Radiators coming on when they shouldnt?

[Patroller]

Hi all. I recently had a new programmer fitted to my system (Drayton LP722) and it worked perfectly for months, independently running the hot water and the central heating separately from each other.

On Christmas day (of all days) for some reason the radiators turned on when they shouldn't have. Now when the hot water comes on for some reason the radiators start getting warm too. They don't really get very hot but it appears for some reason they are having the water warmed up.

When the heating turns on, despite the programmer turning it off as per the digital display, the pump does not stop and it will run for hours and hours, or until I play around with the black bit of plastic sticking out of the blue plastic casing (as in the photos). I don't know what this part is or why it turns off when I play around with it?

I have a very very old standard boiler. I have now turned the heating off completely as it was not turning itself off and using too much gas.

I don't know what you think the problem might be?

Please ask if you need any more information!

Sorry if I have not explained properly.

 

[stem]

Sounds like the motorised valve is faulty. The valve is opened by the room thermostat and when it is fully opened a little switch inside it starts the pump and boiler running. If the valve is sticking open, then when the hot water valve above operates, water will also circulate around the radiator circuit.

Moving the black lever is probably freeing the valve enough to release the internal switch and so stop the boiler & pump running.

The blue unit looks to me like a IFLO sometimes re-badged by various trade companies. Replace it with a Honeywell unit like the one fitted to your hot water system. They are the most reliable valve you can get IMHO.

If you are handy with a multimeter and understand circuits, you can test the valve and its microswitch once you know how it works.

 

[Patroller]

Thank you very much for your advice. I don't know anything about multimeters and wouldn't be able to replace anything by myself (I think) so was hoping to get an idea from people like yourself before I got anybody in to look at it and tell me that I need a whole new system!

Is there any particular model you recommend? Would it be available in somewhere like screwfix?

Thanks again....

 

[stem]

Most plumbers merchants keep Honeywell. So do Screwfix Honeywell Valve

 

[Patroller]

Sorry for being so useless with this!

Is that a direct replacement for the blue box that I have in my system?

What is the small metal box in the picture that I also have along with the blue box?

Thanks again for all your help!!!!!!!

 

[stem]

There are two motorised valves (or zone valves) the silver one (Honeywell) connected to your hot water cylinder lets hot water from the boiler and pump circulate around the hot water cylinder to heat it up. When the water in the cylinder is hot, the valve closes.

The blue valve below is exactly the same but for the central heating. It's controlled by the room thermostat.

Both zone valves contain a microswitch that when the valve opens start the boiler and pump.

It's known as an "S Plan"

 

[Patroller]

Thats very helpful, thanks.

So there is no 100% way of finding out if this is the faulty item but in your opinion it is most likely?

 

[stem]

Yes, there is but you need to know what you are doing. It involves electrical testing with a multimeter as I mentioned earlier, and a test in situ to see if it's 'letting by' when the fault is manifest.

If the system was working correctly and you haven't changed any wiring or anything else since, yes, the valve is most likely. In fact I can't think of anything else that would cause the symptoms you describe.

BTW that pump with the exposed wires looks dangerous.

 

[Whitespirit66]

before I got anybody in to look at it and tell me that I need a whole new system!.

Don't let them sell you a new boiler, those olde Concords are bullet proof. A customer has one that's run for 30 years, and hardly spent anything on it.

Just make sure the cover is secured properly. Have had a couple where the covers were almost falling off, due to the dodgy case clips. Case seals are still available.

 

[Patroller]

That's the same with ours... its over 30 years old. Not exactly efficient though touch wood, never needs anything doing!

 

[Patroller]

BTW that pump with the exposed wires looks dangerous.

 

[CBF]

it's a drayton valve although i'm not sure which re-badged version is blue (stem just for your info iflo is a re-badged drayton not the other way around ), you can change the motor in them but tbh if you haven't done it before you will have springs going everywhere, the easiest thing to do is replace the blue box (actuator), you don't need to drain the system unless you are replacing the whole valve all you need to do is follow the wires back from the old one then change them like for like but do it ONE at a time don't take them all out then forget what went where, but as stem rightly says it's time for a new pump that one has had it & the valves attached to it will req changing (as you will never get the nuts undone on the pump & as soon as you look at the isolation valves they will leak, don't get those type get the gate type pump unions) so the system will need to be drained for that so you might as well change the whole blue valve (body & actuator)

 

[misterdubya]

before I got anybody in to look at it and tell me that I need a whole new system!

Why would anyone do that? Your rads get warm when they should not - just replace your valve if its faulty. What decent plumber wants to replace a system just for the sake of a valve? If one does, I suggest you kick them in the nuts / fanny and tell them to get lost. Replace that pump.

Nicely decorated boiler.

 

[stem]

stem just for your info iflo is a re-badged drayton not the other way around

Thanks for that I've not really taken much notice because I've never installed one...thrown several away though...They even look cheap and nasty.