the best way to recharge a VRV/VRF

[marc5180]

Whats the best way to recharge a VRV/VRF system? In the suction side? in liquid form or vapour form? what about when you have dumped charge as much as possible and you have to get more in when the unit is running, whats the best way?
remeber for all us newbies out there its only easy if you know it!!

[Latte]

Hi,

Well, if yoy are going to use a full bottle (Dumpys or reclaim) you can fill vapour as you will empty the bottle so getting everything out, If the unit has a test mode (Daikin for instance) then use this as this will run the unit at full capacity helping to get the gas in.

Usuall rule is that you shouldn't liquid charge without the correct adapter in line (Anyone actually got one ?) but otherwise SLOWLY fill with liquid. You will soon hear the compressor change sound if you are doing it too quick.

Have you a specific unit in mind so we can go into more detail or is this a theory question

Regards

Fatboy

[marc5180]

im working on a mistubishi heavy duty tomorrow which i will be recovering supposedly 21kg of r407c and then recharging with totally new refigerant if this helps

[iceman007]

The charge needs to be weighed in correctly, and as it's R407C liquid charged. My preferred method is to charge as much as possible with it under vacuum. When the scales stop moving, then get it running and charge in liquid form, which will have to be into the suction line. Throttle back the flow of refrigerant through the charging line sufficiently that it will allow the liquid to vaporise before it's compressed. I think that these machines use scroll compressors, which are somewhat more tolerant than reciprocating models as the scrolls tend to lift apart, but you still need to exercise caution. If you're in cooling mode the suction pipe should be cold to touch, but the only correct way is to weigh in the charge. I remember a similar thread to this some time ago relating to Daikin VRV's.
Best of Luck
James

[iceman007]

im working on a mistubishi heavy duty tomorrow which i will be recovering supposedly 21kg of r407c and then recharging with totally new refigerant if this helps

You MUST liquid charge R407C

[Latte]

Hi Guys,

Yes i know all 400 gasses have to be charges liquid but has anyone actually done any research into what happens if you vapour charge.

No i know that if you leave a bottle standing still the contens COULD !!! seperate and therefore not give the correct proportions when you charge but how often do you charge from a bottle thats stood still for a few weeks.

Personally, Mine get shook about it the back of my van like they are on the roller coaster at blackpool. Then they get taken out of the van and are shook about while carried to the unit.


My Question is this "How long would it take for a bottle to be completly stood still for the gas to seperate and therefore cause a problem when used"

Any ideas

Fatboy

[Andy T]

Refrigerant blends are made of gasses that have different boiling points
It's not that they separate like oil and water. It's when you charge with vapor one gas boils off at a different temperature than the other so leaves the bottle before the one with higher boiling point.

[iceman007]

R407C is made of R32, R125 and R134a. R32 is the most volatile and so when you are charging, the pressure in the bottle drops and causes the R32 to vaporise first, causing the wrong proportions to be charged. Because of the different characteristics the temperatures and pressures are affected along with operating characteristics

[frank]

Does anyone still use the old charging rigs? If you measured the charge into the rig then you could safely charge 400 series gases as vapour

[sakly]

the fan coil connected to a central vrv system ( R407C) has to condensate water during the cooling phase. Such water are collected and drained to pump. However it is found that few droplets are not following the circuit described here above and seems to be ejected with air as a droplets

ANY BODY HAS BEEN ATTENDED to such trouble shooting?

[Dan]

For some reason your face velocity is too high. Any chance you are missing a filter, or have the incorrect fan assembly? These units are designed to avoid entraining moisture back into the air. Maybe something is blocking a portion of the coil, causing a high velocity through the free area.

[old gas bottle]

yer making a big job of this chaps ! ever thought of sticking the bottle on the scales,connecting to the liquid line as you should with blends,connect your recovery machine to the bottle and pump the correct charge in, thats how i do the big chillers to get round the pressure equilisation.

[Andy T]

We had just installed an VRV and found the service port passing.We could not pressure test the system as the nitrogen would push passed the service valve making readings useless.Also risking nitogen in the outdoor unit.Also a vac would never pull down until the unit had lost it's charge.We had to reclaim the 410a from the hole system ,pressure test and vac ,after which we put the correct charge in as liquid on scales.The charge was written on the side of the unit 4.8Kg. £220 of gas and a days work chasing around for equiptment.We were the sub contactors(hope the company who purchased the unit can claim that back).Else they will not be asking us back again on price.The risk we will have to take on doing a good job.

[frank]

The charge was written on the side of the unit 4.8Kg.

This seems awfully low for a VRV charge. Was it the whole charge or just the additional charge?

[Andy T]

4.8Kg this was all we put in. I assume it was the whole charge as this was on the system plate. We also checked with the supplier. He came up with the same number. When we recovered the gas it was about 4. Something Kg. could not be sure as the scales kept switching off. When we charged it the 410a slowed at this point like the system was balanced with the bottle pressure. Not an exact science but it seems to be about right in most cases I found. AirStage J-series

[marc5180]

Are you sure it was a vrv/vrf/ sounds more like a multi unit to me. Iv never come across a Vrv that only holds 4.8kg

[paulwild]

yer making a big job of this chaps ! ever thought of sticking the bottle on the scales,connecting to the liquid line as you should with blends,connect your recovery machine to the bottle and pump the correct charge in, thats how i do the big chillers to get round the pressure equilisation.

hello mate,
could you please go into a bit more detail please on this method i.e do you have gauges inline fully open and recovery unit set to liquid cheers mate

[airconadam]

daikin seam to be having a few probs lately with service ports passing. When pressure testing you think you got a leak then find that its the port passing and got to reclaim the gas, not good

adam

[Lowrider]

Here's my question and a possible answer!

When the valves leak, did you braze the couplings while they where on the valves?


If so there's the answer as to why they leak! The heat damages the seals in the valves!

[Brian_UK]

Are you sure it was a vrv/vrf/ sounds more like a multi unit to me. Iv never come across a Vrv that only holds 4.8kg

These J series where only 15kW units and I suppose with R410a you can do quite a bit of work.