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I was wondering wether anyone could help clarify this question for me from the Gasfitting Craftsman Nov 2007 as the wording is shit house!
Question 3
A contract at a rest home complex requires the removal of an old coal fired boiler and replacement with a natural gas boiler. The boiler is to provide low pressure hot water heating via the existing hot water radiators in each block. 90kW is required for the central heating in each of the four blocks connected to the central boiler house.
If the efficiency of the new boiler is 83%, calculate the minimuminput of the boiler required.
What i cant work out is if the complex requires 90kW (324mj/h) total for heating or if 90kW is required in each of the four blocks (1296mj/h)? I understand there is only 1 boiler but i need to know what its total loading will be!
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How the question reads to me i would say it's 90kw for each block, so it would be 360kw total or 1296mj/h.
Then again how an ordinary person reads these questions to what the pgdb actually mean can be two very different things.
Best of luck.
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Thanks for your take on the question. What bugs me is that you need to use this boiler for the next question in your pipe sizing activity so if you havent understood it correctly your going to miss out on 10 marks for that exercise!
How hard is it to write the question in plain english, its a bloody joke.
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Hi matt, The boiler is to provide low pressure hot water heating via the existing hot water radiators in each block. 90kW is required for the central heating in each of the four blocks connected to the central boiler house.
If the efficiency of the new boiler is 83%, calculate the minimum input of the boiler required.
Surely this statement says that 90kw is required in each of the four blocks that means 4x90kw, how can anyone see it any different? My answer to the question would be:-
4x90=360x3.6=1296 x 17 %(to make it 100% efficient)=220.32+=1516.32Mj/h. What was the answer? You can only answer them as you see them,cheers.
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Hi Matt the question states in each ? they are either trying to confuse people on purpose or they do not understand basic english language. The questions are the same regardless of which exam you sit they are either misleading or open ended . My experience after being here 5 yrs tells me the pgdb dont care. My qualifications are level 3 plumbing drainlaying, d32 assessor/ instructor, corgi domestic /commercial all city and guilds. But here we are just a limited wally. I have written to the pgdb , to the national gov, and the ito and they all couldnt give a monkeys toss. All you can do is keep chipping away at the study, i found the open polytechnic study course very good very helpful. The system here is a closed shop they are looking after their own and they dont want outsiders to infiltrate and thats a fact, sorry about the rant just another pom whinging i suppose exactly how they will address it cheers brian
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Thanks for the response guys its given me a bit to think about. I read the question as 4 x 90kw but that means its a bloody big boiler. Pain in the ass not being able to get the correct answer anywhere.
Thanks for your help.
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hi, i`ve given up trying to figure out "THE BOARD" my advce to anyone in the plum/gas trade and who is young enough(not me)go to university and do an engineering degree(only 3 years),you will be respected and paid well unlike plumbers and gasfitters who should be on $100 per hr for the knowledge that they are expected to know and the exams that they are required to pass,read my posts to see where i am coming from,cheers and good luck with all your efforts.
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Robbo, so is the minimum input 220.32MJ/h or is it 1516.32MJ/h?
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Hi. The way I understand it is
90kw x 4 = 360kw
360kw x 3.6 = 1296mj/hr
1296 mj/hr divided by 83% = 1561.446mj/hr
cheers