Central Heating System Failed!

[Jamie757]

Hi all,

First post so bear with me! Earlier today, my central heating/hot water system failed. The system comprises an Ideal Elan 2 boiler, a Honeywell thermostat, two header tanks in the loft and a cylinder in the airing cupboard.

For about a month now, the CH has only been working with the HW switched on and when it is on, the boiler seems to operate for about 30 seconds before switching off again in a repetitive cycle.

Anyway, a little earlier, the boiler stopped operating and I can't get it to light.

If anybody could shed a little light on my problem it would be greatly appreciated!

Best regards, Jamie.

 

[sonray ltd]

has the boiler tripped and needs resetting

 

[Jamie757]

Thanks for your reply, I've shut the boiler down and relit the pilot a couple of times, it just doesn't seem to want to light! The timer (ACL LP241) is calling for heat as far as I can see!

Best regards, Jamie.

 

[sonray ltd]

can you hear the fan etc coming on the boiler before it trys to light ?

 

[Jamie757]

No, it doesn't seem to be making any noises or doing anything, apart from a click after shutting it down.

Rgds.

 

[sonray ltd]

has the programmer still got a display up ?
when calling for heat etc is the pump running ?

 

[Jamie757]

Ok, so the boiler has just sprung back into life after being switched off for about an hour and restarted, the programmer seems as normal, display, indicators illuminated etc.. I can hear a whirring noise coming from the airing cupboard, can't quite tell if it's coming from the silver box (a valve of some sort I assume ) or the pump though.

Think I'll be phoning for an engineer to come and inspect it!

Many thanks for your replies so far, much appreciated! Any info on the other faults, CH only working with HW would be great, then I can get a feel on what may be wrong, possible costs and whatnot!

Best regards, Jamie.

 

[sonray ltd]

your first fault is with the valve it sounds like its a faulty microswitch.

 

[Jamie757]

Many thanks for your help Sonray! Much appreciated!

Regards, Jamie.

 

[gascob]

Jamie, i'd guess you just need a new synchron motor in the valve in your airing cupboard( the silver thing) this is what is stopping your heating coming on alone budget about 18-20 quid for the part... easy to do once power is positivly isolated!! but don't get ripped off by someone saying they will need to change the full valve and drain the system down etc... 20 minute job to just change the motor!!

The elan doesn't have a fan so you won't hear one... if the pilot stays lit but goes out after a minute or so its overheating so i would suspect the pump or a blockage...
hope this helps...

 

[sonray ltd]

gascob

one question. how do you come to the conclussion of a motor ?

the guy has ch only when hw called for. with a failed motor you won't get heating if the hw and heating are called for as the valve will stay in its relaxed position. A shut B open. (unless lever pushed across) which hasn't been done. telling me the motors ok.

the only way to get ch with hw calling is for the motor to wind across to mid position. (motor working) as the live feed will come from the cylinder stat.
if the cyl stat is then satisfied the grey becomes live so feeding the valve.
the only way then to get heating only is the motor winds across to B closed A open so hitting 2nd micro switch giving live down the orange.
if the micro switch is failed you won't get live down the orange.

so unless you can give the correct info on the fault.
your the one suggesting wrong parts.



but don't get ripped off by someone saying they will need to change the full valve and drain the system down etc

 

[Jamie757]

Hi all,

Quick update, thankfully no further problems with the boiler. I haven't been able to call for an engineer due to work at the moment, but I've had a look at the motorised valve, the switch on the bottom of it is in the middle position with the HW switched on, to either side is 'AUTO' and 'MAN OPEN'. With all symptoms as described before, is this where it should be?

I'm a little suspicious of the room thermostat as well to be honest, with the CH on (HW off), the dial doesn't seem to be responding to any changes in room temperaure. For example, the room temp is 20c, the thermostat clicks to call for heat at 15c no matter what. Also, when the stat clicks to start calling for heat, there is no response from the boiler.

Any further help greatly appreciated!

Best regards, Jamie.

 

[sonray ltd]

jamie what make valve is it ?

 

[Jamie757]

Hi there Sonray,

Sorry to have left that detail out, it's a Honeywell V4073A1039.

Regards.

 

[sonray ltd]

this lever is not a position of valve indicator, is is soley for filling the system and moving the valve when the motor fails.

if the lever has no resistance on it it can either be in mid position (hw/heating) or just heating.

you say hw switched on is the heating on at programmer and calling at the wall stat ?

if the heating is on and hw off and wall stat calling and your boiler is not firing up it is as i told you before the micro switch is faulty.




as we have proved the motor is working cause you get heating when the hw calls that proves the valve is moving to mid position.
but when hw satisfied you loose the live.
so thats when the micro switch comes in to give live down the orange.


are you any good with a multi meter ?

 

[Jamie757]

Ok, so from what I can gather, the motorised valve is in the HW/CH position as both cistern and rads are being heated with the HW on. The normal rest position of the valve(CH/HW off) is HW only. Correct me if I've misunderstood.

Just to clarify, the boiler only fires when the HW is on. With the HW off and the CH on and calling, nothing happens. With both HW/CH on, the thermostat doesn't have any effect.

Something I've only just been reminded of, which may be of some importance, the 3A fuse next to the timer blew a while back, coinciding with when the problems started.

I'm handy with a multimeter - I don't have one to hand though.

I've been doing a bit of searching on the interwebs and am curious if it'd be worth me having a go at changing the head on the valve?

Best regards, Jamie.

 

[gascob]

i'd still try the synchron motor, in my experience on a mid position valve if the motor is weak it is enough to turn the valve but not enough to push it all the way to make the microswitch.. infact i can remember several occasions i have come across this..

Jamie when you put the central heating only on push the lever on the mid pos valve across at the same time as you call for heat to give it a helping hand.. if you hear the pump/boiler fire up you will prove the microswitch is ok and its simply the motor that isn't strong enough to power the valve right over..

good luck with it all...

 

[Deleted member 2053]

Honeywell valves do not move to mid position to give hot water heating. That is their rest position. They move to midpoint to give hw and ch simultaneously and then fully across to shut off the HW heating when the cylinder is satisfiied. SO to get HW only all you need to do is to provide a feed to the boiler, and to the pump if the boiler does not control pump over run. Hence if you can get the ch on when you call for HW the valve is moving enough to open the CH flow and the HW call is firing the boiler. If the valve is making a noise then the motor is probably running leaving us only with a failure of the micro switch or of the gears inside the valve. Or gascob is right about the motor simply being weak, though this would be unusual. Generally motors of this type either work or don't work.

 

[sonray ltd]

mid position is not the rest place for a mid position valve.
a mid position valve in its relaxed state is heating port a closed hw port b open.

to get a mid position valve into mid position it needs power to the white.

 

[Deleted member 2053]

Yes sorry for the ambiguity. I meant that hot water open was the rest position not mid-position was the rest position. Maybe I shouldn't write my posts late at night!

 

[Jamie757]

Hi there,

Just to update people, had an engineer round earlier on (friend of the family) who confirmed a problem with one of the microswitches. He advised buying a new valve and fitting it myself. Many thanks for all your replies, very much appreciated!

Best regards, Jamie.

 

[sonray ltd]

glad you have sorted it now.

>Just to update people, had an engineer round earlier on (friend of the family) who confirmed a problem with one of the microswitches.

i rest my case then.

 

[gascob]

not really still gonna be the synchron... but i guess we'll never know.... done one today exact same symptoms...

 

[sonray ltd]

hows it gonna be the synchron motor if its the micro switch faulty.
two totally different faults. two totally different ways of checking.