Locking a MV permanently open? Any reason why not?

[RigidRaider]

Our heating has MVs on both the downstairs and the upstairs circuit, which the previous owner had separately controlled but we have rigged to one timer. I replaced the motor on the downstairs circuit a couple of years ago and now it's failed again; it refuses to stay open and I have to lock it open manually to get hot water to the rads.

How should this MV be controlled? By the boiler or the roomstat? I can't work it out.

We are having a new boiler in the spring along with some mods to the pipework so we will take the opportunity to get both all 3 MVs (cylinder also) replaced as they are 19 years old. Until then I don't want to be messing around replacing motors when I'm not even sure if it's the motor or the valve that's at fault. The lever keeps dropping off the step and closing, I don't know why. Is it okay to rig up some means of jamming the lever permanently open? The room stat will then take over control of the heating, right? Can this do any harm?

 

[gas_man_gaz]

putting the valve in the flush position should allow ya to get heat to the rads as long as ya other controls are calling for heat and wouldn't cause any harm until the mods have been done.
but it would prob be easier just to fix the fault.. iam quassing you've got 1 timer and 2 room stats?

 

[RigidRaider]

Ha ha, no, the bloke who built the house for himself was a tight wad and he had the upstairs MV controlled by a switch only! Both are now controlled by the same timer with a room stat in the hall.

Thanks for the advice anyway. Would it make sense next year to get the boiler pipework reconfigured so that both heating circuits are controlled by one common MV on the outlet? We will be moving the boiler anyway.

 

[gas_man_gaz]

so both valves run off the timer but only 1 is controlled by the room stat?

wen ya have the work done id have the heating controlled with 1 timer but with the 2 zones then controlled by 2 room stats. keep with the 3 valve design, just have them all located together in the airing cupboard (labelled). its a nightmare trying to repair the heating wen there zone valves and controls are dotted about all over, especially wen the customer doesn't know where they are
or ya could have 2 programmable room stats fitted

 

[RigidRaider]

No, as far as I know one timer and one stat controlling both.

But that's good advice, thanks; I like the idea of controllability and traceabilty. I'll discuss it with the plumber.