CH turning on by itself problem

[mcm]

was asked about a central heating problem the other day but as not done much of this was not sure.

I was told that the central heating would come on by itself even if the programmer was switched to the off position. The heating would come on in the night on its own but on the programmer says its off, the timer works ok on the programer as tested the the on off times, was thinking it could be the valve sticking does this sound right?

The programmer is a drayton tempus six

 

[invisable]

is the boiler located where it can get cold does it have a froststat or a pipe stat installed ? (it could have a internal frost stat on the boiler).
sound like the boiler is coming on at night when the temperature drops to stop pipes freezing.

 

[i=p/u]

sounds good to me, cause this overides ..... but not to clued up either

 

[mcm]

is the boiler located where it can get cold does it have a froststat or a pipe stat installed ? (it could have a internal frost stat on the boiler).
sound like the boiler is coming on at night when the temperature drops to stop pipes freezing.

no the boiler is in the kitchen would'nt of thought it would get that cold. someone said about the valve could be sticking that at night it was moving causing it to come on. think its more than the programmer at fault but not sure.

 

[invisable]

What type of system is it does it have 2 valves (s plan) or one valve (y plan) the vavle could be sticking usally when a valve sticks it would just stay open or closed to let the heat through eg. heating would get hot when hot water is callling.

 

[UNG]

What make is the boiler. A lot of boilers have built in frost protection that activates when the temperature drops it normally kicks the pump in first at around 5° or 6° C and fires the boiler at 2° C

 

[mechelec]

Has the system got a room stat that is incorrectly wired ie in parallel with the programmer and has just been turned down low.
It could be the programmer that has a sticking relay and not switching off, but usually they fail open circuit not short.
Not sure how a sticking valve would cause the boiler to fire.

 

[chris murphy]

What make is the boiler. A lot of boilers have built in frost protection that activates when the temperature drops it normally kicks the pump in first at around 5° or 6° C and fires the boiler at 2° C

"Hello mcm",

I am a Heating Engineer - What UNG stated here could be the case - If the Boiler Frost Protection is operating the Heating should NOT actually run / Heat Up to `Normal` / Hot Temperatures - but the Boiler would Fire Up and the Pump should run and distribute a small amount of Heat around the System - then the Boiler would Go Off until the Frost Protection turned it on again If the Temperature within the Boiler dropped to actuate the Frost Thermostat.



I have noted outside Temperatures here in the London Suburbs of as Low as Minus 6 Degrees C during the early part of this Week - and Boiler Frost Protection turns on the Boiler at a Higher Temperature than this - usually approximately as UNG stated, there have also been some quite Cold Nights earlier in the Month.

Remember that the Cold Air is entering into the Boiler via the Flue - both the Air Intake and the Combustion Products exit - any Wind in the direction of the Boiler Flue will cause this to be more prevalent - Temperatures of much less Cold than I mentioned should actuate the Boiler Frost Protection.

The People in the Home would obviously be thinking that the Heating is `On` - But the Boiler Frost Protection should not actually Heat Up the Home - just Protect the Boiler from Freezing.

Perhaps the Heating is On during the Day normally - or this situation might have occurred during Cold Days also.

If the Members of the Household are out all Day and the Frost Protection had operated during a Cold Day it would usually Not be detectable because not enough Heat should have circulated around the Heating System for anyone coming in to notice.

But It is very likely that People who are Out all Day will have the Heating Set to come On a couple of Hours before they get Home - so they would definitely NOT know whether the Boiler Frost Protection had operated during the Day.

I can only suggest that on a Cold Night someone stays up and actually `Witnesses` the Boiler Fire Up - it should not run for a Long Period - after which it will Turn Off again - this is how the Boiler Frost Protection works.

BUT If the Heating System gets Hot - as normal it would be unlikely to be the Frost Protection - unless that is not Turning Off when it should after Warming the Boiler - then there is a Problem somewhere else.


Chris

 

[mcm]

hi chris

they said the heating was coming on during the night and it was very warm.

like i described I set the times on the programmer to see if they come on and off as they should and it does. Do you think as its getting warm when its ment to be off that it could be a faulty programmer? they say when it comes on in the night the programmer shows it being off any thoughts.

thanks

 

[chris murphy]

hi chris

they said the heating was coming on during the night and it was very warm.

like i described I set the times on the programmer to see if they come on and off as they should and it does. Do you think as its getting warm when its ment to be off that it could be a faulty programmer? they say when it comes on in the night the programmer shows it being off any thoughts.

thanks

"Hello mcm",

I have never come across a Programmer that caused this to happen - in the last 40 Years that I have been a Heating Installer / Engineer.

Especially as You mentioned that when the Boiler / Heating is On the Programmer shows that it is Off - But I would be interested to see if any of the Electrical Professionals on here do know whether this could ever happen regarding an `Internal Malfunction` of the Programmer - ?

When this happens do You happen to know whether the People in the Home decide to Turn Off the Boiler ? - How have they said that the Heating goes Off - Or does it then continue when the Programmer Setting comes to the Morning `On` Time ?


THIS is very unlikely But:


I am wondering if the Boiler Frost Protection Thermostat is Turning On the Boiler and instead of allowing it to just Fire for a short period of time to `Warm` the Boiler [and as a result of that the surrounding Pipework] - it is not Turning Off the Boiler after a small rise in the Temperature but is allowing it to run for a much longer period of time - ?

That would be a Very Strange situation because at what point would the Frost Protection Thermostat then `Turn Off` the Boiler ?

IF the situation with the Heating Turning On is caused by the Boiler Frost Protection Thermostat and the Boiler is then continuing to Run into the Morning `On` Period as determined by the Programmer because the Frost Thermostat is NOT Turning the Boiler Off when it should perhaps then the Frost Thermostat is being `Overridden` by the Operation of the Programmer / Switched `On` and then the Boiler / Heating System works correctly until the operation of the Frost Protection Thermostat again - ??


I would strongly advise that You contact the Boiler Manufacturer Technical Helpline to ask whether this CAN Happen as they would obviously know more about the `Internal Components and Electrical System` than We could ever `Diagnose` on here.

All of the Well Known Boiler Manufacturers have good Technical Helplines - although obviously they are run to be used by mainly Heating Installers / Engineers. - I would suggest that they will probably advise You that this should be looked at by a Boiler Servicing Engineer - You should obviously not speak as if You would be doing any work to the Boiler.

If that is the case You should definitely advise the People in the Home to arrange for an Engineer who actually works for the Boiler Manufacturer to Inspect / Test the Boiler - NOT an Independent Boiler Engineer - If only because the Manufacturers Engineer would have the Facility to Change the Frost Protection Thermostat straight away if He suspects that is causing the Problem - NOT `Have to Order the Stat`.

Obviously whether the Boiler is being Turned On by the Frost Protection Thermostat or the Programmer the Boiler [Heat] Thermostat governs the `Firing` of the Burners [Room Thermostat should not operate with Frost Protection] - SO even IF the fault is the Frost Thermostat causing the Boiler to be Turned On during the Night - the Boiler Thermostat [Heat Setting] will cause the Burners to be Turned On / Off.

I mention this in case anyone reading the Posts wonders why the Boiler does not just `Keep Firing` if turned on by the [Faulty ?] Frost Protection Thermostat.


I cannot think of any other cause of what You described - I hope to see a couple of opinions about the possibility of the Programmer Malfunctioning and causing this - ?


"Sorry" - that I cannot give You a Definitive Answer to this - In My experience it is a Unique Situation ! - as I have not encountered this - although a Boiler Service Engineer MAY have ?


Regards,


Chris

 

[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)