We moved into our house a few months ago. The whole wiring and central
heating we think are amateur jobs.

The problem is air getting into the CH system. It's heated by an old
gas boiler downstairs, the pump is upstairs under the floorboards.
Overall, the CH and hot water seem to work OK, except:

Every time the CH is started up after a few hours off, it gurgles like
mad from the pump and three radiators quickly fill with air - two of
them over half full of air (from feeling where they are warm/cold). It
takes a good couple of minutes to bleed them.

Every time, twice a day.

All the other radiators are OK and these three are fine after
bleeding. Until the next cold start.

Now, the dodgy wiring I can fix, I'm an electronics engineer. But
water has me stumped.

Please, any help?

Rick,
Manchester, UK.