Calculating UFH requirements?

[climbinggeorge]

In a similar vein to others I'm having a bit of difficulty trying to work out if we need UFH upstairs and downstairs or just downstairs.
I'm trying to work it out based on the SAPs and what heat the systems can produce, however I think I'm getting my numbers muddled if anyone can help with pointers.

We've got approx 49m2 downstairs (tiled) and 49m2 upstairs (wood) on a detached timber frame property in the South West, I've plugged my figures into Stroma FSAP 2012 and have the below:

 

 

But I'm struggling to match that to what the ASHP (4kW ecodan) and UFH (wunda are frontrunners, 15mm in screed) produce and how to make sure we're ok day to day in winter.

[ProDave]

Not familliar with that calculation package you are using?

 

What units are the 2 rows of numbers, what are they telling me?

[climbinggeorge]

Apologies for the delayed reply.

The package is Stroma FSAP 2012 from https://www.stroma.com/software/fsap

I think at that point I'd reached the end of my tether with it, will sit down and try and go through it again
Based on this I believe its the kWh/month

 

[Dan F]

LoopCAD is another tool you can use to do heat loss calculations and then simulate UFH design.

 

If you need UFH upstairs will depend on how well the house is insulated because even if UFH on the ground floor alone can meet heating demand, you won't want upstairs much colder than downstairs.