ACS Question stumped me

[ShaunCorbs]

The correct answers are the blue arrows... but by my books are wrong.

I`ve done the course I have my ACS theory in just over a week 🙁

With q 30 I think your getting confused with insulated twin wall flue pipe

In your books there should be a maximum length for single wall flue pipe, also should say about condensation either just before or after

 

[AnonPlumber]

I Don't mean to come off impolite I just edited this for brevity.

Q28... I'm looking in my Site Guide, the answer is clearly 1500mm not 600mm. Not once is 600mm a minimum horizontal dimension regarding OF terminals. Therefore I was correct and the online test was wrong?

Q30... "A" and "C" are both true.

I can find no reference to insulating single wall flues in roof spaces only that its not good to install single wall flue in roof spaces to begin with (regarding roof voids as external environments). Therefore I was correct again?

 

[ShaunCorbs]

23 have a read of this

http://www.pearsonschoolsandfecolle...-in-Plumbing-Studies/Samples/Level3GAS_SB.pdf

30 what statement is not true b and c are true so it only got a left which is not true

 

[AnonPlumber]

23 have a read of this

http://www.pearsonschoolsandfecolle...-in-Plumbing-Studies/Samples/Level3GAS_SB.pdf

30 what statement is not true b and c are true so it only got a left which is not true

Although that document has a lot more information in it and is better organised than the On Site Guide I have been working from the information regarding the horizontal minimum is the same.

Are you saying that it is not 1500mm and should be 600mm?

Also in that document are the exact same tables and diagrams of dimensions regarding Open Flue Terminal placement and minimum clearances that are in the "On Site Guide" I referred to earlier.

Am I incorrect in saying that you don't insulate a single walled flue in an external environment? By the document you linked installing a single walled flue is an absolute no no in external environments so B) is even more wrong.

I'm not gas safe yet but there is definitely something wrong here. Either "I don't get it" in which case I`m in serious trouble or something else is wrong in which case I`m in trouble anyway 🙁

 

[ShaunCorbs]

Although that document has a lot more information in it and is better organised than the On Site Guide I have been working from the information regarding the horizontal minimum is the same.

Are you saying that it is not 1500mm and should be 600mm?

Also in that document are the exact same tables and diagrams of dimensions regarding Open Flue Terminal placement and minimum clearances that are in the "On Site Guide" I referred to earlier.

Am I incorrect in saying that you don't insulate a single walled flue in an external environment? By the document you linked installing a single walled flue is an absolute no no in external environments so B) is even more wrong.

I'm not gas safe yet but there is definitely something wrong here. Either "I don't get it" in which case I`m in serious trouble or something else is wrong in which case I`m in trouble anyway 🙁

Depends on roof angle as it doesn't say, just says steep I would go for more than 45D measurement,

You can't have single wall flue externally, in a loft isn't external

and depending on length and dia it may need to be insulated

Tbh it sounds like you need a few more lessons

 

[Jehannum]

Yeah I hear you. However I just found this one... If you convert the values to either m3/hr or ft3/hr you can answer either C/D. They were looking for the answer in ft3 apparently. The Answer should have been, 94.7 ft3, 2.65 m3 by my math.

View attachment 29578

The fact that they're using units of volume for flow rate (missing the "per hour" bit) would make me mistrust this exam as a whole. It might be OK for practice but I wouldn't fret too much over individual questions.

As for the bathroom question, Technical Bulletin 001, situation 7.5 states that a flueless or non-room-sealed appliance in room containing a bath or shower is ID.

Excessive water vapour in air adversely affects combustion. This is why Regulations prohibit non-room sealed appliances in bath or shower rooms. If an appliance takes its combustion air from a bathroom then obviously the same problem is going to manifest. ID is a perfectly reasonable answer.

The open flue / roof question is complete nonsense and it's very badly worded. The correct answer should be 1500 mm.

 

[Chuck]

Yeah I hear you. However I just found this one... If you convert the values to either m3/hr or ft3/hr you can answer either C/D. They were looking for the answer in ft3 apparently. The Answer should have been, 94.7 ft3, 2.65 m3 by my math.

View attachment 29578

(1 ft^3 / rev) * (1 rev / 38 s) * (3600 s / hr) = 94.74 ft^3 / hr

1 m^3 = 35.32 ft^3
=> 1 = (35.32 ft^3 / 1 m^3)
=> 1 = (1 m^3 / 35.32 ft^3)

Hence (94.74 ft^3 / hr) * (1m^3 / 35.32 ft^3) = 2.682 m^3 / hr

So D seems to be the answer expected.

There is a technical issue with the question. This is that ft^3 is a 'volume' not a 'rate'.

 

[ShaunCorbs]

(1 ft^3 / rev) * (1 rev / 38 s) * (3600 s / hr) = 94.74 ft^3 / hr

1 m^3 = 35.32 ft^3
=> 1 = (35.32 ft^3 / 1 m^3)
=> 1 = (1 m^3 / 35.32 ft^3)

Hence (94.74 ft^3 / hr) * (1m^3 / 35.32 ft^3) = 2.682 m^3 / hr

So D seems to be the answer expected.

There is a technical issue with the question. This is that ft^3 is a 'volume' not a 'rate'.

Agree with the calcs but we gas rate appliances, it's been classified as that for years

Gas Rate = the amount of gas used in an hour / range rated

 

[Chuck]

Agree with the calcs but we gas rate appliances, it's been classified as that for years

Gas Rate = the amount of gas used in an hour / range rated

Interesting. I'm not an installer and am not familiar with that convention.

I've only come across 'gas rate' as an abreviation for 'gas volumetric flow rate' with volume/time units, e.g. on the HHIC benchmark checklist via WB:

"Gas rate [ ] m^3/hr or [ ] ft^3/hr"

or as a power, e.g. in kW, e.g. the 1989 Gas Cooker Regs

"in the case of an appliance fitted with a burner the ignition of which can take place in a closed compartment with the door closed, the gas rate to any such burner which is not controlled by a flame supervision device does not exceed 600 watts;"

 

[Jehannum]

Any 'rate' necessarily includes a time component; otherwise it's not really a rate but an 'amount'.

Every appliance manufacturer's instructions I've seen uses "ft3 / h" or "m3 / h" as the unit of gas rate. This makes sense because the time component (hour) is included in the information. If it were not, you'd have to know the convention that it meant gas consumption in an hour. It wouldn't be self-contained information. It would also be dimensionally incorrect, i.e. the units would not work out properly if you used it as part of a formula.