The hot water is heating the rads

[liverplum]

Morning.

I've got a bit of a confusing one. A system that has worked fine for a decade is now heating the rads when the hot water is turned on. It is as far as I can tell a standard vented indirect system. As soon as you turn the hot water on at the controls you get hot water but the rads also start to warm up.

I have turned the heating controls off and put the back up immersion heater on providing hot water.

A colleague has suggested that it may be because the return for the central heating is tee'd in on the 1st floor and not the ground floor although did not offer a suggestion as to why this has happened now.

Any ideas?

 

[powell30]

With all due respect your mate is talking rubbish....unless you have had serious pipework changes recently!

The diverter valve (3 port) is stuck/broken. Replace it

 

[liverplum]

I thought that it sounded unlikely as there is nothing to suggest why this would have happened... no one is owning up to having fiddled with anything but could it be that someone has changed the settings on the 3 way - it has selector switches on the top and the bottom?

 

[D_Hailsham]

could it be that someone has changed the settings on the 3 way - it has selector switches on the top and the bottom?

Can you post a photo of the 3-way, so it can be identified? Most valves do not have any switched on them.

 

[liverplum]

I think it's a honeywell one - it looks just like they all do with the metal box on top - from memory (i'm not there now) the switch on the top had 3 positions which appeared to be labelled H - M - W.....

 

[D_Hailsham]

I think it's a honeywell one - it looks just like they all do with the metal box on top - from memory (i'm not there now) the switch on the top had 3 positions which appeared to be labelled H - M - W.....

More likely to be a Drayton if there is what looks like a switch labelled H-M-W. It's not a switch, just an indicator of what position the valve is in.
H is Heating only
W is Hot Water only
M is mid position - heating and hot water.

There is also a lever in a slot at the opposite end.

Turn off the power to the system (turning the programmer to off is not enough); this resets the valve. The indicator should be on W. Move the lever across to the other end of the slot. You should feel resistance as you are opening the valve against a spring. If the lever is floppy - no resistance - the valve is stuck in the H position. Remove the actuator (box on top) and check the valve spindle can rotate easily (it will only be about 45°). A small amount of WD40 or 3-in-1 may help.

If the valve spindle is free, opens against the spring and closes when the lever is released, then the fault is either in the actuator or another part of the system.

 

[liverplum]

Thanks very much D_Hailsham....you were spot on, it was a Drayton and it does appear it was stuck - I turned it off at the consumer unit (although the screen on the unit didn't go off I assume as it has back up battery power) and I then took the lid off the attenuator and had a fiddle. I moved the levers as far as possible and there was resistance so applied a bit of 3 in 1 and then popped the lid back on. Once it was on i tried to move the lever and it actually felt like it may have snapped - the indicator - but when it was turned back on it was working fine - heating the rads when asked, the hot water when asked but most importantly not the rads at the same time.

Thanks very much for everyone's help