Is this the heater jiggle valve? I can blow & suck it with no resistance, could this cause the problems?
I also removed the stat while I was in there, is this fitted correctly?
Anyway, after a 30 minute drive through traffic without the stat fitted & the heater set to cold the gauge stayed 1 mark below half without moving, but after a motorway blast the temp gauge dropped to just above the quarter mark, so it seems I'm getting somewhere, hopefully. I'm assuming the gauge dropped because the stat wasn't there to control the flow, both underfloor pipes are now heating up nicely.
Got home & rebled the system & there was a tiny amount of air in the heater, I'll test it again tomorrow night & see if it's still the same.
I'll be testing the stat in a pan as soon as Mrs Daz isn't around
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