Pump down vs. suction accumulator
Pump down vs. suction accumulator
(OP)
I posted a question regarding running DX linesets below grade last week. I have distilled two solutions from the responses I received, modify the system for pump-down operation and add a suction accumulator.
Now I'm wondering, which is better? Which presents greater risk? Is there value in doing both, i.e. the belt and suspenders option?
I'm also considering specifying a suction accumulator with an integrated superheat exchanger. I've seen claims of efficiency improvement but it seems to me these gains are only realized if I operate the unit in off-optimal conditions. Can anybody comment on this?
Thanks,
Tom Moritz
Now I'm wondering, which is better? Which presents greater risk? Is there value in doing both, i.e. the belt and suspenders option?
I'm also considering specifying a suction accumulator with an integrated superheat exchanger. I've seen claims of efficiency improvement but it seems to me these gains are only realized if I operate the unit in off-optimal conditions. Can anybody comment on this?
Thanks,
Tom Moritz





RE: Pump down vs. suction accumulator
It is easier to install, involves no field basterdization of the outdoor unit and probably no brazing or the removal of the refrigerant charge to flare in a solenoid valve.
You will also need a pressure control to cycle the compressor and your control voltage will now energize the liquid line solenoid coil. Your compressor may also require a hard start kit to be able to turn over against the pressure differential it may now see.
Good luck.
RE: Pump down vs. suction accumulator
Why the hard start kit? If I understand the pump down sequence correctly a call for A/C opens the liquid line solenoid valve allowing refrigerant into the expansion coils. The compressor is controlled by a pressure switch on the suction line. I guess if there's not much hysteresis in the pressure switch then the compressor may have a hard start.
What does a hard start kit do? Also, is there any need for a receiver since I'm limiting the volume on the liquid side?
Thanks for the info.
Tom Moritz
RE: Pump down vs. suction accumulator
No receiver, the condensor has plenty of storage volume to accomodate the addition of the pumpdown.