Loopcad design

[Barnboy]

Hi all, I've been playing around with loopcad trying to get a design that fits in my space and is as equal as possible. 

I started trying to use spiral counterflows but I can't get these to fit very well.

In practice I'll take some of the feeds to the kitchen through the wall and extend others to cover the space left by moving these, but I can't work out how to do this without splitting the room up and can only do this in the opposite direction to the way the circuits fit.

 

What do you think of this design ? It's my 5th attempt so far ...

Thanks

[nod]

We’ve used warmup the last two times 

Free design 

[JohnMo]

See zero point have the floor heated below kitchen units.

 

What's the long skinny room with red pipe at 100mm centres?

 

You seem to have set the W/m2 the same throughout but I would assume some areas will have a different target temperature so a lower or higher output would be needed?

 

What did you set your target flow temperature as?

 

Are you zoning or running as a single zone?

[Barnboy]

Ll have a look at Warmup.

I've contacted Wunda as recommended on here, they seem friendly but they've quoted for 10 loops, which seems a lot and without paying a deposit they won't tell me even a rough layout of how they've spanned the loops.

[JohnMo]

4 minutes ago, Barnboy said:

quoted for 10 loops

That's a lot of pipe! I've only 7 loops in 195m2 and one of those is only 40m long. Still only have to flow 35 degs to batch charge.

[Barnboy]

22 minutes ago, JohnMo said:

That's a lot of pipe! I've only 7 loops in 195m2 and one of those is only 40m long. Still only have to flow 35 degs to batch charge.

That's why I want to look at designing the layout myself.

I've gone for 150mm centres in the main rooms and 100mm I  the W/C and hallway, as the hall has the stair opening plus a vaulted opening to the 1st floor, and a 3.7m x 3.6m glass surrounded front door.

There's a set of 3m bi-folds in the kitchen that I tried to get a 100mm loop infront of but the layout didn't work.

I've gone for 150mm as I've got 150mm insulation below the current 65mm screed and intent to put the ufh in a 45mm screed above that again. So the pipes will be just above the half way mark of a 110mm screed. 

[JohnMo]

Many will get as much pipe in the floor as possible to get the lowest flow temperature. But there are practicalities not covered by that sort of statement.

 

Your heat source will have a minimum flow temp, normally about 25. It will also have a restart delta, in my case the ASHP will not restart after a heat cycle, until it sees a delta of between 6 and 8 between target flow temp and return water temp. Now once your actually heating your floor it will settle at 2 to 3 degs hotter than the room. So a return temp is going to be in the 22 to 23 range (once floor is warm it stays warm for many hours). So realistically your min flow temp is about 28/29, so WC curve or set flow temp starts there. 

 

So design the floor loops for about 30 to 32 at the highest demand point (coldest design day).

 

Some comments on the pipe layouts

 

I would move pipe away from external walls, have them a good 200mm or more away. The heat flux will heat the floor in this areas, but the edges will be coolest, so least side way heat losses. You never walk on those areas or there is furniture over so no issues.

 

It's a waste of energy heating under kitchen units.

45 minutes ago, Barnboy said:

that I tried to get a 100mm loop infront of but the layout didn't work.

Your whole floor area is a radiator all exposed areas of that floor will heat the room space. Having hotter bits really makes no difference.

 

Halls are a movement space, yours looks like it will be the hottest space in the house. I have no dedicated loops in the hall at all, just use the pipes that transit through that space spread at 300+mm centres, it always warm because every heated room feeds it it with heat.

 

[nod]

2 hours ago, JohnMo said:

Many will get as much pipe in the floor as possible to get the lowest flow temperature. But there are practicalities not covered by that sort of statement.

 

Your heat source will have a minimum flow temp, normally about 25. It will also have a restart delta, in my case the ASHP will not restart after a heat cycle, until it sees a delta of between 6 and 8 between target flow temp and return water temp. Now once your actually heating your floor it will settle at 2 to 3 degs hotter than the room. So a return temp is going to be in the 22 to 23 range (once floor is warm it stays warm for many hours). So realistically your min flow temp is about 28/29, so WC curve or set flow temp starts there. 

 

So design the floor loops for about 30 to 32 at the highest demand point (coldest design day).

 

Some comments on the pipe layouts

 

I would move pipe away from external walls, have them a good 200mm or more away. The heat flux will heat the floor in this areas, but the edges will be coolest, so least side way heat losses. You never walk on those areas or there is furniture over so no issues.

 

It's a waste of energy heating under kitchen units.

Your whole floor area is a radiator all exposed areas of that floor will heat the room space. Having hotter bits really makes no difference.

 

Halls are a movement space, yours looks like it will be the hottest space in the house. I have no dedicated loops in the hall at all, just use the pipes that transit through that space spread at 300+mm centres, it always warm because every heated room feeds it it with heat.

 

100% agree 25-300 150-200 

None of it makes any difference 

UHF heats up slowly   The idea is to get it warm and have it ticking over 

[Barnboy]

11 hours ago, JohnMo said:

 

So design the floor loops for about 30 to 32 at the highest demand point (coldest design day

So to do this do I take the, total heat loss power for a 30⁰  difference between room and outside air temp and divide it by the floor area, then design the loops for this w/m² ? My outside temp will very rarely go below 0. Thanks

[JohnMo]

19 minutes ago, Barnboy said:

So to do this do I take the, total heat loss power for a 30⁰  difference between room and outside air temp and divide it by the floor area, then design the loops for this w/m² ? My outside temp will very rarely go below 0. Thanks

Just set the flow temp to say 32 in loop cad it uses that to calculate the floor power. As @nod says the loop spacing only really make a difference to heat up time. But once heated you keep it heated for the heating season - you don't let it loose too much heat. Doing setbacks is a waste of time with a thick screed (you will end up with one). So don't go overboard, just do everywhere the same spacing. Keep one pipe spacing away from outside walls, and don't bother with pipe under stuff would be my advise.

[Barnboy]

I've just had a very quick look at loopcad, my flow temp was set at 35⁰, I've dropped that down to 32⁰ which has in turn dropped the w/m² down to 23 ish, according to Jeremy's spreadsheet if I work it out correctly by dividing my coldest outside vs inside temp total heat loss for my projected coldest day by my total area, I get around 45-50w/m². If this is the correct way to work out my requirement the  how do I get this figure upwards ? Loopcad is saying that I only need more heat in my w/c, yet none of my floors hit 46-50w/m². Can I only up the flow temp or am I looking at it all wrongly ? 

Thanks

Edited May 6 by Barnboy

[JohnMo]

Either you are leaking heat like a seize or you have input the wrong numbers somewhere. Would look at air changes first. If you have MVHR set at about 0.3, if no MVHR set at about 10% of your air test result or target at 50Pa.

[Post and beam]

On 05/05/2024 at 08:08, nod said:

We’ve used warmup the last two times 

Free design 

Apologies for jumping into this thread but do they have their own software or do you mean they offer a free design service ?

Thanks in advance

keith

[nod]

42 minutes ago, Post and beam said:

Apologies for jumping into this thread but do they have their own software or do you mean they offer a free design service ?

Thanks in advance

keith

They sell all equipment 

and have a free design service 

[Post and beam]

4 hours ago, nod said:

and have a free design service 

Thanks. I thought there might have been an alternative to Loopcad in the offing

[Barnboy]

I got time to have another quick play last night. I've checked the numbers in both Loopcad and Jeremy's spreadsheet, both seem good to me and as far as I can see. I've inputted custom figures for the loopcad u-values.  Now looking at it I'm wondering if the w/m² shown in each room in Loopcad is what it calculates it is needing as it seems to stay the same whatever I do with the input temp or pipe spacings, with plus figure below it when I increase the input.

So am I getting conflicting requirements from the spreadsheet and Loopcad ?

[JohnMo]

The drawing shows the long L shaped room need supplemental heat, could see any others that do.

 

There is a calculation sheet you can print out in LoopCad, it shows all the room by room details including what is required heat wise and being supplied and temperature and flow rate etc.