Hi folks, I’ve been helping a friend with an inherited Midea R290 air-to-water heat pump. Documentation is fairly poor and there’s surprisingly little to be found online, but I’ve figured out most of the key settings and got things working better.
One feature which is driving me mad is the “eco curve timer”. At first glance, this looks like it should allow me to set a lower temperature curve to be used overnight, which would be an improvement on the current situation of relying on the third party on/off room thermostat to manage night setback. But when I set up the eco curve timer, it seems to fall back onto a fixed, manually adjustable flow temperature at the times when the eco curve timer doesn’t apply, rather than falling back onto the normal weather curve. Thus making it useless, unless I’ve misunderstood something. I can’t imagine why you would want to alternate between a weather curve and a fixed flow temperature on a timer?
I’ve also noticed the system is relying on the temperature probe fixed to the outdoor unit to drive weather compensation. There’s no sign of a standalone outdoor temperature sensor, and I didn’t spot any mention of one from a flick through the installation manual. Is this the norm with Mideas? It’s showing an E7 fault, but is still reporting correct outdoor temperature. The only issue is the temperature readings appear to get distorted by recirculation from the outdoor unit at times.
Interestingly the system was installed to quickly replace a broken boiler, with radiator replacements deferred. It’s been designed to at least 60C flow. I’ll advise the owners to plan to upsize radiators when they get the chance, but it’s interesting to see this application of R290 as a true drop-in boiler replacement in the wild. It’s obviously far from ideal, but if it stops new boilers going in during a breakdown, I think a staged approach can make sense.
Thanks for any input!