Central heating goes off when water up to temperature
Bryan_1950
Posts: 4 Newbie
I've a conventional (not combi) boiler with a hot water tank and three way valve. When cold everything works OK, but when the water in the hot water cylinder reaches the thermostat cut off temperature (60 degC) the central heating won't come on despite the room thermostat calling for heat. Tweaking the cylinder thermostat setting up then down again will switch the heating back on.
Any ideas?
Any ideas?
0
Comments
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Sounds like the three way valve is sticking. They have microswitches in them that can go intermittent.
You should be able to just replace the head unit (actuator) if it's a Honeywell or one of the popular makes.0 -
Yes same happened to me stuck /Drayton Ivesys unit .
Drained down and replaced full unit as existing was early non replace unit .
Newer units that replace the accentuator are just clip on .
But this was gas not oil/ LPG0 -
Thanks for the responses, probably the valve (It is a gas fired system, old, but condensing, Ideal Classic boiler)
I've just carried out another test. When the programmer is set to heating only the heating won't come on, but it does if both hot water and heating are selected.
Maybe also the valve, but maybe also a wiring error? A plumber once told me that he had encountered a large number of systems that were wired incorrectly from new.
Is it possible to visually check the operation of the valve?0 -
Bryan_1950 wrote: »
Is it possible to visually check the operation of the valve?
You can watch or feel the manual lever moving.I am not a cat (But my friend is)0 -
Hi Bryan - as well as visually checking the operation of the valve, you could try to operate it manually, i.e. instead of tweaking the cylinder stat to make the heating work, move the lever on the valve. It could be a wiring issue but this seems unlikely assuming it was working and has now stopped? Valve problems are fairly common which is why the heads/actuators are made so they are easy to change. I would be very careful about doing it yourself unless you are confident with wiring as central heating wiring is far from intuitve.0
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To be honest I don't know if the heating has ever worked when the hot water is not selected as I can't remember ever having selected that combination. However a new actuator for the valve is worth a try I guess. Presumably that can be done without draining the system?0
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Hi Bryan - yes, it can be done without draining the system, the actuator on mine clipped on and off and wired into a special central heating junction box. A new actuator is relatively inexpensive (try eBay) and even if you find this isn't the problem it'll be useful to have as a spare because they do tend to fail sooner or later. Good luck!0
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...as an addtional thought, if you Google "central heating diverter valve wiring youtube" you'll find any background info you want on how the valve works and is wired.0
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Thanks, that makes good sense. I'll buy an actuator, might investigate the wiring when I come to install it.0
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also with the actuator head removed the little shaft that sticks out of the valve body can seize over time , try moving it with a small adjustable it will only move about a quarter of a turn back and forth, then replace head and try heatingThats a good idea thanks muchly.. 😊0
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