Refrigerant Recovery Question?

[lana]

Dear All,

In refrigeration recovery guides, it is said that DO NOT use push/pull method when the system is heat pump or it has suction accumulator.

Any body can give a reason for this?

Thanks
LANA

[lana]

Any ideas?

[install monkey]

You should not use the push-pull method if the air conditioning system contains less than 10 pounds of refrigerant, if the system is a heat pump, or if it is a unit with a reversing valve. In addition, if the system has an accumulator between the service ports used in liquid recovery or if the refrigerant system doesn’t allow for the formation of a solid column of liquid, you should not use the push-pull method.
source
http://www.phaseoutfacts.org/common+recovery+methods+explained.aspx

[lana]

Dear install monkey,

I have read the same article , my question is WHY?

Thanks

[Rob White]

.

In push pull recovery you pressurise the system with vapour from
the recovery machine and that vapour is drawn off the top of the cylinder.
This then pressurises the system and liquid is pushed / pulled out of the
system to the lower pressure cylinder.

That can only happen if the system has liquid and vapour separation.

If a diverting valve was in place or if a suction accumulator was in place
they could effect the flow of refrigerant and cause the recovery process
to be inefficient.

Traditionally, push pull method is connected to the high side and low side.
By pushing vapour into the system you encourage liquid out but diverting valves
and suction accumulators might interfere with that process and prevent the
passing of the liquid??

Regards

Rob

.

[lana]

Many Thanks.

Is this only because the recovery process would not be efficient or would it be dangerous?

Cheers
LANA

[Rob White]

Many Thanks.

Is this only because the recovery process would not be efficient or would it be dangerous?

Cheers
LANA

I can't see why it would be dangerous as long as the pump was set to
cut out before it got to a pressure higher than the rating on the AC system.

But Push - Pull only works when you are pushing liquid out and if the components
inside a heat pump affect the way liquid is transferred, then it will make the whole
process very inefficient.

If liquid gets trapped because all the liquid is somewhere it's not meant to be, that
could be dangerous because you might think all the liquid is out. If you then connect
the pump to pull the remaining vapour out, you might get a slug of liquid into your
pump or worse over you (if you thought all the liquid had gone).

Seems a remote possibility but for a manufacturer it is still a possibility so one
that needs to be catered for???

Rob

.

[lana]

Thanks a lot for the explanation.
Cheers
LANA

[Ian21081974]

Hi there

I have a question on this ?
I have to recover 55kg of r410a i recovered about 15 kg of liquid today now vapour is left also the bottles are over heating so i have been putting them in a bucket.
Its on a vrf so in them instructions i cant use push pull method because of the reversing valves etc.
Is there another way of faster recovery i remember along time ago there is a method.
Where you link the several bottles in a row but not sure what that is called or how you do it.
Any help would be appreciated?
Cheers ian

[Dragonfall5]

Are you using a 50kg recovery cylinder or 5x 10kg ones?

If your pulling 40kgs of Vapour out I'm afraid its going to be a Long Night!

[Ian21081974]

Hi mate

Yeh I've got 6 10kg bottle because of access etc.
But maybe wish i had two large bottles know lol.

Any ideas ?

Ian

[Dragonfall5]

If Its a newer system they tend to Have "recovery Mode" settings that Open all the Internal Valves for You to help get the Gas out, I Also tend to use 2 Recovery Machines.

Not Sure what Else to suggest, apart from a Deck chair and a good Book.

Enjoy!