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Hi, looking for an advice. I've a call in to a plumber but might be sometime before he can get to me.
My central heating has started sticking on full blast. Turned the thermostat off, still on, turned the programmer off and still on. The only way I’ve managed to reset is to turn the mains power off and back on and then all is well for a few hours.
I’m assuming the programmer (timer box) is knackered. Boiler and programmer are two years old
Any ideas.?
Have you got a tank or combi system?
Mine was doing the same and is a tank fed system, it was a diverter valve getting stuck, looks like a rectangular metal box on the pipe work near the boiler.
If you have a combi then something else I imagine?
Could be an electrical failure in any of the parts listed, I'm guessing the thermostat.
Best wait until the guy arrives, they have the test equipment to check these things out.
Thanks guys, it’s a tank system
Probably just the diverter valve sticking ‘on’Quote:
Originally Posted by awright101
Very common fault at this time of the year.
But - the diverted valve switch is dependent on there being a signal from the programmer.Quote:
Originally Posted by CaptainSlow
So - the issue would appear to be in the programmer.
If it was the thermostat in the room - then switching off the timer on the CH would negate that.
Google image: Central Heating Y-Plan - you should be able to logically work through what must be wrong
Thanks, I will look that upQuote:
Originally Posted by blackal
Like I said above, it should look like this, my system has 2 but only one plays funny buggers every now and again -Quote:
Originally Posted by murkeywaters
https://www.plumbase.co.uk/honeywell...-03520474L.jpg
Where the little slot and lever are is where I squirt a bit of WD40 every time mine plays up, this un-sticks the internal mechanism and allows it to switch. It does have an electrical supply which should be controlled by the programmer, if its stuck open it will continue to tell the boiler to run no matter what the thermostat or programmer say.
In the past I have stripped it down but you have to isolate everything being an electric fed switch.
It still only en-passes the signal from the programmer.Quote:
Originally Posted by murkeywaters
So when mine plays up, I switch the programmer to off = no signals being sent, thermostat in frost mode = no signal being sent but the heating still runs at full blast, this is because this diverter valve gets stuck and keeps asking the boiler for heat, I have repaired mine about 3 times now over several years and it works every time.Quote:
Originally Posted by blackal
Combi being fitted after Christmas so i'll be glad to rip all this old antiquated system out!
Quote:
Originally Posted by murkeywaters
Mmmmm....:smug:
- - - Updated - - -
OP
Switch your programmer to off for the heating and hot water, turn down your thermostat to 5c and let us know what happens.
Will do. For now it’s working again as I turned the mains off and on. When it gets stuck again I’ll do as you suggest.Quote:
Originally Posted by CaptainSlow
Many thanks
A quick scan of the S-Plan or Y-plan indicates that the solenoid valve gets a supply to operate the solenoid, and a supply to en-pass to the boiler to switch on.
The en-pass signal comes from the boiler, to me
Has said most of the problems are usually caused with the port valve sticking in one position.
Usually if it is this it usually omits a buzzing sound.
Usually when your heating is on all the time the port valve is jammed in one position, sending power to the boiler (turning it on)
My three way valve went wrong/jammed recently, cost £140 for a good plumber to replace and the heating is all hunky dory again. Good luck.
Exactly the same problem here about 4-5 years ago and it was the valve sticking also
Just open the windows a bit.
HTH
Or sit around in shorts pretending you’re on holiday:smug:Quote:
Originally Posted by Kirk280
It’s better than the central heating failing in winter!
Looking at all the people who have responded who experienced a stuck motor valve - Surely your heating (or hot water) were still being ‘demanded’ by the programmer? i.e - if the programmer was set to ‘off’ on both CH and HW - then there was no boiler demand? Is what you are describing - the boiler running full bore while the timer demands either HW or CH?
In that above scenario - yes, freeing up the valve/switch, will in all probability - solve the problem.
From what the OP says - his heating continues to run with the programmer off? That does seem to indicate that the programmer is sending a “Run” signal to the motor valve and on to the boiler, also energising the solenoid to move the motor valve.
If you have a look at the S-plan and Y-plan, you see that the motor valve being in a ‘demand position’ is not enough to fire up the boiler.
https://www.flameport.com/electric/c...ing_Y_plan.cs4
https://www.flameport.com/electric/c...ing_S_plan.cs4
The programmer must:
1) Feed through the Thermostat, and motor valve position switch - to energise the boiler
2) Energise the motor valve - to move to an open position, and make the position switch above.
Both the above signals must be present to fire up the boiler.
(unless there are systems that are wired up weird)
They are really easy to change, providing you have good access. Pull the fuse for the system, trace the wires back to the junction box, ensure no current to the terminals, make a note of the wiring, remove wires, and the switch will be held on by 4 screws underneath. Unscrew the switch and swap out with the new one, reconnect the wires and off you go. I had a heating engineer out first time mine went and watched what he did. There is no need to drain the system down as the seal is in the "T" piece.
If you need it done asap and feel competent enough have a go, your local plumbing supplier will have them on the shelf.
You’re right - you can investigate a ‘stuck valve’ and hopefully sort it without opening up the water circuit. Certainly as plan A. I got severely put down by a ‘plumber’ on another forum, who insisted that you “change out the entire valve! I’ve been in the trade for XX years!” I guess that’s how they make money!Quote:
Originally Posted by Beanie
It should by probability - be just the switch U/S or simply loose. An easy fix. But- the valve itself may be the culprit. (It might not be stroking fully)
The valves also pass the signal on and can be dodgy out of the box.
I did some work for a boiler manufacturer a while back and we spent days arguing back an forth about a bug in the system very similar to the op’s which turned out to be the valve outputting an out of spec signal.
Weirdly when we moved into our new place a month ago we had odd things happening with our heating, turned out to be, yep, dodgy valve.
Sent from my iPhone using Tapatalk
I’d go with faulty programmer or faulty boiler circuit board.
I’ve got a similar system to the OP and I’ve have on occasions when in the loft manually moved both diverter valves when in the loft just to exercise them and my boiler has never fired up as a result.
So this guy is free falling to the ground and as he's falling he sees a chap hurtling up towards him.
Seeing his chance he calls out, "Hey do you know anything about parachutes?"
"No...." the chap shouts back "...do you know anything about gas boilers?" :icon_biggrin:
Start the car.............
After it not working on Thursday and then again on Friday it’s been fine since.I've got a plumber coming at 9 am tomorrow but not sure what he will be able to diagnose if it’s all working.
In the S plan even if the programmer isn't calling for heat the boiler could still fire due to a faulty motorised valve. The valve has a permanent feed to it which is completely independent of the programmer. Its this feed that connects to the boiler switch live when the valve motor is activated.
Just checked - yes, it could.Quote:
Originally Posted by scottbombedout
Quote:
Originally Posted by murkeywaters
THIS - I had the same
Mine did the same, it was the motorised valve. British Gas installed a new system but left the old valve in place.
Eddie
I had this a couple of times, it was the electronic section of the motorised valve jamming continually sending the boiler a ‘heat required’ signal, the mechanical part was fine and so I only changed the motor part, 10-15 minute job.
Just read up on a plan and didn’t know that the motorised valve(s) actually fire the boiler. So am I allowed to now fall into the it’s the motorised valve camp [emoji3]
The valve is stuck. I replaced mine a few weeks ago, which is about the 4th time over 25 years. It has nothing to do with the programmer, once its stuck the cog wheel in the mechanical bit sticks, so even no power it won't return to the closed position. Squirting WD40 through the slot, won't make much difference as the bit that normally breaks is near the top of the box. You can buy the motorised bit separately from Screw fix, just make sure you get the right one, some are two way valves, some are three. It takes about 20 mins to replace the motorised head, the head should be around £70. You shouldn't need the whole valve. But to check, take off the head, its only held on with a couple of screws, then if you can move the actual valve stem then the head is broken. If the actual valve on the bottom is stuck, then you will need the whole thing, but that doesn't happen often. To change the head, you don't need to isolate any water etc, just the electrics and then just wire it up the same as the one you take off.
Sssssh(sucks teeth as per quote time) ... yes ok, takes a good guy to admit he was mistaken. (Never wrong)Quote:
Originally Posted by IAmATeaf
Last couple I done were actually cheaper to buy complete than just the electronic component, I just take a picture of it hopefully showing manufacturer name and any part number and plod off to the plumbers merchants, I do get a better deal there than screwfix and better advice too.
Thanks. The plumber came this morning and the value was very stiff and felt that would be the culprit. He said there is a spring in the box turn turn the heat to water etc but it does not have that much strength. He said he could try and loosen it but it will stiffen up again. He’s coming back on Thursday to replace the valve and head as together they were not much more.Quote:
Originally Posted by casbar
Thanks for all the advice
Andy
Apologies for the bum-steer...............