No , a plumber would not likely pressure test a domestic heating system to 18 bar .When plumbers install central heating. Under floor in a customers home and use polyplumb. Do they tend to pressure test or Just fill the system. I know. It says to pressure test to 18bar in polyplumb instructions.
and it does actually state 18 bar
So as long as pushed all the way home things should be OK?The reason polypipe say 18 bar for polyplumb is that is an “O” ring first fitting, this means that when the pipe is inserted into the fitting it passes through the “O” ring first then the “grab ring” second.
If not fully inserted the “O” ring can hold the pipe when the pressure is increased even if the pipe has not passed through the grab ring, hence the 18 bar test. This could result in a full bore blow off.
Grab ring first fittings, like the new Hep2o and polymax only need 1.5 times the working pressure, if they are not pushed fully home they will leak but not blow off.
Good practice is to mark the pipe with the socket depth so you know that the pipe is fully home then pull back on the pipe to ensure the teeth bite, in reality this doesn’t happen.So as long as pushed all the way home things should be OK?