No central heating upstairs

[d000hg]

I'm visiting my late parents' house as I do periodically, and confirmed something I was concerned about last time.
The upstairs central heating never comes on even when the controller says it is. I have checked and the boiler doesn't come on at all if only the upstairs heating is on.

The house has separate Honeywell controllers for upstairs and downstairs, each have heating and hot water sliders and can be controlled to come on twice a day, with per-day timings. The downstairs controls downstairs heating and hot water, the upstairs one the hot water control does nothing intentionally.

I used to live here years ago and it worked, but now my parents are both dead so I can't ask questions. I do know the boiler was replaced a couple of years ago by my mum after dad passed away. I wondered if there's a possibility the upstairs circuit was never reconnected, but I don't have any clue how these things work - how the controller tells the boiler to come on, how it makes sure water only goes to the right circuit, etc.

Any advice would be welcomed.

 

[stem]

The system likely is fitted with motorised valves like this.

Untitled

• stem
• 26 Mar 2010
• 6

If you know where these valves are, turn on the heating upstairs and downstairs and turn the thermostats up. The pipes to and from the working valve will heat up. On the side of the valve there is a small lever. On the valve that doesn't heat up, slide the lever to the manual position and latch it there. Wait for 10 minutes or so, and if the upstairs radiators warm up now, the the valve is probably faulty.

If you or someone you know has access to a multimeter and is able to use it safely, a quick check to make sure the suspect valve is getting 230V will confirm this.

Note: If you have a stored hot water system, there may be three valves, if so, one will be for the hot water.

 

[d000hg]

Oh yeah, we had that issue on my system quite recently. I'll have a look although the fact the boiler doesn't even click on for a few seconds is making me wonder... with a cold system even with a closed valve the heating system should turn on briefly shouldn't it based on the thermostat? Then it would heat the water in the pipe almost immediately and turn off again?

 

[stem]

even with a closed valve the heating system should turn on briefly shouldn't it based on the thermostat?

No, that is incorrect, because the motorised valve switches the boiler on by operating an internal small switch when it is fully open. If it doesn't open, it doesn't operate the switch and it doesn't turn the boiler on.

 

[Mottie]

From a complete novices point of view, I'd check that the upstairs controller is set on permanent, check that the rads don't need bleeding and that the thermostat is up high. If still nothing, it could be a stuck zone valve maybe? Do you know how to manually override them? If not, I'd get a plumber in to service and check the system out.

 

[d000hg]

Oh right, thanks for explaining that.

So if I find the valve and put it in manual, this should cause the CH to run 24/7?

 

[JohnD]

if that was correct, it would mean you were tipping money down the drain to constantly heat an empty house, whatever the temperature (inside and out).

show us some photos of the valves and other controllers, such as timer/programmers and thermostats.

Good idea to bleed the radiators to verify that water squirts out forcefully from the upstairs ones. In some circumstances the upstairs ones may be empty of water. This is unlikely if there is a pressure gauge on your boiler, though.

 

[Mottie]

No. Putting the upstairs controller on permanent will cause the heating to run 24/7 if the thermostat is set high enough. As explained earlier in the post with the picture of the motorised valve, if that is stuck shut, it wont run at all.

 

[Mottie]

if that was correct, it would mean you were tipping money down the drain to constantly heat an empty house, whatever the temperature (inside and out).

show us some photos of the valves and other controllers, such as timer/programmers and thermostats.

I meant to do that just to find out what is stopping the upstairs heating from working. Why would anyone suggest running a heating system 24/7?

 

[JohnD]

I don't know.

24/7 is not a term I introduced.

 

[d000hg]

It would depend if the servo had failed so the valve can't open when told to, or the actual valve was stuck and even the manual override can't sort it (no idea if this is likely).

I know the electronic controller is claiming to be on - a big red light comes on I'll go look for the valves later... hopefully they're somewhere easy to access. Otherwise I'll just get an engineer to come figure it out, it's just nice to be able to try and diagnose the issue myself if possible.

 

[Mottie]

I don't know.

24/7 is not a term I introduced.

Apologies. You used the term 'Constantly'. Same thing. I can see how you got such a high post count. Mr Pedantic. Lol.

 

[stem]

So if I find the valve and put it in manual, this should cause the CH to run 24/7?

No, the upstairs radiators would only come on when the boiler was operating under demand from something else. IE downstairs radiators, or hot water (if you have stored hot water)

Edit: Sometimes, but not usually, opening the valve manually may trigger the microswitch at the end of its travel. If it does, the CH may be on permanently. Only trying it will tell you.

 

[d000hg]

I don't know.

24/7 is not a term I introduced.

So can someone explain the relationship between controller box, thermostat, valve and CH? Does the controller talk to the thermostat and open the valve or are they independent systems - the CH will come on whenever the thermostat tells it to, but the valve controls whether this water is allowed to go anywhere which means with a closed valve the CH would come on very briefly when it gets cold but then click off again?

Just interested how the system hangs together. Stem's first post seems to suggest the latter i.e the box simply opens and shuts the valve, and the thermostat simply turns the CH on/off.

 

[stem]

The programmer provides a live supply at the times when heating is required. This live goes to the thermostat. If there is heat required because the room is below the thermostats set temperature, then the thermostat switches the live to the motorised valve which when powered up slowly winds open. When it is fully open, it operates a small switch internally that switches on the boiler.