Timer wont switch off

makfli

My central heating is controlled with a room thermostat and an analogue timer switch with on, off and clock settings. Problem I have is that the switch will not
turn the boiler off. The indicator light remains on when the switch is in the off position. I thought it may have been a faulty switch but got that replaced and the problem is still there. The only way I can turn the boiler off is by the contact breaker on the fuse board.
Appreciate any advice?
Many thanks

nmacc

You'll need to give us a little more information.

When you say the indicator stays on, which indicator? Is it the neon on the timeswitch and does the timeswitch look a bit like this?



If the answer is yes, then the timeswitch was replaced by someone who had no idea what they were doing. Repeat the process with someone who does know.

makfli

Yes thats exactly the same timeswitch and the neon light remains on when the slider is in the 'off' position. A qualified plumber did fit the switch for me and it worked fine for about 8 months . Now suddenly doesnt work . I have not switched the system on for a while and a neighbour suggested the problem may be a motorised valve sticking. Does this make sense ?

nmacc

Your neighbour is using his head (better it seems than I am this morning)

A stuck motorised valve can give this result.

The valve has a permanent, unswitched supply, so if it sticks open - or in the case of some makes, if someone has operated the manual lever, then it will keep the boiler operating and feed back to the timeswitch, illuminating the neon.

See if you can find the motor valve; it will look a bit like this:


Check the lever on the side and make sure it is reasonably free to move. If it is, then the valve is probably stuck.

Let me know what you find and also what the valve looks like and we can take it from there.

makfli

nmacc, help much appreciated thank you. Where would the valve be situated? House is a bungalow and boiler is external with pipes running externally to the attic and then down the walls to the rads. I wont be back until Friday and I will have a search and take photo then. In the meantime many thanks again.

nmacc

Try the hot press. If you have one thermostat for the house then there is possibly another thermostat on the hot water cylinder giving you separation of heating and hot water. You may have either two 2-port valves or one 3-port valve. Two separate 2-port valves would be more common in Ireland and easier to work on.

Irrespective of the status of the central heating or hot water, either valve could be at fault. When you know what you've got, post the details & we can take it further.

makfli

Thanks again. Why is it necessary to have a motor valve ? I presume the thermostats can simply knock off the power to the boiler when the room and or water is up to temp ?

makfli

Sorry ..stupid I get it now so that space heating and water heat are independent .

Kevin McCloud

nmacc wrote: »

The valve has a permanent, unswitched supply, so if it sticks open - or in the case of some makes, if someone has operated the manual lever, then it will keep the boiler operating and feed back to the timeswitch, illuminating the neon.

Stuck valve can cause boiler to stay on but with your theory it cannot backfeed to neon on time switch. Live out would be to coil on valve, switching contacts on valve are a seperate identity.

nmacc

Kevin McCloud wrote: »

Stuck valve can cause boiler to stay on but with your theory it cannot backfeed to neon on time switch. Live out would be to coil on valve, switching contacts on valve are a seperate identity.

D'you know, you have a point there Kevin, I knew I should have gone to bed earlier.

So we're back to incorrect wiring. Of course we don't know what kind of incorrect wiring.

I suppose Occam's Razor suggests the original time switch died - as that type so frequently does - and the replacement was wired arseways.

Kevin McCloud

nmacc wrote: »

the replacement was wired arseways.

By a taxi driver no doubt.

Wearb

It worked fine for 8 months. Probably is a faulty timer.

makfli

Many thanks really appreciate all the interest.
The previous timer was an apt and exactly the same symptoms worked for about a year and then would not switch off. The replacement Immermat was installed by a professional as was the apt and as I said worked fine for 8 months and now wont switch off. Surely its odds on to be some issue other than the timer ?

Wearb

Post this in the electrical forum.

I have seen a problem many years ago caused by a small current being induced in a switched off wire. In the case that comes to mind, it was caused by power from a neighbouring live wire in the same conduit. That time a certain bulb holder kept blowing the bulbs.

May not be the cause of your problem. I only mention it to show how difficult it can be to pin down some problems.

Kevin McCloud

Has the room stat a permanent feed I wonder and is calling for heat, if you turn down the stat to minimum that would eliminate that.

nmacc

Once again I didn't read carefully enough. If it was replaced and worked correctly for a year, then obviously the wiring is correct.

My money would be on a second faulty timer. In my experience these things are definitely the most unreliable timer on the market. It seems to be a function of the design, as I've had repeated problems with Flash and APT makes.

I suggest you go for a simple digital timeclock like this:



You'll be limited to a maximum of three on/off periods per day, but it'll be much more reliable; you won't even have to reset the clock if the power fails.

makfli

Thanks Kevin , I will try that.
On Wearb's point re the induced current, would this be sufficient to override the switch contacts in the timer ? or just affect the indicator light .

Wondering if I can just use the boiler for rad the heating and work the hot water off the immersion heater. If I close down the h/w cylinder circuit using the manual valve at the cylinder and then disconnect the motor valve from the power supply and leave it open. The boiler then would be used to supply only the rads. Would this eliminate the motor valve and the induced current apparent issues ?
Does this make sense ?

makfli

Sorry nmacc , I didnt see your post until after I posted this morning. Hard to believe that these clocks are so unreliable in fact now that I think about it the Immermat is the 3rd clock that has been installed the two previous being APt.
Though it still would not solve the induced current problem ?

Kevin McCloud

makfli wrote: »

Though it still would not solve the induced current problem ?

I seriously doubt you have an induced current problem, and on another note them apt timers are rubbish so them failing is no suprise.

Wearb

"Post this in the electrical forum.

I have seen a problem many years ago caused by a small current being induced in a switched off wire. In the case that comes to mind, it was caused by power from a neighbouring live wire in the same conduit. That time a certain bulb holder kept blowing the bulbs.

May not be the cause of your problem. I only mention it to show how difficult it can be to pin down some problems. "

Kevin McCloud

Wearb wrote: »

I have seen a problem many years ago caused by a small current being induced in a switched off wire. In the case that comes to mind, it was caused by power from a neighbouring live wire in the same conduit. That time a certain bulb holder kept blowing the bulbs.

This makes no logical sense whatsoever, was it mens shed that this discovery was made?

Wearb

Kevin McCloud wrote: »

This makes no logical sense whatsoever, was it mens shed that this discovery was made?

No men's sheds in those days. Do you understand how a current can be induced in another non current carrying wire by induction? Are you aware that this is how transformers work? This is not an unknown phenomenon amongst experienced electricians.

Those sort of problems are often not understood by non electricians (you are an example of this) and that is why I asked that this question be posted in the electrical forum.

It may be only a coincidence that both timers broke down, but there may be something else at play.

Mod: play nice now please.

Kevin McCloud

Wearb wrote: »

No men's sheds in those days. Do you understand how a current can be induced in another non current carrying wire by induction? Are you aware that this is how transformers work? This is not an unknown phenomenon amongst experienced electricians.

I am well aware and educated on how induction works, can you explain exactly the situation that you experienced, the voltages, cable csa, amount of cables in the conduit, what voltages were the appliances, what wattage etc.

Those sort of problems are often not understood by non electricians (you are an example of this) and that is why I asked that this question be posted in the electrical forum.

Ill choose to ignore that Infantile comment on my knowledge, we can all put up theories but if we cant explain them and pawning it off when put on the spot is then these theories are only a conspiracy.

Mod:as above.

Egass13

If its just the neon staying on , without the boiler staying on . Could there be a chance theres reverse polarity sending a bit of voltage down the neutral to power the neon ? Could be way off of course but its worth a punt

Kevin McCloud

Egass13 wrote: »

If its just the neon staying on , without the boiler staying on . Could there be a chance theres reverse polarity sending a bit of voltage down the neutral to power the neon ? Could be way off of course but its worth a punt

Even if you had reverse polarity the neon would not light, then again i could be wrong as im only an alleged non electrician.

makfli

Many thanks to all for continuing interest.
Just to clarify the boiler operates and the neon light remains on regardless of the position of the slider switch. ie when switch is off boiler is firing and neon light is on.

Also appreciate comments on the following:
Wondering if I can just use the boiler for rad the heating and work the hot water off the immersion heater. If I close down the h/w cylinder circuit using the manual valve at the cylinder and then disconnect the motor valve from the power supply and leave it open. The boiler then would be used to supply only the rads. Would this eliminate the motor valve and the induced current apparent issues ?
Does this make sense ?

nmacc

There are no 'induced currents'. Your new timer is broken - replace it and use a decent one this time.

agusta

makfli wrote: »

Many thanks to all for continuing interest.
Just to clarify the boiler operates and the neon light remains on regardless of the position of the slider switch. ie when switch is off boiler is firing and neon light is on.

Also appreciate comments on the following:
Wondering if I can just use the boiler for rad the heating and work the hot water off the immersion heater. If I close down the h/w cylinder circuit using the manual valve at the cylinder and then disconnect the motor valve from the power supply and leave it open. The boiler then would be used to supply only the rads. Would this eliminate the motor valve and the induced current apparent issues ?
Does this make sense ?

It doesnt make sense.Also an immersion is more expensive than oil to heat water.If it we re me id be fitting this time clock
http://www.pjmatthews.ie/products/flash-31031-single-channel-timeclock-1 ,or a more expensive digital clock with a boost button

makfli

I have a Siemens RWB27 controller which was replaced in my mothers house. I think this is working ok. Before going to the expense of getting a new one installed and finding that it is not a timer problem, I would like to try this out. The connections are 4 3 2 1 L N. Could anyone advise how I sub this for the Immermat switch ?
Many thanks again for all the interest.

Kevin McCloud

Post up picture of the timer and its connections.

makfli

Thanks Kevin will do. I wont be back home until the week end and I don't have a broadband connection so will be Tuesday before I get the pic up. From memory there are two twin cables thus 2 brown and 2 blue.

Kevin McCloud

Isolate the power, open timer, identify live out and disconnect it from the timer, power back up, boiler should now be off unless you have some other backwards wiring in your installation.

skippy5

Have you a frost stat on your boiler. Could be faulty.

Egass13

Kevin McCloud wrote: »

Even if you had reverse polarity the neon would not light, then again i could be wrong as im only an alleged non electrician.

Theres every chance a neon could light with reverse polarity. Ive seen it on boilers, spur switches and believe it or not , time clocks . But as the boiler is firing then its ruled out anyway.

Dtp1979

skippy5 wrote: »

Have you a frost stat on your boiler. Could be faulty.

Yes, this is just what I was gonna say

Kevin McCloud

Egass13 wrote: »

Theres every chance a neon could light with reverse polarity. Ive seen it on boilers, spur switches and believe it or not , time clocks . But as the boiler is firing then its ruled out anyway.

Im not disputing a neon lighting with reverse polarity, its the reverse polarity sending a bit of voltage down the neutral to power the neon bit that is not possible, the induced current theory is more plausible.

Egass13

Kevin McCloud wrote: »

Im not disputing a neon lighting with reverse polarity, its the reverse polarity sending a bit of voltage down the neutral to power the neon bit that is not possible, the induced current theory is more plausible.

Why isnt it possible?

Kevin McCloud

Egass13 wrote: »

Why isnt it possible?

A neon will light no matter how its connected, same as wiring a simple pendant drop, the bulb will still light.
Are you on about if the clock is wired backwards and that the neutral of the clock will be now live that the neon stills light when the clock is off?

Egass13

Kevin McCloud wrote: »

A neon will light no matter how its connected, same as wiring a simple pendant drop, the bulb will still light.
Are you on about if the clock is wired backwards and that the neutral of the clock will be now live that the neon stills light when the clock is off?

Not necessarily the clock. You could have a plug on an appliance wired incorrectly and when plugged in could cause reverse polarity on the circuit . and providing the timeclock is wired off the socket circut , could impact on the timeclock. Im confused when you say reverse polarity could cause it , but power on the neutral isnt possible. When my understanding of reverse polarity is just that, when the neutral becomes live ?

Kevin McCloud

Egass13 wrote: »

When my understanding of reverse polarity is just that, when the neutral becomes live ?

And the live becomes neutral, neon lights im in agreement with you as i said earlier. Or is it something else?

If the clock was wired reverse polarity the problem of the neon lighting would be there from day 1 based on your suggestion.

makfli

Once again thanks to everyone for the interest. I think firstly I will replace the timeswitch. I have a Siemens RWB27 digital switch which I will try. Connections are :
IMAG0233.jpg

The Immermat switch has connections, from the left
Brown= L in, Blue = N in, Blue = N out, Brown= L out:
IMAG0226.jpg

Appreciate advice on how to wire up the Siemens switch.

Also I found the motor valve which is a Sunvic there is no lever on this as nmacc suggested that I check for free movement:
IMAG0232.jpg


Many thanks again for any help