Clunking Programmer and boiler

[marcus99]

Happy Christmas to you all. Wondering if somone may have an answer to my query. Moved into our current house last year.My central heating all works well, but the last four days the Sunvic 270 programmer ( guess at 8-10 years old) and Ideal Classic boiler (similar age)"clunk" at the same time. The clunking happens every 2 to 5 seconds after the boiler has fired up and only when HW and CH are both ON. This can go on for up to a couple of minutes, but if you switch off either the HW or the CW while its clunking it stops clunking instantly. The boiler stays lit, and the flame seems unaffected by the clunking. You can feel the programmer vibrate when it clunks and the red lights on the programmer flicker with each clunk. In my laymans speak, I am guessing that the programmer is defunct and trying to tell the boiler to light when it is already lit. Is my guesswork correct?. Any help much appreciated. Regards.

 

[bhm1712]

I dont think your guess work is correct as the logic doesnt quite work like that.

inside the timer are some relays. Once these are energised (to bring on HW or CH) they do not keep cycling on or off during a timed on period.

Once the relays are energised there will be 240 volts going to the boiler through the roomstat/cylinder stat unless they de-energise. the timer cannot keep re-sending a signal to the boiler when it already has 'sent' the initial 240 volts to the boiler. You say that this only happens when both CH and HW are selected, and de-selecting either HW or CH stops it. In this situation i would be tempted to say that it is something other than the timer which is the problem. It seems as though something is momentarily drawing alot of current which is causing the sag in voltage you are seeing. The vibration in the timer is likely to be the relay chattering because the coil is losing its supply for a split second, which will also give you the slight flickering of the LED's.

Are you 100% sure that turning off either CH or HW stops it when they are both on, or does it stop with turning off only the HW or only the CH when they are both on? Just trying to narrow it down to component level

 

[bhm1712]

can we also have a bit more info please??

How long does the clunking go on for if you leave it without turning something off?

are you sure the boiler stays ignited whilst the LEDs flicker on the programmer?

are there any other noises (perhaps mechanical) noises which occur at the boiler or nearby when the clunking is going on?

Can you feel any clunking through the radiator or HW pipes or maybe even the boiler casing itself?

 

[BHP]

Better Still send us a picture of the clock and boiler agree with BHM

 

[marcus99]

Hi, and thanks for the replies. The clunking has only happened in the mornings. It lasts between 20 seconds and a couple of minutes. Will re happen when the heating comes back on ( when the thermostat tells it too). The clunks happen evrey 2 to 10 seconds ie. multiple in a row then odd ones now and then. The boiler flame is unnaffected and other than aclunk coming from it and the programmer on the other wall in the airing cupboard it seems to work fine.We run the CH and HW on all day, with the temperature set by a variable time/temp digital thermostat. If you turn off the CH while its clunking it stops immediately. The same happens if you turn off the HW. I don't know if the clunking happens with just the HW on in the mornings,as the wife and child have flu and I can't leave the heating off for any considerable time. Funnily enough, so far this am, there has been no clunking.i would like to nip in the bud this problem before it possibly causes a complete failure. Regards.

 

[marcus99]

should also add that the clunking is only in the timer and at the same time the boilern not in rads or any pipes. To me it seems electrical rather than mechanical. Everthing at the moment works, but obviously this noise is not right. The odd thing also is that it never happens in the afternoon and evening when everything is ticking over ie,up to temperature.

 

[marcus99]

Hi again. Happy New Year.
Over the New Year period the clunking mysteriously stopped and all was well.Has now restarted this week. There is no clunking in anything other than the programmer and boiler.There is a very slight boiler flame flicker in time to the clunking, but its hardly noticeable. I have now been able to work out that when the boiler is heating the CH and HW that clicking off either on the programmer stops the clunking and vice versa..when its heating just the CH or HW, that clicking on the other instantly starts the clunking. The clunking can clearly be felt with your hand on the programmer, which I think is faulty but cars not heating are my thing. Any guidance and help greatfully received. Regards Mark

 

[bhm1712]

what programmer is it you have??

Without being able to see it and in the abscense of having had a pro to look at it, i would suggest buying a cheap replacement programmer from the likes of screwfix (if its an RWB2 type backplate then you can get a programmer for 25-30 quid) and trying it out.

It might be the programmer.. i never ruled it out, i only suggested that i thought it might be something else with the symptoms you are getting.

First step is to try a new programmer. Post which type you have now,

 

[marcus99]

Thanks for the reply bhm. The programmer is a Sunvic 207 (not 270 as I thought) I would guess is at least 8-10 years old , may be more. the writing on the buttons is almost worn off. I think I could directly replace with a Sunvic 207XLS ?, as according to the sunvic website the back plate is interchangeable. Seen one on the web for £36, so I think I will give that first shot. Will let you know the result.

 

[marcus99]

Just for future info. I replaced the old Sunvic select Programmer with a new Sunvic 270 XLS, using the same universal back plate. So far, four weeks of peace and quiet.