How is air getting to my central heating pump

[sxturbo]

you would be better off spending that £470 on a new boiler,

i know you haven't got the budget, and you are trying to make it liveable, but at present the house wont be liveable without heating and hot water, so i would do without some niceties until later on. You also dont want to get it all looking nice then have to pull half of it apart again to install a new boiler, or find you have leaking pipework when the system gets pressurised and ruins all your new decor

to get you out of trouble get a cheap boiler with a couple year warranty, theres a few on the market vokera are are good budget boiler https://www.toolstation.com/vokera-...X8S6JwGkeN5N9mv6QiM2hySCCsl436ihoCA9cQAvD_BwE

 

[Gasguru]

Stop using the Auto mode...try the pump on fixed speed 1 to start with and if the temperature gradient across the boiler flow/return is excessive (greater than say 10 or 15 degrees) try speed 2.
You'd want a cast iron guarantee that powerflush will solve it....most powerflushing does little.
Follow the pumped circuit..you've probably got a check valve (anti gravity valve), these can block.