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

[Creakyride]

Hello everyone,
As per thread tile, can't switch water off the controller.

I can have the water ON on its own but not the CH on his own.

Basically it has been the same since the late 80s. Now i have read somewhere that the controller (POTTERTON EP 2000)has possibly been wired wrongly.

The CH system is about 37 years old. It's a vented system with a vented hot water cylinder.
It has 2 valves on them and they are working according to a heating installer. He said to get an electrician to install a new programmer on it. Talked to a couple of electricians and they were not interested and referred me to heating engineers...

Now, I am waiting for a quote for a possible air source heat pump but the waiting can be very long.
In the meantime I just want to save some money by not heating the water when not needed but still having the heating on. Is this possible?

Here are some photos of the system.

 

[Creakyride]

Found an online user manual for the controller and it explain why the hot water will automatically come on when the CH is on.

"The HW & CH sliders have a mechanical interlock to protect simple heating systems which can only heat the radiators when the HOT WATER is on. If yours is a simple system, the interlock will automatically cut the programming facilities that your system cannot cope with. This means the HOT WATER is automatically turned ON when CENTRAL HEATING is on."

How do I know if mine is a simple system hence hot water must come on when Central Heating comes on?
I assumed the 2 separate valves would allow the CH to operate independently from the HW.

 

[Geoff1946]

In the most basic old fashioned "simple" system there would be no valves at all. Switching on the boiler would cause the water cylinder to heat up by thermo-syphon, working on the principle that the cylinder was located reasonably close and above the boiler. The central heating was controlled by switching the pump, usually via a room thermostat to circulate heated water to the radiators.
Consequently it was impossible to have heating without hot water and the controllers reflected this either by design or by swapping links on the back. (I have no knowledge of your particular programmer)
Your system appears to have two valves, which MAY be the hot water circuit and the heating circuit, separately controlled and both pumped.
In that case the two could be independently controlled with a two channel programmer. The boiler and pump would be switched by the contacts in the motorised valves, such that either valve could call for heat.
Changing the programmer MAY be as simple as unplugging the existing one and plugging in a newer type, if it is on a standard backplate.
It's a pity really that your heating engineer wouldn't see through the modification he suggested. The considerations are just as much plumbing/heating issues as electrical.

 

[Andy™]

doesnt look like a gravity system. if you cant have CH only because the switch wont physically let you select it, it probably just needs taken off the wall and the settings on the back adjusted. many older programmers like that are adjustable between gravity & fully pumped systems

 

[Creakyride]

The HW tank is close to the boiler and I have 2 plastic tanks in the loft, one for cold and another for the hot.

 

[kerching]

Can you slide the heating and hot water switches independently.?
Or does the Ch one make the Hw one move BUT the Hw one doesn't make the Ch one move?

 

[Creakyride]

They slide independent from eachother.

 

[kerching]

In that case it's most likely a stuck motorised valve on the hot water and/or a failed cylinder stat

 

[Andy™]

or one of them has been manually turned to on

 

[Barx]

Many programmers have an operation mode to allow for gravity or pumped / valved systems. Sounds like yours is set to gravity. Which works like the old mechanical clocks. Hot water only OR Heating & Hot Water. No Heating only. It could be a case that the programmer is wired ok, but just set wrong, Have a look in the manual for such setting. It could be a combination of buttons to set it or a Jumper link on the back of the programmer.
Just remember what you do, so if it doesn't work, at least you can put it back to how it was for now.

 

[michael8554]

Try switching CH and HW between OFF and 24HRS and feel/hear for the motorised valves operating.

You can remove the "tin boxes" and operate the valves by hand, that might clear the action if stuck

The signs of leakage on the HW valve could be a clue.

 

[Creakyride]

The pair of heating engineers that came to check it, both said they believe that the valves are working ok. One of them was listening to the valves, the other was switching the CH and HW on and off from the controller and also setting the thermostat to maximum to test the CH valve too.

They did not open the HW valve casing to check inside.

Because of that lime scale showing in the photo, they were reluctant to touch anything and basically said to leave everything as is because it could be a costly affairs and that the money could be better spent on a new system.

Until now, I have to only changed 1 pump since the boiler installation about 37years ago, it's been an extremely reliable boiler!
I hear from friends about
their new more efficient boilers that they had to repair them often, this has been the reason why I have not considered replacing it in the past.

I will have a look if I can open the valve cover an do a test to see if it shows signs of movement.
I will also try to open the controller and take a photo of the wiring and upload it here for opinions.

 

[Geoff1946]

That limescale looks to me like a long term leak from a badly made joint, rather than from the valve itself. Hardly cause to condemn the whole system and more like a, "don't really want to be bothered with this", diagnosis.
Don't be put off too easily. The valves complete are neither particularly expensive nor difficult to fit, and sometimes you can just replace the motor/head assembly which is by far the most unreliable part, without even draining the system.
A simple way to check valve functioning is to have the system cool and put your hand on the pipes to feel the temperature rise.

 

[michael8554]

That amount of limescale may mean that the horizontal run to the valve is blocked ?

 

[Sharpend]

Have to concur with Geoff here, start with basics. Have everything cold and turn on one at a time and follow pipes as they warm, see if pipe either side of each valve warms when it should.
If this doesn’t narrow down the problem (which it should) then you’ll have to remove each valve head (metal box), either a pinch together action on the sides or one/two screws holding it on.
Then at programmer operate heating and check for movement on the underside of valve head. Repeat for hot water.

Report findings back here.

 

[Andy™]

when its all off, move the manual overrides on the valves. you should feel some resistance as it opens, then allow it to close, youll feel it pushing your finger away towards the closed position. if either (most likely the HW) doesnt, its stuck open

on some designs, it may be possible to feel the motor resistance bu the actual valve is stuck, so not always a definitive answer

 

[Creakyride]

Thank you everyone for your help, it's really appreciated, unfortunately as I have a disability, I can't get inside the airing cupboard, which is located on top of the bannister, on the landing and it's too much of a stretch for me to trying removing the screws on the valve cover. Hopefully my back will get a bit better soon so that I can try your suggestions.

 

[poni]

removing the screws on the valve cover

I would not remove the cover ,just move the manual override leaver and you should feel it move the ball valve below ,it might come back on its own but you can lock it in the open position by lifting the leaver at the end of its stroke up or down into the notch at the end,

 

[Barx]

I don't see the point of messing with the valves at this point, If you get HW on it's own and HW + Heating, then it's pretty much 90% the valves are working, it's just that the programmer is setup for a gravity system. You either need to change the setting on existing programmer to pumped (if supprted) or fit a new programmer that does support it. All modern one's I've come across do as it is the de-facto now. Gravity systems are a thing of the past.

 

[Sharpend]

I don't see the point of messing with the valves at this point, If you get HW on it's own and HW + Heating, then it's pretty much 90% the valves are working, it's just that the programmer is setup for a gravity system. You either need to change the setting on existing programmer to pumped (if supprted) or fit a new programmer that does support it. All modern one's I've come across do as it is the de-facto now. Gravity systems are a thing of the past.

I think you’ll find this is a gravity fed system. ??