in the summer and is often preferred for that reason.
Ideally you ant the surface of the floor to be as close to body temperature as possible to avoid feeling hot or cold, ie the floor loses heat all the time so the supply temperature needs to be above 38 deg K.

You should be aware that UF heating builds up heat over time, it is not instantaneous as it acts like night storage heaters do. The heat cannot be 'turned off' on warm winter days nor would you get instant heat on cold days.

Boilers are best run at maximum output for short periods supplying thermostatically controlled hot water [normally limited to 60 to 90 deg which is why radiators are efficient], so it is usual but not essential to run the UFH pipes through coil in a heat store [well insulated large volume hot water cylinder] where the hot water scan be stored at a constant 40-45 degrees K. This is more efficient and can be coupled with a solar hot water coil to use the sun's free heat and also supply hot water taps and showers through a separate coil and removes peaks and troughs.

 

[swee'pea99]

Interesting - thanks for that. I think it's right that the boiler'll be working less hard for longer. I've now learned that the UFH runs on the water on its way back from its meander thru' all the radiators in the house, so it is (as it needs to be) less hot than it needs to be in the radiators. So if I've understood correctly, User482 is spot on - if anything, the boiler will need to work less hard than it would have done, since it now has three fewer radiators needing really hot water, instead just a bit of tubing that needs not-that-hot water.

 

[Archie_tect]

It's usual to have 2 separate zones or circuits for rads and UFH as the demands are totally different- using a thermostatic splitter valve which can activate the boiler sensing the temperature of the flow/return water. Not come across a linear system which relies on the UFH operating temperature through the system reducing to a useable level solely as a result of heat loss on the way.

Normally the radiators will shut-down on their themostatic valves as they reach operating temperature so that the water from the boiler then bypasses the rads returning much hotter water back to the boiler which sensing the higher returning temperature only fires up enough to raise it back up to it's thermostatic limit to then pump it round again- otherwise you risk the returning water from the UFH being at such a lower temperature that it causes the boiler to fire up constantly to compensate which just overheats the system.

Speak to your plumber who can advise as he/she'll need to work out the demand from the radiators and the UFG to balance the system.

 

[Speicher]

There is an expert in Oxfordshire who would be able to help you. Not sure exactly where he is. He is possibly a Scot. I think you will find him in "Under Wychwood".

 

[darth vadar]

I saved myself a few bob by wearing slippers.

They work a treat.

 

[threebikesmcginty]

I don't have the faintest idea. It was done as part of a full refurb of the house, which involved replacing a very antiquated boiler anyway.

We're getting a bit further on with this now...

Did your builder have to dig out the screed to allow for insulation, just wondering if there's an insulation product for wet underfloor heating with a depth that doesn't mean you loose too much room height? It's easy enough for us to raise the ceiling, I'm trying to avoid the faff of raising all the internal door lintels to compensate for a higher floor level.

 

[srw]

We're getting a bit further on with this now...

Did your builder have to dig out the screed to allow for insulation, just wondering if there's an insulation product for wet underfloor heating with a depth that doesn't mean you loose too much room height? It's easy enough for us to raise the ceiling, I'm trying to avoid the faff of raising all the internal door lintels to compensate for a higher floor level.

Sorry, you're asking the wrong person. It was effectively a brand new room - an old extension was demolished and completely new foundations were dug.

 

[rsvdaz]

We're getting a bit further on with this now...

Did your builder have to dig out the screed to allow for insulation, just wondering if there's an insulation product for wet underfloor heating with a depth that doesn't mean you loose too much room height? It's easy enough for us to raise the ceiling, I'm trying to avoid the faff of raising all the internal door lintels to compensate for a higher floor level.

There is this:
http://ufh-ie.wavin.com/master/mast...4088&middleTemplateName=oc_middle_service_sub

its in the thickness of the chipboard decking..so reduces the thickness..it can be laid over an existing concrete floor..but, as Archi'tect suggest if that floor isnt insulated some of the heat will be going into the ground.
I would suggest the following:
existing concrete floor.
a foil backed membrane tr-iso or similar (10mm)
your chipboard with the ufh in (22mm)
membrane for engineered timber floor finish (6mm)
engineered wood floor(15mm)

this give a overall thickness 53-55mm (2 inches)...you shouldnt need to raise lintols..rather just lop the bottom of each door

a wet underfloor heating system should be zonal and is run off a manifold in between the boiler and pipes....you need to find out if you boiler will run said manifold