Problems with boiler overrun and boiler overheating

[Annieblue]

Hi - wonder if anyone can shine any light on our current problem.

Moved into house 2 yrs ago and inherited the existing plumbing and heating. We have had various bits and pieces done since then, including, about 15 months ago, a new diverter valve.

Since fitting we have had some issues which are intermittent but occurring more often than not now.

Firstly the heating sometimes stays on after the timer should have turned it off - this happens intermittantly, sometimes after the morning session (2 hours) and sometimes in the evening, not always and not every time. Currently we are trialling a new timer (fitted by plumber 2 days ago and so far so good) but he has literally just fitted it, not changed any wiring etc.

The other problem, also intermitant over last year, is that the boiler just keeps going long after the thermostat should have cut it off (we normally have it set to about 20 - 21) - I've paid particular attention the last few days and it mostly seems to happen when the water is on too, the rooms end up like a furnace and the boiler stays on. When I checked the diverter valve the switch was in the mid position even though the water was timed off, and when I switch the whole thing off from the electric switch the diverter valve shifts across to the HW position.

I originally thought it was a wiring problem, from when the new diverter was fitted, the plumber has checked and says no - but now I'm thinking the diverter valve may be a bit dodgy.

Has anyone got any ideas - I've searched and searched and come up with nothing else hence my post... and TBH I'm not entirely sue about the new timer and an still waiting for that to fail (But I am now very cynical).

(Apologies for any spelling mistakes).

Rgds,

 

[dcawkwell]

Faults like this are nearly always the diverter or 2 port valves.

Wasting your time replacing timer very unlikely to be fault.

You can usually see if the timer is still on and easy enough to test.

 

[Gas2Air]

Faults like this are nearly always the diverter or 2 port valves.

Wasting your time replacing timer very unlikely to be fault.

You can usually see if the timer is still on and easy enough to test.

I've had a few timers giving power on Y plan and causing this issue. OP you say diverter was changed? Was it the complete valve and actuator or just actuator?

 

[Annieblue]

Forgive me I don;t know what an actuator is, but the thing that was replaced is a box about 4" x 3" with a black stick on the bottom that moves between the 3 points and a wiggly stick at the side that apparently should always wiggle.... and it does. I did wonder if it was the thermostat but it seems to work otherwise.

Thanks for your help,

 

[Gas2Air]

The box is the actuator. You have a sticking 3 port valve body, it will have 3 ports and made of brass. Get the plumber back to change that.

 

[Annieblue]

Will do - it does move, just doesn't seem to move as it should. But of course - tonight it hasn't gone ballistic when the water came on, and has behaved itself - probably knows I'm talking about it. Will monitor over next few days and feedback to you all with outcome.
Many Thanks,

 

[Gas2Air]

Will do - it does move, just doesn't seem to move as it should. But of course - tonight it hasn't gone ballistic when the water came on, and has behaved itself - probably knows I'm talking about it. Will monitor over next few days and feedback to you all with outcome.
Many Thanks,