Boiler not switching off in line with timer

[CJLees01]

We had a Vaillant ecoTec Plus 630 combi boiler + Honeywell ST9400C timer installed a few years ago.

Everything seemed to go well until last autumn when we realised that the (water) underfloor heating in our kitchen was warm in the morning even though the heating should have been off all night. The missus loved it of course but sure enough the resulting gas bill was eye-watering.

Some experimenting later, we have found that the boiler seems to be operating independently of the timer. In other words if the timer says the heating/water should be on from 8am-9am and then 3pm-4pm, we often find the boiler going full-pelt at noon even though the house is already warm and we haven't used much water.

Admittedly we haven't had the boiler serviced, but beyond this is there anything else I should look at?

 

[foxhole]

I have same problem, since new boiler installed last year, still have no solution , fitter and manufacturer [Greenstar from Worcester] both failed to find a solution.

 

[CJLees01]

Do you have the same combination of timer + boiler?
Is there the potential for some sort of "compatibility" issue between them?

 

[picasso]

More likely to be a sticking motorised valve, have a look near your hot water cylinder for two of these.

honeywell 2 port

• picasso
• 18 Oct 2010
• 31

 

[picasso]

I have same problem, since new boiler installed last year, still have no solution , fitter and manufacturer [Greenstar from Worcester] both failed to find a solution.

do you have a greenstar RI on a 3 port valve ?

 

[CJLees01]

Found one of those (Honeywell 272848) next to hot water tank but can't find a second one?

Toggled the one I have to manual and back to auto to see if this makes a difference.

 

[foxhole]

I have same problem, since new boiler installed last year, still have no solution , fitter and manufacturer [Greenstar from Worcester] both failed to find a solution.

do you have a greenstar RI on a 3 port valve ?

Yes I do, Danfoss controller changed again last week, and Honewell 3 port valve changed last month.

 

[picasso]

Found one of those (Honeywell 272848) next to hot water tank but can't find a second one?

Toggled the one I have to manual and back to auto to see if this makes a difference.

The second one will be there somewhere, its this one (the one you cant find) that controls your heating and is sticking, you gotta find it.

 

[picasso]

Yes I do, Danfoss controller changed again last week, and Honewell 3 port valve changed last month.

You should have started a new thread but anyway have a look here

//www.diynot.com/forums/viewtopic.php?p=825253#825253

 

[foxhole]

Yes I do, Danfoss controller changed again last week, and Honewell 3 port valve changed last month.

You should have started a new thread but anyway have a look here

//www.diynot.com/forums/viewtopic.php?p=825253#825253[/QUOTE]
Link dead?

 

[picasso]

Working ok from here, if you cant get it to work do a search on here for worcester bosch 24 ri by keego.

 

[foxhole]

Working ok from here, if you cant get it to work do a search on here for worcester bosch 24 ri by keego.

Tried a search with that criteria, got zero results?

 

[picasso]

Thanks for that Andy. I rang Worcester Tech today & they confirmed what you said about the capacitor, it seems they've known about this for a while yet obviously decided this bit of information is not worthwhile putting in the MIs for the boiler.
For future reference the capacitor is a 0.47uF 275v MPX2, £1.58 from Maplins
This links the neutral & switched live to boiler ( Orange wire in the wiring center )


thanks to keego for this

 

[foxhole]

Thanks for that, but it's from 2008 I read the problem does not afflict the later boilers [mine fitted Nov 2011].
Would it explain why my system sometimes/often ignores the room stat when heating is on?

 

[picasso]

Well you have changed the valve and controller , cant see spending about a fiver to see if it cures the problem being wrong.