What spaces between flow and return pipes in UFH

[joe90]

Hi Guys, I have received my plans for the UFH which I am installing myself ( with the help of a plumber mate) but the plan shows feed and returns to the six zones very close together and I would think they should be separated to stop heat transfer. What distance would be sensible to stop heat short circuiting from the flow to the return?.  Also I plan to put the feed and return to the manifold from the ASHP between the EPS sheets in the floor insulation, I know electric cable can be affected by EPS ,but is plastic water pipe affected?.

Edited October 27, 2016 by joe90

[PeterW]

Close as in ~100mm apart..? if its only for a short length such as 2-3m then it will be fine but beware of overheating that area

[Onoff]

Pretty sure my red Polypipe formers set the pipes 100mm apart.

[joe90]

Here is my plan:-

 

 

R12212 John Hodges PIPELAYOUT 13.10.2016.pdf

[PeterW]

So that spacing is OK but that hallway cupboard floor will be warm !

 

Surprised they have gone for a serpentine flow though with multiple loops in the same zone.

[joe90]

I have just scanned the tinternet and other sources say 200 to 250 mm spacing for a well insulated floor ( and mine is) are Wunda ( my supplier) wrong going with 150mm spacing ( another site says 75mm between flow and return to manifold).

[Guest Alphonsox]

We went for a 200mm spacing for our build. Like you we have put the manifold under the stairs. This area is likely to get a bit warm but the heat can dissipate to the upper floor so shouldn't be a problem. The big difference is that we have gone for a loop layout rather than linear (at Nick's instigation iirc). The gives a better heat distribution over the whole floor rather than a hot end and a cool end.

UFH_5_loop_a3.pdf

[PeterW]

1 hour ago, joe90 said:

I have just scanned the tinternet and other sources say 200 to 250 mm spacing for a well insulated floor ( and mine is) are Wunda ( my supplier) wrong going with 150mm spacing ( another site says 75mm between flow and return to manifold).

 

Its not as simple as that ! You need the heat loss per room to work out the spacings - I have some with 200mm, and some with 150mm...!

 

You can always run it a bit cooler and maximise the COP on the ASHP - running it hotter as you've spaced out further may give you other issues

[CC45]

Some areas are at 150, others 200 with us.  Our manifold is under the stairs but we fed direct under the timber frame into rooms - you could do this to the lounge and dining room - shorter runs and less local heating under the stairs.

 

CC

[Nickfromwales]

Simple folks, just insulate every other pipe in the congested areas . 

9mm wall armorflex will be ample. 

[joe90]

18 hours ago, CC45 said:

Some areas are at 150, others 200 with us.  Our manifold is under the stairs but we fed direct under the timber frame into rooms - you could do this to the lounge and dining room - shorter runs and less local heating under the stairs.

 

CC

Ah, now then, another question, we are having our slab poured in one piece on top of the internal block skin and over the internal block walls. I know you should not run UFH pipes under fixed cabinets etc but would it be ok to run it under a single skin block wall for just 100mm, this would shorten runs and stop congestion in the doorways!.

 

PS, anyone want to comment on my question above about the pipes feeding the manifold being installed within the insulation under the slab, plastic water pipe in contact with EPS ?

 

PPS, Sould I consider a different design rather than loop (Nick!)

Edited October 28, 2016 by joe90
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[joe90]

21 hours ago, joe90 said:

Ah, now then, another question, we are having our slab poured in one piece on top of the internal block skin and over the internal block walls. I know you should not run UFH pipes under fixed cabinets etc but would it be ok to run it under a single skin block wall for just 100mm, this would shorten runs and stop congestion in the doorways!.

 

PS, anyone want to comment on my question above about the pipes feeding the manifold being installed within the insulation under the slab, plastic water pipe in contact with EPS ?

 

PPS, Sould I consider a different design rather than loop (Nick!)

 

Anyone???

[Onoff]

I can't see an issue with pipes sitting in direct contact & between the EPS.  Read loads where it gets stapled direct.

 

Under a wall then you could just insulate that bit as said above.

 

Loop over serpentine is my understanding as it's more even.

 

Don't forget to make a decoiler!

 

 

 

[joe90]

Thanks  onoff , I have already saved this picture so I can copy it.? I tend to agree with you regarding loops etc but that was the way it was designed, I think I will ask Wunda if they will design it the other way for me. Glad you don't see a problem going under walls either. Ta.

[ProDave]

I'm late to this thread.  My comments:

 

Do NOT bother with an UFH zone in the hall. Our present house, which is nothing special in terms of insulation etc has one, and it NEVER turns on.  The hall is in the middle of the house and it only has a tiny wall area at the front to lose heat. It will gain much more heat from the adjacent rooms, so save pipe and effort and forget any UFH circuit in the hall.  This will then allow you to space out any pipes that happen to flow via the hall to get to their destination.

 

Same for a landing upstairs, that never turns on either so again do not bother with UFH on a landing upstairs.

 

Don't cram the pipe runs from the manifold all into oner little gap, but space them out evenly across the width of the hall, and evenly where they pass under the stairs. This alone will heat the hall all it needs.

 

The under stairs cupboard will be warm from the manifold, ventilate it to let some of the heat out to the rest of the house.

 

[Onoff]

I'm planning to have no UFH pipes in our "stairs" room. It's central to the house, the manifold will be under the stairs with circuits running to adjacent rooms. 

 

In the bathroom the UFH doesn't (eventually won't ) heat the large cupboard area or under where the bath is.

 

Tbh the layout does go a bit "serpentine" where it exits the room.....but NICK says it's alright!

 

 

 

 

 

[joe90]

Thanks guys, the reason for the hallway UFH is there being no heating upstairs so any small amount of heat will rise to the landing etc. All the UFH will be one zone. Any more comments on pipes under walls?

[ProDave]

16 minutes ago, joe90 said:

Thanks guys, the reason for the hallway UFH is there being no heating upstairs so any small amount of heat will rise to the landing etc. All the UFH will be one zone. Any more comments on pipes under walls?

In which case, I would space out the flow and return pipes that are "passing through" at the same spacing as everything else, then make the hall zone what is left over.
 

[Onoff]

31 minutes ago, joe90 said:

Thanks guys, the reason for the hallway UFH is there being no heating upstairs so any small amount of heat will rise to the landing etc. All the UFH will be one zone. Any more comments on pipes under walls?

 

I'm thinking you would want to sleeve (flexible conduit) any pipes under walls even if you weren't insulating them. If nowt else it might help protect the wall itself if it sprung a leak there. Makes threading them through a doddle too with nothing to catch it / snag.

 

 

 

[Nickfromwales]

On 29 October 2016 at 15:15, joe90 said:

 

Anyone???

Bit late to this party as I'm 350mph with work at the mo ?

No problem whatsoever going under the walls, just sleeve or insulate it and you'll be fine ( 100mm wall transit would be 300mm of cover. 100 before - 100 under  - 100 out the other side  ). 

Loop method is the anti-Christ unless your in spreader plates, so go reverse / inverted whenever possible.

[joe90]

Thanks Nick, sorry your so busy but it just goes to show how good you are and in demand.

[Nickfromwales]

Don't be sorry ......it pays the bills. .