Under floor heating

[loftus75]

Over the last few months I've been exploring under floor heating as a posiibility for my ground floor. The house was built in 1884 and has a basement, I mention this becauase even with insulation and carpet, the floor is always cool and if I'm going to lay a wood floor it will be worse.

As I intend to lay a floating floor I need to have the underfloor heating placed as near to this as possible, therefore laying the pipes between joist's isn't really an option. Thermoboard make a product where the pipes are prelayed into chipwood panels, but at £35.00+vat (600mmx2400mm) per panel it's a bit out of my price range. However the concept isn't that difficult to replicate with a router, though it might take a while to grove out all the inlays for the pipe, I'm confident I can achieve the right results if I use 19mm sub-flooring panels.

My plan is to inlay the pipe work (10m) into the sub-floor about 100mm spacing, use foam underlay between the sub-floor and floating floor, and of course add more insulation under the sub floor.

I doubt that I will find anyone that's done something similar, but would appreciate any constructive in-put from the heating engineers on this site. I could do with some advice on manifolds, controls and calcs for the job etc...

 

[AnonymousImport]

hello loftus, im not an heating engineer but some of the houses i have built underfloor heating has been installed, it is supposed to be very good, but ive only seen it with a screed over the top,the installers told us to raise the dpc 2 courses from concrete floor we laid, the pipe work and insulation was laid then 50mm screed on top to finished floor level dont know if this is any help to you.... Ian

 

[AnonymousImport]

another thought loftus it might not be any use though, :eyes could you put a radiator in the basement to make it a bit warmer might save installing the underfloor heating Ian

 

[loftus75]

Thanks for your replies Ian, I did consider In did consider laying rads in the basement at one time, but in practical terms this would have cost a lot to run with little benefit gained. I have tracked down a few web sites that seem to have a lot of the data I've been looking for. Never-the-less I'm still open to ideas or opinions, you can never have enough data when trying something this new and you never know when someone will point out the obvious things you might have missed. Thanks once again.

 

[breezer]

i have been to a friends' friends house and they have under floor heating.
Each room (5 in all on the ground floor, upstairs is normal radiators)has its thermostat, and electric valve (controlled by the stat)
Each electric valve is fed directly from a manifold that comes from the boiler, all the valves and manifold are in an understairs cupboard.

Seeing as you are going to lay a new floor instead of routing out a groove for the pipe could you not raise the new floor by the thickness of the pipe (10mm ?)or is that too impracticle?

 

[loftus75]

Thanks for your input Breezer. Raising the floor might have been an option, but I built an extension about 2 years ago which I have to marry the UFH'ed side to, either by raising the extension's floor or by allowing for a difference in height, something I'm not keen to do. Routering in a grove minimises the effects on all the other areas as well, door heights etc...

At present I've to decide whether an extra pump will be needed to drive the water round the various (4) zones that will be created. It seems the only variation I'm introducing is the method of pipe laying, and the method I've chosen is acceptable with certain proviso's:

1/ the insulation is effective
2/ the distance between pipes could be up to 300mm depending on pipe size. Too close, say less than 100mm and you're waisting pipe, too far and you could get cold spots.

Of course there are other major issues such as choice of manifold, servo's and stats. Polyplumb do a system which allows for me to buy the assembly in part or in whole if I needed. They also have a website which I've found very useful if anyones interested http://www.polyplumb.co.uk. It has PDF files that tell you everything you'll need to know.

As for the routed grove, I expect to be on my knees for about 8 hours and it will probably be very noisey, so I've got my knee protection ready and asked my neighbors to tell me when they'll be out for a day

 

[loftus75]

I thought I might just add my latest position on this subject. Over the last couple of weeks I've been researching the subject and have found a mountain of data out there in net land. But there are only a few plumbers and manufacturers that have actually been involved in this area in the UK. So here are a few observations;

1/ Don't believe everything a manufacturer tells you.
I contacted Polyplumb about my proposed new UFH system. I spoke with one of their technical advisors, who seemed completely baffled by the variation in installation, he suggested I buy one of their very expensive accessories and then after further discussion agreed that I could do what I planned without any additional gear. But it did take a few rounds to get him to concede

2/ Underfloor heating is for the moment a bit mystical, only because of it's rarity in the UK. However, it's not complicated and once you get your head around the idea that you're only fitting a rad on it's side, the rest begins to fall in to place.

3/ the most important factors connected to UFH is the boiler pump, (head of water), length of pipes and insulation.

Finally if any one wants to know more about it I found an absolutely brilliant site at http://www.radiantdesigninstitute.com/page48.html.

 

[breezer]

Good luck Loftus 75, and remember not to use too long nails / screws when fitting carpet gripper