changing condenser and compressors

[seraaco]

Hi guys i have a question and i know there is more than one answer, but i'd like to hear diferent opinions

if you have to change compressors at rack and condenser at the same time, how do you do it?
do you pull all refrigerant out of the sistem? or just remove it from one side to another (evaps)
by the way the store is in another country, so you have to carry just what you need.
....lets find the best way to do it.
think about it.
thanks in advise :cool:

[750 Valve]

Hi guys i have a question and i know there is more than one answer, but i'd like to hear diferent opinions

if you have to change compressors at rack and condenser at the same time, how do you do it?
do you pull all refrigerant out of the sistem? or just remove it from one side to another (evaps)
by the way the store is in another country, so you have to carry just what you need.
....lets find the best way to do it.
think about it.
thanks in advise :cool:

Ideally I would look at installing the new rack first if there is room in the plantroom - same with the condenser. All prepped and ready to go that way you can pull a vac on the new rack, pump down the old one and bomb charge the new one with as much of the refrigerant from the old one as possible. If you need to keep both going while you change over circuits then obviously you will need more refrigerant to start up the new rack.

If space is not available then it gets tricky, let us know what the circumstances are re: plantroom size and space for new condenser.

[seraaco]

Thanks 750, there is no new rack, only new compressors and a new condenser and are a diferent brand than the old ones, the machine room is a metal container (36 feet i think) with rack inside and an air cooled condenser on top of it (outside). The store is open and busy and by the way the store is located in a very small island, later.

[750 Valve]

you'll need reclaim gear then, the way we would do it is as follows.

- turn off evap fans in case and rooms and let evaps hold a lot of liquid refrigerant

- block condenser or shut off fans and allow HP to rise (this is to minimise liquid in condenser, let it get way up to something like 50 to 55 SCT)

- shut off comps, isolate evaps (so you don't slug liquid on start up) and isolate cond.

- reclaim vapour from cond and disch/liq return lines (or transfer to another rack if there is one)

- cut and change condenser

- pipe up and evacuate (can pressure test if you want to but don't exceed pressure in disch or liquid receiver just in case valves do not hold and nitrogen leaks past valves)

- open up disch and liquid return lines, double check for leaks

- start up comps and leave liquid supply to cases shut, throttle suction at ball valves so as to not allow liquid to slug into header and hit comps

- once all stubs open then open up liquid supply to cases and let it operate.

Come back another day and do the comp changes, they are a lot easier, maybe a bit of discharge and suction piping due to the differing brands of comps but you can pre fab all the pipework and just punp the rack down and reclaim the suction header (if no individual comp isolation).

[seraaco]

thanks 750 you are correct
one more thing, I was thinking living the receiver with refrigerant , closing inlet valve (after head rises), then remove vapor left in condenser to this side of the system so i can have refrigerant from receiver to suction header, and not letting flood back at start up.
i was thinking change compressors at the same time as condenser but it's a good idea to change condenser first.
thanks