Hot water not working

[666]

Although it works when my CH is operating, my hot water cylinder does not heat when my CH boiler is set to Hot Water alone.

The pump runs when set to 'CH', as does one of the motorised valves that controls the CH and HW, and I wonder if the problem is the other motorised valve that controls the flow to the HW cylinder as the motorised lever does not move automatically when the system is set to 'HW' alone.

If there is a problem in the motorised valve, can/does this affect the correct operation of the system?

 

[D_Hailsham]

You mention two motorized valves.

Are they both like this:

View media item 11762
or is one like this:

View media item 5946
Can you post a pic of your hot water cylinder?

 

[666]

Hi, the two valves are like the one in the top image. I'll take an image when my wife returns with her camera but, in the meantime, I hope that you can follow this description:

The 28mm feed from the boiler runs into the pump. Then after about 6 inces the pipe has a 28mm 'T' one branch leading to the house CH via a 28mm motorised valve, then a 28mm pipe, and the other to the HW cylinder reduced to a 22 mm pipe before it reaches the 22 mm motorised valve, following which it enters the HW cylinder about a third of the way up from the bottom of the cylinder, before it exits and runs into the 'return' about 4" from the bottom of the cylinder.

I have just checked again and have noticed that one of the blue wires from the boiler control appears to have broken and wonder if this could be/has caused the problem?

I'll check to see if it is 'live' now.

 

[D_Hailsham]

I have just checked again and have noticed that one of the blue wires from the boiler control appears to have broken and wonder if this could be/has caused the problem?

I'll check to see if it is 'live' now.

Your description will do, so there's no need for the pic.

Blue wires usually mean they are the Neutral, so shouldn't be live. Can you identify what the cable it is part of is connected to?

 

[666]

Thanks for that. I never like messing with electricity.

Yes, there are two cables which come through the wall - I assume running from the timer/controller, each of which contains 6 coloured single wires that then run into a connector block from which they are connected to the two motorised valves. If the disconnected/broken wire comes from the HW section of the control unit and I reconnect it then it should work - hopefully.

Is my logic correct?

 

[D_Hailsham]

Yes, there are two cables which come through the wall - I assume running from the timer/controller, each of which contains 6 coloured single wires that then run into a connector block from which they are connected to the two motorised valves. If the disconnected/broken wire comes from the HW section of the control unit and I reconnect it then it should work - hopefully.

You haven't mentioned any thermostats. Do you have a room thermostat and is there one on the side of the HW cylinder (see pic)?

View media item 10596
The normal wiring is that the programmer supplies the thermostat, which then supplies the motorized valve. So, if there is a call for heat, the thermostat closes, supplying voltage to the valve motor, which then opens. The switch inside the valve connects grey wire to orange, putting 240V onto the boiler, which then lights.

Can you see anything where the blue wire might have been connected? e.g a terminal block with only one wire going into a pair and nothing coming out?

 

[666]

Thanks again.

Yes, that's the cylinder stat.

What I think I'd better do is to wait until my wife gets back from 'The Sound of Music' in Leeds with her camera and then take an image of the wiring and upload it; but after I've had my tea, I'll check to see what's connected to what so that I can provide more-meaningful information tomorrow.

Thanks again.

 

[666]

View media item 35160
Rather a jumble of wires.

The two black cables run to the valves whilst the white cables run to the pump and the cylinder stat. Sod's Law stuck again and the camera's battery expired after taking this image!

 

[D_Hailsham]

Do you have a multimeter (and know how to use it )?

If so do the following:

Turn CH OFF and HW OFF at the timer; turn the cylinder stat to min

There is a lever on the side of the HW valve in a slot marked Auto-Man. It should be at the Auto end.

Move it to the Man end. You should feel some resistance as the valve opens against a spring. Let go and the lever should move back with a whirring sound.

If the lever offer no resistance, the valve is stuck open.

If the valve is not stuck

Turn HW ON at timer

Measure the voltage between brown and blue of the HW valve. Should be 0Vac. If it is 240Vac the cylinder stat is wired incorrectly.

Turn cylinder stat to max

Measure the voltage between brown and blue of the HW valve. Should be 240Vac.

You should hear the valve motor run and the lever should go floppy as the valve opens

If it doesn't - the motor is faulty.

If it isn't 240Vac, the valve motor isn't being fed by the cylinder stat. So you need to check the voltage on both sides of the cylinder stat.

If there is 240Vac one side of the stat but not the other, the stat is faulty.

But if no voltage either side of the stat then check voltage at the HW ON terminal of the programmer. If 240Vac then faulty wire to stat; if no 240Vac then faulty timer.

If you get 240Vac on the HW valve brown wire, check the voltage between valve orange and blue and between valve grey and blue. It should be 240Vac in both cases. If only one reads 240Vac, you have a faulty microswitch in the valve actuator (the metal box).

In most cases you can buy replacement actuators and swap them yourself.

 

[666]

Thanks Gaian.

I did that before I came to the forum and there was/is little, if no, resistance so it looks like I need to buy the motorised piece as opposed to the full valve as I did before.

Do you think that the loose wire is anything to worry about - apart from putting a connector on it?

 

[D_Hailsham]

Thanks Gaian

Who's he?

I did that before I came to the forum and there was/is little, if no, resistance so it looks like I need to buy the motorised piece as opposed to the full valve as I did before.

You ran through all the tests before posting??

No resistance could mean the valve is stuck open.

Do you think that the loose wire is anything to worry about - apart from putting a connector on it?

Have you identified what the other end of the wire connects to?
Have you found anything that the loose wire could have come detached from?

 

[666]

Sorry, 'Giain' is actually 'again' - my dyslexic fingers!

I will do and see what happens.

Thanks