First Underfloor heating install advice and tips

[RayPlumb]

Got an underfloor heating to install and Ive done a few repairs on manifolds etc but this is the first design and install for me. Advice and tip requested. The job is a kitchen extension with under floor heating this .will be added to the existing rad heated house.
The new heated areas will be the kitchen and adjoining utility room (which ill put maniufold). The new kitchen extension room will be area 7.5x 6mtrs of which the available new floor for pipes will be 4.6mtrs x 6mtrs.
How do you work out heat required on new floor area to heat up whole room ? There is also a lot of Glass (french doors) on two walls so higher heat loss compaired to insulated walls. Again heat loss. Do you put in heated room size and with required calculated pipes length put closer together to fit in smaller available floor area to gain more heat??
The ajoining utility room (2.5 x 2.4 mtrs) is new floor so will do as a new zone with stat.
Which floor pipe fixing system is recommended ?
With pressure testing how long do you recommend this is done and should I leave it pressurized when screed laid on top. Do you fix manifold and pressurize all that as well. Practical questions for ease of install.
Any advice and experiences would help
Thanks Ray

 

[oz-plumber]

Pick a supplier / company that you want to use and get them to design the system for you.
Too many variables to give you any advice, without leaving you in trouble if it doesn't work

 

[IND_Nick]

Send the plans over to Uheat,they sponsor this forum. Give them the details and they do all th calculations for you. If you have any questions they are very helpful and will source answers. I've used them for a few years and they are great, very competitive prices too.

 

[RayPlumb]

Send the plans over to Uheat,they sponsor this forum. Give them the details and they do all th calculations for you. If you have any questions they are very helpful and will source answers. I've used them for a few years and they are great, very competitive prices too.

Thanks emailed them .

 

[king of pipes]

Have to agree send over details to uheat Jake he is very good and will design a system for you , use their staple system it's easy to lay you will need the stapler which can be hired , I've done several of their systems all worked out great , fill vent and pressurise to 3 bar while floors laid ,your systems relatively small so I'd say 150 mm to 200. mm centres would be ok you'll struggle getting it any tighter than 150 mm . Kop

 

[Timmy D]

I’d also like to endorse Jake at U Heat.

Has helped me, designed and sold me the kit at a very good price.

Top notch

 

[exedon2]

We do a fair bit of underfloor after using several now polypipe installer's. Gives you chance to negotiate price with any number of merchants and under screed its a 15mm system .
So any odd ends of tube use up
What do you do with bits of 16mm apart from skip?

 

[ShaunCorbs]

We do a fair bit of underfloor after using several now polypipe installer's. Gives you chance to negotiate price with any number of merchants and under screed its a 15mm system .
So any odd ends of tube use up
What do you do with bits of 16mm apart from skip?

Hot and cold and heating if it’s wras approved

 

[RayPlumb]

I know its hard to say but I'm trying to gauge how long it will take to lay so I can quote labour.
Uheat have quoted the ultra fix rail system. 2 zones (2x 100mtr in one zone and 1 x 50mtr in the other)
Fix rail system then pipes at 150mm centers , The two zones floor area is approx 35m2
Install manifold with 2 port valve and 2 wifi thermostats . Pressure test.
I'm sure seasoned installers can wiz through this small install . I'm expecting it to take me longer than normal as first one.
Any advice on how much time I should allow as don't want to under estimated time taken to install.

 

[ShaunCorbs]

I would allow 2 days as it’s your first

Chances are you will be able to do it in a day once you know the ins and outs wtc

 

[king of pipes]

I could do it in 2 days but allow 4 as it's you first one £1000 to lay it and connection to the system isn't far out I'd say . 👍

 

[RayPlumb]

Would 150m x 16mm pipe have much of an impact on the expansion vessel, as this water will not be as hot as the rad water. Is there a online calculator or should I just see if expansion vessel copes?

 

[ShaunCorbs]

Your adding roughly 16litres extra so maybe 2-3l extra of expansion max

 

[Ric2013]

I used Uheat 5 years ago. Wanted to try out UFH in my own house which doubles as my guinea-pig for.. everything. They sold me a spreader plate system (which was what I wanted). Jake was helpful, but miscalculated the number of spreader plates I'd need (he didn't take into account the MIs that required an unheated perimeter so now I have a box of them I don't know what to do with). The room thermostat in the kit had Chinglish instructions and uses a bewildering variety of irrelevant and counter-intutive symbols. Uheat gave me contradictory advice on it as he didn't understand it either and, while it is CE marked, Jake didn't understand what I was on about when I asked for the Declaration of Conformity (I called it a Certificate of Conformity, so probably my fault). On the other hand, the kit is still working 5 years later (although I think the heat output underperforms slightly as the spreader plate design did not make good contact with the pipe itself, something I modified for the better in one zone but not the other).

I have seen far more detailed design and installer guidance on a kit a customer had had installed (by another firm that then installed it wrongly and ignored the instructions) who even specified the exact pipe layout and gave the exact lengths of pipe required and was impressed. But I expect the far more detailed firm came at a far higher cost: the Uheat kit was very well priced.

General tips: Putting the pipe in in general is really much easier with an assistant. Hours not days, but you need planning time as you need to know where the pipe is going to end up before you start putting it in and getting it wrong. If the manufacturer does not design the exact pipe runs for you, you can have the fun of deciding what kind of layout you will use. And if it's your first time, a tip from me is to have two hoses to commission: I didn't, had to rely on turning off the water as soon as it started to gush from the opposite manifold so there was still air in the system, and wasted much time using the manifold pump to clear airlocks, which is not the best way!

Stuff nobody told me at the time included to fit biocide to the heating system due to the low temperatures. At the time, look at what Heat Geek has to say about UFH and particularly about CCTs (with lockshield valves) near the manifold was not an option as he hadn't made the videos back then, but I would recommend it now.