Motorised valve wll not shut off - possible programmer fault

[GNorcliffe]

We have had a brand new Honeywell 3-way motorised valve fitted, controlled by a Landis & Gyr RWBXP programmer. It is an open system, with header tank.

The boiler is an Ideal Classic FF230, which was serviced in 2013 and given a clean bill of health.

If we use the CH option (manual or via timer) the motorised valve is still switched on and warm to the touch.

The only way we can get the valve to shut off is turn off the power to the central heating boiler/motorised valve/pump. The motorised valve cools down until the next time it is turned on.

The plumber/electrician who fitted it do not know what is wrong. Our only thought is the RWB programmer is not sending the off signal to the motorised valve, so should we go ahead and replace the programmer with a direct replacement RWB29 unit.

 

[D_Hailsham]

The new valve works fine on HW only, CH only and HW+CH, but does not shut off when the programmed time ends, or when we turn on the system via the programmer.

The only way we can get the valve to shut off is turn off the power to the central heating boiler/motorised valve/pump. The motorised valve cools down until the next time it is turned on.

Does this only occur after CH only has been on?

 

[GNorcliffe]

We get the problem on CH and HW when using the programmer. It also happens if we manually boost the CH during the day and in an evening.

We have to turn off/on the power to the whole heating system to get the motorised valve to reset itself.

 

[D_Hailsham]

We get the problem on CH and HW when using the programmer. It also happens if we manually boost the CH during the day and in an evening.

We have to turn off/on the power to the whole heating system to get the motorised valve to reset itself.

This does sound like normal behaviour for a mid-position valve.

If CH is the last to turn off, the valve will stay held in the CH only position until either (a)HW is called, or (b) the power to the whole system is turned off. The metal cover will feel hot as the valve motor continues to run when CH is last to turn off.

You have found that it stops when the power is turned off. The same thing will happen if you call for HW - the valve will return to the rest position and the motor will cool down.

There's nothing to worry about. It's a 'feature' of the mid-position valve.

 

[oldcardriver]

I don't claim to be a plumber, just a jack of all trades and I fitted a Drayton 3-way motorised valve and it works in all situations.

Admittedly, I had previously fitted a new Drayton programmer because I though that was at fault as it was interfering with the radio in the kitchen.

Both the originals were Drayton and I just replaced like with like, consequently, I wonder if your valve and programmer are compatible.

 

[GNorcliffe]

We have been wondering if the programmer has failed, so we have decided this afternoon (9/10/14 15:30) to order a Landers + Glyn RWB XP with a Siemens RWB29 (multi-settings) unit once we had managed to get the old unit off the wall and back on successfully!

When the new programmer arrives and has been fitted, I will update the thread.

 

[Hugh Jaleak]

I have set my system so the HW remains on for half hour or so after the heating is timed to switch off. Theory is this gives the valve some chance of returning to the rest (HW) position during the day/overnight as long as HW is called for before the system goes off completely.

Whilst the valves are designed to be held open to CH under certain circumstances, a voltage is being applied to the motor to do this. To my mind that's a waste, (albeit a small amount per valve, but a lot over every valve in the country!), and also could lead to a possible fire hazard and/or premature failure of the valve components. If valve can be allowed to return to HW only (rest) position this issue should be negated. (I hope!)

 

[stardanny]

It happened on mine, Danfoss HS3 mid position valve. All I have to do is disconnect the wire from hot water off terminal on programmer and make safe.

Of course it mean you can't have heating only but I set my programmer for heating to come on with hot water as well so it will heat hot water to top up and heating as well. Heating can still come on regardless of hot water calling for heat or satisfied as long hot water is on at programmer. Valve will turn to rest when both heating and hot water is off or on timed.

Daniel.

 

[GNorcliffe]

Thank you to everyone who has responded to my post.

We have a work around, that we are currently using as follows:

When the CH has been run, either by the programmer, or manual boost, we turn on the HW for 1minute, which resets the motorised valve.

This has been suggested in various posts. It looks like we are going to have to set the programmer times to ensure HW is run after CH, to turn of the motorised valve.

 

[D_Hailsham]

We have a work around

Is it really worth the effort???

The motor is 6 Watts.

If it was left running for 24 hours a day for all the year it would consume:

6 x 24 x365 = 52.56kWh. At 5p per kWh that would be £2.63 per annum or 0.72p per day!!!

 

[oldcardriver]

We have a work around

Is it really worth the effort???

The motor is 6 Watts.

If it was left running for 24 hours a day for all the year it would consume:

6 x 24 x365 = 52.56kWh. At 5p per kWh that would be £2.63 per annum or 0.72p per day!!!

Maybe, but the life of the pump will probably be reduced.