CH/HW motorised valve replacement

ThisIsWeird

TMSG said:

The valve itself seems perfectly ok, no rust, no dirt and it can be moved relatively easily (though as you said only a small way). When there's no water flowing there are no sounds at all but when the water flows, it makes pretty diabolical THUNK, with the pipework visibly shaking for sec or two.

I left the MA1 off the valve, the argument being that if it's not connected to the valve it has no real work to do, if you know what I mean. The thing goes reliably from HW to CH and when it's on CH on only and HW is switched on, it goes to mid pos (as it should). However, if we then switch off CH but leave HW on, it should go to HW (I think) and it does... sometimes. At other times it just remains stuck on mid pos. So... I think it's perhaps not totally broken but not reliable either. What's your (or others) take?

Also, there's something loose inside the actuator, a rattling noise if the things is moved or shaken.

EDIT: And a further Q... if I wanted to replace just the actuator itself (not the valve), is it then a question of a 22/28mm version? It seems the actuator is the same anyway but not at all sure./EDIT

"it can be moved relatively easily". Smoothly over its whole arc? And a nice firm thunk at each end? Cool - it's likely fine.

"it makes pretty diabolical THUNK, with the pipework visibly shaking for sec or two." yes, because without the 'head' on it, it's 'loose' and the water flow can push it around - tsk tsk. :-)

"So... I think it's perhaps not totally broken but not reliable either." That's the most likely conclusion.

I suspect the same actuator is used for both sizes - almost certainly. Should be easy enough to Google, or email Dayton.

There remains a possibility that it's a fault with the programmer - ie it isn't sending out a clear signal due to burnt relay contacts and stuff like that, but if you wish to attempt a DIY repair, then I'd personally go 'new actuator' first. There is no 'wiring' with these models, so if you buy new and find it isn't the issue, you can rebox it and sell it on for virtually the same price.

TMSG

Thank you very much, that really helps.

The last time this was replaced (time flies, was more 2 years than 1, I checked) was done by our plumber when we had other things done with the heating, but I assume I can simply connect the same coloured wires to the same points on the board, one after the other (and also take one or two photos beforehand anyway, just in case).

Again thanks!

ThisIsWeird

TMSG said:

Thank you very much, that really helps.

The last time this was replaced (time flies, was more 2 years than 1, I checked) was done by our plumber when we had other things done with the heating, but I assume I can simply connect the same coloured wires to the same points on the board, one after the other (and also take one or two photos beforehand anyway, just in case).

Again thanks!

Ah, I thought the MA1 was the model with the plug-in cable? No? Rats.

Ok, the secret to swapping them is to TURN THE POWER OFF - and then go to the wiring centre where the cable goes. Take some clear photos. 

Then, snip each of the 5 wires an inch from their terminals in that centre, so you leave a bit of each wire with the coloured insulation still on it.

Then swap them with the new, one at a time :-)