CH turning on by itself problem

[drew35]

Hmm I'm just a lowly electrician but I find programmers that go faulty regularly, switching on when they're not set. I changed one on Saturday, that was Danfos. And I witnessed the fault when I went to look initially, the heating and hot water where both on, the hot water is always set to off, and the heating wasn't within its set demand time. The Y plan valve was operating correctly, I checked that, after switching the FCU on and off it sorted itself out. So I fitted a new programmer, sorted.

And there was another just a few weeks ago where the heating would come on outside its set time and not during the demand time. I didn't change that one I left it to someone who knows more as it was a complicated system at a village hall, but the guy who deals with the heating only changed the programmer. I thought this was common?

 

[chris murphy]

Hmm I'm just a lowly electrician but I find programmers that go faulty regularly, switching on when they're not set. I changed one on Saturday, that was Danfos. And I witnessed the fault when I went to look initially, the heating and hot water where both on, the hot water is always set to off, and the heating wasn't within its set demand time. The Y plan valve was operating correctly, I checked that, after switching the FCU on and off it sorted itself out. So I fitted a new programmer, sorted.

And there was another just a few weeks ago where the heating would come on outside its set time and not during the demand time. I didn't change that one I left it to someone who knows more as it was a complicated system at a village hall, but the guy who deals with the heating only changed the programmer. I thought this was common?

"Hello drew35",


Although I am a Heating Engineer I do not carry out Boiler Repair / Heating System Fault Call Out Work - I have spent My Self Employed Working Life Designing and Installing Heating and Plumbing Systems - It may well be that what You have described and Personally come across IS a fairly common occurrence - BUT I have never Found or Heard of it happening.

Just like Plumbers who carry out mainly Maintenance and Repair Plumbing Work - Boiler Service and Repair Engineers and Electricians probably come across what I would consider to be `Unusual Faults` on a regular basis - this Fault - If it is the Programmer that is Faulty - may be `Well Known` to Boiler Service and Repair Engineers but NOT to Heating Engineers who carry out Installation Works only.

I would be interested in finding out exactly what can occur within a Programmer that causes this situation to happen - ?

Could some other Electricians please comment on How Well Known the `Faulty Programmer` causing the Heating System to be Turned On during `Off Periods` situation is amongst their experience - ?

If I was involved in Investigating this Fault the FIRST Thing that I would do would be to Fit a Used Programmer to see IF it was the Programmer that was Faulty / `Rule Out` the Programmer - I have various Programmers that I have removed when Replacing or Upgrading Heating Systems - BUT I could NOT advise mcm to tell the People in the Home that they should Purchase a New Programmer when I had never heard of a Programmer causing this Fault.

Nor did I advise Him to arrange anything that would Cost Money - Unless it was confirmed by the Boiler Manufacturers Technical Helpline that the Boiler Frost Protection Thermostat COULD be causing the Boiler to be Turned On AND then NOT Turning it Off when the Boiler had `Warmed` to a situation when it was not at Risk of Freezing.

As You and the other Members on here know it is Very Different matter trying to `Diagnose` a Fault on either a Heating System / Boiler or an Electrical System / Component on here as opposed to actually being `On Site` where Testing or Swapping of Controls etc. can be carried out to `Rule Out` items / Find the offending Item.


I take it that My Post will now be deemed to be giving `Incorrect Information & Advice` ??


mcm - I hope that it does turn out that it IS the Programmer that is a Fault - at least it would be a fairly Inexpensive `Fix` by just replacing the Programmer.

As I have NOT come across this `Faulty Programmer causes Heating to come On during Off Periods` in the 40 Years of working in Heating - Plumbing & Gas - and I assure You that I answered Your Post in all sincerity - Could You Please Post the Outcome of what is found to be causing the Fault - "Thanks".


Chris

 

[PC Electrics]

Had one just last week, a Potterton EP2002. Usually a very reliable product, well liked by clients. This one had it's display go blank and it's lights were off, but the heating was running. Fortunately it was only a month old so was changed under warranty.

Question for the client: has the sysem always done this or is this a new problem and when did it start.
You could prove it's not the programmer by removing it from its base plate overnight and see if the problem recurs. You could temporarily wire up a 2G light switch to provide manual on/off control.

I would check (in this order):
frost stat
programmer
correctly wired

 

[chris murphy]

Had one just last week, a Potterton EP2002. Usually a very reliable product, well liked by clients. This one had it's display go blank and it's lights were off, but the heating was running. Fortunately it was only a month old so was changed under warranty.

Question for the client: has the sysem always done this or is this a new problem and when did it start.
You could prove it's not the programmer by removing it from its base plate overnight and see if the problem recurs. You could temporarily wire up a 2G light switch to provide manual on/off control.

I would check (in this order):
frost stat
programmer
correctly wired

"Hello PC Electrics",


An Excellent Idea - Would there be situations where the Wiring to the Boiler / Permanent Live for the Frost Protection Thermostat would be interupted by removing the Programmer - ?

I ASK this as I am not an Electrician and although I am `Trained and Registered` for the Defined Scope / Heating Appliance - Systems section of Part P - and I do know how to Wire Up the main types of System - I do not Wire Up My own Heating Systems - preferring to engage a Professional Electrician to carry out the Wiring and Notify and Certify the Work.

Obviously the Boiler would have to have a Live Feed in order that the Frost Protection Thermostat could work, But I am sure that if it is required a temporary Live Feed can easily be wired up.


Rather than Me trying to work out the Answer to that - I`m sure that You or another Member will answer that very quickly.

Also I would suggest that this is tried during a Forecasted Period of Cold Nights and left for a few Nights if necessary - not just One Night unless the Frost Thermostat IS Faulty and displays the situation where after Turning On the Boiler - It does NOT Turn it Off after a short period of time.


I should add a comment regarding Faulty Programmers - I have often seen / heard about Faults on Programmers - BUT - Never that they would Turn On the Heating at Night / Times that were NOT in the Settings - But then seem to Work Correctly for the rest of each 24 Hour period.


Chris

 

[sambotc]

Turn the room stat down to 0 over night. If the programmer is at fault, the stat will stop it from firing. If the heating comes on still you know it is from an external influence (e;g frost stat although unlikely to be the cause in my opinion)

 

[oldtimer]

First of al I take it is a domestic system where you have hot water storage tank and central heating yes ? plus you say it comes on itself so when does it come on ie low outside temp or internal thermostat so you need to find out how it is wired then as a test turn off the timer / programmer and then turn up the room stat if the boiler kicks in the the stat should be wired in series with the programmer I hear about frost stats but this is usally found on commercial systems ie schools office blocks etc

 

[chris murphy]

"Hello sambotc and oldtimer",


IF You saw My Posts `Addressed` to You earlier this evening - I must Apologise - I came here from a Link in a Post Notification Email and because I have been Writing Questions and suggestions on another Central Heating Problem I confused the Two Subjects.

I had Posted some answers to both of You - But I was writing about the OTHER Subject - "Sorry"

I am glad that I noticed this just before leaving the website or it would have made Me look as if I had Posted completely Irrelevant comments !

Also I Apologise to anyone else who read My Posts before I Deleted them - and wondered what I meant.


Regards,

Chris

 

[Guest111]

Hi had this happen to me a while ago turned out it was a motorised valve that was playing up,found out which by testing the grey wires to see which went live when it fired by itself,only problem is it aint easy to do when you dont live there as its pure luck catching it doing it,

 

[chris murphy]

Hi had this happen to me a while ago turned out it was a motorised valve that was playing up,found out which by testing the grey wires to see which went live when it fired by itself,only problem is it aint easy to do when you dont live there as its pure luck catching it doing it,

"Hello phil d",

I am interested in How a Zone Valve could Turn On the Boiler / Heating System if the Programmer is in the Off Setting / Period - So theoretically there is NO Power supplied to the Thermostats and Zone Valves - ?

I assume from what the Original Poster stated that the Heating System Wiring was `O.K.` until the recent malfunction occurred.

Regards,

Chris

 

[chris murphy]

Turn the room stat down to 0 over night. If the programmer is at fault, the stat will stop it from firing. If the heating comes on still you know it is from an external influence (e;g frost stat although unlikely to be the cause in my opinion)

"Hello sambotc",


The reason that I started writing about the Frost Protection Thermostat possibly turning on the Boiler at Night was because:

Firstly I had not heard about a Faulty Programmer turning On a Heating System / Boiler when it was in an `OFF` Setting and then apparantly Operating during the Day / Evening Correctly.

And because a Frost Thermostat on a Boiler is Designed to Independantly Turn On the Boiler - obviously in circumstances when the Boiler is `Off` on the Programmer - Although it is very unlikely that the Frost Thermostat would Turn On the Boiler AND then NOT Turn it Off again after `Warming Up` the Boiler - I doubt whether that is `Impossible` - ?


Regards,


Chris