head pressure issue

[gas-n-go]

i have a r22 low temp rack set up for hotgas defrost using a liquid differental valve. this rack is set up with air reclaim but its primarly used for dehumidification and limited times for heat. apparantly they had some glass door reach in cases icing up. what they determined was the head was crashing so low when it was in reclaim and trying to defrost a sys at the same time,that it wasnt do much of anything. they said thee head was dropping from 190 down to 90, so someones solution was to put in a relay that would shift the three way heat reclaim valve back into refrigeration mode when something would go into defrost. my question is this wouldnt it make more sense to install a holdback valve to keep your head up and would there be any merit in setting up the hold back valve to increase your head while in defrost from say a 190 setpoint up to maybe 225.

[R12rules]

I guess there's no CPC on the rack!?

By "Hold-back valve", do you mean headmaster valve?


Yes, that would serve your system well.


Also need to remove that wiring someone did to "fix" the symptom.

[gas-n-go]

yes r12 a holdback valve is kinda like a headmaster valve it holds back refrigerant, floods the condensor, maintains your head pressure. its installed between the return line and the reciever.

[gas-n-go]

oh yeah one other thing r12 the rack does use cpc but what difference does that make????????