Search the forum,

Discuss Low gas rate on Worcester Greenstar Junior 28i in the Gas Engineers Forum area at PlumbersForums.net

Messages
13
Hoping someone can give me advice with this one. At an annual gas service today I found a Worcester Greenstar Junior 28i to be using only running at around 12kW on high when carrying out the gas rate. The CO readings were where they should be, fan speed was okay and inlet working pressure was 22mbar. Can anyone suggest what the problem might be? What was strange to me was the fact that the hot water quality was great with great flow rate. In my experience hot water quality drops significantly when the gas rate is cut back. Part of me thinks there might be an issue with the meter but I’m still quite new to the industry and always looking for input from experienced engineers. Any advice would be greatly appreciated.
 
It might of been tweaked on the gas valve due to the hex being dirty but also might be a faulty meter / reading needs investigate as it’s outside spec
 
Check / confirm with a negative pressure reading on the hex test port in man instructions then clean as per instructions with a new electrodes and bearing plate eg nrv
 
Hate to sound ignorant but what is the hex test port and why would new electrodes be required? I work for a housing association and only change electrodes if there’s an ignition problem or I’m changing the burner seal and the electrodes are beginning to show signs of wear. As for cleaning the heat exchanger, the MIs state this only needs to be done if the fan speed falls below -3.9mbar. I’ve heard in the past low gas rates can be caused by the bearing plate cover sticking but to this day I haven’t had to replace one.
 
:) as it’s a Worcester they require a full strip down clean inc removal of the baffles every 4 years max 5 else they stick / weld themselves in as per photo and you have to replace the hex as the readings skyrocket as the hex becomes blocked with alu oxide and then people instead of fixing the problem tweak the gas valve to reduce the readings to a normal state but the gas rate drops

Hex test point is on the top of the fan with the cover on it in front of you you will need air pressure tube

1670449492073.jpeg
 

Attachments

  • 4CE371C0-0284-4098-8BB0-396A39E158A7.jpeg
    4CE371C0-0284-4098-8BB0-396A39E158A7.jpeg
    399.5 KB · Views: 7
Apologies bro, just me being a tit 😂 I didn’t realise you meant heat exchanger when you were referring to hex test point lol It’s been a long day. Yes I test the fan pressure on every Worcester I work on, I just don’t normally clean the heat exchanger if the fan pressure is still okay. I think what was throwing me today was the fact that the gas rate was so low yet the hot water quality was still really good and the tenant told me that he’s had no issues with his heating. I’ve struggled to get those baffles out in the past myself and had to order a new primary hex. The job can be a ball buster at times. Thanks for your help mate, really appreciate it.
:) as it’s a Worcester they require a full strip down clean inc removal of the baffles every 4 years max 5 else they stick / weld themselves in as per photo and you have to replace the hex as the readings skyrocket as the hex becomes blocked with alu oxide and then people instead of fixing the problem tweak the gas valve to reduce the readings to a normal state but the gas rate drops

Hex test point is on the top of the fan with the cover on it in front of you you will need air pressure tube

View attachment 79840
 
If you have the right temperature rise for the flow rate, the right WP on gas, the right fan/chamber pressure, the gas rate can't be less than half of what it should be. If it is, we all want one lol.

Don't take it wrong but could you have calculated the gas rate wrong?
Could the boiler have stopped during the read (you wouldn't necessarily notice on a digital/electronic meter).
 

Reply to Low gas rate on Worcester Greenstar Junior 28i in the Gas Engineers Forum area at PlumbersForums.net

Creating content since 2001. Untold Media.

OFFICIAL SPONSORS

OFFICIAL SPONSORS

Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock