I had a boiler 8L made in China so we know which one, running a 5lpm pump as a result the boiler would get hotter due to a lack of flow, This resulted in the boiler over heating and by the time the overheating switch engaged or did not .Its was to late and the boiler burst, as I was packing in the pole at the back door were it was fasted.This resulted in me getting scolded on my arms and the upper legs.Fortunately it was the very cold spell we had in the start of last winter and I riped my top off and put snow on the burn markes which resulted in not getting badly burned. I did write about the bursting boiler but felt foolish as it was a mistake by me by not fitting a bigger pump.
I now have a 7liter pump and 5 liter boiler which due to the flow not been high will only produce water to 60 degrees.
Been doing some research into U P hose nd found out that it will only keep its shape at a max of 60 degrees and will come out of the John Guest fittings like a few have experiencing already. The so called P U hose is in fact a poly Urthane Ester hose which will work which is fine till 60 degrees then will distort. Not the same as UPVC which makes a swollen sausage like and then bursts.P.U. will not burst. This is all from the horses mouth.