Distance between pipes in certain scenarios

[meakinsl]

Hi,

Having wet underfloor heating put in and been doing some reading, think pipe spacing is going to be 200 but read somewhere 100 from walls & sliding doors/bi-folds - is that correct ?
What distance would people recommend from kitchen units ? I have a run against one wall and then a 1200 gap to island, could go 200 spacing from units and have 5 pipes or 100 from the units & island then 200 between rest giving 6 pipes ?
Also one wall is going to have speakers, tv (on wall) and tv unit with various boxes along it - would you run underfloor heating under this or come off the wall 600 to avoid any overheating issues on the electronics ?

Many thanks,

Lawrence

 

[ShaunCorbs]

Haven’t you got a design plan to follow 200 seems a big space normally 100-150 depends on heat and source

 

[meakinsl]

Haven’t you got a design plan to follow 200 seems a big space normally 100-150 depends on heat and source

Thanks for reply, there isn't really a design, just the plumber laying it down, pretty sure he mentioned 200 on pipe centres - does it depend on pipe diameter - assumed 16 and read for that is usually 200 but very new to this but so it seems is the plumber !

 

[ShaunCorbs]

😀 that’s a bad recipe what pipe is he using ?

 

[meakinsl]

😀 that’s a bad recipe what pipe is he using ?

That was my worry - will try and get hold of him and ask some more details as is a concern think was just going to whack it down without a design.

 

[ShaunCorbs]

I would stop him if there’s no design or a guarantee that he’s liable if it doesn’t work / heat correctly in writing

 

[exedon2]

As Shaun says needs to be properly designed.
Polypipe will get a design/quote out in around 3 hrs in normal working hrs .
All the underfloor manufacturers offer a design service.

 

[meakinsl]

As Shaun says needs to be properly designed.
Polypipe will get a design/quote out in around 3 hrs in normal working hrs .
All the underfloor manufacturers offer a design service.

So have spoken to plumber this evening, is 18mm pipe and he reckons always uses 200mm spacing, there has been no design done and he said we can work it out together when on site Friday which kind goes against everything being said here. he also said would go right up to the kitchen units and then 200's from there. Not sure what to do as I believe he has done quite a few and is also doing boiler/rads/plumbing and has come recommended but the spacing does have me a bit spooked on the floor.

 

[ShaunCorbs]

Ask him what’s the Heatloss of the floor and what temperature is he running it at due to the floor covering x (inset what your having )

 

[EvilDrPorkChop]

I never use a design, and never have any issues 🤷‍♂️

 

[Timmy D]

The manufacturers install guide will tell you what spacing to use for a certain heat output.

From memory, you want to aim for around 100-150 watts per m2.

 

[Gasmk1]

Doesn’t spacing also depend on what the flooring is going to be eg: tiles or wood or laminate

 

[Ant87]

Spacing as a rule of thumb is 200mm for a boiler and 150mm for low temp i.e. heat pumps.
This will be affected by heatloss so if your room has a lot of glass or poor insulation then the boiler UFH system would likely need to be increased to 150mm centres to overcome the overall heat loss.

18mm is usually used in commercial settings and 16mm/15mm or 12mm in domestic.

Polypipe use 100mm centres as they only use 15mm "plastic barrier" pipe which has a lower output than 16mm "al barrier".
Polypipe at 200mm centres with mean temp of 45degC would give you 63w/msq whereas at 50degC mean
temp would be 76w/msq.
All Polypipe quotes are generally assumed at 55w/msq heatloss unless stated at time of quote.

Pipe lengths play a big part so shorter pipe lengths would have a lower deltaT, long pipe runs would have a wider deltaT (maximum is usually 100m per circuit).
Floor coverings play a large part, if it's tile your fine, if it's carpet then you will need to be looking at a combined TOG of less than 1.5.

100w/msq is around the max you can get from hydronic/water UFH as the surface area is limited to around 29degC.
If your heat loss is an average of 120w/msq then UFH wouldn't work, if your average heatloss is 40w/msq then 200mm centres with mean temp of 40degC would work.
Most new builds (2016 onwards) should have an average of less than 55w/msq.

 

[Ric2013]

I used Uheat once. They didn't give me a design as such, just certain parameters such as distance from walls etc and it was left to me to decide how to lay the pipe (I went for a double serpentine pattern) . In the end, the system output (calculated by working out the flow x Delta T x specific heat capacity of water) did suggest a slight underperformance, but in the context of the overall project, that was fine. At least it was a relatively inexpensive system to purchase.