The purpose of the reciever in an Air/water heatpump

I have question regarding the use of an receiver in an air/water Heatpump.
I thought that you always needed one to make sure that you always have enough refrigerant depending on the running conditions.

There must be a big differnce in refrigerant flow (and the amount of refrigerant in the evaporator) depending on the outdoor temperature / evaporation temperature, this perticular heatpump is designed to be used from -20 to +40 degrees C.

And i found that someone had removed the reciever from the system.
So what happends at low temperatures when the flow is lower?
Or are my thoughts regarding all this wrong?

there are accumulators in heat pumps not recievers, and located on the suction line before the compressor. the accumulator catches liquid refrigerant so it will boil off to a vapor and not slug the compressor. they are only needed in the heat mode due to freezeup at low temperature.Trane systems do not have them.They are in the shell of the climatuff compressor. Most all other brands have them.

if it is an accumulator mbe put it back! on air to air accumulators are pretty much a reqiurement,air to water during reverse cycle would prob give the same liquid flood back problems when your out door coils your evap. there could be a use for a reciever if the water temp increase's and theres problems with condensing liquid in the evap(now the condenser) . where exactly was the missing receiver/accumulator installed?

hello micstiebel
i'm intriquied as to wat the differences are on a heat pump in sweden that runs at minus twenty and the carrier 50 eq,pq and dq that i was working on 15 years ago in glamourous wood green or somewhere that used to have frozen outdoor coils at 5c ambiant,a defrost cycle that was a series of pipe mounted sonsors and an unfathamable defrost mechanical timer ( not that complex actually,just dumb)iff there were no aux electric heaters forget it!and then the free cooling damper motor with the enphalpy controller and mixed air stat was even more fun,fresh air dampers usually wide open.i thought that a hairdrier was a peice off essential kit(moved on to a shifter hitting the end off a driver 4 the coils,sort off a defrost mod)at least the staff could huddle round me baby bliss to keep warm.it were about that time i got divorced.found a lot off machines back then with f.s.c's operating in heat mode ...... Cool.