Why is my boiler on...when it should be off?

[Tiggsy]

Feeling quite excited now!

Next step is to fit an Owl Intuition remote wifi thermostat thingy and fire up the ipad!

[Brother D]

Brother D said:

I have exactly this issue at the moment and new actuator head sat next to me, except the microswitch was stuck and the valve closed, resulting in the boiler boiling water and banging...

I think one of the earlier posters mentioned drayton - and I have previously had this issue with a Drayton, and I probably should try another valve rather than like for like which are appearing to be unreliable... Recommendations? - I stuck with drayton as I can just swap the actuator in a few mins

Typical... the other zone valve apparently failed - so my tenants have left the heating running 24x7 for the past couple of months! Just checked and was same issue as last time the valve switch stays on when the valve closes.

[jryan123]

You guys seem to be really really helpful on this topic and I am really struggling to get my head around a very similar problem with my boiler.

I have a drayton (RF1 but modified by british gas and seemingly without many of the features of the proper one) wireless controller and a worcester bosch greenstar 28i junior combi mk iv. At the moment the boiler is firing fine when the controller calls for heat at its pre-programmed times but if it is set onto manual and then put back to auto settings the boiler seems to get out of kilter and fire of its own accord. The most frequent time for this seems to be in the evening (10pm onwards) and it will heat the radiators all night. A check of the controller confirms it isnt calling for heat and the same still happens even if the controller is turned off or batteries are removed.

Never seems to happen during the day and it seems to make no difference at all resetting the wireless link.

I am just puzzled, but could someone tell me if it might be the same issue discussed on this thread with the valve?

[Troubleatmill]

i started a thread similar to this a couple of weeks ago.

I got the answer as to what the problem is.

I have this thing in my pipework called a DRAYTON ZA5 actuator.

It has a reputation for being a piece of unholy poo.

The micro switches are prone to being sticky - so that when the heating/ water is switched off at the timer - this DRAYTON thing is supposed to do what is instructed- and tell the boiler.

Sometimes it does.
Sometimes it doesn't.

It is going to be ripped out for a Honeywell unit.


I'd wager you are experiencing something similar.

[Rickyy]

jryan123 said:

You guys seem to be really really helpful on this topic and I am really struggling to get my head around a very similar problem with my boiler.

I have a drayton (RF1 but modified by british gas and seemingly without many of the features of the proper one) wireless controller and a worcester bosch greenstar 28i junior combi mk iv. At the moment the boiler is firing fine when the controller calls for heat at its pre-programmed times but if it is set onto manual and then put back to auto settings the boiler seems to get out of kilter and fire of its own accord. The most frequent time for this seems to be in the evening (10pm onwards) and it will heat the radiators all night. A check of the controller confirms it isnt calling for heat and the same still happens even if the controller is turned off or batteries are removed.

Never seems to happen during the day and it seems to make no difference at all resetting the wireless link.

I am just puzzled, but could someone tell me if it might be the same issue discussed on this thread with the valve?

You've a combi boiler, unless you have zoned heating, there isn't likely to be a zone valve.

It's most likely a fault with the wireless stat. My 5 year old Honeywell CM927 has started doing the same recently.

Try changing the batteries in the stat, low battery can play funny buggers with them.

[jryan123]

Thanks guys. I have changed the batteries in the stat, although I do suspect the receiver may be funny that is located next to the boiler as it often receives an "on" light when the stat is not calling for heat.

With regards to the actuator DRAYTON ZA5 mentioned, where about would I locate this or identify if I have one of them?

Correct in terms of it being a combi and not having heating zones.

[Rickyy]

jryan123 said:

Thanks guys. I have changed the batteries in the stat, although I do suspect the receiver may be funny that is located next to the boiler as it often receives an "on" light when the stat is not calling for heat.

With regards to the actuator DRAYTON ZA5 mentioned, where about would I locate this or identify if I have one of them?

Correct in terms of it being a combi and not having heating zones.

You won't have one, they are usually only used on conventional boilers to control the flow of heat to the radiators and the hot water cylinder.

Sounds like the stat is the problem.

[jryan123]

Changed the stat out for a salus one with different frequency control. Works a treat now. Heating engineer believed that the stat was probably picking up a signal from either another similar wireless controller or a rogue wireless device on the same frequency. It was all wired in fine and the boiler was working fine. Might have cost £90 but its a problem solved and the old wireless controller is going on Ebay!

[vickyL]

Just came across this forum because my boiler is constantly sounding like it's on all night long the last few nights even though heating and water is off; my boiler is in my loft and its is -6 overnight at the moment so is that why? Because I imagine our loft is pretty chilly at night! Is thee anything I can do to stop it??

[vickyL]

Just came across this forum because my boiler is constantly sounding like it's on all night long the last few nights even though heating and water is off; my boiler is in my loft and its is -6 overnight at the moment so is that why? Because I imagine our loft is pretty chilly at night! Is thee anything I can do to stop it??

[essayer]

It's to be expected given how cold it is at night.
It shouldn't be using much gas, it just runs to stop it freezing up (which would be very bad news)
Nothing you can do to stop it except move the boiler to inside the house

[yekaj]

Rickyy said:

With a two port set up, it works as follows:

Hot water is selected, this sends power to the cylinder stat, if the cylinder stat is calling for heat. it sends power to the brown wire on the two port. This operates the motor, which opens the valve and also operates a micro switch. This micro switch has a permanent live supply on one side (grey wire) and the other side gets wired to the boilers switched live (orange wire). The microswitch is what fires the boiler. All the timer does is eventually open the valve.

When the demand is over, the valve is sprung return to the closed position, releasing the micro switch. If the valve is stuck, it won't return and the switch stays in the "on" position. The boiler will fire continuously until the water inside the primary circuit (not the cylinder) reaches the temperature set on the boiler's control stat.

Three port valves are different. Most rest in the HW only position when there is now power. Demanding HW will power the cylinder stat. The "demand for heat" wire from the cylinder stat is wired direct to the boiler switched live, the valve does nothing.

When heating is selected, the white wire is powered, which moves the valve into the mid position.

When heating is selected and how water is off/satisfied, the grey wire and white wire are powered and the valve moves to the heating only position.

If it is a three port valve, its possible that the microswitches are buggered. If that is the case you could probably get away with changing just the actuator head.

THANK YOU THANK YOU!!!

I spent days searching YouTube and plumbing forums to no avail. This one post solved my problem in minutes - on a car forum!!??

I checked my actuator was opening/closing, the motor was working as it should be - what I didn't realise was the microswitch could stick whilst the valve itself operated normally. A quick check of the grey and orange cables showed an open circuit*, and hey presto, problem, solved.

• Previous experience with electrics - NEVER work on a live circuit unless qualified.