Conflicting info regarding R22 and R422D

[JayeJaye]

Hi all

Hope you can shed some light on this, as I am getting mixed info from various suppliers regarding the "drop in" replacement, R422D.

My distributor, who is nationwide UK, has said that the R422D can be added to top up a system running R22, so long as the compressors haven't burned out, the reasoning being that R22 soaks into the seals on the various joints, and unless it is completely out of refrigerant, that I should leave it in and run it with the top up. Apparently flushing and using pure R422D leads to a lot more leaks and problems further down the line.

Another (A-Gas) have said, you cannot mix the gas at all, it has to be completely flushed (which I can do, however massively increased costs from the extra to fill a large system), and subsequently change expansion valves and driers etc.

Opinions please?

FYI, the system is a large nightclub, which has 4 x condensers running M125 Compressors (1 per unit), which then all go to a common evaporator, with a 3m x3m fan inlet and 1000mm twin evaporator fans. The purpose of the system is to provide cool air into the venue on inlet ducts, dotted around the dancefloor areas and bars.

Currently one unit is running all good, however it is nowhere near capable on its own of providing the cooling capacity required for the venue.

Obviously I prefer to top up, as the costs are less and with the looming opening deadline, time is short, however at the same time I don't want to ruin the system, for which a compressor costs £1700 each, 4 required (one per condenser unit).

Thanks in advance,

Jaye

[monkey spanners]

You should not mix different refrigerants. It would make a new blend and non of the txv's would know what they were doing then, PT charts would be inaccurate etc.

Since the start of the year there has been a service ban on any system containing R22, you can continue to operate the system while it is running ok but are not allowed to work on it without changing the refrigerant. Basically the only time you are allowed to fit your gauges is to remove the R22 when either the system is scrapped or it is converted to a different refrigerant.

[JayeJaye]

Ahh ok, I was advised that it was a ban on topping up the system with R22, not a ban on any works!

[Glenn Moore]

HI JJ
R422D is a so called drop in for R22. You must remove the R22 and replace the whole charge with the R422D. In theory R422D runs OK with the original Mineral oil charge in the compressor and simply replacing the gas is all that's required. ( Never mix refrigerants !.)
In practice this is often not the case, . Using the original mineral oil often has caused oil return problems with R422D, and some engineers have used a small amount of POE oil with the Mineral oil to get the oil to return from the system.
Most of the larger companies when doing an R422D retrofit also change the complete oil charge to POE to avoid potential oil return problems.
Retrofitting with R422D can also cause a loss of system duty ,as much as 28% , a lot of this duty can be recovered by changing the expansion valve to an electronic type with R422D in its refrigerants parameter list.
Therefore from working with a number of companies doing retrofits I would recommend recovering the R22 Charge and the mineral oil charge. Pressure test ,fit a new drier,replenish the oil charge using POE oil, vac and charge . Adjust the TEV to get the best stable superheat possible. This would be the cheapest solution , as Ive seen companies spend weeks trying to get the mineral oil to work with this gas. Doing the above should get it done in one go without all the other heartaches. The Loss in capacity shouldn't really be noticed in a nightclub

[JayeJaye]

Hi Glenn,

Thanks for the info and insight, I am only a small company but work directly for the owner of the club so end up with a lot of the headaches lol!

Will the ManEurop Compressors run ok on POE oil, as they are stamped Mineral Oil on the casing. One of the lines is running wet anyway, so have already budgeted for a new drier, just has to be 4 now instead! At least they are not too expensive for a Sporlan.

Big old system though, built in 1991, commissioned in 1992, started faulting 2 years ago. First eyes on it too.

Suction is 1" and liquid 7/8". Going to need more brazing rods......

[joe-ice]

If going to change the oil to poe ,would it not be better to change to 407f and just put new seals in the solenoids. I get the feeling 422d wont be around too long ,its already hard to come by here with wholesalers not stocking it. It would also put you in better standing with the upcoming new fgas regulations in 2020

[JayeJaye]

There's only 4 more years on the lease for the club, so not too much of a concern tbh, they would look at renewing, however it's getting bulldozed for a new leisure complex.

[joe-ice]

Just on a sidenote i know of people who have topped up r22 units with 422d and 407a for the last couple of years and the units are still running ,no oil change or anything?. They are all high temp units .

[Glenn Moore]

Hi JJ
I used to change a lot of new R22 Maneurop compressors to POE oil . Get the Maneurop POE oil then you know its the right grade. You will need 4 litres per machine for the MT125.
If you haven't already started to use R422D then do as Joe has pointed out , ie use R407F refrigerant. It can replace R22 , you will need the POE oil and you can now get R407F expansion valves. I know Danfoss do them and I suspect other manufacturers do also.
With these blended refrigerants it is always best to replace the O rings seals if possible, as with R22 O rings can expand to up to 50% larger in diameter but with the new gases O rings only expand a few % and can therefore leak, so during service always fit new seals.
R407F has a higher discharge temperature so make sure the suction superheat is set down to a reasonable level to keep the discharge Temp under control GIRFT (Get It Right First Time ) Good Luck

[JayeJaye]

At this point, I haven't started to use any replacement, as I held off because of the query on the gas, my friend who is working on the job has down'd his tools until we work it all out, which is fair enough as it's on our heads. I've replaced a few of the Danfoss ones before but not for R407F, 407A and 134A yes.

I heard as well that the blended can not only do less expansion, but can actually contract the seals, leading to more leaks also!

[Glenn Moore]

Hi JJ
The Danfoss TE2 expansion valves are designed for use on both R407F and 407A as the refrigerants are very similar. Supermarkets seem to use R407F on the HT cabinets and R407A on the LT cabinets.

'O' Ring seals typically are made from Chloroprene rubber, and during manufacture are dosed with a softener to make them flexible and supple. This gives the O ring a shiny finish. 'O' rings have a useful lifetime of about 2 years and then they start to lose their suppleness and decay. The 'O' ring is affected by heat , UV, Ozone etc. When storing 'O' rings they should be kept in a black plastic bag to preserve them. Never leave them near the windscreen of your van as the sun and heat will start to destroy them.
The old refrigerants when they impregnate the O rings can expand the seals dramatically, but during a retrofit to one of the new refrigerants during the system evacuation the old refrigerant is removed from the O ring and the new refrigerant takes its place , but in an older O ring its ability to slightly re expand enough to re seal has been compromised and can cause leaks , by fitting a new seal the O ring still has its suppleness to help seal with the new refrigerant even when the expansion is very small.

[JayeJaye]

Ah I get you, that makes a lot of sense. I've had to do O rings before where they have become cracked or damaged, normally after a burn out where either the oil has migrated and sat there, or where a fan has failed and heat just hasn't been leaving the system.

Seriously though, thanks for all your advice so far!

[joe-ice]

I cannot add to your rep glenn ,I have to spread it around but to summarise if you change from 22 to anything else everything rubber is going to leak like sh@@t unless its replaced

[hookster]

Hi Jaye Jaye

This is the usual quandary for the refrigeration industry! We have a product removed from service due to environmental impact and look to replace it with another product of questionable environmental impact but in an alternative form.

Personally I would advise that you look to replace equipment.
Drop in is a short cut that will over the next 4 - 5 years cost the customer more to operate and have a higher environmental impact and be more expensive to run.

4 x 15Kw condensing units, so +/- 60Kw evaporator is not really big in my opinion but I guess its relative!
My worry as per other systems that are approached on a budget drop-in program is the equipment is 25 years old i.e. reached its end of life cycle. Your leakage potential is very high prior to even adding a refrigerant more prone to leakage.

You have a poor system that you say has been faulting since warranty ended (funny that!) I would guess that there are some balance issues on the design. This will be compounded with oil issues and from experience with 422D you can have some SSH problems, now add compressor imbalance and oil returns to the equation.Age of equipment will be prone to breakdowns and potential leakage. R422D is an expensive High GWP refrigerant due to the patent costs.

I would apply some diversity to the system and look to replace with a system capable of 60/70% of design this is 40Kw single condensing system. Night club will only notice at peak load i.e. it is full and owner will be raking it in at the bar. Breakdown potential is minimal and if installed right the system can run with no intervention for the remaining 4-5 years. If club is not full operating costs will be lower and owner can save on overheads.

[hyperion]

Jaye jaye,
The original design of the system probably took into account that smoking was probably still allowed in the building and the amount of air changes required would have been higher to cope with that.
By carefully checking the air changes per hour that you currently achieve, you may be able to reduce the airflow through the plant by putting an inverter on the main fan motor or at least changing the pulleys.
With the reduced air changes you could then downsize the cooling duty by perhaps 40%, which now means that you might only need about 36-40kW of cooling.
This would then tie in with hooksters suggestion above.
You could select one 40kW unit and the correct expansion valve and DX coil or even 2 x 20kW units to give even better efficiency during low occupancy.
If for whatever reason you decide on the retrofit route, you cannot afford to mix the refrigerants and you might want to consider R434A as an alternative.
It is claimed that this will work with mineral oil although as with all drop-ins there may be a reduction in cooling duty.
Make sure that you client is fully aware in writing that you cannot guarantee the longevity of the plant once a drop-in has been added. Ensure that you have stated in writing that there is a greater possibility of leaks in the future which may not be your responsibility.
Despite you currently having a good relationship with the client and trying to save him money in the short term, make sure that you have every eventuality covered or he could completely drain your resources if something goes wrong in the future 4-5 years.