3WAY VALVE PROBLEM

[piechipscurry]

Hello all - 1st post for me here goes

We have a Rayburn oven driven open CH system over 3 storeys.
For a couple of years the top 4 rads have been stone cold for ages then all of a sudden hot. Once the bottom 2 storeys rads had been on for say 1 hr, they suddenly went hot.
All this week they havent come on at all.
After searching the internet for a likely culpritvI started looking for a motor valve & found one.
Moved the lever down under its' 'hook' then HEY PRESTO all rads in the house working.
Could anyone suggest why its packed up and what is its' purpose.
PS its a 3 way.
Many thanks

 

[Hugh Jaleak]

These pack up for a past time, motor worn out is often the cause. 3 way valves control the flow of hot water from the boiler to either or both outlets, usually one port for central heating, the other the hot water cylinder.

Known as a 'Sundial Y plan' system, the roomstat and cylinder stat open valve to required port when call for heat is required, valve opens, operating a microswitch which then energises boiler and pump.

It may be that your property is 'zoned', the 3 way valve allowing different room temperatures on different floors.

 

[matt1e]

It may be that your property is 'zoned', the 3 way valve allowing different room temperatures on different floors.

or it may be that its a diverter valve just doing the one zone

Matt

 

[Hugh Jaleak]

Been a long day...

 

[piechipscurry]

Thanks for the replies - Yep I didnt realize there were so many parts to a heating system.
I managed to identify the valve in question is a honeywell v4073a.
I found a coloured drawing presumably by the installer with what teminals to test when the heating / HW is calling etc. Ive checked with a multimeter and everything tallies when I call for CH voltages on Grey & brown so I'm 99% sure the fault lies with the valve.
The manual lever Ive been moving about the last couple of days is now solid in the B position (closed I think) and I cant budge the motor at all.
The slider is free for the 1st third then it is solid and wont move further. The lever is bending.
Am i correct in thinking the spindle is seized somewhere?
Am i best changing the syncro motor or actuator or even draining and changing the whole lot?
Thanks again Jon

 

[piechipscurry]

Just forgot to include some more info. from reading about typical 'Y' setups it seems like ours is pretty non standard in that only the bedroom rads are fed by the valve (A) which also flows (B) to the HW cyl.
Also I have no programmer to control the HW on its' own. I guess just the boiler stat does the calling for HW.
The programmer Landis Staefa RWB9 does have a hot water timing facility but this has been wired to switch the oven burner on /off. Rayburn dual burner.
Cheers