I have this misapplied Tili multi head unit that has been giving me a headache.
outdoor mod M30C-27HRDN1-M (27KBTUH heat pump)
with 3 indoor heads, 2 are MSV11-09HRDN1-M and 1 is a MSV11-12HRDN1-M
the unit is servicing heating and cooling for 3 separate suits in an old house that has been separated into different apartments
its installed with the outdoor unit hanging off the wall 15' in the air, the 2 9K heads are about 2' above the outdoor unit and the 12K head is 12' below with an oil trap on the suction/discharge line, all the lines are insulated and run on the outside of the building, ODT was about 35* at time of testing
got a no heat call yesterday, the 2 9K heads were calling for heat, but blowing only cold air, the 12K head was turned off and not being used. I had a call before for this unit, and I had found and repaired a leak, so I was already expecting it to possibly be low on charge. threw gauges on, was getting 180PSIG head pressure (R410a), discharge temp on 1 head was 135* on the other head, 65*(already a little confused). I couldn't immediately get access to the lower unit, so I decide to recover remaining charge, leak check and weigh in new charge. just as I get my equipment set-up, building owner was able to gain access to lower unit and fired it in heat. Instantly my discharge pressure went up to 450PSIG, discharge temps increased to around 130* on all 3 heads, and all units were blowing heat.
what i think happened:
the unit uses electronic expansion valves (located in OD unit) as the LLS for each head, the suction/discharge lines are then just connected to a common header inside the outdoor unit. I think that the lower unit being off for such a long time, got stacked full of liquid refrigerant, when it activated, it brought all the ref back to the OD unit, and then was operating fine.
this makes sense to me, but how the heck do i fix it?!?!?
anybody else experience things like this with other mini-splits? because i see lots of these units installed on a roof with the heads below them, seams to me that this could happen a lot, am i missing something