Jimbo77

I've been wondering the same. I added some zigbee temperature sensors to the ducts at the top of our Sentinel Kinetic Plus B, in the hopes of being able to see that the summer bypass does do something. The bypass was turned off for one of the days in the chart below - I can't remember exactly which! We have a gound/air heat exchanger on the inlet side (Rehau Awadukt), and even though the incoming air stays a lot cooler than ambient, the supply side into the house follows the extract side temperature quite closely, no matter what state the summer bypass is in. (The sensors are strapped to the outside of the ducts right where they go in to the MVHR unit, so it's not that the air is being warmed once in the ductwork...) We have the internal temperature target set to 22C, and the limit on the incoming air temperature set to 16C (which, if I've understood correctly, is the point at which it turns the summer bypass off). So even when the internal temp is above the target and the incoming air is cooler (thus the summer bypass should be open - I've also observed it working with the cover off), it makes little difference to the house supply air temperature. It does, however, do a reasonable job of cooling the extracted air before sending it outside... 🙄 It's a shame we miss out on the colder air overnight, but I'll take 21-22C incoming over the 30C+ daytime air temp [literally] all day long...