Performa 24 Eco 24 Gas rate well under...

[ChrisR]

Commissioning one of these, I found boiler input working pressure 19mbar, Burner pressure 10+mbar (correct), Gas rate (input!) equivalent to 21kW. Temp rise below book figure but I didn't have full thermometer kit with me. Flame picture identical on all burners.
Called Potty (21 mins), they had no suggestions except an engineer call out.
Main question is whether anyone has seen similar.
Second question - it's hardly unsafe, but how low would it have to be to be AR?!

 

[chrishutt]

Could the low input reading be due to inaccurate measurement of gas by meter? Hard to think of other explanation off hand (unless it had wrong size injectors!).

As for "at risk" situation arising, as long as burner pressure was above minimum and ignition gas rate levels, I can't see that there would be any "risk", just gross inconvenience at low heat output. The boiler would normally modulate anyway towards the low burner pressure setting (maybe around 2 mb?).

 

[blahblah]

Hi Chris,
Isn't there a Potty engineer who posts on here? Can't see that at risk comes into it if the supply is there and the boiler's just not using it. Some kind of sensor type fault not letting it get there perhaps? Can you set ch to full output on those and see if burns to max?

 

[Baxi-Remeha]

imput gas pressure is ok, burner presure ok, temp rise questionable???

check your flow rate, if the flow is too high, you wont get the temp rise, as there is no flow erstrictor.....

 

[blahblah]

Having read (and hopefully not mis-read) the question again -my post was bollx. Thought you were saying it wasn't rating high enough- but its only a baby isn't it? Just too used to 35kw I suppose. Thought it was a bit obvious for one so knowledgible- should have known better!

 

[ChrisR]

It's s 24kW combi - or supposed to be. On my last ACS I learned that tolerance on gas rate is + 5%, -10%, but it's worse than that. I suppose that makes it NTCS.
I thought that one of the injectors might have had a bit of swarf or summat, but all the burner bars' flames looked identical.

One - the only - possibility I could think of was a set of undersized injectors, which seems unlikely. It didn't occur to me the meter might be going slow!
(Remember burner pressure was spot on)

 

[doitall]

What is the gas rate after 10mins Chris. should be 2.62 m³hr.

Perhaps the valve is sticking.

Injectors should be 15 x 1.18mm or 0.77 for LPG

 

[ChrisR]

The gas rate didn't change really from near cold through to warm.
I did check against the book figure!

I didn't dismantle far enough to get to the injectors, and I don't have anything other than hss drill to check the 1.18mm!