Wunda or Nu-heat for my setup?

[Zentachi]

hi everyone,
 

I have had a survey to install a heat pump with the results as following:
- Total Heat Loss (total) 5.2kW
- Heat pump proposed 6kW (Daikin)
 

In addition, I am thinking that maybe now is a good time to convert the ground floor to UFH (two-storey) . For a floor area of 40sqm, will need a 2.8kW load assuming 70w/sqm

Suspended timber floor with 100mm rockwool insulation most of the ground floor. Exemption the kitchen with concrete slab (5.2sqm out of the 40sqm).

Will UFH work well in my setup? Thinking of having 6 loops (zones).
 

Which one should I go with? Wunda or Nu-heat? 

Retrofit so it will be between Rapid Response and LoPro, respectively.

Thanks,
Zen

[JohnMo]

Couple of things

 

Low flow temperature is required to get a low running costs.

 

At 70W/m2 you will need 100mm pipe centres, even then the flow temperature is likely to around 40 degs or above depending on floor covering.

 

Zones and loops are different things, loops are just circuits of pipe, while a zone is a controlled area of heating with its own thermostat. Lots of zones isn't the best thing for a heat pump efficiency and will drive you to a buffer.

 

Also the insulation under the floor isn't the best for UFH will likely lead to excess downward heat losses, especially at elevated flow temperature.

 

Not sure I would go with either the vendors you suggested. Get the whole heating system designed by your heat pump installer. Get them to do it as part of the grant.

[Zentachi]

14 minutes ago, JohnMo said:

Couple of things

 

Low flow temperature is required to get a low running costs.

 

At 70W/m2 you will need 100mm pipe centres, even then the flow temperature is likely to around 40 degs orca ove depending on floor covering.

 

Thank you for the info.

Wunda had a calculation based on 70W/m2 but I was planning to have run with low flow temperature like 30-35C.

 

14 minutes ago, JohnMo said:

Zones and loops are different things, loops are just circuits of pipe, while a zone is a controlled area of heating with its own thermostat. Lots of zones isn't the best thing for a heat pump efficiency and will drive you to a buffer.

 

I agree but in my case each zone will have it's own loop. I was afraid that maybe this isn't the best approach. So maybe I will check to with having two zones.

14 minutes ago, JohnMo said:

Also the insulation under the floor isn't the best for UFH will likely lead to excess downward heat losses, especially at elevated flow temperature.

 

Not sure I would go with either the vendors you suggested. Get the whole heating system designed by your heat pump installer. Get them to do it as part of the grant.

 

I have hoped the insulation was sufficient enough. Unfortunately the heat pump installer doesn't do UFH so maybe I should just stick with radiators.

[Nickfromwales]

Are the radiators all going to be changed (upsized) to cope with the low flow temps?

[Zentachi]

1 hour ago, Nickfromwales said:

Are the radiators all going to be changed (upsized) to cope with the low flow temps?

2 radiators will be added and 2 will be replaced (upsized). Total around 24,000BTU in the ground floor if I counted correctly.

Currently the u-value of the suspended floor with the rockwool is around 0.3W/m2K if I add 25mm Kingspan Kooltherm K103 it will bring it down to 0.22W/m2K. Will that a good improvement?

Even if UFH will be a bit less efficient, I don't mind sacrificing it for more convenience and comfort!
 

Edited 2 hours ago by Zentachi