Old 3/4'' 20mm copper.

[cdavie2002]

Is it ok to use a 22mm compression fitting on (20mm)/(3/4'') pipe to connect to modern everyday 22mm copper? It's holding this far, took a bit of torquing!

 

[Dannypipe]

Thanks, I know for next time.

 

[Killy Bing]

Danny. Wade fittings will seal imperial on the smaller sizes.

 

[AWheating]

im the same as danny, ive used plenty of 22mm fittings without a problem in my younger days. Probably lucky that the fittings/olives where alot better made i guess. Ive seen what happens when a 22mm fitting pops off a 3/4 pipe when a work mate at the time did it. The damage come to many thousands of pounds. Not ever worth the risk when a 3/4 olive costs very little, just carry a few on the van.

 

[Mike Jackson]

I did a standard to combi boiler swap a couple of years ago. The system was about 40 years old and the guy that had done the previous swap had used a 22mm compression on 3/4 pipe. The system was very low head and when I pressurised it the fitting blew off. Luckily it wasn't on a low point of the system so not much water came out or i could easily have flooded the flat below.

 

[Centralheatking]

I have mixed up some refrigeration fittings with my normal plumbing ones - it is a nightmare CHK

 

[Reg Man]

Don't bother with compression, the imperial pipe rattles around the metric fitting. Just use a CU1M for the old boys or YS1M or end feed equivalent soldered fitting with lots of steel wool to clean the old pipe up before hand.