Help and Advise to diagnoise faulty central heating

[SteveyJ]

Hi All, I'm new to this forum and have registered as there seems to be a lot of knowledge, and so hopefully someone can help with a problem I have.

I have a gravity fed water system, which is currently running the central heating permanently, not running so it kicks the boiler or pump in but continuously as if the valve is letting by and so water running through the rads, even when the controller on central heating is switched to off.

So what I have is a threeport valve, and have tested the electrics and the central heating side all seems to be operating ok, when the thermostat and controller call for heat the white wire on the motorised valve becomes live along with the orange wire. On the hot water side, the grey wire is permanently live, even with all the controller set to off, and the orange wire becomes live when you tell the hot water to come on, but the grey stays at 240v all the time? Is this correct? I wondered if it was getting a back feed through the cylinder stat, so replaced this and has the same problem. Its not wired back to front either, (number 2 is wired to grey wire and common is to live to controller) I then replaced the motorised valve head for a new honeywell one and still has the same problem.

When I took off the valve body the spring seemed to operate correctly, i.e. when you pull the lever towards you it returns slowly to 'the middle' via the spring, but when it is on the brass body (and even when the brand new one gets put on) the lever is all the way to one side and is very very loose, sometimes it returns slightly to the middle but has small bit of resistance to feel the sprin g when pulled all the way to the end.

So have I done something wrong, is there something I have missed, or is it the actually valve body and something is stuck, or is it the programmer? Either of which can I test somehow?

Hope it all makes sense, and sorry if alot is ramberling, its hard to explain what I mean in words.

Thanks Steve

 

[Simon F]

Welcome along.

Wiring Diagrams - Honeywell UK Heating Controls

have a look at the y plan wiring diagrams.
the controller will give a live to the grey when hw is off.
a three port will stay in the last position, it doesn't work like a 2 port.

so is the boiler firing constantly or just the pump running continuously?

 

[doitmyself]

I wondered if it was getting a back feed through the cylinder stat, so replaced this and has the same problem.

I then replaced the motorised valve head for a new honeywell one and still has the same problem.

First Rule: Never throw parts at the problem in the hope that, eventually, you will solve it.

When I took off the valve body the spring seemed to operate correctly, i.e. when you pull the lever towards you it returns slowly to 'the middle' via the spring, but when it is on the brass body (and even when the brand new one gets put on) the lever is all the way to one side and is very very loose, sometimes it returns slightly to the middle but has small bit of resistance to feel the spring when pulled all the way to the end.

When you say valve body I assume you mean the actuator, i.e the metal box on top of the brass body.

With actuator in place on the valve body:

1. Turn the power off (setting programmer to CH OFF and HW OFF is not enough.)
2. Move the lever from Auto to Man
You should feel resistance
3. Release lever
It should return to the Auto position

If the lever does not have any resistance

4. Remove actuator
5. Rotate the valve spindle (will only turn 10-20 degrees)
It should turn easily with the fingers

6. If the spindle is at all stiff, lubricate it with a little silicon lubricant.

If that doesn't work, you will have to replace the valve. (If you have a Honeywell, you can buy a repair kit.)

 

[SteveyJ]

Welcome along.

have a look at the y plan wiring diagrams.
the controller will give a live to the grey when hw is off.
a three port will stay in the last position, it doesn't work like a 2 port.

so is the boiler firing constantly or just the pump running continuously?

Thanks Simon!
Thats really helpful, OK so Grey is meant to be live, as its holding the Hot water off.

The boiler and pump are not running unless the timer and thermostats are meant to be on then it all fires up.=, and thats working correctly. Its as if the valve isn't shutting off and letting water through to the heating port when the water has been heated up in the morning/evening for use in cylinder. I don't know if this is possible??

 

[SteveyJ]

First Rule: Never throw parts at the problem in the hope that, eventually, you will solve it.


When you say valve body I assume you mean the actuator, i.e the metal box on top of the brass body.

With actuator in place on the valve body:

1. Turn the power off (setting programmer to CH OFF and HW OFF is not enough.)
2. Move the lever from Auto to Man
You should feel resistance
3. Release lever
It should return to the Auto position

If the lever does not have any resistance

4. Remove actuator
5. Rotate the valve spindle (will only turn 10-20 degrees)
It should turn easily with the fingers

6. If the spindle is at all stiff, lubricate it with a little silicon lubricant.

If that doesn't work, you will have to replace the valve. (If you have a Honeywell, you can buy a repair kit.)

Hi thanks for the step by step operation, when I wrote valve body, your right I mean actuator (complete metal box). The spindle did not move, I couldn't turn it with fingers, and when the actuator was on the valve the lever went from manual to auto easily without any resistance and did not return to any normal position. So will try some silicone lubricant on the spindle but I guess its stiff, should it be facing any particular way/direction before the actuator goes on?

I understand you about throwing parts at it, but I am a tiler by trade and spoke to a plumber I know who I tile bathrooms for and he advised me it was the actuator and then the stat, and then when that didn't fix it he told me he hates 3 port valves and doesn't really get involved with diagnosing and maintenance on them as a pain in back side as its hard to work out where the problem is coming from????? and so best speaking to an electrician?? But considering so many vans I see with plumbers being Gas Safe and NIC registerd I thought I would put a post on here as there are probably much better and knowledgeable plumbers on here who could help!! 🙂

 

[doitmyself]

doesn't really get involved with diagnosing and maintenance on them as a pain in back side as its hard to work out where the problem is coming from

No problem if you know what you are doing and go about the task in a logical order.