- 27 Feb 2017
- Reaction score
Very unlikely as your mains pressure would be higher than the system pressure. It has to be otherwise it wouldn’t pressurise the system. Did your shower head hose have a non-return valve? Only time the non return valve would do it’s job would be if your mains were switched off, you had released the pressure in your mains system and then there was a leak in the pressurised central heating system back into the mains system and that would only work if the flexi was still connected and both ends were open.I could yes, but I needed to use the Non-Return Valve that came with the loop, otherwise boiler water may have flowed back and contaminated my mains.