Leaking flow switch / generally confused

[AndyRV1]

Hello,

I bought my first house last summer, it's got an oil fired Grandee boiler controlled by a Grasslin QE2 controller.

When I first moved in the boiler wouldn't fire for heating but it would for hot water so I swapped out the controller and all was good again up to today when I noticed a soggy carpet.

Upon inspection the Sika flow switch is leaking with a slow drip, my first question is can you replace the seal or should I fit a new flow switch?

My second question relates to how this boiler operates, all literature for the controller seems to say that if you want heating / hot water you either need to program it to come on at a set time or press a button to provide an hours worth of heating / hot water, just turning the hot water tap on would not cause the boiler to fire.

This initially seemed strange to me but I put it down to being my first experience of an oil boiler and / or a cr*p control system.

Now this leads me back to the flow switch, what would be it's purpose in this system?... Or was it damaged and not working from the point that I moved in and really the boiler should fire when I turn the hot water tap on???

Thanks,
Andy

 

[ALCPlumbing]

Not sure with your system as I've not worked on oil boilers but generally only a combi will fire up when you open a hot tap. If you have a hot water cylinder it is run off the timer/programmer and a cylinder thermostat. If this is the case the flow switch maybe to prove the pump is operational so the boiler knows there is circulation before firing as otherwise it will overheat.

I'm sure someone who has experience with your boiler will be more specific.

 

[oilhead]

If the boiler is on, whenever the tap is turned on, the flow switch should operate the pump and burner, although depending on the temperature of the boiler, the burner may not run immediately.
If the leak is from the seal of the flow switch, then you could try a new seal, but make sure when fitting you have the flow switch in the correct orientation.

 

[AndyRV1]

Thanks for the replies guys, the boiler is a combi.

I've been quoted £230 for a replacement flow switch, I thought they would be £50 tops!

 

[Agile]

Is the £230 for visiting, diagnosing the fault, then returning with the new part?

In that case he has already visited and diagnosed the problem, unpaid apparently!

People foolish enough to do that, have to quote rather higher to cover the occasional customer who does not allow them to complete the repair when they have already spent time there!

Tony

 

[AndyRV1]

Tony,

No that's from me sending an email to Sika requesting a quote for the part!

Andy.

 

[oilhead]

Try Parts Center, Heating World of Spares or Abgo. The price will be much cheaper, especially from the last two.