gas rates combi

[newgas10]

good evening. im due to to take the acs in 4 weeks time and would like some advice. got my portfolio done but the guy i trained with does mainly installs and a bit grumpy!!

combi badge says min rate 7kw max rate 25 kw. run hotwater and get 20kw. do inlet working pressure test on boiler reads 19mb. thus gas meter, pipesize are fine. should you really adjust the gas pressure considering that its gas rate is dependant on rate of hot water flow, thermistors etc so they could be faulty.

ultimately considering it is designed to modualate between 7kw and 25 kw does it really a safety matter if its at 20kw from a safety perspective? thank you. im sure thats not on the acs but would like some advice when i hit the tools

 

[stumpydick]

why is 19 mb "fine"? what is working press measured at meter?

 

[newgas10]

as i said. its a just a scenario . 19 mb inlet working pressure at appliance is fine because 18-20mb i believe is the required inlet working pressure to any boiler

 

[stumpydick]

the reason i mention w.p. at meter is that pipe sizing is crucial, and you are only allowed xxx drop betwixt meter and boiler [with all other appliances operating]. you must ensure basics are correct before gas rating. really ,this should be on combustion chamber,where you will get better help from people cleverer than me. see if you can get on somehow. there are some on this forum who pose as installers, but are chancers, who build up knowledge from snippets of info.

 

[newgas10]

thanks but combustion chamber is only for corgi reg guy and im just starting out in the trade

 

[stumpydick]

yes, you are correct, sorry. corgi book "essential gas safety vol 5" is worth getting, see if you can get one via your registered workmate.

 

[Paul Barker]

In the real world not the scenario if the combi is functioning properly and there is more than 17mbar working pressure the gas rate will be cock on with the controls on max and the bath and basin taps full flow as long as BP is correct. The only time you find the wrong jet is when it's a massive cock up. Seen it twice myself on new appliances one biasi and one alpha in both cases installer error (bought and fitted wrong boiler didn't check gas type
). Frightening thing is neither picked it up, I got called under warrantie to fix boiler.

When there is something wrong the sorts of things you mention it is usually blatantly obvious.

The other obvious cross check is the weir guage thermometer delta T test.

You would never consider adjusting bp out of specified range to achieve specified gas rate. After ensuring correct bp You would find the fault from the following:-

wrong jet, fault, gas supply.

 

[gas4you]

No disrespect, but all these posts of late from the many doing their ACS just goes to show that ACS teaches you absolutely nothing to work in the real world

 

[stumpydick]

paul, his senario states a fault which needs explanation and as he is new, the basics shuold be mentioned.your comment does not apply to zero rated gov. appliances. you cannot check bp on say, vaillant. only inlet pressure and gas rate. there is no jet, they are sometimes a mile out when new. you need an analyser or service call if gas rate is incorrect and you are sure pipe size is adequate

 

[Agile]

thanks but combustion chamber is only for corgi reg guy and im just starting out in the trade

If you can give evidence that you are taking the ACS shortly then you probably can get registered for the combustion chamber where we can give you much more detailed help.

However, its clear that you dont have enough basic understanding to deserve to pass so you are going to have to do a lot of catching up in the next four weeks.

The first port of call would be your college lecturer but that may be too late. Alternatively find a CORGI who is prepared to actually teach you what you need to know.

Dont expect to get paid when you are just learning. I suspect you are getting paid for installation work but without receiving any proper training.

Tony

 

[spacethegas]

Agile.

i can understand where your coming from, but lets face it thats the way things are now. i don't agree with it either, but at least the op is looking for answers.

i think your being a bit harsh.

 

[Agile]

Agile.

i can understand where your coming from, but lets face it thats the way things are now. i don't agree with it either, but at least the op is looking for answers.

i think your being a bit harsh.

I dont think I am being harsh at all. I am trying to help him by making it clear that he needs serious further learning if he is going to have a good chance of passing his ACS.

It even crossed my mind that if he could get himself to London then I could teach him exactly when he needs to know. But thats less likely to be possible and in any case I dont know if he has been taught badly or if he is a bad learner!

I had a rasta rental neighbour who had spent his first 10 adult years on the dole smoking ganja and listening to reggae. He had been sent on a six month crash gas course promoted by BG. Every third week was devoted to customer service issues.

This guy was amazing, I was testing his knowledge and there was nothing I could ask him which he did not immediately answer, UEL, LEL, let by requirements, when you do when you first enter the property etc. I lost touch with him when he was evicted.

Unfortunately, he thought that he was worth £500 a week paid with cash as a trainee, otherwise I would have taken him on as a trial. I did wonder how customers might react to his appearance when he called though. Its very difficult to balance appearance with technical compentence.

Tony