Paul,

Again just for info now I understand the scale of the job, the drop in replacement for R22 is R417A they list R417A as an interim and long term replacment. It will operate with mineral, alkylbenzene and polyol ester oil although if you were retrofitting from R22 a 50/50 mix of mineral/alkylbenzene oils is prefrerred, so the contractor would have a bit of work to do....

Cost wise you would be looking at a refrigerant with a cost price of approx £15.00 per kilo, alkylbenzene oil is approx £9.00 per litre...


HTH

Ian