Pumping down Split system

[asmaircon]

Hi Guys,

Can any one tell me in simple steps whats the process for pumping down split systems to recover the refrigerant into the reciever in order to remove flares and carry out work on the system

Thanks

[Tayters]

Gauge on suction port, small service valve closed, run system until gauge reads zero psig, quickly wind in big service valve, turn off system.

Cheers,
Andy.

[asmaircon]

By small service valve you mean the thinner pipe of the two? so you wind that in then run the system once the gauges show no pressure wind in the larger pipe? does it matter about sequence ?

[stufus]

Yes sequence matter's
If you think of it as smaller pipe is liquid line,you are stopping it leaving the condenser ,and say the bigger pipe is suction , you are using the suction to draw back what is in the liquid line after the valve and the evap.
If you suspect a leak on any of the flares or anywhere outside the condenser for that matter don't pump down to a vacuum .Wind in the suction about 5psi. And kill the power.
Cheers
Stu

[install monkey]

shut ur thin service valve then ur fatter service valve once the system is pulling a vac,but then keep ur gauges on the system to ensure the valves arent passing-ur suction gauge will show positive pressure if this is the case, also be carefull pressure testing ur work afterwards as u could pass nitro into your condenser (full of refrigerant) creating non condensibles and problems.

[charlie patt]

or press the pump down button or move the dip switches depending on model and make and most splits will dump all into condensor just above a positive pressure as most dont have a receiver on splits. this also temp bypasses fault code errors and does not record any faults for future diagnosis as above watch your pressure on nitro test if older units the nitro bypasses the service valves a real problem on lg units any more than 200 psi and that nitro floods into your condensor

[Brian_UK]

Follow Charlie's advice in post #6 and also you could read the manual or even the instruction sheet attached to some modern units.

[chillerman2006]

shut ur thin service valve then ur fatter service valve once the system is pulling a vac,but then keep ur gauges on the system to ensure the valves arent passing-ur suction gauge will show positive pressure if this is the case, also be carefull pressure testing ur work afterwards as u could pass nitro into your condenser (full of refrigerant) creating non condensibles and problems.

Some good points there, not tobe overlooked

R's chillerman

[r.bartlett]

And I bet he's F-Gas registered too... God this industry is in a s.h.i.t.e state (and deservedly so I fear)

[Mick13]

Another thing.... your first step will be to put your suction gauge on the suction line, make sure u purge this line, as when u pump it down it WILL suck the air that was in your gauge line before u connected it into the system, causing impurities/moisture/non-condensibles.

[chillerman2006]

Another thing.... your first step will be to put your suction gauge on the suction line, make sure u purge this line, as when u pump it down it WILL suck the air that was in your gauge line before u connected it into the system, causing impurities/moisture/non-condensibles.

Well in that case, would you not install the discharge line 1st and purge lines/gauges

In case the low side is already in a vacuum... which you never know until you put the gauges on

[Grizzly]

And I bet he's F-Gas registered too... God this industry is in a s.h.i.t.e state (and deservedly so I fear)

A very valid point there RB.
We are all rushing to help those that know less.
Which is what I believe the forum is all about.

Sadly we used to be able to in some small way vet the individuals as they posted.
So as to decide as to whether to get involved.

no disrespect to you asmaircon.

But you have to admit that your question could be read as somewhat basic?

Now if you don't normally work on a/c then your question has merit.

However if this is your "Normal" discipline then questions do exist.

[Mick13]

Well in that case, would you not install the discharge line 1st and purge lines/gauges

In case the low side is already in a vacuum... which you never know until you put the gauges on

that is true, although if the unit is working correctly, pipe temperatures good and on say on r22 its probably pretty safe to assume there is positive pressure in the suction line, considering most splits nowadays come with just one schroeder valve on the gas pipe anyway, which makes it difficult

but you are right.... that is the right way to do things.... you can never be certain what pressure is in the system until your gauges are fit

[Boxer]

Hi Guys,

Can any one tell me in simple steps whats the process for pumping down split systems to recover the refrigerant into the reciever in order to remove flares and carry out work on the system

Thanks

Sorry to say asmaircon but if you dont Know how to do the above you should NOT be any where near a split system.
Shame on all you who have been giving him advise. A little Knowledge can turn out to be very dangerous for him and others.

[Tayters]

Shame on all you

Ah, I can remember my Mum saying that to me when I was a kid. Looks like some things don't change.

Sometimes a question veers off and what seems to be a simple answer suddenly become less so. For example I didn't consider purging the lines as Mick suggested so as not to drag air into the system when pumping down.

For the poster he/she may well be a danger but somewhat less so I believe after reading the replies. If anything it may make him/her realise how much more is involved in the task and at least the question was asked in the first place instead of blinding on regardless.

Cheers,
Andy.

[sinewave]

I think some are forgetting one simple possibilty in advising the OP?


A lot of split systems have had a significant trim charge added at the install stage!


If this charge is significant then the condensing units receiver may not have the capacity to store the full system charge and in which case a recovery machine and cylinder should be used.

[stufus]

I think some are forgetting one simple possibilty in advising the OP?


A lot of split systems have had a significant trim charge added at the install stage!


If this charge is significant then the condensing units receiver may not have the capacity to store the full system charge and in which case a recovery machine and cylinder should be used.

Any receiver on a circuit should be capable of taking 100% of the system charge ,so if a unit comes charged for 30mtrs and the max connection is 50mtrs the receiver should be able to take the charge for 50 mtrs ,Providing the installer hasn't over charged.
How many VRV/VRF systems have you pumped down??
The units capacity to pump down will tell a lot,
If you know what to look for.....
Cheers
Stu

[install monkey]

but stufus if the additional charge is 30gram per meter then thats an additional 600gram of gas on your example- but luckily the hp switch will operate if ur pumping down a system and the reciever/condenser isnt sufficiently sized - so then you will have to reclaim some charge-
30g/mtr is based on japanese splits the more popular/reliable ones not naming any names haha

[stufus]

That's the point I was trying to make .
I was only back from the boozer.
If the max allowable connection is 20mtrs over the precharged amount,the receiver should be sized to allow for the max connection volume .IE. Factory charge +600g
Cheers
Stu

[cold.man]

asmaircon

what work do you want to carry out once pumped down?
there is alot more involved in recommissioning.

can you tell us how you intend to recommission?
only reason i ask is if you dont know how to pump down you may damage your split system.
im not going to jump to conclusions you may be new to the industry?
i hope this is the case anyway.

[asmaircon]

I have worked on splits for about 2 years, got F Gas doing my NVQ2 atm, just wanted to know others views on it to see how different people out there do things in different ways, I'm asking about pumps downs in a case where a system needs to be removed and fitted somewhere else or to vac and pressure test a system that has been fitted by a handyman who didnt have the refrigeration tools, i have had so many customers get splits DIY fitted by rogues and been to put them right, for instance, kinked pipes, superglue around the flare nuts, wall plates put on upside down and condensate pipe going upwards without a pump LOL

[install monkey]

u dont need to pump a system down to reroute the condensate drain!haha