Central heating has a mind of its own

[Ifonlyiweretaller]

We have separate controls for: upstairs heating; downstairs heating; hot water; towel rails. The house was extended approx 8 years ago so had a huge new system installed, which is arguably way over-specced (or so service engineer said).

However even when the upstairs heating is off (during the day) quite often the radiators are still generating lots of heat. I don't understand why?

The towel rails - again these are timed, generally to be on a couple of times a day morning and night. However some come on and some don't. We have 2 downstairs, 4 upstairs.The downstairs loo (the one place we really need it to work) is like an ice box as the radiator seems to have a mind of its own & come on only sporadically. I know they are not designed to heat a room, but still. Some heat would really help that little ice box of a room. The temp is set to 45 degrees. Should it be higher than that?

There also seems to be conflicting information on whether we should leave the downstairs heating and hot water on a lower temperature all day, or to just fire it up morning and evening.My energy supplier said to leave on, but the service engineer said not to!

Can anyone make any suggestions please?

I'm wondering what your thermostat is set at. Despite being on a timer, our heating used to come on randomly when the temp dropped below the set temp. We adjusted the thermostat (with difficulty! Stupid electronic thing!) and now it just comes on at the set time.

Wow, that was quick -thanks. Surprisingly considering how hi-tech the system is, the thermostats are the basic Honeywell type. Both are set at around 19 degrees (unless my OH is home when he sneaks it up a bit!)

Your heating will react to where the thermostat is which may not reflect the whole house .
I sympathise, mine seems to do what it wants when it wants. Think we have some sensors on the way out. Combi boiler. They are always shit. We are living with it at the moment. Hot water fine but the heating will fire in when it feels like it.

...I'm still puzzled. If I've physically turned the upstairs heating off then regardless of what the upstairs thermostat is set to, the upstairs heating still shouldn't come on, surely?

If it's segregated you may have a number of 2 port valves. If one is stuck open this could cause the connected rags to heat up when ever the boiler fires. Easy way to tell is set the system to hot water only, all rads should be cold, set system to upstairs rsds only, downstsirs should be cold. You can usually tell when the valves are motoring, if the valves motor at inappropriate times then it's likley the controller/thermostat at fault. Hope that helps a little.

My water heater comes on when its not supposed to. Apparently its because the valve is faulty and doesn't close properly.

Thanks engineer. I've just done the first step - turned them both off (I'm home alone at the minute so can just put another jumper on if i get cold!). I'll let you know how I get on when I've done the next step later.

Any thoughts about my stupid unpredictable towel radiators?

Okay, I've now done step 2 as well engineer. Both did as they were told (i.e. were on when they should be, off when they should be). So where do I go from here?

Ok
It sounds like the valves are working ok. The controller/thermostat is the next port of call. Are they positioned in the correct areas and not subject to drafts from the other areas? If they are wireless check that the batteries are ok - or replace them if unsure. If wired are they old no metal types or more modern thermistor types? If old bimetsl types it could be that they are too insensitive (bimetal types have a large hysteresis and get worse with age). Assuming that they are moderns and working ok just have a double check tgat there is not a second timer somewhere.

Are the towel rails independently controlled? If so are they connected to the central heating or are they electric? If on the same wet system but not independently controlled then it sounds like it's not circulating. Try adjusting the tail stocks (valves) on each side. Note the system needs to be balanced. The tsol stocked could be closed too far or blocked, two turns open and two turns closed mayjust v've enough to get it flowing again.

Gosh Engineer - this is getting technical! Both thermostats (one in each hall) are the Honeywell type. One was replaced about 12 months ago, the other is 7 years old, so wouldn't have thought they were the fault. They 'click' when I turn the dial up so i presume that means they're okay?
There is definitely not another timer - just the "Channelplus H47XL Horstmann" programmer.

Re the towel radiator conversation - they are independently controlled on the wet system (run on the same programmer as the CH & Water) & the temp is set to 45 degrees. (Not sure if this is roughly higher or lower than it should be?).
Can you explain in a bit more what you think i should try re the valves on them - clockwise / anti clockwise turns? Do i have to do either side? i really don't understand the first thing about these things as I think you've probably realised (wink) so I totally understand if you'd prefer to just step away from the keyboard and leave me to get someone in!! I have apreciated your help so far of course...

Ok
The earlier comment about the towel rail is onlt relivant if it never gets hot. Beginning to sound less like a fault and more like the set up on the controller (re read earlier posts). Check that the clock is set to the correct time.
Have you got a manual? You can find one online. Draw a diagram of the system showing each zone, mark the thermosts on too (sounds like you must have states controlling the towel rails too). Then follow the zone set up flow diagram foe each zone you've sketched. I think this is most likley. It's difficult to diagnose without seeing it.
If it does seem to be set correctly:
When was the last time it did work? Do you have thermostatic radiator valves?
Have any recent adjustments been made to the tailstocks/rad valves on the radiators?

Just a quick update for engineersthumb . I dont know which bit of your towel radiator suggestions worked, but something did....it's coming on now!! So a huge thanks for that!

We have booked a chap in to come and assess the rest of the system for us and make sure everything is working as it should.

I appreciate the time and effort you put in , thank you.