Boiler comes on even when timer set to off

[mickayr]

I've got an Ideal Classic FF350 boiler, the timer is set to turn on the boiler in the morning for a few hours and again early evening.

Works fine during the summer just heats the hot water and during winter months, when it heats the water & radiators. However for a while now, including during the summer months, the boiler fires up even when the timer is set to off.

It fires up, for no apparent reason, both during the downtime in the day and at night. I've checked the manual and no mention of a frost stat being fitted

When its not on the programmed times it fires up for a about 30 seconds or so about every hour.

During the programmed times when you use hot water, as you would expect, the boiler fires up to heat the added cold water.

I've used hot water during the off periods and it doesn't fire up nor do the radiators get warm. Just seems to be random and at a total loss here.

I assume, apart from wasting gas, there is no major problem, but it is beginning to get on our nerves now as we hear the boiler fire up during the night.

Be grateful for any thoughts

 

[twgas]

do you have 1*3 port or 2*2 port valves?
Try turning programmer to off rather than "timed off" and monitor it, it could be not switching HW off at set times and then firing as the tank cools.

 

[mickayr]

Many thanks for quick thought, I have no idea how many valves!! but will try your suggestion about turning the timer to off as opposed to on timer.......in fact will do it right now and listen out if it fires up.

If it doesn't fire up then what could be the cause?

 

[mickayr]

As suggested turned the timer off (both hot water & heating).....after about 10 minutes..........yes the boiler still fired up......stayed on for about 10 seconds

 

[D_Hailsham]

Many thanks for quick thought, I have no idea how many valves!!

You should have either one, as in the left pic, or two, as in the right pic.

View media item 5946 View media item 11762

 

[mrgas]

What kind/make of programmer/programmable roomstat do you have?
Sounds like it could be something like a pump exercise function malfunctioning?

 

[mickayr]

Got one as on the left hand side pic.

As I said in my previous, when the timers were completely off, the boiler fired up after about 10 mins and then again about 20 mins later.

I've now turned both timers back on.

 

[mickayr]

The timer (in the airing cupboard by the tank) is a Drayton Lifestyle LP522 and the thermostat (in the hall) is also a Drayton.....no idea of model

 

[D_Hailsham]

The timer (in the airing cupboard by the tank) is a Drayton Lifestyle LP522 and the thermostat (in the hall) is also a Drayton.....no idea of model

No pump exercise function in that programmer, so we have to identify the faulty component.

1. How comfortable are you working with electrics - disconnecting and reconnecting wires etc?
2. Do you have a wiring centre (junction box) into which the timer, valve etc are all connected?

 

[mickayr]

In answer to your first, no worries about connecting & disconnecting wires (as long as instructions are clear!!!!) and to your second question, yes there is a junction box where all the wires go in

I have to say, though I wasn't sure, I always suspected it was electrical. Logic tells me that something is sending a signal to the boiler to light when it shouldn't

 

[D_Hailsham]

In answer to your first, no worries about connecting & disconnecting wires (as long as instructions are clear!!!!) and to your second question, yes there is a junction box where all the wires go in

Then we can begin Oh! I should have asked: is there a cylinder thermostat on the side of the HW cylinder? I'll assume there is.

View media item 10596
Testing motorized valve

Turn power off at main feed to heating system (turning CH and HW OFF at programmer off is not enough)

The valve will reset. There is a lever in a slot on the side of the valve; it should be at the Auto end.
Move the lever to the other end. You should feel some resistance as you are opening the valve against a spring. When you release the lever the valve it should move back and you will hear it moving.

If there is no resistance - lever is floppy - the valve is sticking.

On most valves you can remove the actuator (box on top) to reveal the valve spindle. Try turning the spindle with a pair of pliers (it may only turn 20°). If it is very stiff, apply a little WD40 or similar. Then reassemble and check if the problem has gone away.

If the valve is not sticking or the problem does not go away:

Turn Power OFF
Remove lid of junction box
Testing CH Only
Disconnect the valve White and Grey wires (note terminals) and connect them to a permanent Live terminal in the junction box (usually terminal 1)
Turn Power ON
The valve should motor over to the CH only position and the boiler run (check the pipe from valve to radiators is hot and the one to cylinder is cold).
Turn Power OFF (valve should return to rest position as tested above)
Testing HW Only
Turn Cylinder stat to min
Disconnect White and Grey wires and make safe temporarily
Locate the wire to the common of the HW stat (usually terminal 6 in junction box)
Disconnect from (terminal 6?) and connect to permanent live (terminal 1?)
Turn power ON
Turn cylinder stat to max
Boiler should fire; HW pipe from valve get hot, pipe to rads stay cold
Turn Power OFF
Testing HW and CH
Cylinder stat to Min
Reconnect the White wire to a Permanent Live (terminal 1?)
Power ON
Valve should move to mid position
Turn cylinder stat to max
Boiler should light
Both HW and CH pipes from valve should get hot.

Turn power OFF and reconnect White, Grey and Cylinder stat common to their original terminals

I think that's enough to get on with

Time for a progress report.

 

[mickayr]

What a fantastic reply, and yes there is tank thermostat. We have visitors now so it will have to be Monday before I try it, would hate for anything to go wrong whilst they are here.

Many thanks for that very comprehensive reply, I'll get back on here with the results. Fingers crossed one of those things will cure it, or at least identify what, if anything needs replacing

 

[mickayr]

Had time to try part one. Isolated from power and moved the front lever across. Definite resistance and could hear it moving back, I did it twice to be 100%. No problems, therefore did not remove the top box and do the WD40 bit.

Turned the power back on, and as both heating & water were timed as off, pressed the CH over ride button and the boiler fired up immediately. The lever moved, turned it off and it moved back. Did the same with the HW, same thing happened.

About 15 minutes later, yes you guessed, the boiler fired up even though both CH & HW timer set to off.

Did notice that when it came on, apart from the lever which I did your test with, there is another lever on the side which has been marked W at one end and H at the other (hand written with marker pen) assume done by the installers. Anyway when it fired up that lever was towards the W.

To confirm what was going through my mind, I pressed the CH over ride turning it on and that lever went straight towards the H.

Trying to apply logic, the only constant is the HW, this is timed to come on and off throughout the whole year, combine that with my observation and as the boiler keeps firing up out of programmed hours all year, is it not more likely that the HW is what is sending a signal for more heat as opposed to the CH cycle?

All the above leads me to think that it might be the side cylinder thermostat (as in your pic)......probably rubbish but I think you can see the way my mind is working!!!

A natural question is, if the thermostat is faulty how does it bypass the timer to tell the boiler to fire ?

I wont fiddle in the junction box until you have a read the above, and confirm that it is the thermostat or tell me I'm talking b....... !!!

 

[D_Hailsham]

Had time to try part one. Isolated from power and moved the front lever across. Definite resistance and could hear it moving back, I did it twice to be 100%. No problems, therefore did not remove the top box and do the WD40 bit.

That says the valve is not sticking.

Turned the power back on, and as both heating & water were timed as off, pressed the CH over ride button and the boiler fired up immediately. The lever moved, turned it off and it moved back. Did the same with the HW, same thing happened.

Just to clarify exactly what you did:
CH and HW both OFF at timer
Turn power on
Press CH override
Valve moves over to CH side
Boiler lights
Cancel CH override
Boiler goes out

Everything is OK so far then you say:

Valve moves back to HW side?

That should not be happening. It's one of the quirks of the mid position valve that is stays in the CH position when CH goes off. It will only return to the HW position if HW is turned on or the main power is turned off.

About 15 minutes later, yes you guessed, the boiler fired up even though both CH & HW timer set to off.

So the boiler must be getting a supply via the valve HW OFF terminal or the HW stat SAT terminal, which has 240v on it. This voltage should be dropped to about 100-150v by a resistor in the valve, so the boiler will not work. This means that either the actuator or the boiler gas valve is faulty.

Did notice that when it came on ... there is another lever on the side which has been marked W at one end and H at the other (hand written with marker pen) assume done by the installers. Anyway when it fired up that lever was towards the W.

Presume you mean when it came on, but shouldn't have.

All the above leads me to think that it might be the side cylinder thermostat (as in your pic)......probably rubbish but I think you can see the way my mind is working!!!

That's logical.

A natural question is, if the thermostat is faulty how does it bypass the timer to tell the boiler to fire?

That 's easy! There is a connection from the programmer HW OFF terminal and the HW thermostat SAT terminal to the grey wire of the valve. When HW is turned off, or reaches temperature, 240v is applied to the grey wire. It needs this to be able to go fully over to the CH only side. As I explained above this voltage should be dropped to 150V or so.

It would be worth checking the voltage on the Orange wire (connected up as normal) when the problem arises. If is is 240v, the problem is in the actuator. If it is 100-150v, the problem is in the boiler gas valve.

 

[mickayr]

So there are no ambiguities I repeated the whole exercise and whilst in situ, wrote down each action and observations. What I didn’t realise was how frequently the boiler fired up when not on the timer. Seems to be every 15 minutes or so (well while I was doing this exercise). Maybe we have got so used to it that we don’t notice. Anyway sequence of events, a bit wordy but wanted to cover everything:

Turned off the power to the timer
Front lever on the actuator moved from the wide end of the slot to the narrow end
Side lever is towards W
Did the test – Stiff resistance on front lever when moved and noise when it moved back to narrow end
When moving the front lever from the narrow end, the side lever moved to the midway point between W&H and as the front lever moved back to the narrow end, the side lever moved back to W
The boiler then fired!

Turned power back on to the timer
The boiler switched off!
Both timers are set to off
No movement from either lever

Pressed HW override
Boiler lights – Slight delay approximately 1 minute
Neither lever moves
Cancelled HW override
Neither lever moves
Boiler stays on for a while then goes off

Pressed CH override
Front lever moves to the wide end of the slot
Side lever moves to H
Boiler lights – Shortly after lever movements are finished
Cancelled CH override
Neither lever moves
Boiler stays on for a while then turns off

Power is now on but timers set to off
After about 10 minutes or so, boiler lights
Front lever is still towards wide end of slot
Side lever is still towards H
Boiler goes off after about 15 seconds

After another 15 mins boiler fires again
Front lever is still towards wide end of slot
Side lever is still towards H
Boiler goes off after about 15 seconds

To test out a theory I reversed the override sequence this time ending on the HW, so at the end, the front lever is towards the narrow end of the slot and the side lever is towards the W

Power is now on but timers set to off
Again after about 10 minutes or so boiler lights
The front lever is towards the narrow end of the slot
The side lever is towards the W
Boiler goes off after about 15 seconds

Another 15 minutes or so the boiler fires again
The front lever is towards the narrow end of the slot
The side lever is towards the W
Boiler goes off after about 15 seconds

Based on this experiment it seems that whatever system last asked for heat is the one that continues to do so when the timers are off!

Hope this makes sense to you

It is now the 7th of Jan and judging by the number of hits on this topic it would seem loads of people are interested or have the same problem. Unfortunately there was no reply to all the stuff above 'hope this makes sense to you' so I am no further forward.