Clocking my gas meter

nicholas bonham-carter

On my Peerless 211A, 1,050,000 BTU, the 10 cubic foot gas meter dial takes 38 seconds to make a complete rotation.
Does that equate to that input?—NBC

JUGHNE

3600 X 10 X 1000 = 36,000,000 / 38 seconds = 947,368 BTUH.

The 1000 is the btu content per cubic foot. It could be higher.
MUD could tell you the btu content. Sometimes 1040.

In that case 37,440,000/ 38 =985,263 btuh.

Sounds right?

Zman

There is probably more than one way to slice this. Assuming you are working with low-pressure gas, I would figure it like this.
10,370 (BTU content of 10 CF) /38= 272.895 BTU/second.
272.895 x 60 = 16,373.67 BTU/minute
16,373.67 x 60 = 982,421 BTU/hour

JUGHNE

Zman, I wouldn't do it that way without a calculator! too many decimals

EBEBRATT-Ed

60 min in an hour 60 seconds in a minuite= 60 x60=3,600 seconds / hour

3600 sec/38 seconds =94.73 10 cfh revolutions/hour.

94.73 x 10=947.37 x 1000btu/cubic ft of gas (assuming your gas is 1000 btu/cu ft) =947,368 BTU/hour

EBEBRATT-Ed

This might help

PC7060

at close to a million btu a hour the differences between the 3 responses are pretty small.  Almost in the fly poo in the pepper range. 

Zman

The only difference is the assumption of BTU content.
This thread has great info on cheater cards and pressure compensation. https://forum.heatinghelp.com/discussion/180758/wallet-cards-for-clocking-gas-meters#latest

Chris_L

Does your gas bill list the BTU content? If so, no need for assumptions.

In many places, gas is billed in therms or other energy units (BTUs or multiples thereof). Since the meter measurement is always volumetric, the bill shows the conversion from volume units to energy units.

For example, my last bill from what was once Boston Gas has a "thermal factor" of 1.0304, i.e., 1030.4 BTU/cubic foot.

nicholas bonham-carter

Thanks all-So it appears I am pretty close to the rated input.
last winter, during a cold snap here, I noticed my pressure getting up beyond a pound, which almost never happens. I read that our gas company were mixing other gasses into the mix, and thought maybe the BTU value was higher.
Since then I have taken down all my 17 Gorton 2’s, and rinsed them out, as I noticed my back pressure of venting was up to 4 ounces, instead of under 2!
when it’s a bit more chilly out, I will observe again.—NBC 

EBEBRATT-Ed

@nicholas bonham-carter

The gas company especially in areas with low pressure mains or anywhere where they are hurting for capacity when it's cold out they jamb propane into the mix to keep the pressure up.

It's called "shaving" but I don't know why they call it that

PC7060

EBEBRATT-Ed said:

@nicholas bonham-carter The gas company especially in areas with low pressure mains or anywhere where they are hurting for capacity when it's cold out they jamb propane into the mix to keep the pressure up. It's called "shaving" but I don't know why they call it that

Seems like it should called “boosting” since propane has 2.5x the BTU of same volume of NG. Wondering if they mix it with nitrogen to get the right energy mix. 

nicholas bonham-carter

Still working on this, and because of the suspected over-firing, I think my 0-15 oz. gauge has been tweaked, so it does not rest at zero. Both gauges-boiler, and rad have been affected.
I wonder if it is worth an attempted repair.
I did have someone put a gauge on the gas line test port, and the pressure is in spec; however that was during higher daytime temperatures, when they might not have juiced the gas mix and pressure.—NBC 

ratio

Have you tried zeroing the gauge? Adjust the li'l screw in the middle (with the + & - sign) until the needle rests on zero—I turn it back & forth a few times so it's not loaded one direction more than the other. Use the right screwdriver, too big a head will tear up the slot in the screw.

JUGHNE

NBC, wouldn't the vaporstat have controlled the pressure to prevent over pressuring?

Are you sure that gauge wasn't pulled back by vacuum?

Is there a stop peg for the needle?

EBEBRATT-Ed

@nicholas bonham-carter

Decent gauges like the one you have can be adjusted as @ratio mentionned

nicholas bonham-carter

There are 2 screws-one marked +, and the other marked -
I’ll have to visit the Wika website, and see what information is there.—NBC 

ratio

I think you'll find the two outer screws hold the face on, and the '+' and '-' are directions for the center screw.

nicholas bonham-carter

I turned the zero adjustment screw, and still no joy, so my WIKA 0-15 ounce gauges need replacement.
Can anyone recommend another low pressure gauge with better vacuum resistance, (maybe Dwyer?), while I work on solving my vacuum problem?—NBC

neilc

a compound gage ?
15 0 15 ?

nicholas bonham-carter

Ideally, a compound gauge with a big scale showing ounces on the positive end of the scale, and able to tolerate a vacuum.—NBC 

Chris_L

Did you remove the gauge before trying to zero it? And make sure there is no water in it?

The pigtail can create a vacuum. If water gets into many low-pressure gauges, it can cause an inaccurate reading (unless the gauge is specifically designed for liquids).

Daveinscranton

Maybe a big big water manometer.  Could see vacuum and pressure.

ethicalpaul

This one is kinda pricey for eBay but search for similar ones: https://www.ebay.com/itm/234330450621?hash=item368f2eeabd:g:zPEAAOSwCJBhtL9y

This model handles +/- 15 psi regardless of the gauge range

fentonc

I just tried this measurement for my nominally 140K BTU/hr boiler, and it clocked in at 120 ft^3/hr, or 123,360 BTU/hr with the conversion factor provided by my utility. That's only 88% of its rated output - I'm surprised it was off by that much! Is that primarily because the utility is providing lower pressure than the nominal input pressure the boiler is rated at?