Three way motorised valve is squealing?

[Jimmyjammy]

Recently had to get a new pump for the system. But the problem is everytime the water is on for about an hour, there's a loud squealing noise. (pump set on 2 and then 1 and still does it)

Someone said it was the pump (not enough water going through it?) and someone else said it was the three way motorised valve. Something to do with the fact that when the tank filled up with hot water, it would try to switch off the hot water but was failing?

Does this make any sense? Does it mean I'd have to get a new valve? It's annoying as we can't have the heating on for long.

Would be grateful for any advice

Cheers Jimmy

 

[seco services]

no it don't make any sense about the motorised valve.
i would say more likely the pump.

 

[Beeches]

Hi there,
I'm not so sure it is not the motorised valve. There are a few variations on how these are wired up, but the valve is NOT an on/off valve. It either routes the flow to the left, or to the right, or both if the paddle is in the central position.
There is a simple test you can do. When the sqealing starts, go to the cylinder in the airing cupboard and turn the cylinder thermostat (Held in position by a fabric band around the cylinder, so it may be around the back) I guess it is set at about 60, but make a note before doing anything. Now turn this thermostat up to say 80 or so. The motorised valve will now move to "Full on hot water" which sounds as if it is your usual start position. The pump will still be running, so if the squealing stops then the sound is the clutch inside the valve motor box. The motor is struggling to get the paddle fully over and will remain powered until the paddle is fully over.These valves do get limescaled up and so do need periodic cleaning or renewing. DO NOT FORGET TO RESET THE THERMOSTAT BACK TO WHERE YOU STARTED. Too hot water will scold children. Before dismantling anything go to a merchant and have a look to see if "Fernox" additive can help you. Although not cheap, it is cheaper than a new valve usually. Let us know how you get on .
Beeches

 

[seco services]

The motorised valve will now move to "Full on hot water"

what is full on hot water ?
where will it be then if left on 60 degrees ?

 

[Beeches]

Sorry to confuse. Reading my comment again I could have been more clear. These 3 position diverter motorised valves have 3 positions which are electrically controlled by the actuator.(motor). Position 1 is Hot water only (Which I called Full on Hot Water) where the internal paddle is say fully to the left and hot water from the boiler and pump goes through the heating coil in the cylinder. When the hot water in the cylinder(not the coil) reaches the temperature asked for by the cylinder thermostat, it tells the motorised valve to move to position 3 Central Heating only. the motor then moves the paddle fully to the right. As hot water is used, the motor will move the paddle to a central position allowing boiler water to heat both cylinder and radiators.
This is an oversimplification and I shall now be swamped by heating engineers telling me I am wrong, but this is basically how it all works.
For the benefit of Jimmy, can I just say there is further tests he can do without getting into water, so don't panic, just ask. Some valves, Honeywell, I believe, have a lever under the actuator for manual operation. If you have this, watch which way it moves and help it out when you get sqealing.

Beeches

 

[seco services]

1, when the cylinder is satisfied the mot valve will only move to heating only if theirs a call for heating otherwise the valve will be held in its last position, by the grey wire. so their for the lever will be loose.

2, the lever will not tell you the position of the valve as such as this lever is only a means of getting heating when the motor has failed.
when their is a call for hw only their is no power on the valve at all, as the valve willbe in its relaxed position. port A shut port B open.

 

[Beeches]

Quite, but Jimmy is obviously attempting to run heating, and this I think is where the squealing occurs.

If the test I suggested above is inconclusive, then when the sqealing is happening Jimmy could take the actuator off the valve. As you know there are only 2 small screws. If the squealing stops, the problem is with the valve or actuator. He could then switch everything off and try turning the valve shaft with a spanner( not the actuator) through it's full movement from left to right and pressing quite hard at each end of the permitted arc of movement. Don't break it!!!, this may give a little more movement available to the motor and solve the problem. When removing the actuator note the position of the shaft and put the shaft in the same position when replacing the actuator.
Must get on with some work now.
I await Jimmy's comments with interest.

Beeches.

 

[Jimmyjammy]

Hi all, Thanks for the advice breeches and seco services. It's true the screeches tends to happen when the heating is on. (or when they are both on after 1-2 hours)

I think the theory about the lime scale holds water (pardon the pun) There is a big limescale problem. Going to check the valve and see if it can be cleaned otherwise might have to replace it.

I'll let you know the results.

Cheers Jimmy

 

[Beeches]

Hi Jimmy,
Before buying a new valve, just undo the 2 actuator screws and remove them. If the acuator rotates a little and the screeching stops, then the problem is with the valve. Do as I say above and rotate the valve shaft with a spanner, right through it's total movement. It may free up enough distance to solve the problem.
I did recommend a product to help you, but it was taken out by the censor, so without naming names, go to a plumbers merchant and ask for an additive to flush out and treat the water in your system.
One final trick which I learnt many years ago. If you are still not quite sure where this noise is coming from, get hold of a metal rod such as a knitting needle or meat skewer. Place one end of the rod on the motorised valve (Keep away from electrics) and put the other end of the rod between your teeth. Now put your fingers in your ears. Any noise from the valve or pump will be amplified and you can immediately locate the scource of the noise. If anybody else tries this, let me know here how you got on.
Beeches.