Boiler Problem

[thomasar]

We have a Vaillant ecoTEC Plus 428 boiler which is making banging/kettling noises when the heating starts in the morning (water and radiators) and after we have used the shower. We thought it was probably the Heat Exchanger but if we turn off the water heating it never happens when just heating the radiators. Also we normally have the dials for water and radiator in the boiler turned to the maximum (about 20 past the hour) but if we turn then back a little (about 15 mins past the hour) we don't get the banging. Anybody got an ideas? Does it sound like the Heat Exchanger? We had a plumber in who thought it was the circulation pump in the airing cupboard upstairs which we doubted but told him to go ahead and replace the pump and it made no difference at all.

 

[steadyon]

1. If it doesn't make a noise when just using the central heating, its unlikely to be the heat exchanger.
2. Its not a combi, so using the shower won't cause an immediate call for hot water heating.
3. My first port of call would be air in the hot water primary coil, although this wouldn't explain the shower issue.
4. Try bleeding the primary coil.
5. Also test that:
5a. The motorised valve is working properly.
5b. The hot water cylinder thermostat is in full contact with the cylinder's metal and is working properly.

 

[thomasar]

1. If it doesn't make a noise when just using the central heating, its unlikely to be the heat exchanger.
2. Its not a combi, so using the shower won't cause an immediate call for hot water heating.
3. My first port of call would be air in the hot water primary coil, although this wouldn't explain the shower issue.
4. Try bleeding the primary coil.
5. Also test that:
5a. The motorised valve is working properly.
5b. The hot water cylinder thermostat is in full contact with the cylinder's metal and is working properly.

Thanks for the reply. I've made a note of your suggestions if we need to get a plumber to have a look at it. The strange thing is that we have had no banging at all since we turned the dials on the boiler down a little and it seems to be working perfectly so we don't really know whether that has made the difference. When the plumber put in the new pump and tested it we got the same noises but then he started talking about a possible air lock and I noticed he undid some screws on part of the flue at the top of the boiler. However, when he tested again after this it still made the same noises.

 

[Murdoch]

Maybe the pipes are getting blocked with muck ..