Heating system stopped working Thorm Apollo Boiler

[energy-saver]

Hi Guys,

I've been helping a friend with no heating or hot water over Christmas at all!

Another mutual friend (commercial heating engineer) confirmed pump had gone; it was banging about beforehand.

I fitted a replacement pump OK, filled system with water (could probably do with a proper flush as its quite old& dirty looking) and fired up. All seemed well, boiler lit, pump working ok, and hot water cylinder soon filled with lovely hot water. But I noticed at no time did rads get warm!

I checked most rads and all had water squirting out when bled. Before it failed, but noticed that when I turned down room stat, boiler went out (twice checked this) On third time boiler & pilot went out. Re-lit pilot several times but now it won't stay lit when system is switched on.

The motorised valve is within a big blue box on pipework next to tank. It'smarked with "heating" position and "hot water" position as well as (I think) two other posiions but I notice when it failed it was in hot water position - if that's significant. Any advice help would be grateful. Friend is spinster and not easily able to pay for expert engineer (which is where I try and help...)

I can tackle most things but will always leave a gas job for a CORGI expert engineer. So for example I'm happy to try thermocuple if it may be that but not the gas valve . All your expert views are welcomed. Many thanks.

 

[technical engineer]

try to relit the pilot first off and hold the green button in for at least 3 mins if the pilot doesn't hold check that the thermocouple is screwed into the interrupter properly then retry again if no joy thermocouple needs changing there not the best to change and you will need a corgi bloke to do it as safety is a big aspect in changing this thermoucple its pretty it can be pretty tricky if you don't have acess the corgi bloke will and must assure that all seals are in tack failure to do so could result in injury or death

 

[petit_pablo]

When the system is calling for heat does the valve move to heating or stay in hot water position. Im assuming it stays in hw as that valve would rest in heating unless there is a demand for hw again.

There is an interrupter overheat that quite probably knocked out the pilot too. Was the heating on for a while before it knocked the pilot out?

Is start by checking the function of the motorised valve

 

[technical engineer]

forgot to mention that its worth checking to make sure the pump is running, the h section is not blocked up with sludge and the 3 port valve is not jammed up with sludge and not cuasing the boiler to overheat as that would knock that pilot out also

 

[energy-saver]

Thanks guy's for help thus far.

I think the MV stopped in the "hot water" position but the rads never heated up at any time. Note also the comment on safety on the thermocouple and will take onboard.

System ran for over 20mins certainly long enough for a full tank of hot water be built up from completely cold start, but no htg at any time, no pipes or rads. All heat was contained with A/C pipework and cylinder.

Is it coincidence thermocuple could go at the same time as the pump, or does one cause the other?

I don't understand why room stat being turned up (clicked on) would switch OFF boiler then switch boiler on again when roomstat clicked down (clicked off)

 

[bones001]

try to relit the pilot first off and hold the green button in for at least 3 mins

what are you talking about 3 minutes? 10 seconds is long enough for a thermocouple to produce enough voltage to hold the electromagnet

if the pilot doesn't hold check that the thermocouple is screwed into the interrupter properly then retry again if no joy thermocouple needs changing

if there is an interrupter (overheat stat) then how can you tell thats not faulty?? how can you tell its not a faulty electromagnet in the gas valve?? if the thermocouple produces around 25mvDC after 10-15 seconds it is fine