Worcester Greenstar Junior CH problems

[tennooge]

Hi guys

I'm a gas safe engineer and am currently struggling with a breakdown.

I was called to the property to fit a new filling loop (remove external and fit worcester integral filling loop) and service the boiler.

I've fitted the filling loop and all seems fine. I then went on to service the boiler, cleaning condensate trap etc and checking CO, Co2%, ratios. I set the Co2 to 9.2% as it was a little low.

Since doing the above I've been called back because the heating fires up, runs at full rate for about 5 seconds, modulates down and then shuts down and does this over and over again, HOT WATER IS WORKING FINE. I've checked the flow temp and it never gets above 45 deg (I can only check the pipe work from the heat exchanger, what the actual temp is inside, i'm not sure.). I spoke to worcester technical and they advised me to fit a new primary thermistor - Done but to no avail. The radiators do eventually get warm, but not hot. It's almost as if there's an air lock or restriction somewhere (Pump working fine). I've checked the diverter valve and the motor is working fine. I was advised again by technical to replace diverter valve mixer module in case it is not fully diverting flow to ch circuit - so this is my next port of call, unless anyone has any thoughts. The customer has also had to reset the boiler a few time because it's locked out (flashing red reset light) - Possible overheat.

I've also checked the system for sludge and all seems well - system was flushed 2 years ago and treated with inhibitor.

Any advise would be appreciated as I think the customer is going to lose faith. I can't imagine that the service I carried out would have caused the above, but I can hear the customers voice now in my head saying the classic "It wasn't like that before you touched it!"

Cheers

Dave

 

[Millsy 82]

Have you set high and low CO2 look in MI's.

 

[jtsplumbing]

Its not somthing silly like you forgot to open the valves under the boiler (F & R)

 

[villa_tom]

Have you set high and low CO2 look in MI's.

I would go with this aswell.

 

[tennooge]

Looks like it was the CO2. My flue gas analyzer (Spint V2) had gone **** up and was giving me false readings. A few days after this job, it failed on me completely and wouldn't display o2, ratios etc. Sent it off to Gas & Environmental Services Ltd (great service) and they replaced the O2 sensor and calibrated. I've since been back and rechecked levels, sure enough, the O2 levels were way out of whack.. So, just goes to show you can't always trust your analyzer even if it is within calibration period (due 22/10/12)!! It was pretty embarrassing explaining to the customer that my tools were at fault..

 

[DirksPlumbing]

Looks like it was the CO2. My flue gas analyzer (Spint V2) had gone **** up and was giving me false readings.

I would still advise you to have another read of the manual regarding CO2 on this. The Junior normally has a high 9.8 and low 9.2 setting which does not mean that this can be between 9.2 and 9.8 but 9.2 +-0.2 in the low setting and 9.8 +-0.2 in the high setting.
Might be wrong but I think its 5 flashes for high and 3 for low?

add on: By the way, if it is been out check the inlet pressure. But it might indeed just have been the FGA.

 

[desrob]

little suspicious my friend i'd be relieved to blame the analyzer

 

[arran197]

I can't remember the number of times this has happened after someone has serviced a boiler and adjusted the gas valve wrong. I'm not saying I disbelieve you, just that it's a common thing. I had a Baxi doing the same recently that was extremely out. I was cautious that what I was doing was actually working, because it was so far out.

Just make sure when ever you adjust a gas valve you check it on both high and low afterwards to ensure it's working ok.

 

[Nostrum]

I am forever resetting these gas valves because engineers don't read the book and use the 4mm allen key (MIN) to adjust the MAX setting. This is the result every time, failure to stay alight on low flame.

Not saying this is what happened in this instance, but it is a common occurrence for me at the moment (at least twice a week!)

 

[tennooge]

I am fully aware of the service procedure :fuk2: As mentioned in my first post. High CO2 was fine, checked low CO2 and it was a little low and made the adjustment back to 9.2%. At this point I've obviously set this value wrong, probably because my FGA was on the blink. I'm almost certain it was the machine and not human error - I'm quite capable of reading numbers. The next time I went to use the FGA it would not display readings for CO, CO2, Ratios just a "###". Anyway, all is back to normal now. Thanks for your replies.

 

[Kev the gas]

Loving the smiley !!

Dont know how long it will stay there for tho !!!