Motorised valve problems (& can they make droning noise?

[BobSpoons]

Hi
Please could somebody help with a bit of advice on my heating system and motorised valve. I would be extremely grateful of any help oradvice.
Our motorised valve seems to be faulty at the moment and our heating has also been making noise for some time so I am wondering if they could be the same issue (just getting worse) and I could fix both by replacing the whole motorised valve assembly.

The heating has not always been kicking in recently whereas the hot water has had no problems at all. Replaced the roomstat but it was not that. After tonight the heating not kicking in, I looked at the motorised valve and after pushing the manual lever, felt the valve move and then the heating kicked straight in. Makes me believe the vale is on its way out.

Our heating has been making a droning noise for a long time now. When its only on hot water, there is pretty much no noise. When its on heating and water, the noise is small but there. When its on just heating, the noise is much louder. It’s a kind of constant drone.
The system is fed from a standard boiler (not combi) which goes to the motorised valve and then to both cylinder and rads. It is a pressurised system and the pump is remote from the airing cupboard, back down with the boiler, the noise doesn’t sound to be coming from the pump to be honest. The noise sounds worst in the airing cupboard where the cylinder and motorised valve is but its difficult to pinpoint the origin. There’s also a small hole in the floor of the airing cupboard so it could even be coming from the first-floor void.
The valve is a 3-way danfoss motorised valve.
Our pipe work is mostly polypipe, not sure if that makes a difference. Do the polypipe joints maybe let in a little air that could cause the drone? The system doesn’t seem to loose much pressure over time, just needs topping up a bit once or maybe twice a year.
Id hate to have to raise floorboards to find the noise as we have laminate floor and skirtings fitted after. The skirtings would damage wallpaper and plaster in order to get to the floor and take up the boards so I’m so much hoping the noise isn’t coming from the floor void.

I do so hope that its possible that motorised valves can make noises like this and in this instance as it would be great to be able to replace the whole assembly and hope for both problems to be fixed.

Thank you very much to anybody who takes the time to read my huge post and also thank you so so much to anybody who is able to give me any advice or help with these problems.

Thank you

Alex

PS: How do I know if its a shoe or paddle design please?

 

[MANDATE]

By pushing the lever you opened the valve and by opening the valve it activated the microswitch and heating worked. The valve is not moving to the CH only position. Is this due to stiffness of the valve spindle. Is the motor at fault. The tension on the return spring increases as it moves towards CH only, so the motor has to overcome this tension and any stiffness.
Does the motor work at all. If you select HW only, power is removed from the motor and the return spring turns the motor backwards to the HW only positon.( although it might already be there) Now select HW and CH.
The fact you've brought CH into play, the motor should drive the valve from HW only to mid position and you should hear the motor turn.
If the actuator head can be removed you can check valve spindle for stiffness and observe the underside of the valve as you try various positions. If the spindle is easy to turn then why change the valve/body. It may just need new motor or a new actuator head.
I would resolve the motorised valve problem first, because it might resolve the drone also. If the drone is there when you're on HW only then it can't be coming from the motorised valve. I think I would be looking at the pump.
I'm no expert so sorry can't be more helpful. but you'll get other responses.

 

[ChrisR]

Certainly worth finding the pump.
Try a different speed, to see.

See danfoss website -
eg
HPA3 Paddle
HSA3 Shoe

 

[BobSpoons]

Thanks very much guys for the thoughts thats great.

As the drone "sounds" to be coming from the valve, I had wondered if it could be a problem with the outlet to the CH part of the actual valve. This way, if the problem was there, it would explain why the drone is absent when HW is chosen and also less when both are on (As less pressure may be being forced through that part of the valve assembly).

The pump is downstairs away from the airing cupboard and while you can still hear the noise down there, it is not as lound and you can get close to the pump and it doesnt sound to be coming from it.

Also, when the HW is on by itself, doesnt the pump still kick in to pump the heated water up to the cylinder to warm the water in there? If so, then if the pump was wearing out I would have thought it would also drone when HW is chosen or certainly when both HW&CH are chosen as this would be the biggest load on it.

I think it may well be the case that only the top motorised part of the valve that needs changing but the seperate issue of the noise MIGHT be coming from the CH outlet of the valve itself so I thought about just changing the whole assembly.

I had looked on the Danfoss site previously but the instructions for the paddle and shoe type seem to be identicle so I couldnt tell what the difference is between the two.



Anyways, thanks again for the advice

Does anybody know if it is possible that the droning noise may be coming from my polypipes or their joints? If its not possible then thats great as it removes the scary aspect of ripping the floor up

PS: I have bled the system on occasions to make sure air isnt in there and that did not seem to be a problem.

Many thanks

Alex

 

[BobSpoons]

Ive had a look at my pump again.
It doesnt sound to be making the noise to be honest but I dont know if the noise could be carrying down the pipes and being heard elsewhere.

The pump is on speed 3 out of a choice of 3. No idea if this is correct for my system so not sure if turning it down to 2 as a test is a good idea, dont know what the consequences could be. Any thoughts please?

Also it occurs that if the drone is coming from the valve (of motorised valve), then turning the pump down would ease pressure on the valve and so could result in less noise even if it is not actually the pump thats at fault.

Any further help at all please?

Many thanks again

Alex

 

[MANDATE]

You say the drone is absent when HW is chosen. Well in these circumstances the pump is still operating so it would rule that out. Regarding the actual valve positon, there is no difference between HW only and CH only, one side being blocked off and the other side fully open.
But coming back to the motorised valve. HW only means the motor is rolled back by the spring and there is no power to it from any other source so it is stopped and if the drone is also stopped then it must be related to the motor.
Two things to remember about the motor, CH can be in either of two modes HW with CH or CH only.
The motor moves in two stages, during first stage there is a dual voltage and when the mid point is reached it drops one of the voltages and leaves a lower voltage constantly applied. This is to prevent the motor rolling back, but it's not strong enough to drive the motor forward.
The next stage is if there is no HW called for or it has been satisfied there is a separate power supply and this takes over from those in the first stage. This drives motor forward to the end stop, but again the power is constantly applied.
Now I'm thinking this constant application of power is related to the drone and would explain why it's not there on HW only.
There is however a slight problem with this theory which is worth checking out. When CH only is selected and it is then switched off after a minute, that constant application of power is still there hold ing the valve against the stop. So if the drone was from the motor you would still hear it under these conditions.
Also there's no harm in turning pump speed down to try it. It just means water circulates slower.

 

[BobSpoons]

Thanks Mandate ill give those suggestions a try and see what I come up with.

If I switch the MV to CH only (constant motor power to fight against spring) and then switch it off after a minute, am I right in thinking that the controller will relay a message to the MV to say "were all switched off now" and so it will stop feeding power and the spring will return the vale to the default position of HW only. At the same time the rest of the heating system will also power down like pump and such. Hence the system should go quiet.

I will try turning the pump down tomorrow and see what affect that has too.

Thanks a lot for your time and suggestions I really appreciate it

Alex

 

[Gasguru]

Take the head off the valve body - you will then see the valve body type.

If its a shoe valve run the heating with the actuator off and set the spindle in the correct position (see the underside of the actuator for where it should be).

If ist a paddle type use pliers to hold the valve in the heating only position.

Then you can tell if its the actuator resonating or not. (Perhaps the switch contacts are high resistance and motor is not fully stalled at mid position)

 

[MANDATE]

Alex you're not quite right in your thinking. The HW switch in the programmer is like a two way switch, so it does not just break the circuit like a one way switch. It breaks one circuit but makes another.
This other circuit known as the HW OFF is the supply to the valves grey wire, this is the supply that takes over when HW is not required. Likewise the cylinder stat is like a two way switch, when HW is satisfied it drops the power supply to the boiler and diverts it to the same grey wire on the valve.
If everything is functioning correctly and you have CH only selected the valve will be in the CH position. Now if you switch if off at the programmer you have stopped the supply to the room stat which cuts off the supply to the boiler but the valve does not return to the default position because of the HW OFF supply.
This means if the valve is at CH only when it turns off, then it stays there until the next time it is used.

The thing to remember here is if HW only is selected then valve goes to HW position and stays there. Similar for CH only,
But if you selected HW and CH shared, this does not mean the valve moves to mid position and stays there. It shares it until one side is satisfied and moves the valve to give all the heat to the unsatisfied side.
I believe the HW gets satisfied sooner than CH.The CH is losing heat through the radiators a lot quicker than HW, which is stored in an insulated cylinder.
If you run off some hot water and it is replaced with cold it triggers the cylinder stat and brings the valve to mid position (depending on the state of CH). This brings the boiler into use and explains how you get CH along with HW but not on its own.

 

[BobSpoons]

Thank very much for all the help, explanations and advice youve all given.

Ive adjusted the speed of the pump and it seems to make little/no difference to the noise.

Ive also had to use the manual switch a couple of time now to get the CH-only to actually kick-in.

This morning as well, a new symptom. Put the controller on for HW-only and we got both HW and CH.... suggests maybe stuck valve or worn-out motor??

Anyway, the pump has an isolator valve either side so I can always replace that later without draining the system if the noise isnt solved by replacing the Motorized valve.
As for the motorized valve, seems it is definatly defunct in some form or other so I plan to replace the whole valve while im at it (Whole valve and head unit about £50 on screwfix).

Only one thing left now, how do I know whether it is a paddle or shoe type please????
Need to know in order to buy the correct on from screwfix?

Thanks again folks

Alex