Modulating vs. non-modulating ASHP (Thermia)

[Tom_DBN]

Hello all,

 

I am currently deciding on a ASHP for a 260sqm new-built home. 

 

Initially the plan was to go with an 11kW Thermia Atec as proposed by the supplier. Now I have seen Thermia has an iTEC version which is a modulating ASHP. 

By no means an expert, but what I have read so far is that the modulating heat pumps are superior compared to the non-modulating ones. 

Wondering if someone has experience, especially in those 2 Thermia ASHPs? Would you go for the iTec or the Atec?

 

Next thing would be the size.... presumably 11kW are a bit oversized? It`s a newbuild with tripple glazing, 3 bathrooms and cavity walls (U=0.13). MHRV is installed as well  - therefore I am inclined to go with a 9kW version. What do you think?

 

Cheers, 

 

Tom

[SteamyTea]

5 minutes ago, Tom_DBN said:

presumably 11kW are a bit oversized

Ideally you want an ASHP oversized as this reduces the airspeed though the external heat exchanger.  This keeps noise levels lower and improves the CoP (lot of air, cooled a little, rather than a small amount of air, cooled a lot).

Modulation is really to do with matching the airflow with the thermal extraction to the temperature (and RH) differences needed.

Modulation ASHPs also tend to draw a lower current when starting, which stops the lights dimming.