Can't switch water off when Central Heating is on. Need help please!

[Andy™]

So, yes, I have to say that it is a Gravity fed HW with a pumped CH, S plan system.

yours appears to be a fully pumped S plan. its possible that its gravity with zone valves for the CH but not likely

if your confident playing with electricity, it would be possible to link out the DHW & CH separatly at the controller bypassing it, if it works then its the controller

 

[Creakyride]

yours appears to be a fully pumped S plan. its possible that its gravity with zone valves for the CH but not likely

if your confident playing with electricity, it would be possible to link out the DHW & CH separatly at the controller bypassing it, if it works then its the controller

Thanks Andy.
Yes, I am fairly confident on carrying out the test if I know where the link is located. Would it show at the back of the programmer?

 

[Andy™]

Thanks Andy.
Yes, I am fairly confident on carrying out the test if I know where the link is located. Would it show at the back of the programmer?

should be a diagram on the back on the programer. put a wire between the switch contacts for CH. in the case of the image that Poni attached earlier, itll be between 4&5 but yours may vary

switch power on, this should have heating on only. if you get hot water too, then its not the programmer (shouldnt need to wire the hot water off, id expect that terminal to have no cables in)

dont forget to turn it off first

 

[Creakyride]

should be a diagram on the back on the programer. put a wire between the switch contacts for CH. in the case of the image that Poni attached earlier, itll be between 4&5 but yours may vary

switch power on, this should have heating on only. if you get hot water too, then its not the programmer (shouldnt need to wire the hot water off, id expect that terminal to have no cables in)

dont forget to turn it off first

Well... It is a non starter... I removed the fuse after switching the programmer off and I tried to remove the front of the programmer by inserting a short, wide, flat end screwdriver under the bottom right, between the comer and the back plate, pushing upward and at the same time pulling the programmer from the bottom but it won't shift. Seems like it's welded in. Am I doing something wrong?
being located low near the worktop makes it more fiddly.

The good news is that the fuse is 3A, the correct one.

 

[Sharpend]

Did you remember the little screws underneath?

 

[Creakyride]

Can't see any screws under it.

 

[Creakyride]

Looking at the photo that Poni posted earlier as a reference, I notice that the front side of the controller has long recess on the top and bottom, on mine these recesses are incased into the wall porcelain tile that has been cut around the programmer!

 

[Geoff1946]

Can't see any screws under it.

Very tiny and right up against the wall.
If some expert has-tiled them in you will have to break a bit off the tile below or remove it completely.
(Starting to see why your heating engineer made a quick exit)

 

[Creakyride]

OK... That was a struggle but the programmer is now off the wall. Had to use a Dremel wit a diamond coated bit to remove the grout.

Here is a photo of the wiring. It looks quite different from the other photo that Poni posted.


By the way, I didn't find any screws under the programmer.

 

[Stevie G]

To creakyride ,i take it your background is not electrical ,as the 3amp fuse is only in play not to protect programmer, boiler, pump ,Valves etc but for over current protection of the wiring (cable) size .
All 3pin plug fuses are solely there to protect the cable flex.
As i mentioned earlier call for HW and see if pump, boiler and valve spring into action . Then do the same for CH .
As you said previously the programmer HW & CH switches are not mechanical interlocked ,ie you can put the CH ON without calling for HW.
AS for linking (shorting) out at programmer ,be careful as there is no mention whether the wiring (37 years Old ?) has RCds's ,Rcbo protection against electrical shock !
The backup battery for the programmer you used to get from RS components , and is for keeping the programmer time and schedules on a mains power failure .

​

 

[Creakyride]

Hi @Stevey G
No I am not an electrician.

I know that the fuse is for the programmer.

You must have read my post wrong, as the HW can be switched on its own but not the CH.

I appreciate you are trying to help me though.

 

[poni]

looks much the same to me

 

[Barx]

Now there was me thinking that gravity fed was because the mass of water is fed at gravity pressure ie without the mains pressure and pressurised tank!!
Perhaps I’m not as old as I thought!!

Like I say, I'm probably using the wrong term.
I understand what you are saying, but the system I was on about is gravity circulated. i.e the hot water from the boiler heats the hot water tank coil through the force of hot water rising above cold water. There is no pump of valve connected to this part of the system. Hence you cannot isolate the Hot water and just have heating only. It's how the old coal fires and early back boilers were plumbed up. then they started adding valves for extra control. That and the fact the hot water tank would sometimes 'kettle' from the coal fire and no way of turning it off

Surely you remember the old mechanical clocks that had the switch on the side for 'hot water only' - 'off' - 'heating and hot water'

 

[Creakyride]

Sorry Poni i got confused with another photo I saw on the internet, where it shows wiring. I blame the medications

 

[Creakyride]

Okay, I think I will have to reconsider trying to solve this problem I thought I could do this with your help but I admit defeat.
There is no link in 4 and 5 plus on 5 there are two wires and I don't want make more problems. I have put up with it for over 37 years, I have to wait for a quote on Air Source Heat Pump, failing that, a new more efficient Boiler, it's well due.

Thanks everyone! It is appreciated.

 

[Barx]

I saw a video on YouTube last might and the guy was illustrating the different system types.
My system seem to match the S plan type.

My hot water is definitely not pressurised as I have an electric power shower.

So, yes, I have to say that it is a Gravity fed HW with a pumped CH, S plan system.

I think I will splash out on a replacement controller as it at times don't obey the HW clock time, it doesn't switch off when it supposed to, hence I have to press the button myself. Also, I didn't even know there was a battery in there, so that would need to be replaced.

I will also check for the correct fuse rating, as it should be 3A.
Apparently the controller it's likely to be damaged if any other rating Fuse is used.

I can't find an installer manual, only a user manual. Before splashing out, I personally would take the cover off and see if there is a 'Gravity <> Pumped' switch or maybe one that says interlock. If there is either of those switches (or sometimes it's a jumper link) toggle it and see what happens.
I like to live life on the edge a bit...

 

[poni]

Okay, I think I will have to reconsider trying to solve this problem I thought I could do this with your help but I admit defeat.
There is no link in 4 and 5 plus on 5 there are two wires and I don't want make more problems. I have put up with it for over 37 years, I have to wait for a quote on Air Source Heat Pump, failing that, a new more efficient Boiler, it's well due.

Thanks everyone! It is appreciated.

all looks ok to me, L is live, and its looped over to 5 then out to the valve, 4 is the switch to the C/H valve/ and 3 is the switch to the stat on the tank, then out to the other valve

AS for linking (shorting) out at programmer ,be careful

put a wire between the switch contacts for CH.

if you think that you are up to this ,it would me my next step

 

[Geoff1946]

Removed initial comment after re-engaging brain. It concerned that 10 programmes / 16 selector, but it appears correct now.

 

[Creakyride]

I can't find an installer manual, only a user manual. Before splashing out, I personally would take the cover off and see if there is a 'Gravity <> Pumped' switch or maybe one that says interlock. If there is either of those switches (or sometimes it's a jumper link) toggle it and see what happens.
I like to live life on the edge a bit...

Like I said on a previous post, I am unable to get to the valve because of mobility problem, and i wouldn't trust my brother to touch it.
I too like to live life a bit on the edge... but I am not desperate.

 

[Creakyride]

all looks ok to me, L is live, and its looped over to 5 then out to the valve, 4 is the switch to the C/H valve/ and 3 is the switch to the stat on the tank, then out to the other valve


if you think that you are up to this ,it would me my next step

Thanks Poni.
It's reassuring that the wiring looks good.

I can follow simple instructions up to a point, after that I need to see photos and\or videos...
What it might be simple stuff to you, it's not to me. Once I do something for the first time, then it becomes simple the second time around.

Generally I tend to learn relatively quickly and enjoy DIY projects, much more before my disability. I did spend quite a few years in building sites and I was always fascinated watching other traders doing their stuff, all of what I learned has really helped me when working in my home but electrics is not my forte.