Heating works but no hot water: any suggestions?

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Sarrusophone

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Hi all,

We have an old-ish open vented system from the late 1990s.

The hot water has stopped working but not the central heating.

Tracing the hot pipes, I notice that after the 3-way-valve the pipe into the cylinder gets notably cooler. It is reasonably hot just past they motorised valve but soon becomes cool. The return pipe to the boiler from the bottom of the cylinder remains cold. I therefore wonder the hot water is not making it through the 3-way-valve towards the cylinder?

I’ve tried the following: a) opening the air vent before the feed from the boiler enters the cylinder: there is no trapped air and I get a spirt of warm-ish water; b) checking the immersion heater works; c) checking the valve on the return to the boiler from the bottom of the cylinder is fully opened; d) checking the thermostat on the cylinder is turned up sufficiently; and d) ”turning it off and on again”!

I’m not terribly good at plumbing but I am wondering if this suggests the 3-way-valve is stuck in the CH-only position? It’s an Altech ALTHC011 which I think was also sold as a Salus MV322 or MV328.

The manuals for the Salus (I can’t find one for the Altech) seem to suggest that the switch on the bottom can be manipulated into a manual position but I can only get that to lock with the cover of the valve off and it doesn’t seem to make any difference.

Could anyone help me with the following: a) is there anything else I can do to confirm the diagnosis? b) if I do confirm that the valve is dead, is there any way of manually setting the valve to heat both the HW and CH whilst I investigate a replacement? (I’d prob. get someone in since whilst I am confident I could rewire it correctly, I’m not so keen on the plumbing aspect).

Thanks!

Jacob
 
The Y plan valve is stuck in the CH position. This may be mechanical or electrical. If the manual lever is floppy, then isolate the electrical supply and you should hear the valve 'whirr' closed. If it doesn't, then it is either a seized synchron motor, or the valve body itself. If it does close, then you have an electrical problem. My best guess is a seized synchron motor.
 
Thanks. There is no sound from it when turning the CH, HW or CH + HW on. When turning off, I get no sound from the CH but when it’s the HW or CH + HW there is a noise which doesn’t sound like a whirr of a synchron motor being powered for a couple of seconds. It sounds more like something flowing through an unpowered bearing or similar. The manual level is completely floppy. I’ve seen a few videos on Youtube and I notice that when you set it to manual you are manually working the motor and get the whirr of it being moved by hand. I don’t get that.

I’m wondering if it is worth taking the actuator unit off the valve body and seeing whether the valve opens and closes freely? If so, I presume I can keep that and get a new unit?
 
Thanks everyone. A bit more fiddling makes me think the motor is gone. It was red hot when I removed the cover which is never a good sign and didn’t sound very happy when being run removed from the unit (i.e. not under load) or when I manually turned it myself. With the motor removed, the springs in the actuator are capable of closing the valve so I assume it’s not a problem, although they do do so quite slowly. I guess it may be a combination of the motor is failing and the valve is becoming a bit more resistant which has just tipped over the edge today. The annoying thing is never having done one of these before, I don’t know if the amount of resistance from the valve is excessive or not.

Unfortunately, I haven’t managed to get the actuator off the valve head. It seems to be held on by the valve itself. I might play with it some more later.
 
Sarrusophone said:
Unfortunately, I haven’t managed to get the actuator off the valve head. It seems to be held on by the valve itself. I might play with it some more later.
Click to expand...
These are from the Salus MV322 instructions, maybe this will help?
 

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Sarrusophone said:
Unfortunately, I haven’t managed to get the actuator off the valve head. It seems to be held on by the valve itself. I might play with it some more later.
Click to expand...

It looks as if the actuator may not be removable from the water valve, so it looks like you may need a complete valve and actuator swap, in which case it might be worth your while to fit a more reliable MOMO type of valve and actuator. Buy the right type and they are a direct swap for what you have from an electrical point of view. Unlike the type of actuator you have, where the motor is under power yet stalled, the MOMO type just move, then switch off. The MOMO also don't use a very strong spring, fighting the motor, so much less strain on the mechanism.

The Altech ALTHC011 seems not to be Salus MV322 or MV328, the latter has an easily removable head, just held in place by 2x 6mm screws.

The motors can be replaced, but often it is simply not worth while, because if the motor is worn out, the mechanism will be too.
 
Harry Bloomfield said:
It looks as if the actuator may not be removable from the water valve, so it looks like you may need a complete valve and actuator swap, in which case it might be worth your while to fit a more reliable MOMO type of valve and actuator. Buy the right type and they are a direct swap for what you have from an electrical point of view. Unlike the type of actuator you have, where the motor is under power yet stalled, the MOMO type just move, then switch off. The MOMO also don't use a very strong spring, fighting the motor, so much less strain on the mechanism.

The Altech ALTHC011 seems not to be Salus MV322 or MV328, the latter has an easily removable head, just held in place by 2x 6mm screws.

The motors can be replaced, but often it is simply not worth while, because if the motor is worn out, the mechanism will be too.
Click to expand...
Thanks. That all makes sense. Especially why I couldn’t get the actuator off the valve!
 
CBW said:
Have you found information/image online? I’ve just found some, that appear to have a gap between head and valve, which suggests, it can be removed?
Click to expand...

It could be the valve to actuator fixings are under the mechanism, meaning it would involve stripping the working parts down to release the actuator - basically the whole thing built on a bench, making field replacement of the head impossible.
 
As I said in post 2, the synchron motor is goosed, judging from you later comments. It has two screws, IIRC, to undo and remove it and the same to replace with the connection of 2 wires. Get a genuine Synchron from Screwfix, about £20 inc.
 
Are they generally interchangable? Screwfix only sells one: https://www.screwfix.com/p/drayton-synchronous-motor/28670

Since it doesn’t look lie the actuator will come off that is probably my only option short of replacing all the pipes (which is a bit too much into plumbing territory for my tastes!).

I’ve had bad experiences in the past in trying to fit replacement synchro motors (albeit that was for a rotating lamp).
 
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