I confess that I cheated here, and limited the flow temp so that it wouldn’t get too excited [like MyForest does]. However, I don’t really like doing this as it adds more complication to the system, and is another thing to go wrong if I mess up. Sometimes the house struggles to get warm as a result. I’d prefer to let the HP do its own thing, overriding as little as possible. Interesting to experiment with though.
A few further thoughts…
- Today was much colder and I saw my first defrosts of the season. I was worried that this “relay” was interfering with that process, though looking back at the data maybe not as the compressor was still being used during the defrost.
- I also worry that turning the HP off (via MelCloud) is perhaps too abrupt for the system; I’d hope that the controller would stop gracefully, but I don’t know if it does.
An alternative strategy I’m trying is to drop the target flow temp right down for a short while after each cycle, letting the HP come to a stop when it’s ready. - After the DWH cycle finishes, I actually want the SH cycle to start immediately, without any forced pause [another thread]. This means making the “relay” more sophisticated so it can tell the difference between cycling and a mode change.