UFH Loopcad Design help

[MrWhat]

Hi guys, I have been trying to get my head around designing my underfloor heating circuits in Loopcad but im concerned I have missed something!  When I started the design Lopcad started with 300mm pipe spacing so I just went with that.  At a water temperature of 29-30 degrees it seem that all of the rooms will be heated sufficiently, except for  a couple in which I have reduced pipe spacing to get it warmer.  It is a new build with good insulation. I am going to have an ASHP.  I have not changed any flow rates or other settings in loopcad and am wondering if I should have changed something as Im surprised that the 300mm spacing seems to be sufficient?  Here are some screen shots of the system design from Loopcad.  Does this look correct?

[MrWhat]

Ive just realised that I have location set to the nearest to me but it has a temperature of -0.4 which I assume is the lowest outside temperature I should expect.  However, changing that to a different location with to a -3 temp has made little difference except to the heating load figure which as gone up from 4800 to 5383w.  I assume this figure is a indication of what size ASHP I should get?   

[JohnMo]

300mm centres works fine, your delta T is going to be closer to 4 when running. But if you have balanced to rooms in Loopcad, all you need to do is set all the flow meters on the manifold fully open and let the heat pump get on with settings flow rates.

 

Coupled with thick screed don't expect the reaction times to be quick, it's a very slow and steady system.

 

You may find you actually don't need the UFH upstairs except for bathrooms, unless you like bedrooms really hot.

 

Bathrooms, I did those at 300mm centres, but a bathroom cannot be too hot, most of the floor space is taken up with showers, toilet etc, so reduce spacing to 150mm.

 

Can you not get rid of the dedicated hall loops downstairs? Generally reduce the number of loops?

 

Not a fan of going under internal walls.

 

Can you reduce the manifolds to one upstairs and one downstairs?

 

Some of you loop lengths look really short.

 

Not sure I would want UFH in a gym?

 

I am 192m² ground floor area and have only 7 loops, you are on 40+ and six manifolds?

 

[MrWhat]

Thanks for your reply, I understand that adjusting temps will be slow but it will hopefully just be on all the time at a set temp.

 

 Upstairs has been added as a just in case.  Like you say, there is a good chance that it wont be needed except in the bathrooms but as least its there. 

 

Good point, I will change the spacing to 150mm in the bathrooms/ensuites.

 

I have kept the loops per room in case in the future room temp control was wanted in stead of the open system.

 

It is actually one manifold upstairs and two down.  They are all shown on each diagram so I have 22 loops and three manifolds.  

 

Ill have a look and see if I can reduce the number of loops a bit.

 

The Gym has heating just in case it is used for something else later.  I will isolate that.

[MrWhat]

Internal walls are all stud walls so Im not concerned about pipes underneath really

[JohnMo]

22 minutes ago, MrWhat said:

Internal walls are all stud walls so Im not concerned about pipes underneath really

As long as they are deep enough not to have a drill through them, for the bottom stud wall rail fixings. That was my concern.

[Nick Laslett]

For my design I targeted 90m long loops. The piping comes 100m long reels. I went with 200mm centres which I think is the rebar grid distance. Anyway they follow the rebar grid whatever size that is. My installer fitted less pipe than on the plan, but it doesn’t seem to have affected the house.
Some good discussion here. 
 

 

[MrWhat]

Thanks,  I have a decided to increase the spacing to 200mm so as to increase the capacity of the downstairs from 72 to 102 litres so hopefully wont need at volumiser.  My rebar is 200mm grid too so that will also make installation easier.  I have only two small loops now, all the others are over 70m.    I will be doing all the stud work so will have to remember the pipes underneath!

 

[Nickfromwales]

Any reason that your plant room is huge?

[MrWhat]

The plant room is also the utility room so that is the reason for the size.