Pump down mini split and after

[PoorOwner]

Hi, I want to move my Mitsubishi unit and reinstall at a new location after maybe, 6 months.

Besides capping off the 2 flares coming out of the head unit, is there anything special such as purge and fill it with nitrogen?

I am not sure oil residue remaining in the coil would absorb moisture, turn acidic or other bad things.

 

[chinboys]

I suggest you hire a HVAC-R resource to decommission the system. They can either recover the refrigerant within the condenser and any extra to a recovery tank or recover all of the refrigerant to the recovery tank.
The condenser unit will be in a state of vacuum with its oil.

 

[fitter30]

Close the service valves and cap the valves. After reconnecting, leak checking, reclaim any refrigerate in the condenser, pull your vacuum and weigh the charge in. These units are critical charge.

 

[American Locomotive]

You can really only do a pump down if you are sure no extra gas was added to the system beyond what came in the outdoor unit. Mitsubishi single-head units are typically pre-charged for up to 25 feet of lineset. If you have more than that, gas was added, and you may not be able to pump down.

You close the "liquid line" valve on the condensing unit, hook up your gauges to the test port, push the "Emergency Cool" button on the indoor unit, and wait for your gauge set to indicate 0 PSI. Then close the "gas" side king valve and turn off the power.

Purging the indoor coil with nitrogen and quickly capping the ends would be a good idea.

 

[danski0224]

Last I heard, one is NOT supposed to use a scroll compressor to do a pumpdown of the system into the condenser, down to a vacuum or 0 psig.

That can damage the compressor, no different from energizing it if the system is in a vacuum- compressor is garbage if that happens.

If the OP wants to try and "save money", then close the king valves and then evacuate and weigh what comes out, then add that back later.

Some systems DO have a programmed pumpdown and isolation service step, so read the manual.

If there is no factory automatic recovery process, then the best thing to do is to just evacuate the whole thing and weigh it and start over.

And some systems have a required process to follow to manually open all of the valves and stuff in the unit, once power has been applied, in order to ensure a complete evacuation.

Again, one MUST read the service manual and not rely on random answers from the internet.

 

[PoorOwner]

Hi all, I did not say that I added any charge to what the factory came with, but good point.

I believe the mitsubishi manual says pump down and then dispose of the unit properly .. have to double check on that. Is the mitsubishi a scroll compressor?

I might have a tech recover and dispose of the refrigerant, I would just weight in new charge when I reinstall it.

The lineset is 1/4" liquid and 1/2" suction. if anyone know I can connect the 1/4" hose gauges straight to flare of the coils to purge with nitrogen? They are all 45 degree correct? Then I would use one of the hoses that has a ball valve and close the ball valve.

 

[American Locomotive]

Mitsubishi minisplits do not use scroll compressors. They use rotary compressors.

The pump-down procedure I posted is directly from a mitsubishi service manual, and the manual explicitly says do this if you plan on moving the unit.

 

[danski0224]

Cool, then you read the instructions.

 

[ToolsRCool]

Do the pump-down procedure, vac the line set(s) for a while to remove any moisture once re-installed, and it should be fine.