How to measure volume of L.P. being used

[gpjazz1023]

Does anyone know of an "in-line" flow meter, or gauge, to measure the volume of L.P. gas that is being used by a furnace? I've had a customer ask me about this but I'm not sure if I've seen anything other than the type of meter that natural gas companies would use for the main supply line. And I'm not sure if those type of meters could be calibrated for L.P. The issue in this situation is that the homeowner seems to be using an excessive amount of propane, (or at least the gauge on the L.P. tank says so) but doesn't believe the furnace could be using that much. The home owner is at the mercy of the propane supplier filling the tank properly and charging $$$ accordingly. I have checked the system and found that there are no leaks in any of the lines and the furnace is operationg properly with correct pressure settings and correct orifice's installed for the burners. It is a York 2-Stage furnace at @ 93.7% efficiency. (80,000 btu at high fire) The furnace is the only thing in the house using the propane and the house is also well insulated. Coldest temps in this area have been in the teens and the customer has had their 500 gal tank filled twice already this season. And now the gauge on the tank is nearing empty again. The homeowner and myself just don't believe the gauge on the tank is accurate, but the propane supplier is charging $$$ according to what the gauge says, and not the actual amount of propane in the tank. This is where it would be nice to have an in-line meter to measure exactly how much L.P. is being consumed and verify the problem with the tank. Any feedback on this issue would be greatly appreciated

[cem-bsee]

search online --
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WWGRAINGER
MCMASTERCAR

what is their indoor t-stat setting?
duct leaks?

gal LP vs degreeday vs sq ft?

what does LP supplier say?
how does he know when to fill?

LP trucks I have seen have gauge at "spiggot" which measures delivered quantity --
Let customer ask when it was last calibrated.
Customer can also ask bureau of weights & measures -- just like for gasoline pump check, maybe.

[mayguy]

Wow, that's a lot of gas!

I think my parents burns about 1,000 in a year, and everything in the house is gas (Stove, dryer, fireplace, water heater, and furnace.)

[gpjazz1023]

cem-bsee,
T'stat supposedly kept at 70,, ductwork looks good with supplies & returns in every room (no ret. in kitchen or baths). H.O. hasn't talked to supplier yet. L.P. is filled after cust calls. I'm not too familiar with L.P. trucks. I am located within city limits and primarily see natural gas and some oil. I know oil trucks have gauges to measure delivered quantity but don't know about L.P. trucks. Even so, it's possible that the person filling the tank is only looking at what the gauge on the tank reads and not necessarily what they are actually putting in. Don't know when tank was last calibrated. Homeowner is new to this residence. I do know the propane tank is from 1989. Unless the H.O is opening all the doors and windows after I leave, then I just can't see using 900+ gallons of L.P. within 4 months time of 25 - 30 avg. temps. and a properly functioning high efficient furnace.

[gpjazz1023]

mayguy,
Yes it is a lot. The L.P. is dedicated to the furnace only. Everything else in the house is electric.

[rsmith46]

Just google propane flow meters and you'll find lots of them. The propane supplier has a meter on his truck, he doesnt go by the customers tank guage.

Did the homeowner have the new furnace put in thinking it would be cheap now to heat his house with propane?

[markwolf]

Propane is sold by the gallon using a pump meter alot like the one at the gas station when you fill up.The propane company does not care what the dummy guage on the tank says they are not accurate & only intended for a general guideline.You have either a leak or an energy problem.Check the pressure regulators for leaking vents/failing diaphragams,the tank relief,tank valve packings,tank connections,all threaded & welded fittings on the tank,etc.
a return air in an attic with a missing cap pulling in outdoor air could cause high gas usage,even more so if the fan is run in the on position.An energy audit & looking for leaks would be money well spent.
You said you tested the lines I hope that meant the underground too especially if the tank was set in 89.Dead grass is a telltale sign of underground gas leaks.If there is a patch of dead grass between the tank & house then I would have a new line run even if it had to be on top of the ground for temporary if the ground is frozen.

[beenthere]

As Mark said check that duct work.

Recheck your gas lines.

Look at yur customers LP delievery ticket.
It should be a printed ticket from the meter head of the LP truck, not a hand written ticket.

Could have a dishonest delivery driver, that is topping his own tank before going to your customers house.

Ask your customer to go out to the delivery truck as soon as it gets there next time. He should watch for the driver to insert the ticket. If the ticket is in the meter before the driver gets out of the truck. Have the driver cancel out that ticket and start a new one.

[fixitmanmc]

Had one like this last year & they found the leak in the underground tubing.

[gpjazz1023]

The homeowner is new to this house and the furnace and L.P. tank was already there... I did a pressure check on all lines, including underground, and it tested OK. Also checked around all fittings at tank and regulator. No dead grass anywhere either. Doesn't seem to be a leak of any sort... There are no return ducts in any unconditioned space which would be sucking in cold air... As far as the ticket on the delivery truck, I don't know what the driver does. The delivery always comes when no one is home and then they send the bill later. The receipt/ticket is "printed" but only indicates % of fill "start" and % of fill "stop" and then calculated to gallons filled. It may be a dishonest delivery driver... That's what is trying to be determined. Like I said, the H.O. is new to this house and this is the 1st heating season for them. They have gone through and paid for 900+ gallons of L.P. already. And at $3.13 per gallon, that's an expensive heating bill for average temps in the upper 20's !!

[cem-bsee]

honey bees also like propane --
= good indicator of leaks

[gpjazz1023]

honey bees also like propane --
= good indicator of leaks

No honey bees that we're aware of. At least not yet

[Shophound]

You mention the customer not being present when the tank is filled, possibly indicating house is unoccupied during the day. Does the customer have a setback thermostat, and if so, how sharp of a setback is he using? IOW they might be using up a good amount of gas trying to get the house to occupied setpoint before anyone arrives home. Maybe not THAT much, but it's possible..

[hearthman]

You said it is a 500 gallon tank and two refills yet 900 gallons? Let's see:

500 gallong water capacity x 80% max filling= 400 gallons minus the 20% minimum= 300 gallons of useable fuel. That's three refills.

900 gallons at, let's use 95,000 BTU/ gallon (because this varies with sp. gr.), = 85,500,000 total BTUs comsumed according to your delivery guy. Divide that by your 80,000 BTU/hr burner (on high) and you get 1068.75 hours of burning at full blast! That's 44.53 days of burning full blast constantly!

Now, let's say you were confused and mean to say the tank was stamped 500 w.c. or water capacity. If that tank can hold 500 lbs of water, which, at 8.25 pounds per gallon equals 60.6 gallons of liquid stuff. Now, since you cannot fill over 80% or let it run under 20%, you have only 60% useable fuel or 24.24 gallons per tank. That 900 gallons of fuel would have refilled 37 of this size tank.

Clearly, my math is way off or the LP supplier is. Someone correct my math, please.

You can pass a static pressure test but still have a bad diaphragm. Does this system have two stage regulation or just a single stage? If it freezes up, the diaphragm could leak fuel out the vent.

If this clown is printing tickets off the tank's % gauge and estimating the bill, call the District Attorney's office and the State Bureau of Weights and Measures. This sounds about as crooked as a dog's hind leg. ;)


FYI, you can install a gas meter on LP. You'll need a temperature compensating meter then just do the math to convert your readings. The actual flow is 0.64% of the meter reading based on a sp. gr. of 1.53. I have one in my shop with the conversion formula written on it.

HTH

[gpjazz1023]

You mention the customer not being present when the tank is filled, possibly indicating house is unoccupied during the day. Does the customer have a setback thermostat, and if so, how sharp of a setback is he using? IOW they might be using up a good amount of gas trying to get the house to occupied setpoint before anyone arrives home. Maybe not THAT much, but it's possible..

No, cust does not have setback t'stat. White Rodgers 80 series non-prog. But that doesn't mean the cust is not manually turning temp down when no one is home then back up again. They claim they are not, but...

[gpjazz1023]

You said it is a 500 gallon tank and two refills yet 900 gallons? Let's see:

500 gallong water capacity x 80% max filling= 400 gallons minus the 20% minimum= 300 gallons of useable fuel. That's three refills.

900 gallons at, let's use 95,000 BTU/ gallon (because this varies with sp. gr.), = 85,500,000 total BTUs comsumed according to your delivery guy. Divide that by your 80,000 BTU/hr burner (on high) and you get 1068.75 hours of burning at full blast! That's 44.53 days of burning full blast constantly!

Now, let's say you were confused and mean to say the tank was stamped 500 w.c. or water capacity. If that tank can hold 500 lbs of water, which, at 8.25 pounds per gallon equals 60.6 gallons of liquid stuff. Now, since you cannot fill over 80% or let it run under 20%, you have only 60% useable fuel or 24.24 gallons per tank. That 900 gallons of fuel would have refilled 37 of this size tank.

Clearly, my math is way off or the LP supplier is. Someone correct my math, please.

You can pass a static pressure test but still have a bad diaphragm. Does this system have two stage regulation or just a single stage? If it freezes up, the diaphragm could leak fuel out the vent.

If this clown is printing tickets off the tank's % gauge and estimating the bill, call the District Attorney's office and the State Bureau of Weights and Measures. This sounds about as crooked as a dog's hind leg. ;)


FYI, you can install a gas meter on LP. You'll need a temperature compensating meter then just do the math to convert your readings. The actual flow is 0.64% of the meter reading based on a sp. gr. of 1.53. I have one in my shop with the conversion formula written on it.

HTH

The tank is stamped "500 gallon" . When the HO 1st moved to this residence there was some L.P. in tank. Using the tank gauge to est. gallons left in tank initially plus what the supplier has charged the customer for is what adds up to the 900 gallons mentioned. The system has only single stage regulator. And there are no signs of the vent leaking. (at least you can't ever smell it anytime you are there to check)
Question hearthman... You stated 95,000 btu/gal. Where does that number come from? I have not dealt with L.P. very much in my area and I'm not completely familiar with all the specific details of it. And I have learned that a natural gas meter can be used, but not sure how exactly to convert the readings. What is the conversion formula for L.P.?

[hearthman]

Is this a buried ASME container or a vertical DOT cylinder? Can you provide what it says the "w.c." is?
The industry posts various values for propane per gallon. However, LP gas is not just propane. It is a blend of various hydrocarbons. The more crap in there usually the higher the BTU content, the higher the specific gravity and vapor density and the lower the grade it is considered. The "good stuff" with a sp. gr. of 1.50 and a vapor density of 0.504 would be, for example HD-5 super high grade. That's 95% propane and less then 5% ethane. I have it in a pipeline from Belvedere, Tx to Chester Co, Pa. However, since there are about 300 refineries serving the U.S., I could get 1.56 sp. gr., 0.550+ vapor density crap that soots the hell out of everything.

NFPA 58 required 2 stage regulation on all residential except BBQ grilles. Must be changed.

Using a temp. compensated NG meter, connect it in series and run it for as long as you can. The longer, the more accurate. Try for at least 30 days. Read the dials and calculate the cubic feet. Multiply this number by 0.64 to covert the reading to LP.

Now, There are approx. 2,488 BTU per cubic foot; 21,548 BTU/ pound of liquid phase fuel at 1.50 sp. gr.--more for higher sp. gr.s. Propane expands 270x when it vaporizes. There are 36.38 cubic feet per gallon or 8.66 cubic feet of vapor per pound of propane.

So, 500 gallons would make 18,190 cubic feet you should have read through the meter. Take 500 gallons x 91,502 btu/ gallon=45,751,000 BTUs in that tank. Divide that by 80,000 BTU input from the furnace and you get 571 hours of firing on high per full tank, which equals 23.82 days firing full last on high.

FYI, Bobtail delivery trucks have meters that read the gallons dispensed. This is required for record keeping. Older units use a rotary dial while newer ones have a digital readout at the rear with a printout in the cab.

HTH

[gpjazz1023]

hearthman,, thank you for the info. The tank is not buried and it's not a vertical cylinder. It is positioned horizontal... looks like a tylenol. I can get the "w.c." but don't know it right now. And I will certainly do the research on 2 stage regulation and bring it up to the customer. Would that be the customers responsibility or the L.P. suppliers? Now that it's getting towards the end of the heating season, all this will be less of a concern right now. But this issue is not gonna go away or change itself for next year. So I am still gonna keep looking for answers to help resolve the situation.

[dan sw fl]

They have gone through and paid for 900+ gallons of L.P. already. And at $3.13 per gallon, that's an expensive heating bill for average temps in the upper 20's !!

Now you can offer to install a heat pump !