baffled by pump over-run ??

[twgas]

But, if the either stat is still calling for heat, the boiler will be ignited, so the pump would not be in over-run mode.

For the pump to go into over-run mode there must be NO voltage at the switched live. This is only true if:

(CH=off OR CH=satisfied) AND (HW=off OR HW=satisfied)

thats exactly what i meant, well put D_H

 

[andyca80]

I think I have a similar problem with a 24Ri fitted last month, but I am not a plumber and having to learn this very fast… I have a separate pump which does not switch off after the boiler turns off. Also the Boiler will randomly turn itself on when the timer control is in 'off mode', although this is usually only for a few seconds. There is a switch on the pump that is labeled 1,2,and 3, switching these around I am able to turn off the boiler when it’s supposed to be off but really I just want it to be on when I want it to be on and off the rest of the time and not to keep me awake at night with a continuously running pump. Was there a resolution to this issue that may help or does it sound like I have a different problem?

I also don’t have any thermostatic control valves on the upstairs radiators which I have read is a requirement for this type of system. The timer can set times for both CH and HW which I think makes it an ‘S’ Plan system? Finally I have a thermostat which appears to do nothing other than show the current temperature.

The plumber cut so many corners elsewhere I want to be sure I know what I am talking about when he comes back to try and fix it.

 

[londonboy]

You should have started a new topic.

Your system sounds to me like its operating correctly! It runs the pump for longer to dissipate the heat from the boiler, and also does it every 24 hours (I beleive) to ensure it doesn't stick.

 

[andyca80]

The major problem is that once the boiler has decided to turn the pump on it will run continuously, (for ever) no matter if the boiler comes to the end of it's time cycle or I turn the boiler off manually. The only thing that stops the pump, is flicking the isolation switch off. I accept overrun should last a few minutes but it should not keep the pump going for days.

I will start a new thread as suggested.

 

[mysteryman]

The pump overrun on some boilers is temperature contolled. The purpose of pump overrun is to dissipate residual heat from the boiler. This can't happen with an S Plan because both the valves are closed on shutdown. The pump will continue to run without any flow through it; this will make it cavitate and overheat - and wreck the pump. There may be capacitors required with some makes of 2 port valves.

 

[andyca80]

Just to close this one off - my problem was caused by the boiler being incorrectly wired by the installer. This was fixed and the problem resolved.

 

[Agile]

Well as you had obviously employed a complete nupty thats only what you expected two years ago!

Hopefully you will now realise that the cheapest is not usually the best solution!

Tony