I need to connect to a 22mm femaile thead on my heat pump. I've bought a couple of different fittings from Screwfix both of which have a 22mm thread on one end but neither will fit the 22mm compression fitting on my heat pump. The pipe slides into the fitting and the nut will rotate about one turn but then jams. Looking at the two side by side, the thread on the screwfix fitting is broader than the thread on the one in my heat pump. Can anyone tell me what the top one is called and where I might get a fitting for it?