r404a charging

Paul S_3

Correct me if I'm wrong. ..a refrigeration system (freezer)r404a....With liquid reciever...cannot be charged with subcoooling because of liquid receiver....and if you cannot how do you charge. .. System has txv ,so cannot charge with superheat.....do I weigh In with line set length calculations? Thanks Paul S

Techman

You charge to a "full liquid line at the TXV" just as the TXV wants/needs .

Paul S_3

So I should install MISG at TXV?and if yes how to charge if existing system don't have one thanks Paul S

EBEBRATT-Ed

If you just charge to a full glass you will still have a mostly empty receiver so you need to put more gas in it than that. I don't know what you have for head pressure control. Usually you have to have enough gas to flood the condenser if needed in the winter to keep the head pressure up but not so much that you have high head pressure in the summer. You can check the receiver level by running a torch up and down the receiver and looking for the sweat line.

Techman

I check the LL at the TXV w/ an UltraSonicElectronicSightGlass or you can put the SGMI in where it is SUPPOSED TO BE, right at the TXV, or you can put the SG at the CondUnit.

This full LL doesn't care what type of MINIMUM HEAD PRESS CONTROL, there is.

Paul S_3

I have a head pressure control valve in the condensing unit ....and how full should the reciever be Paul S

Techman

Your head press control got a MN# , Kinda like a "head master" device?

Paul S_3

Is like the sporlan LAC-4....3 way valve works off discharge pressure thanks Paul S

Techman

Yup, like that, what are the next 3 #'s? Sporlan has a "Flooded system charging bulletin" that will explain how much freon to add.

unclejohn

If you charge to a full sight glass at start up with a warm box you will be over charged. Slowly add refrig. until you get the box down to temp. and then add until SG is full. You will then be pretty close to a good charge. For a correct charge call the equipment manufacture.