Central heating not coming on when scheduled but triggering with hot water control
I installed our Tado system (wireless receiver, wireless temperature sensor and 2 TRVs) last winter and it worked like a dream.
I recently installed 2 more TRVs and turned our scheduling on as the evenings started to get a little chillier. Since then we have been having a lot of problems. Often the heating does not come on when scheduled to do so. The app behaves normally and I hear a click and activity from the wireless receiver when the heating is turned on, but the boiler often does not fire. It would eventually come on after resetting the wireless receiver multiple times.
I reset all of the devices and it started working correctly for a little while, but now it is not coming on when scheduled again. I've noticed that the boiler will fire up straight away if I manually turn on the hot water, and then the heating comes on as well.
To make things even stranger, today I noticed that our bathroom radiator (which is always open) was hot even though the heating was not scheduled to be on. This happened to coincide with the time that the hot water was scheduled to be on. This implies that the hot water control is triggering our central heating.
I have changed nothing with the wiring configuration since last year when everything was working correctly. Anyone have any idea what could be causing this issue and how we can resolve it?
Answers
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From your wiring it looks like you probably have a three way valve in your heating system. I suspect the valve is sticking and not moving to the hot water only position. With the usual configuration of a 3 way valve it is the valve itself that calls the boiler to fire when in heating only mode, but only if the valve physically opens.
When in hot water mode the Tado directly calls the boiler to fire, via the hot water cylinder thermostat. If the 3 way valve is sticking in the central posistion then the boiler would fire correctly in hot water mode but the water would be flowing to both circuits.Many 3 way valves have a lever on them that you can see moving between the 3 positions, if this is not happening you might be able to free the valve by moving it manually.
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As starconf suggests, I’d be suspicious of the motorised zone valve. It may the electrical motor head or a sticky/jammed valve.
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We had same. New 3 way solved it0
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Thanks for the replies everyone.
We do indeed have a 3 way valve. It's a honeywell V4073a1039.
The level wasn't in the auto position, but moving this doesn't seem to have helped so I think it's probably faulty.
So if I am understanding correctly, the central heating schedule will not fire up the boiler if the valve is not successfully moving to the heating only position, as the boiler does not fire until this has happened?
I have a plumber coming round tomorrow to service the boiler and check over the system. I'll point him towards the valve and hopefully he can sort it out for us.
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I've just installed the Wireless V3+ with the same receiver set up as the picture above. My new Honeywell 3 port valve was working fine with my old controller, until I installed the Tado, so it can't be that - unless there's a compatibility issue?0
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My issue turned out to be both a faulty valve and the old motor that didn’t have enough strength to move it between positions anymore. Replacing both solved the issue for me.0
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I have just installed the v3+ and I can’t get the heating to work, I’ve got water but boiler will not fire up for heating, there was nothing wrong with the old programmer and I had a new motorised valve fitted last week, all working fine but now after installing this I have no heating, I should have stuck with what I had😡 I ve spent all day on it and I think I’ll have to put the old programmer and wireless stat back on!
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This is me today. My Tado also thinks I have a system without independent CH/HW!
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