Faulty central heating programmer?

I have a Tempus 6 (B&Q) programmer which is refusing to turn on the central heating on without the hot water in the evening.

In the morning it works fine.

I have checked the room thermostat which appears to be working ok.

The programmer is just 2 years old.

The 3 way motorised valve is only 1 month old.

Is there a reset button or is the programmer fininshed?

Any suggestions?

Reply to
GSz
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When you say that it works fine in the mornings, do you mean that it successfully provides heating without hot water - or do you want both anyway?

Some programmers have an internal (removeable) strap for use on gravity hot water systems - to force the boiler (AKA HW) on whenever the CH is on. I presume this isn't your problem?

Reply to
Set Square

It's most likely programmed to think it is on a gravity circulated hot water system that can't be turned off when the heating is on. Read the manual to see how to turn this mode off, if this is indeed the cause. It may be either a jumper setting, or done using the progamming keys. The difference between evening and morning may be the state of the cylinder thermostat as you won't have drawn any hot water by the time the heating comes on in the morning, whilst by the evening, your hot water might be nearly exhausted.

Christian.

Reply to
Christian McArdle

Is the CH light on the programmer coming on (without the HW light)?. You can reset it see -

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.I presume it has worked OK in the past, which rules out incorrect jumper settings? I've got a Tempus 7 and it is a bit tempermental - it locks up when I try to change times etc. Suggest you reset it and then reprogram as required and see how you get on.

Reply to
Rory

Thanks for all of your comments.

I will try a reset.

However,

I have done further tests:

If I turn the hot water to the off position on the programmer, before the time it is due to start in the evening, then the central heating worked as programmed.

However, if I turn the hot water to the off position once the start time has passed the central heating does not work!

I turned on the hot-water, on the programmer, and then went to feel the heat in the pipes - I am sure that the heated water was going into the central heating circuit and not much to hot water!

I recall that in February of this year I had a plumber out,as the motorised valve was not working, he merely replaced the motor, but since that time the hot-water was on when the central heating was on.

I thought that the valve had gone and so replaced it myself a month ago but now I am thinking that maybe when he replaced the motor he incorrectly wired it up and so when I replaced the valve I merely copied the wirng and so the fault. Is there an easy to use circuit diagram with colours that I may check anywhere - or is this a job for a more competant central heating engineer (I am a good copier but as to finding whihc wires come from whihc device is beond my experience?

There is no fancy junction box merely a strip of connectors.

Reply to
GSz

For a circuit diagram, go to

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and look at the Y-Plan diagram. You should have equivalent connections even if they're not in a fancy junction box.

There should be a 5 core cable coming from the mid-position valve actuator. You need to find the connections at the end of this. You need a voltmeter capable of measuring 250v AC.

Of the 5 wires, blue is neutral and green/yellow is earth - so these should never vary. The other 3 wires should selectively be live (i.e. at 240v with respect to neutral) at various times, depending on what is supposed to be happening.

Whenever there is a hot water demand (i.e. on at the programmer *and* cylinder stat) the Orange wire should be live.

Whenever there is a heating demand (i.e. on at the programmer *and* room stat) the White wire should be live. [The Orange wire should also be live - because it will be switched on by a microswitch inside the actuator if there isn't a hot water demand at the time].

Whenever there is *no* hot water demand (i.e. either switched off at programmer and/or cylinder stat satisfied) the Grey wire should be live.

If you can find which of those things *isn't* happening, it should be possible to work out what's going wrong.

I'm just wondering whether there could be a plumbing problem as well as a wiring problem. The outlets on the mid position valve should be clearly marked for heating and hot water. Yours aren't arse about face are they?

Reply to
Set Square

Thanks very much for this I will try and test it out today.

In the mean time I have changed the programmer so that the central heating starts 10mins before the water and 'touch wood' it all seems to work fine. This leads me to think that it may also be the hot water themostat which is telling the boiler that the water is hot enough and so overiding the room thermostat? I will study the circuit diagram and see if it is a wiring problem.

Thanks once again.

Reply to
GSz

Update

There is definately soemthing going wrong with the motorised valve, when the central heating is on the hot water pipe also appears to on as if the valve is in the mid-position.

I reviewed the wiring and it is too difficult to tell whihc wires come from where. Is it just the case that the grey, orange or white wires are incorrectly wired?

Reply to
GSz

Have you checked that the valve is *physically* the right way round, and not reversed - as I suggested earlier?

Have you checked that the Grey wire is live when HW is supposed to be off?

Reply to
Set Square

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