Radiators getting hot when heating is off

[Avocet]

Hi all,

1995 Worcester Heatslave oil combi boiler. It's roasting here at present, so the central heating is set to "off" on the programmer, but the hot water still comes on twice a day.

I was surprised this afternoon, to feel the radiators getting hot, when the boiler fired up to heat the water! As far as I'm aware, the diverter valve is original. It's one of those motorised valves with a little lever sticking out of the side. Might it be a reasonable guess that it's that which is failing? (We've had trouble over the last few months with the opposite happening on occasions (we try to run a bath and the water starts to run cold after a minute or two).

 

[lostinthelight]

Sounds like a reasonable guess to me, if you turn HW on and hold your hand on the pipe the heating side of the 3 port valve, assume “Y”plan , a foot away , if it gets hot your right.

 

[fixitflav]

Sounds like a reasonable guess to me, if you turn HW on and hold your hand on the pipe the heating side of the 3 port valve, assume “Y”plan , a foot away , if it gets hot your right.

On a combi, the diverter valve is inside the casing. Not a Y-plan with external 3-port valve.

 

[lostinthelight]

On a combi, the diverter valve is inside the casing. Not a Y-plan with external 3-port valve.

Ah! missed the combi bit.

 

[Avocet]

Thanks guys. Here's the part. Can I just replace the motorised bit in the "tin box", or am I looking at a drain-down of the system and the complete jobbie, including the bit that sits in the pipework?

 

[fixitflav]

Thanks guys. Here's the part. Can I just replace the motorised bit in the "tin box", or am I looking at a drain-down of the system and the complete jobbie, including the bit that sits in the pipework?

Could be wrong, but from your symptoms I think it's more likely to be a problem with the valve body, not the actuator. But it might be worth removing the actuator, check that it seems to do what you'd expect, and doesn't smell like burnt electrics.

 

[Deleted member 267285]

Hard to tell with that valve, looks old enough to be a drain down type, perhaps @Exedon knows, or maybe another engineer.

 

[Avocet]

Oh dear... I could be in the brown stuff here! Looking online, it seems that the ACL A679B316-52L0 is well and truly obsolete!

Closest I can find, is this on eBay. Looks the same, but different part numbers...

ACL MOTORTROL 3/4” 3 PORT VALVE A672B314-30L0 NEW OBSOLETE | eBay

<p>ACL MOTORTROL 3/4” 3 PORT VALVE A672B314-30L0 NEW OBSOLETE</p><br /><p>GENUINE BRAND NEW IN ORIGINAL BOX </p><br /><p>SOME SLIGHT COSMETIC MARKINGS ON THE VALVE THIS IS PURELY COSMETIC AND FROM STORAGE </p><br /><p>VERY RARE COMPLETELY OBSOLETE EVERYWHERE </p><br /><p>PLEASE MAKE SURE YOU...

www.ebay.co.uk

 

[Deleted member 267285]

Oh dear... I could be in the brown stuff here! Looking online, it seems that the ACL A679B316-52L0 is well and truly obsolete!

Closest I can find, is this on eBay. Looks the same, but different part numbers...

ACL MOTORTROL 3/4” 3 PORT VALVE A672B314-30L0 NEW OBSOLETE | eBay

<p>ACL MOTORTROL 3/4” 3 PORT VALVE A672B314-30L0 NEW OBSOLETE</p><br /><p>GENUINE BRAND NEW IN ORIGINAL BOX </p><br /><p>SOME SLIGHT COSMETIC MARKINGS ON THE VALVE THIS IS PURELY COSMETIC AND FROM STORAGE </p><br /><p>VERY RARE COMPLETELY OBSOLETE EVERYWHERE </p><br /><p>PLEASE MAKE SURE YOU...

www.ebay.co.uk

I would have thought there’ll be a Drayton equivalent? Afaik Drayton merged with ACL or bought them out?

 

[fixitflav]

Oh dear... I could be in the brown stuff here! Looking online, it seems that the ACL A679B316-52L0 is well and truly obsolete!

First, I'd make sure what the problem is with the existing valve. If you remove the actuator you can examine that, and then you might be able to remove the valve innards, without disturbing the pipework (need to partially drain the system). And see whether anything looks knackered.