UFH - Supply and Return pipes...

[JohnMo]

Trouble is they are just making pretty pictures.  There is zero balancing of room output.  All designed around a thermostat controlling the room temperature.

[Nickfromwales]

4 hours ago, JohnMo said:

Trouble is they are just making pretty pictures.  There is zero balancing of room output.  All designed around a thermostat controlling the room temperature.

Plus, it’s just dogshit (pretty pictures). 

[Mulberry View]

12 hours ago, JohnMo said:

Trouble is they are just making pretty pictures.  There is zero balancing of room output.  All designed around a thermostat controlling the room temperature.

 

Awesome!

 

Anyone up for productively helping out with this for some beer tokens?! 🤣🍺

 

This guy is primarily a screeder by the way (and one that came highly recommended by someone I really trust), so I'm not holding it against him too much. I also think he'll be a good supplier for the kit, perhaps just not so much the design!

[Nickfromwales]

12 hours ago, JohnMo said:

Trouble is they are just making pretty pictures.  There is zero balancing of room output.  All designed around a thermostat controlling the room temperature.

It’ll be running such low temps that it won’t matter imho. Balancing on the manifold is fine to get flow rates fettled in, and after that it should be plenty good enough. 
 

I’ve never done loops by room, and I only make overall adjustments for changes like this (200mm cc or 150mm cc or 100mm cc) for different types of heat sources.
 

The only time I change loops per room (or space) is for adding tighter loops in bathrooms, or for hallways where the area is open to the 1st floor etc and needs a little more ‘oomph’.

[Nickfromwales]

1 hour ago, Mulberry View said:

Anyone up for productively helping out with this for some beer tokens?! 🤣🍺

Send me a PM if you’re stuck. It really doesn't need to be this hard .

[JohnMo]

Computer models just use some basic science.

 

This chart and room by room heat loss calculation is about all you need. You then vary spacing to suit your needs.  Start in living room with say 200mm to 300mm spacing and then move the spacings around to W/m2 based on heat loss and target room temperature. Your flow temp max shouldn't be above 30 degs.

 

Key to this knowing room heat loss. @SimonD has a tool in boffins corner I think.

 

As @Nickfromwales says loops don't need to be by room. One of mine partly heats hall, bathroom and kitchen.

[Tetrarch]

20 hours ago, JohnMo said:

 

This chart and room by room heat loss calculation is about all you need. You then vary spacing to suit your needs.  Start in living room with say 200mm to 300mm spacing and then move the spacings around to W/m2 based on heat loss and target room temperature. Your flow temp max shouldn't be above 30 degs.

 

 

 

I have jacked my UFH to ~40 degs. We already have a slow-responding UFH system as my pellet boiler takes ~25 mins to ignite and get to operating temp, and whilst it is very clever in maintaining its internal efficiency it means that on cold winter mornings it takes a while to really get going, also it is a little noisier so starting super early in the morning can be disturbing

 

Am I doing any real harm in running my UFH at that temperature?

 

Regards

 

Tet

Additional info:
UFH Pipes in eggboxes so 100mm centres
80mm screed

100mm PIR (I know, I know)

 

[JohnMo]

You are really running your UFH like a radiator system, it's your system your choice, but keep an eye on floor surface temperature. Actual flow temp doesn't mean much, floor surface temp does.

[SimonD]

On 30/08/2026 at 12:34, JohnMo said:

Key to this knowing room heat loss. @SimonD has a tool in boffins corner I think.

Yep. https://openheatloss.com. It will do all the UFH output calcs room by room based on flow/return temps, room heat loss, pipe spacing and floor covering etc. and provide floor surface temps and over temp warnings.

[Super_Paulie]

On 31/08/2026 at 09:29, Tetrarch said:

 

I have jacked my UFH to ~40 degs.

 

i run mine at 42 at the manifold. Any lower and its short cycle city from my combi which is at 50.

[Mulberry View]

20 hours ago, SimonD said:

Yep. https://openheatloss.com. It will do all the UFH output calcs room by room based on flow/return temps, room heat loss, pipe spacing and floor covering etc. and provide floor surface temps and over temp warnings.

 

I've only just clicked on this, looks like a comprehensive tool, thank you. What steps do I need to complete for the UFH calcs?

[Mulberry View]

Just to update this, I've put it with an independent heat-loss consultant who has done a much more thorough heat-loss analysis. Very comprehensive and far more believable. I'll be sharing his details on here once I have the full work in hand so I can make a proper recommendation.

 

I realise many can do this themselves, but there are clearly some out there with far more knowledge than I can hope to attain in the short time I have to get this sorted.

 

Good news is that he makes our total heat loss a more respectable 5.45kw and has already hinted at 300mm pipe spacings with a 5kw heat pump.

 

I hope to have eyes on the UFH layout plan next week.

[Oz07]

29 minutes ago, Mulberry View said:

Just to update this, I've put it with an independent heat-loss consultant who has done a much more thorough heat-loss analysis. Very comprehensive and far more believable. I'll be sharing his details on here once I have the full work in hand so I can make a proper recommendation.

 

I realise many can do this themselves, but there are clearly some out there with far more knowledge than I can hope to attain in the short time I have to get this sorted.

 

Good news is that he makes our total heat loss a more respectable 5.45kw and has already hinted at 300mm pipe spacings with a 5kw heat pump.

 

I hope to have eyes on the UFH layout plan next week.

What kind of fee do these heat loss consultants charge? Do they also do the ufh layout?

[Mulberry View]

1 hour ago, Oz07 said:

What kind of fee do these heat loss consultants charge? Do they also do the ufh layout?

 

I've paid £195 for a heat loss analysis with a hefty report. £295 for the UFH layout and for that he's going to route the manifold supply and returns too.

 

Honestly, I think he'll pay for himself in what he's looking like he'll save us on kit already.

[SimonD]

2 hours ago, Mulberry View said:

 

I've paid £195 for a heat loss analysis with a hefty report. £295 for the UFH layout and for that he's going to route the manifold supply and returns too.

 

Honestly, I think he'll pay for himself in what he's looking like he'll save us on kit already.

That's cheap.