Boiler problems

[david.cawkwell]

My boiler seems to have developed a fault. It is a Vokera mynute HE system boiler (hot water tank this is not a combi) It seems to be running all the time. After resetting the boiler I mark both hot water and radiators to manual off and the boiler keeps running.

There are two 2 port valves one for switching on the hot water and the other for switching on the radiators. I notice that the radiators 2 port valve can be opened and closed with a lever on the side and I can hear the valve move both electrically and when I do it with the level. However the hot water the lever moves straight across to open without any resistance (does this mean it is stuck open??).

Any other thoughts about why the boiler has suddenly decided to keep running.

[david.cawkwell]

Problem found. I set to with a screw driver on the hot water 2 port valve as I did so it shut. The boiler then shut down. A sticking 2 port valve.

[fred]

In article , [e-mail] writes

Well done.

In answer to your question about why the boiler was staying on, it is common to feed the demand from the a cylinder or room stat to the zone valve and then use the output from the status microswitch in the zone valve to create the demand for the boiler. That way the boiler isn't fired until the zone valve is open.

[Roger Mills]

. . . but, as the OP has discovered, the downside of this system is that if the valve sticks open, the boiler fires continuously - regardless of demand from timers and stats.