Boiler firing up randomly and hot water tank constantly hot

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Morning guys,

First post to the forum but have been lurking around for a while getting hints and tips.

Over the last few weeks we have been experiencing an issue with our Ideal boiler where it will just randomly kick in and fire up without any obvious call signal for hot water or heating. For example the hive does not light up for either and yet the boiler will run for a minute or 2 and switch off again only to repeat after a few minutes.

As a result my sons bedroom (above the utility room where the boiler is) is becoming unbearably hot. After a bit of snooping around last night I noticed that the central heating pump is constantly running and the pipework around the water tank in the upstairs cupboard are always really hot. My wife has noticed that our gas bill has been well over double for the last few months so looks like something is causing the boiler to kick in whenever it feels like it.

I took the cover off the pipework under the boiler and had a look at the valves etc. although cannot see anything obvious so I was hoping someone could point me in the right direction as to what I should be checking.

Initially I thought this could be a sticking valve - possibly the Drayton Zone Valve Actuator. (ZA5)? (I have attached an image of the valves)

Either that or could I have possibly wired my Hive up incorrectly? It has been installed for over a year and works perfectly but I wouldn't rule it out. Basically, all I had to do was remove the original programmer from the back plate and the Hive was a direct replacement. I then removed the old manual thermostat from the hall wall and chocolate blocked / insulated the wires before fitting a blanking plate so this could be reinstated.

Any advice on this issue would be much appreciated as this is costing a fortune and causing the house to get so warm my kids struggle to sleep.

Thanks folks.

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No photo visible. Try copy and paste into your reply.

Show us the thermostat on your cylinder please.

Is your timer set to 24 hours for hot water?
 
Sorry - I'll try and upload the photos again. I am currently at work so I' ll have a look for the cylinder thermostat when I get home and get a photo.
IMG_20190924_225149_resized_20190925_083753765.jpg IMG_20190924_225132_resized_20190925_083753381.jpg
With regards to the timer being set to 24hrs do you mean from the Hive? I have a schedule set to heat in the morning for showers and again in the evening for the kids baths but other than that it should be off. It has an immersion heater as well which is switched off at the breaker to rule out any heating from this as it is generally never used.
 
cant rule out a wiring problem from when you fitted the Hive, do you know what the programmer was that you replaced ? most are the same wiring but not all
 
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If I remember correctly it was a Drayton LP522 which was replaced. I thought I had lucked in as it appeared to just fit directly on however there could well be 1 or more wires in the wrong place. Again, once I get home tonight I will dig out the Hive install manual and see if I can check the wiring over.
 
had a look at the valves etc. although cannot see anything obvious

Depending on how the system is configured one possibility is that the micro-switch in the zone valve is defective and thus the boiler is firing when it shouln't be.

Very good explanation HERE
 
Depending on how the system is configured one possibility is that the micro-switch in the zone valve is defective and thus the boiler is firing when it shouln't be.

Very good explanation HERE
wouldnt heat up the HW cylinder though, a seized motor would, with the HW set to off try the lever on the HW zone valve and see if it has resistance or is it in the open position, if it is in the open position switch the power off to the system, if the motor returns you have a wiring problem if it doesnt the motor is seized
 
Thanks all - this has provided me with a plan for tonight once I get the kids to bed.

I'll check the motor is functioning as it should and also see how free the valve spindle is to turn to check if it is seized.
I will also check my Hive wiring to rule that out and have a look for the thermostat on the cylinder itself.

Much appreciated.
 
One other thing I noticed but forgot to mention was the second zone valve lying at the bottom left hand side of the photo. The valve in my other photo is fitted at the top right behind the silver Honeywell unit. The second valve appears to be wired up into the junction box however it was just lying disconnected at the bottom of the cupboard space.
Could it be that this is meant to be connected up to another valve in the system or is it normal practice to have a spare motorised valve wired in?

Thanks.
Brian.
 
Quick update:
The second valve was disconnected inside the junction box and taped up at the ends so I assume this is one that has previously failed but was never removed.

I removed the Hive completely and turned on the mains to the boiler - it fired straight with nothing calling for heat away so hopefully this rules out any wiring issues.
Next I removed the actuator from the valve under the water tank. When I turned on water heater from the Hive app (I refitted this prior to carrying out the next checks) the valve did not really move much so it seems like it might have seized up a bit. I tried to free it off manually and when refitted it it seems to be working as it should - the boiler is turning off when it should so it looks like this actuator is the problem.

Although this seems to be working I have ordered another valve to be on the safe side.

Thanks to all who helped me with this issue - much appreciated.
 

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