Are you for real? What's a minimum gas safety qualification? Who did you work for? If you say you ID appliances etc, what were they for? If you left inlet without being sealed, you left a AR, as said, I think you need to train in another game tbh.
By scope they have basically said it is not a boiler issue and therefore a system issue of which they have no reason to continue. Potterton didn't fit the system did they! New build, from day 1 you say, what does that say to you? Yes boilers can be faulty out of the box but this is different...
So by the first mention of the pump blowing fuses, the fitter changed it and fuses stopped blowing, in April? You say programmer controls heating and hot water? It's now February. Actuator was changed?
Nothing wrong with the pump you've changed. Your fitter changed this due to it blowing a...
I reckon this 3 inch plastic pipe he's referring to is the flue. I also reckon the PRV may now be passing as was stated earlier when engineer filled it to 3 bar and didn't drain after to correct pressure. Plus any engineer would know how to test for a passing PRV.
"exorbitant" Another one that forgets about their boiler until something happens. Then expect it to be fixed for minimal amount or for free. Take your car in after it's not had oil in it for years and see what they say. "exorbitant" you'd probably say. The engineer has diagnosed correctly and...
Might have an over-heat stat wired up somehow ;) Sad story, maybe if people gave a toss about their heating and hot water and not having expensive cars on their drives, new bathroom, new kitchen our advice to change them when offered wouldn't seem so bad. Needs must eh!
Pretty much. The PCB on the new boiler controls pump over-run, anti seize etc if wired back to it's input. A 5 core cable is normally used, run from junction box. External controls such as your 2 valves are wired into the switch live bringing on boiler and pump.
Search mixer passing. Common fault. "Combo" boiler does depend on flow rate and temp coming in from mains cold supply so reducing the flow at taps can help if no other faults are to blame.