Cold rooms

[fathihvac]

Hello,
What are the low pressures to reach when charging cold room systems with vapour ( positive and negative temperatures) with:
*R12
*R502

[nike123]

Hello,
What are the low pressures to reach when charging cold room systems with vapour ( positive and negative temperatures) with:
*R12
*R502

Pressures will depend on temperatures of room among other things. That is not way to charge system.
System with TXV is charged by target subcooling value.

[Scramjetman]

With the system running, charge the system to a full sightglass with what ever refrigerant the system is designed for. Make sure there is a receiver and a subcooler fitted when using this method. If either are missing, you can't do this without the risk of overcharging the system.

If the room is hot and the sight glass is full, the system is going as hard as it can go. As the room cools, less liquid is required and the excess will back up in the receiver.

A full head of liquid arriving at the tx valve is required to maintain stable tx valve operation. Any flash gas at the valve will generally cause it to become unstable and hunt which is why the sightglass must be full.

Hope this helps.