Originally Posted By: cbottger
This post was automatically imported from our archived forum.
Sorry guys my plate has been overflowing.
Pumps down system was kind of a play with words on my part trying to disguise my true true thoughts hoping to make you think a little harder.
Pump downs are not particularly wide spread but can be anywhere not just in my area. It is just one of many forms of zone Cooling.
I will describe just one example here. Lets say you have two furnaces two A-coils and just one condensing unit sized for both A-coils. I hope IF you ever see this set up that you would not report that someone has stolen one of the condensing units : ![icon_wink.gif](upload://ssT9V5t45yjlgXqiFRXL04eXtqw.gif) : The A-coils would have as described above a liquid line solenoid valve just before the coil and would be controlled strictly from the thermostat. There will be no low voltage wires between the furnace and the outside unit. The low pressure switch not to be confused with the low pressure safety switch is wired to start and stop the compressor from pressure only. The LP switch becomes an operating control for the compressor contactor and opens roughly at 5 psig and closes at 35 to 40 Psig. This pressure is determined by the opening and closing of the liquid line solenoid valve controlled open when ever the thermostat calls for cooling from either either or both A-coils
This can also generate another question I will wait to see if someone comments on the two coils and one condensing unit??????
Thanks for waiting I am old and slow.
Don't argue with an idiot someone watching may not be able to tell the difference.