i have a baxi bermuda back boiler which had worked very well since 1989 until the thermostat was left disconnected after an annual service a couple of years ago. within half an hour of the boiler being switched on the water had overheated and all the valves were blown. the company admitted no liability but a team of upto five engineers rebuilt the boiler practically from scratch which must have made it an expensive job. six months later when i was investigating the source of a leaking overflow pipe - which later i established was leaking whenever the boiler came on - i discovered that the tap for the 'expansion' tank (? the smaller of the two water tanks) had not been switched back on and the tank was bone dry...
my first question is, what damage might this have caused to the system?
the system began to become less and less efficient that winter - the radiators were only luke warm although there was hot water in the tank and taps. the original company with my service contract became increasingly unreliable and when a powerflush for #600 was suggested i decided to terminate my contract.
some nice chaps that i found on 'rated people' came along and did the job for less than a third of the price but when the flushed water came through it was clean! however the system still did not work properly. it seemed to be some kind of block between the boiler and hot water tank - at this point i become lost - some pipework was cut out and new piping was installed between the hot water tank and one of the cold water tanks i think... this was all done for within #200 quoted for the power flush and got the system working again so i was extremely happy.
however this year the system has gradually become worse again. the chaps that i had found on 'rated people' came back to have a look. they seemed to think it was air in the system and tinkered with it to get it going better, but i remain unconvinced. the radiators are warmer but not as hot as they used to be. i was advised to regularly bleed a valve at the top of the pipe which had been cut off next to the tank. i can believe that this may well help but it is not the solution i was looking for. the guys said that if the system got worse again they would install an automatic valve on the top of this pipe. i paid relatively generously for this visit compared to the first.
my second question is, would an automatic valve be the solution?
the pump was working but it needed turning down to 1 to stop the water which was trickling up into the 'expansion' tank. i was told that the water was trickling because the pump was sucking too much air into the system at any speed above 1. it didn't used to do this.
i would dearly like to understand what is going on so that i know if i am getting good advice from this new company that i have become reliant upon. they do seem rather keen to install a combi boiler for me and from looking at system diagrams i can see why, but in practical terms it would be a nightmare for me with all the floors needing ripping up!
i would greatly appreciate any advice.
many thanks for your patience.