Advice on what undefloor heating products to use

[Shercobob]

Hi,

We have had an extension built and are having the layout of the house completey changed so thought it would be a good time to install underfloor heating. I'm a boiler guy by trade but have never installed UFH but it doesn't seem too complicated.

Firstly I assume that in the new extension the approx 190mm (to top of existing floor board, 170 to top of floor joists) is enough room to get foam, pipes and screed down?

As far as zones the bathroom i'm thinking would be one zone, the hall a zone, the lounge another and finally the living/ kitchen room I'm thinking would be two zones due to a height difference of the pipe beteen the old and new parts of the house (top screed above pipe needing to be thicker than floorboard thickness)- so 5 zones. I'm not overly fussed about the study this could have UFH or just a radiator.

The walls I've drawn in red are stud walls and yet to be fitted over the top of whatever the new fitted floor is

The thing I'm having issues with is what system to choose for the existing house, I've seen plates that sit across joists, there are foam mouldings that sit in between joists and there are other methods too.

What is the best solution for the floorboards? Should I take them all out, fit some kind of tray and insulation then put all the boards back? or instead of the boards going back on, chipboard sheets? I like the idea of the aluminium trays fixed over the top of the joists with insulation mounted lower between the joists.

What is the easiest method for the concrete section? pre moulded plastic or insulation boards look good.

The floor finish will either be Amtico vinyl or laminate.

Is there some kind of spec or reference available?

Thanks for your time.

Rob

 

[Bonni]

Normally, your plumbers merchants will send a guy out from the suppliers to map out the zones, parts required and where to route the pipes. The pipes are in one length so larger rooms might be split into 2 to 3 zones.

I know Travis Perkins do this but they're rip off merchants so I never use them.

 

[SandyLyon]

Google hepcalc it’s a Hep2o UFH calculator that will produce a detailed quote and list of materials for you.

It will then give you an idea of how many circuits (zones) you need and how many ports on the manifold.

 

[cully]

Hi, Rob
some observations on your thread.
The position of the manifold is ok but be mindful of the noise from the pump, valves and pipework (where is the boiler?)
My son's is in a plant room in the utility with the boiler and cylinder and there is noise / vibration from pipework that resonates around the room but it is a big installation, mine is in the garage out of the way.
Screed for UFH pipe needs to be 50/55mm min. depth when thinking about insulation thickness in the extension.
With regards to zones I would have, study, hall, lounge, living, bath and kitchen.
All the zones apart from the kitchen would be controlling one pipe loop each (one manifold port) the kitchen would need two but I would include the utility into one of those loops (utility / kitchen door always open creating cold area)with the issue of differing floor levels, new to existing, there must be a way to resolve it.
I have no experience with retrofit UFH but one issue is cold spots between joists, I suppose it come down to the amount of work you are able to accommodate but if I was faced with a similar conundrum I know my answer to the question.
With regards to installation, I have installed a few without any issues using staples to fasten the pipe to the insulation, no need for templates.
You need to get your floor plan to a UFH kit supplier for pipe centre info, pipe lengths (max 90m) and price.
Ensure that the manifold is carrying reliable, replaceable parts.
Laminate amtico carpet etc is Ok over screed provided you inform the supplier it is going over UFH
Re; Zones I use heatmiser programmable stats to individually control each room.
Just some thoughts for you to consider
Paul C

 

[Shercobob]

Thanks for all your advice.
Cully, yes I could put the manifold in the garage (it's not shown on the diagram but it would be at top of diag. the other side of the wall to the utility and kitchen etc. The boiler and horizontal megaflo are going in there.
The zoning makes sense, as for ext and existing being on same loop, the ext pipework would sit lower than the existing house by approx 30mm, my worry is air being trapped but I guess as the flow and return are higher in the existing then that may not happen. I'd never be able to drain the ext. Pipework but if the water quality is kept good then it shouldn't need draining.
With regards to screed thickness being set, can you get different thickness insulation or would i need to adjust the level of the sub base to suit?
I think taking all the joists out and pouring concrete in the whole downstairs is too big a job really. If it would give a far better result then I can always ask for a quote to do it.
Rob

 

[cully]

That 30mm isn't going to be an issue with air but if you have concerns give the utility it's own loop (circuit) eight port manifold
I have had my UFH in use since 2000 with no issues re; water quality (alway keep plenty of inhibitor in the water.)
The insulation thickness generally can be obtained to get you near what you need re; screed depth, look up this supplier "seconds & Co "for damaged insulation that has been rejected by house builders because the packaging was damaged. Cheap insulation but you need to give them time to get what you want.
Re; pulling joists out, an alternative could be to cross lay insulation, in other words try and get some insulation to lay adjacent to the underside of the joists then the infilling between joists cancels out cold area's (as they do to comply with warm roof building regulation)
Do what's necessary to keep heating costs down.

 

[Shercobob]

I just did the hepcalc and it came in at £4.5K. I didn't expect it to be that much, I thought 3 tops. Mind you that is 7 zones and what seems like 3 manifolds.
I've sent the drawings to some UFH companys so i'll see what comes back.

 

[cully]

Thats sounds expensive are they sending screeders and installers to put it in?
I have always used "UFH1" a Doncaster supplier, .
If you visit their web page and look at their UFH kits I would presume you need the following,
One number eight port manifold (six rooms, incl. utility, have one circuit each and the kitchen with two circuits totals eight, (if you are having the utility circuit separate from the kitchen))
So their eight port kit which includes 120 sq mtrs of pipe laid at 150mm ctrs (they will do your calc and requirements) is around £900 incl vat
Seven heatmiser slimline programmable room stats @ £50 ea +wiring centre £60 is around £1300 plus the cost of the retrofit overfloor boards, their web page shows various costs per board
(don't bother with smartphone control you wouldn't us it on UFH)
I have noticed that the manifold actuators are not listed on their product list, won't work without them!
see how you go!!

 

[Shercobob]

Cheers cully, I'm going to do some phoning around tomorrow and I'll be sure to phone them.
I've worked out i think I've got the room to use a floating system which would be a lot less work. I'd remove the floorboards off and screw chip board or ply (maybe I could go thinner than 20mm with ply) then lay this floating system on top. Seems straightforward.

http://www.theunderfloorheatingstor...rowarm-18mm-low-profile-floating-floor-panels

 

[Shercobob]

Had a few quotes at 2 to 2.5k so that's a bit more like it.

 

[Shercobob]

Ive got a quote that looks good from 'the underfloor heating store'.
Very comprehensive and using branded parts like a grundfos pump and heatmiser controller. The pipe Is triple layered with aluminium.
Anyone had any dealings with the underfloor heating store, on the face of it they seem the best out of a few

 

[Gasguru]

Just make sure that spare parts are obtainable...when the manifolds start leaking or the mixer valve plays up you need to know that these items are available.
There are no end of companies knocking out U/F kits with no names on the parts with spares impossible to find.