Critique my UFH plan

[LiamJones]

UFH will be installed in 100mm self compacting concrete slab tied to a142 mesh (hence 200mm pipe spacing to line up with mesh). 200mm PIR below.

 

ASHP, flow temp 31.1c, DT 3-5c, heat demand for whole house 2600W. 'm hoping to not have heating upstairs, so have aimed for 26W/m2 over the 100m2 ground floor.

 

ufh.01.PDF

[BotusBuild]

The design of the pipe layout is OK.

 

Will it be zoned?

I presume with that flow temperature you are going to install a HP. If so, and you are going to be zoned likelihood is you will need a buffer tank

[LiamJones]

8 minutes ago, BotusBuild said:

The design of the pipe layout is OK.

 

Will it be zoned?

I presume with that flow temperature you are going to install a HP. If so, and you are going to be zoned likelihood is you will need a buffer tank

Hey, thanks for feedback. Yes, it's ASHP, no zones, fully open. Has about 50L volume, ASHP likely to be 5kW and i've read rule of thumb is 10-15L/kW, so should just about be okay, i think.

[nod]

Warm up will do you a FREE design via one one there approved installers 

[LiamJones]

Just now, nod said:

Warm up will do you a FREE design via one one there approved installers 

 

Not tried warmup, tried a couple others and they've been 💩, I trust this forum more than the wider world.

[JohnMo]

Your bathroom, reduce spacing to 150mm, you never have enough heat.

I would be inclined to the kitchen area on 225 to 250mm centres.

 

Dump the hall loop, use the loops transiting through the hall and borrow that heat. I do similar, my kitchen loop does the shower room first, then zig zags by the front door, then does the kitchen diner. Works well, do hottest area first.

 

Operate as a single zone, electric towel rail in bathroom, that adds a second heating zone and keeps building regs happy as well.

 

Unlikely your dT will work, you will be nearer 4 to 7 in reality.

 

 

[LiamJones]

1 minute ago, JohnMo said:

Your bathroom, reduce spacing to 150mm, you never have enough heat.

 

I would be inclined to the kitchen area on 225 to 250mm centres.

 

Dump the hall loop, use the loops transiting through the hall and borrow that heat. I do similar, my kitchen loop does the shower room first, then zig zags by the front door, then does the kitchen diner. Works well, do hottest area first.

 

Operate as a single zone, electric towel rail in bathroom, that adds a second heating zone and keeps building regs happy as well.

 

Unlikely your dT will work, you will be nearer 4 to 7 in reality.

 

 

Thanks you, am i getting to caught up on the 200mm spacing lining up with the a142 mesh size? any diversion from that and i'll have pipes running through the spaces in the mesh. I'm worried about the concrete pour and them standing on unsupported pipe?

[LiamJones]

I guess for just one small room they can avoid standing on pipe, right. So yeah, i'll get the bathroom down to 150c, but probably leave the kitchen at 200c and reduce flow rate if i need to?

[LiamJones]

Going down to 150c in bathroom has allowed me to drop flow temp by 0.5c (apparently) and get a lower DT 🏆

 

ufh.04.PDF

[nod]

2 hours ago, LiamJones said:

 

Not tried warmup, tried a couple others and they've been 💩, I trust this forum more than the wider world.

I’ve used warm up on the last two

Absolutely fine and FREE 

The all use the same software 

[Chanmenie]

5 hours ago, LiamJones said:

Thanks you, am i getting to caught up on the 200mm spacing lining up with the a142 mesh size? any diversion from that and i'll have pipes running through the spaces in the mesh. I'm worried about the concrete pour and them standing on unsupported pipe?

Could you consider fibre re inforced concrete and ditch the a142 mesh ?  be much cheaper.

So much easier to staple the UFH pipes direct to the insulation plus you are not driven by the mesh size, and the pipes are fully supported 

Edited February 8 by Chanmenie

[LiamJones]

59 minutes ago, Chanmenie said:

Could you consider fibre re inforced concrete and ditch the a142 mesh ?  be much cheaper.

So much easier to staple the UFH pipes direct to the insulation plus you are not driven by the mesh size, and the pipes are fully supported 

 

for bits i could ditch it, but the a142 is also providing structural properties over old foundations to help with differential movement.

 

I also like that on mesh (on chairs), it can sit half way up the slab. should be more efficient? by how much i dont know.

 

I think ill probably stick with the mesh, but thanks for the alternative.

[Moonshine]

do you need a manifold cabinet like this?

 

https://www.wundatrade.co.uk/shop/home/underfloor-heating-manifolds-and-pump-sets/underfloor-heating-manifolds/small-surface-mounted-waterproof-manifold-cabinet/

 

i have got one knocking about after my build (brand new in box)

[Chanmenie]

4 hours ago, LiamJones said:

 

for bits i could ditch it, but the a142 is also providing structural properties over old foundations to help with differential movement.

 

I also like that on mesh (on chairs), it can sit half way up the slab. should be more efficient? by how much i dont know.

 

I think ill probably stick with the mesh, but thanks for the alternative.

Ah I did wonder if there were structural reasons. 
not convinced the rebar chairs do make it any more efficient as you still heat the whole slab