Samsung R32 ASHPs - when is a defrost not a defrost?

[Old_Scientist]

@Michal_S

Frost prevention is running when outside temp is below 5C. Sarah got info from technician it’s 3C but my observations says 5C. And yes, I’ve “fixed” it with a relay. Basically i connected relay between DHW terminal on the controller and the 3-way valve. I have the relay (shelly 1) ON all the time when space heating is running. When the pump wants to really heat the water I switch this off by automation in home assistant and the valve change its position since is without power. But in case the pump is only opening DHW circuit to steal the heat for the frost protection cycle the relay is still on and won’t allow 3-way valve to switch to different position. I know, nasty, but it works

@Michal_S That’s really interesting, I’m glad people are exploring solutions, and it’s got me thinking too. I’m wondering if tricking the outdoor temperature sensor may be a simpler approach?

Maybe a switched resistor in place of the temperature sensor, corresponding to a value of 10C for example, may work. One could then switch between the genuine ambient temp sensor and a fixed value (that is above 5C) to temporarily ‘disable’ the anti-freeze protection.