Replacement Refrigerant for Heat Pump

[HeatPump77]

I have a fairly old but effective heat pump for a large property fitted with two Danfoss (Maneurop) MT80 compressors, one of which has just failed. I have a brand new compressor waiting to be fitted but because of the phase out of R22 I'm struggling to find anyone with recovered R22 who will do this. Some time ago I was told by my local service co. that the oil in the compressors could be changed and R407 refrigerant used but thev have now backtracked on that and say that the whole system is obsolete.
Can you advise,
(a) is R22 still available for such operations?
(b) can the oil/refrigerant be changed to comply with new regulations so that I can extend the life of the system?

[monkey spanners]

(a) Recylcled R22 is still available here but is very expensive.

(b) In theory the oil can be changed from mineral to polyolester (poe) oil, Maneurop poe oil is very expensive.

I have had problems converting R22 Maneurops to poe and HFC refrigerants, the system suffered from waxing of the expansion devices for months afterwards.

I would be tempted to look at either R404A or R407F for replacement of the R22. I do not like R407C. But this is just my opinion, your local engineer may have his own preferences.

Any rubber o rings and seals will need changing at the same time as the refrigerant is changed as the will leak once the R22 is gone (it makes seals swell).

Safest money would be system replacement (money would be saved on running costs too) but if you are willing to cover all the costs both upfront and those that show up later in theory a conversion should be possible (would need to be familair with the system to say for sure)

[HeatPump77]

Thanks Monkey Spanners - what does "waxing of the expansion device" mean in practice?

Don't know if this forum allows for contact but I'd be very pleased to hear from anyone with R22 who is in France or can travel......

[HeatPump77]

Have just seen a company promoting this an the best alternative to R22 - any comments??

ISCEON® MO29 or R422D is an easy-to-use, non-ozone-depleting HFC refrigerant for replacing R22 in low- and medium-temperature direct expansion (DX)........

[monkey spanners]

The waxing issue is when the wax used in lubricating the compressor motors copper wires as they are wound in the factory, and wax from the old mineral oil (wax which is not soluable in the new type refrigerant) solidifies in the pipe just as it enters the evaporator, issures are restricted flow, poor duty, poor expansion valve operation.

Using R422D can lose 20% system efficientcy.

Why do you need more refrigerant? Surely you can use the same R22 it has in it now, recover it fit new compressor, put it back in again!