Hi Guys and girls. I am having a problem with my Danesmoor 20/25 oil fired boiler where by it doesn't respond when I turn the central heating on. It works fine with the hot water and I can get heat into the radiators if I manually move the 3 way valve switch over to the manual position but this is only effective while the boiler is heating the water tank. Once it is hot the boiler shuts off and the radiators get cold. I have downloaded the installation manual for the boiler and checked the wiring to the thermostat for the tank and room and all seems to be connected properly and the stats operate fine. I am getting a switched live feed when I press the timmer advance buttons for each circuit. I contacted Worcester today who were very helpful but they have quoted a figure of £260 for repair/call out. In my head I can't help feeling it is something simple hence me being reluctant to pay £260 without proper investigation first. If it helps, I am not sure if it has ever worked correctly as we just bought the place and the house including wring has had an attack of bodgery to it. Any advice would be greatly appreciated.
Worcester Danesmoor 20/25 boiler problems
- Thread starter Stevie1963
- Start date
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You need to follow that switched live for heating to the next stage which would normally be the Room Thermostat. If the live feed in and out of the Thermostat is there, the next place will be the 3 way valve. So at this stage suspect either the thermostat is not working or there is a fault with the 3 way valve
I would add that having the parts correctly wired does not mean they are operating properly. If the Room Thermostat does pass the switched live on then the 3 way valve should respond to it.
for information, what is make and model of the 3 way valve.
Detailed explanation of a Mid Position Valve operation is in the link added Mid Position Valve
I would add that having the parts correctly wired does not mean they are operating properly. If the Room Thermostat does pass the switched live on then the 3 way valve should respond to it.
for information, what is make and model of the 3 way valve.
Detailed explanation of a Mid Position Valve operation is in the link added Mid Position Valve
Hi there, Thanks for coming back to me so quickly. The 3 way valve is a Honeywell V4073A. I suspected that wasn't working correctly when I moved in so I replaced it straight away with a new one but that didn't make any difference.
Your problem is related to the 3port valve.
There are a few things that go wrong
Working backwards there is no power coming from the valves orange wire to light the boiler.
It's because a micro switch has dirty/burnt contacts or it's not being triggered.
If its not being triggered its because the valve has not moved from mid position forward to trigger it.
If it's not moved forward from mid position the motor is not receiving the power.
This could be due to dirty/burnt contacts in a different micro switch.
Or it could be there is no power being fed to the valves grey wire which is where the motor gets it's power from for the second half of the range.
You're getting CH when both are on together, this proves the room stat is OK and the motor is OK and one set of contacts is OK, otherwise the valve would not go to mid position
A lot depends on whether or not the grey wire is live when it should be.
When both CH and HW are on and the HW becomes satisfied the cylinder stat diverts it power to the grey, using a wire from cylinder stat satisfied terminal to join the grey in the ten terminal box. Making the grey live will result in the valve moving forward.
Of course if HW was not selected, the cylinder stat would have no power and the grey could not be made live by that method.
So if this is the case use is made of the programmers HW OFF terminal (this terminal being live whe the HW ON terminal is dead)
So your problem falls into either incorrect wiring or correct wiring but faulty valve.
You can carry out a couple of tests.
look at the ten terminal box and see whats connected to the grey wire and test voltage on grey when CH and HW are both off.
You can also remove the actuator head off the spindle and check spindle for stiffness.
Now turn the head bottom side up and observe the D shape hole.
When you now put HW on the valve will either not move because its in the HW position or if in any other position it will unwind to HW position.
If you now add ch the valve will move to mid position (take note of the D shaped hole)
Now here comes the important one. Turn HW off.
The valve should move forward. If it does then second micro switch faulty.
If it does not then first micro switch faulty or no power into the grey wire.
You can try CH only from the start. Power on white drives valve to mid position. power on white is dropped by micro switch at mid point and power on grey is picked up to drive valve forward. Is it doing this or not.
There are a few things that go wrong
Working backwards there is no power coming from the valves orange wire to light the boiler.
It's because a micro switch has dirty/burnt contacts or it's not being triggered.
If its not being triggered its because the valve has not moved from mid position forward to trigger it.
If it's not moved forward from mid position the motor is not receiving the power.
This could be due to dirty/burnt contacts in a different micro switch.
Or it could be there is no power being fed to the valves grey wire which is where the motor gets it's power from for the second half of the range.
You're getting CH when both are on together, this proves the room stat is OK and the motor is OK and one set of contacts is OK, otherwise the valve would not go to mid position
A lot depends on whether or not the grey wire is live when it should be.
When both CH and HW are on and the HW becomes satisfied the cylinder stat diverts it power to the grey, using a wire from cylinder stat satisfied terminal to join the grey in the ten terminal box. Making the grey live will result in the valve moving forward.
Of course if HW was not selected, the cylinder stat would have no power and the grey could not be made live by that method.
So if this is the case use is made of the programmers HW OFF terminal (this terminal being live whe the HW ON terminal is dead)
So your problem falls into either incorrect wiring or correct wiring but faulty valve.
You can carry out a couple of tests.
look at the ten terminal box and see whats connected to the grey wire and test voltage on grey when CH and HW are both off.
You can also remove the actuator head off the spindle and check spindle for stiffness.
Now turn the head bottom side up and observe the D shape hole.
When you now put HW on the valve will either not move because its in the HW position or if in any other position it will unwind to HW position.
If you now add ch the valve will move to mid position (take note of the D shaped hole)
Now here comes the important one. Turn HW off.
The valve should move forward. If it does then second micro switch faulty.
If it does not then first micro switch faulty or no power into the grey wire.
You can try CH only from the start. Power on white drives valve to mid position. power on white is dropped by micro switch at mid point and power on grey is picked up to drive valve forward. Is it doing this or not.
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While it may not be often a valve is faulty from new check again and make sure the "CH on" live from the programmer is being passed down the line through the thermostat to the white wire on the mid position valve. It is the white wire that when live should drive the valve open.
If the white is live but the valve is still not working check you have correctly connected the neutral from the mains all the way to the motorised valve.
With a good live and neutral to the valve motor (white and blue on the valve lead) is should operate and when open will make the orange live to fire up the boiler (Please note the orange will also be live if the Hot water is on so make sure it is off when testing)
For your information, if the old one was wired up incorrectly and you just did the same it will still be wrong!
Please post back your findings or call in an electrician.
If the white is live but the valve is still not working check you have correctly connected the neutral from the mains all the way to the motorised valve.
With a good live and neutral to the valve motor (white and blue on the valve lead) is should operate and when open will make the orange live to fire up the boiler (Please note the orange will also be live if the Hot water is on so make sure it is off when testing)
For your information, if the old one was wired up incorrectly and you just did the same it will still be wrong!
Please post back your findings or call in an electrician.
Wow, thanks to you both Blagard and Mandate. I will run the tests you have suggested tomorrow and let you know my findings.
We're sat in front of our log burner so at least we're not freezing, just the rest of the house is currently a bit chilly
We're sat in front of our log burner so at least we're not freezing, just the rest of the house is currently a bit chilly
The fact it's already moving to mid position tells me there is no problem with CH ON terminal or the room stat or the white wire or the motor or the neutral (blue).
So it's got to be related to the 'grey' of the valve, if its not moving forward either no power on grey, or power on grey but failed micro switch No 1 (2nd set of contacts).
Or if it moves fully across, then contacts on micro switch No 2 (2nd set of contacts)
So it's got to be related to the 'grey' of the valve, if its not moving forward either no power on grey, or power on grey but failed micro switch No 1 (2nd set of contacts).
Or if it moves fully across, then contacts on micro switch No 2 (2nd set of contacts)
Sorry but I don't agree - It is doing Hot water only i.e. valve with CH closed and ball full to one side. He wants it mid position to get CH with HW and can only do that manually to the venting position. If he wants CH and no HW the valve is fully driven over. Presently the motor is not driving an inch!
You're right to disagree, I did not realize it was being moved to mid position manually. In which case, all concentration on the 'white' wire as you say.
I must read the detail in future! I should never have gone on the 'rapid reading course'
I must read the detail in future! I should never have gone on the 'rapid reading course'
But you have reminded me to tell the Poster to release from the manual venting position when testing!
thanks again Guys. I will ensure the lever is released before testing tomorrow.
I will report my findings.
I will report my findings.
Good morning Gentlemen. I have checked the wiring as you mentioned and here are the results.
The grey wire is permanently live - With the hot water thermostat turned down to low so it is off and the central heating turned on with the timer advance button and the room stat turned to on the white wire becomes live but there is no movement from the 3 way valve motor. I then removed the cover from the 3-way valve motor and spotted the 2 micro switches. I pressed the lower one in by hand and the boiler burst into life !!
Do I assume from this that the servo motor on the valve is faulty ? I have checked the neutral and earth connections and they look good plus I have tested them with a multi meter from a known good permanent live and received a displayed voltage of 249 volts so I am assuming there is no poor connections or loose terminals. Is there anyway I can power the servo motor directly to confirm this is the problem ?
I really do appreciate your help, patience and advice with this as I couldn't have got this far with the diagnosis without your assistance
The grey wire is permanently live - With the hot water thermostat turned down to low so it is off and the central heating turned on with the timer advance button and the room stat turned to on the white wire becomes live but there is no movement from the 3 way valve motor. I then removed the cover from the 3-way valve motor and spotted the 2 micro switches. I pressed the lower one in by hand and the boiler burst into life !!
Do I assume from this that the servo motor on the valve is faulty ? I have checked the neutral and earth connections and they look good plus I have tested them with a multi meter from a known good permanent live and received a displayed voltage of 249 volts so I am assuming there is no poor connections or loose terminals. Is there anyway I can power the servo motor directly to confirm this is the problem ?
I really do appreciate your help, patience and advice with this as I couldn't have got this far with the diagnosis without your assistance
when you removed the cover did you test the voltage at the motor.
(remember between the ingoing white wire and the motor is a set of contacts)
If you did and it read 240v and you have already proved the neutral, then it is just the same as applying power directly from a different source.
Also the most likely problem stopping the valve moving forward from mid position,knowing the grey is live is a dead motor.
Also when heat is turned off at night, the programmer stops power to room stat, this cuts power from orange and boiler stops, BUT the grey stays live and motor stays energised with valve at CH position, so the motor does a fair amount of work.
A new motor is about £20 a new head I would think about £45.
Remember with CH off and HW off the grey wire is live so don't think all the electics in the head are dead. If you're going to poke anything in there don't use fingers or metal
(remember between the ingoing white wire and the motor is a set of contacts)
If you did and it read 240v and you have already proved the neutral, then it is just the same as applying power directly from a different source.
Also the most likely problem stopping the valve moving forward from mid position,knowing the grey is live is a dead motor.
Also when heat is turned off at night, the programmer stops power to room stat, this cuts power from orange and boiler stops, BUT the grey stays live and motor stays energised with valve at CH position, so the motor does a fair amount of work.
A new motor is about £20 a new head I would think about £45.
Remember with CH off and HW off the grey wire is live so don't think all the electics in the head are dead. If you're going to poke anything in there don't use fingers or metal
I agree (slightly awkward grammar in there, but I know what you meant)
Motors are a fairly common failure so if it were me I would try replacing that first. If you have to do the head, believe me there will probably be a time when that motor is needed!
All these motorised valves work on the principle of the motors stalling at certain positions. If you test it out of the head you may find it will run, but it will stall too easily and that is the fault. As the link I posted explains. Stall the motor on a vacuum cleaner and it will issue blue smoke and die! These motors are designed to take it!
(slightly awkward grammar in there, but I know what you meant)Motors are a fairly common failure so if it were me I would try replacing that first. If you have to do the head, believe me there will probably be a time when that motor is needed!
All these motorised valves work on the principle of the motors stalling at certain positions. If you test it out of the head you may find it will run, but it will stall too easily and that is the fault. As the link I posted explains. Stall the motor on a vacuum cleaner and it will issue blue smoke and die! These motors are designed to take it!
Thanks again Guys. It does all seem to point to the motor as there is power getting to it.
I poked around inside the switch with a neon screwdriver as it is insulated and I would at least get a warning if I touched something live but thanks for the warning, much appreciated
My last question is, I see loads of replacement heads and motors on the internet that aren't Honeywell but generic replacements. Am I better off sticking to Honeywell replacement parts or are the cheaper ones, such as Tower etc just as good ?
I poked around inside the switch with a neon screwdriver as it is insulated and I would at least get a warning if I touched something live but thanks for the warning, much appreciated
My last question is, I see loads of replacement heads and motors on the internet that aren't Honeywell but generic replacements. Am I better off sticking to Honeywell replacement parts or are the cheaper ones, such as Tower etc just as good ?
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