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# how to tell btu input when label is missing?

Member Posts: 6
If gas and if you have orfice drills take out one orfice check size then times the amount of burners you have. This works on the smaller units.

• Posts: 0
how can i tell the btu input of a boiler

whose label plate is missing?
• Posts: 0
its gas-- (nm)

• Member Posts: 2,542
Using a stop watch...

find out how many seconds it take for one complete revolution of the smallest reading dial, usually 1/2, 1 or 5 Cubic Feet indicator. Then using a calculator, take 3600 and divide it by the number of elapsed seconds for one complete revolution. Take the result of that number and multiply it times the unit of measure for the one revolution (usually either 1/2, 1 or 5 cubic feet),then take the result of the calculation and multiply it times the caloric content of the gas you have in your area (depends on altitude and supplier). The resultant number is the btuh input of that appliance.

Make sure that you have all other gas appliances served by this meter off line during this test or your results will be skewed.

Good Luck

ME

• Posts: 0
thanks Mark

i had a customer ask me, his plate was missing...i told him i'd get back to him on it, i knew there was a method but had never had to do it before. thanks.
• Member Posts: 75
Mark

??? then take the result of the calculation and multiply it times the caloric content of the gas you have in your area (depends on altitude and supplier).

never heard of this, what is it??

Chris
• Member Posts: 2,542
In Denver and the metro area

it varies between 1050 at the well head and 600 at 10,000 feet ASL. In most other low altitude areas, it is around 1,000 btus per cubic foot.

Best bet is to check with your fuel purveyor.

ME

• Member Posts: 2,542

using the larger dial reading usually gives you a more stable reading. Sometimes, the 1/2 Cu Ft needle is pretty jerky.

ME

• Member Posts: 75
.

next time I see my propane supplier, I will ask. I wonder if they know, and I bet they have never been asked before!

Chris
• Member Posts: 6,106
Clocking a gas meter from Bacharachs site

here is a link from perhaps the best technical training website around.

http://www.bacharach-training.com/referpage/clocking_gas_meter.htm

hot rod

• Member Posts: 855
lower cv ..

or calorific value is directly related to elevation and available oxygen. On nat gas appliances up to 400,000 btuh (120kwh) - it must bear a rating plate for high altitude (up to 4500 feet) above that derate 4%/1000ft. It's not uncommon for a customer to plunk down an LPG unit at the 8500 ft level of his favourite cat ski operation and watch a greasy yellow flame.
Cheers
Glen
• Member Posts: 410
Also, clocking meter the meter is...

a great way to check if a Natural gas boiler is at the proper firing rate. I've find that probably 10 to 15 % are underfiring.... mainly due to undersized gas lines or Honeywell gas valves not passing the gas they are rated for.
I clock the meter on every new install!

Boilerpro
• LP Gas

Chris most LP gas people use 2550 as the BTU content for their gas with 1.52 specific gravity.
• If you are interested

I have a Troubleshooting Guide availabe that explains all the procedures for measuring input with both natural gas and propane with the factors for altitude adjustment.

Just another point if you have AMR on the natural gas meter. That is an Automatic Meter Reading device, no more meter readers coming to the house, then do not use the 1/2 foot dial as it is erratic with that device. Better to use the 2 foot or 5 foot dials.
• Member Posts: 186
burner count

after doing the calc as suggested. Divide the input calculated by 15,000 the integer should be equal to the number of burner tubes. (Each Burner Tube usually puts out around 15MBH
• Member Posts: 186
burner count

after doing the calc as suggested. Divide the input calculated by 15,000 the integer should be equal to the number of burner tubes. (Each Burner Tube usually puts out around 15MBH
• Member Posts: 43
is there any other identifying marks that would

give you a clue as to who the manufacturer is? If you post a pic, someone could tell you what is is.
• Member Posts: 79
It sounds like

you are trying to size the boiler for replacement, it maybe over sized why not do a heat loss calculation?
• Member Posts: 83
Why do we have to make this so complicated?

The easy way to "clock" a natural gas appliance is to shut down all gas burning equipment except the appliance being clocked. Start the burner running until the flue is hot and you are at steady state. Count the number of revolutions on the 1/2 foot dial of the gas meter for exactly one minute. Multiply the revolutions by 30. The result will tell you how many cubic feet per hour the burner is utilizing. In most parts of the country natural gas has a heating value averaging around 1000 BTUs per cubic foot. EXAMPLE: 2.5 revs/min. X 30 = 75. This is equal to 75,000 BTU/Hr. 4 revs/min. X 30 = 120. This is equal to 120,000 BTU/HR.
• I assume you are talking

about gas buners. They are not all 15,000. It depends on the size of the orifices as to how many BTU's per burner, then take the number of burners times BTU's per burner for total input.
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