Competent loopcad design ?

[Post and beam]

Would anyone like to comment on this design proposal please. Done for me because i cannot get around Loopcads trial expiration today.

I expect a Vaillant 7kw @ a 35 degree maximum flow temp if possible. do the flow rates look good?

 

Anything else to note

Drawing R2.PDF

[JohnMo]

Think the person that designed has missed a trick.

 

Study and WC could be one loop - well within 100m pipe length. 1 loop removed

 

The hall could be heated by the pipes that transit through the hall by just spreading the pipes at 150 to 200mm centres instead of bunching them all up against the walls. Another loop removed

 

The utility could be heated with the same loops in the kitchen. Another loop removed.

 

So 3 loops removed without much thought.

 

Ignore the flow rates. Flow rates, you set all flow meters fully open, set the flow temp to get the colder room to temp, rooms which are too warm reduce flow at the flow meter. This will give the heat pump the opportunity to have all the flow it wants, so it can modulate freely. This assumes no buffer, fully open system on a single zone.

 

I have 7 loops over 192m² on a very loose 300mm centres and very rarely exceed 35 degs flow and that at around -9 outside. So you should never exceed low very low 30s, maybe high 20s ever.

[G and J]

Not started thinking about UFH loop design yet but as a principle, by removing loops as you describe do you diminish or remove individual room control?

[SteamyTea]

10 hours ago, G and J said:

diminish or remove individual room control?

Not really the thinking behind house heating these days.

In the past, rooms were effectively separate compartments within the building, they had varying thermal properties i.e. air leaks, high wall U-Values, fixed usage i.e. kitchen, living room, bedroom. This meant, because of the relatively high cost of thermal energy, that it was more normal to heat one room, then crowd people into it.

Now we have well insulated and more airtight buildings i.e. windows that actually close shut, no open fireplaces, floor, loft, wall ect insulation.

So rather than overheat one part and allow the energy to spread throughout the building, while reducing in temperature, we more evenly heat the whole building, in the knowledge that the exposed to ambient parts of the structure are thermally good.

 

This more modern thinking is taking a long time to override traditional thinking, especially as people think that little used rooms should/can be a a lower mean temperature.

This will become much more important as ASHPs take over from combustion technologies because the CoP diminishes as flow temperature rises i.e. running a heat pump for 2 hours at a flow temperature may use more primary energy than 5 hours at a much reduced flow rate (be careful when calculating this as a percentage).

[Nickfromwales]

11 hours ago, G and J said:

Not started thinking about UFH loop design yet but as a principle, by removing loops as you describe do you diminish or remove individual room control?

Rooms adjacent to each other and set to different temps will just fight to acclimatise to one ambient, I had this explained to me properly by my go-to ASHP & MVHR suppliers. Seems madness to think it would not do as it says on the tin, but the cooler space will just attract heat from the others, and that’s just down to physics. 
 

Then add a quality MVHR with excellent heat recovery statistics into the equation and you’ll also have a bit of ‘heat balance’ from moving air right around the property 24/7.

 

Individual room control afaic is more about wanting to sporadically heat one room or space for comfort use, and then allow it to revert back to playing nicely with the rest of the house.
 

You’ll struggle to reduce the temp of any one space significantly eg by turning the heat off / down, as it’s wrapped around by other heated spaces that will attempt to contribute.

 

I’ve learned so much about this, over the last decade or so, a lot from here, but most improvements have been made since dumping everything I (thought) I’d learned in the 25 years or so prior to the last 10.
 

You genuinely, really do have to reprogram your brain to disregard the way we’ve lived previously in poor housing stock, and start over when considering solutions for anything built to a good standard (eg NOT to British building regs) that is airtight and well insulated, with quality doors and windows and so on. It’s just night and day different, but people get stuck in the old ways of thinking and that needs to be a million miles away for sure!

[JohnMo]

13 hours ago, G and J said:

Not started thinking about UFH loop design yet but as a principle, by removing loops as you describe do you diminish or remove individual room control?

As described very well above. Individual room control means zones.

 

One of my loops does, main bathroom, then meanders around the hall near the front door area, then does the kitchen diner. All with a 100m of pipe. Bathroom is routed through first as that wants to be warmest. Just a matter of a little logic. The room isn't really warmer than anywhere else, just feels warmer because the floor is slightly warmer.

 

[G and J]

Hmmmm, I can believe that I need to do a factory reset in my heating brain cells but I can’t find the button. 
 

I'm committed to the single zone, WC, approach, with UFH throughout downstairs and limited upstairs heating (Fancoil in bedroom and electric UFH and towel rads in bathrooms). 
 

I'd figured I’d have a loop solely for the utility room which could be turned off to start with but brought on if needed.  Taking the above comments to their logical conclusion I could almost forget the internal walls and simply pipe out in the most efficient manner to give equal loop lengths.  So all can be more or less left wide open.  
 

I think. 

[Post and beam]

Another aspect of single zone thinking of course is because of the need to allow air to move more freely around because of the MVHR. Larger gaps under the internal doors for example. This makes a mockery of even attempting to have different temperatures in differnet rooms.

[Mike]

Apart from the factors mentioned above:

• I'd run the pipes under the kitchen & utility units too. Then, if someone changes the layout at a future date they won't have cool patches on the floor (I've seen it happen).
• I wouldn't run the pipes directly under the WC. It will need screwing to the floor and you don't want to drill through a pipe!

[G and J]

38 minutes ago, Mike said:

I wouldn't run the pipes directly under the WC. It will need screwing to the floor and you don't want to drill through a pipe

Ah, got that covered.  We’re going for trendy wall mounted potties. Which unless I lose loads of weight building will need some big bolts to hold em up!

[JohnMo]

9 hours ago, Mike said:

I'd run the pipes under the kitchen & utility units too. Then, if someone changes the layout at a future date they won't have cool patches on the floor (I've seen it happen

No direct pipes in utility, as the UFH manifold is at the back of the utility so all pipes transit through, had to insulate most to keep room temp down.

 

Don't really buy the need for loads of pipe on a kitchen either, you may be shocked how little pipe I even have in there (yes I am running a heat pump). So kitchen diner is an L shapes room. Kitchen is the bit with the single pipe in it, the pipe runs between wall units and island. Does it work - yes, kitchen is currently 20.2 degs and it was 3 degs overnight.

 

Total floor area is 192m² for bungalow and less than 600m of pipe.

 

[Post and beam]

10 hours ago, Mike said:

I wouldn't run the pipes directly under the WC. It will need screwing to the floor

Actually not these days. Mastic all the way around the bottom and at the rear. It wont move. But i do take your point.

[Nickfromwales]

3 minutes ago, Post and beam said:

Actually not these days. Mastic all the way around the bottom and at the rear. It wont move. But i do take your point.

Same here. Haven’t screwed a WC down for prob 20+ years. CT1 nowadays; bed of clear under and sit the pan down into position. A load of baby wipes to clean the displaced goop until you have a nice ‘crevice’ and the CT1 is no longer visible. 
48 hrs to cure, then whip around with a cosmetic bead of white silicone. When that gets grubby you peel it out and refresh.

👊

[JohnMo]

22 minutes ago, Nickfromwales said:

CT1 nowadays

Me too

22 minutes ago, Nickfromwales said:

cosmetic bead of white silicone

Didn't do that, but good idea

[Nickfromwales]

8 minutes ago, JohnMo said:

Me too

Didn't do that, but good idea

Yup. Problem with white CT1 is a) it goes off-white (yellows) noticeably over time, and b) good luck trying to tool or finish that cosmetically! Sticks even to a wet finger 😣

[Nick Laslett]

4 hours ago, Nickfromwales said:

Same here. Haven’t screwed a WC down for prob 20+ years. CT1 nowadays; bed of clear under and sit the pan down into position. A load of baby wipes to clean the displaced goop until you have a nice ‘crevice’ and the CT1 is no longer visible. 
48 hrs to cure, then whip around with a cosmetic bead of white silicone. When that gets grubby you peel it out and refresh.

👊

These modern adhesives are amazing, our door frames were fitted with special expanding foam adhesive, no other fixings. (These were fitted by the manufacturer’s fitters)
 

I think if you are a novice DIY plumber, use CT1/OB1 with a little caution. I did screw down my first toilet pan as per MI, but when fitting the second toilet, I realised I had the supply pipe around the wrong way. So it was a relief that I could unscrew the fixing and put right my mistake. 
 

When I mocked up my first shower tray, I had the rubber seal on the trap in the wrong place, the funny thing is I ran the shower into the trap for 10 minutes, and it didn’t leak even though it was not connected correctly. 
 

Not a fan of the modern trend for floating toilet pans, not sure why. Anyway the frame system does make it easy to fit them. 

Edited March 14 by Nick Laslett

[Temp]

On 13/03/2025 at 00:05, G and J said:

Not started thinking about UFH loop design yet but as a principle, by removing loops as you describe do you diminish or remove individual room control?

 

We went for lots of loops but think we over did it. If building again I'd keep separate loops for each bedroom and each upstairs bathroom all on individual programmable stats. It can be nice having a warm tiled bathroom floor even when no heat is needed in the bedroom.

 

I'd eliminate/merge quite a few loops downstairs. People leave doors open and the MVHR probably helps balance out the rooms. 

 

We have a manifold and freezers in the utility room which keep it warm without a loop.