My MILs house currently has a propane furnace. This is her first winter living there (just outside of Hearne, so not super cold). However, her furnace is burning through propane like it's going out of style. We already had everything checked for leaks. That was addressed, and we thought we were good, but if she turns her heat on, she is burning around 20 gallons of propane a day. Without the heater on, her propane use is almost nonexistent despite the dryer, stove/oven, and water heater all being gas.

The furnace she has was installed in 2009. So not super new, but also not super old (her HVAC is REALLY old, but it runs like a champ, and we like it that way lol).

She just wants to get a larger tank (currently has a 250 gallon tank), but that doesn't address the insane gas usage, which is quite costly.

Am I crazy for thinking that, instead of getting a larger tank and spending $500-1200/month on gas in the winter, money would be better spent looking at upgrading the furnace and potentially going to electric?

That's kind of my concern, but I know everything *should* be in good working condition. The house was purchased this summer, and as part of the sale, we had an AC/heat specific inspection done since it is such an old unit. Everything checked out fine. The house was largely unoccupied from when purchased until about mid December.

Who checked her system? Propane company? HVAC company? Home inspector?

Our 18-in propane logs can heat 1000-1500sf house in normal winters if full time
but it runs ~7.5-12hrs/day @ 2.5-4gal/day

Your 20gal/day would then suggest a 6000sf house or 160000BTU furnace, so EZ to agree something's fishy in Denmark ... ignoring WH, Dryer, Cooking, etc. e.g.
Most furnaces fall somewhere in the 80,000 to 100,000 BTUs
water heaters have a BTU rating of 30,000 to 40,000 BTUs that don't run all the time
Burners with a mid-sized BTU range between 2,000 and 18,000 and are on-off
most ovens delivering around 16,000 total BTU, running maybe 4hrs when on


Propane heat alernatives
heat pumps to be 5 to 25% higher costs than propane furnaces
Mini-split (heat pumps) can be as efficient as propane & more room-room comfortable, even in 17d winters BUT, the interior units are not pretty and must drain to the exterior (exceptions apply)

It seems obvious to me that the best path is
propane heater is repaired or replaced while checking DUCTS for leaks, then insulating them where possible & safe +
as large a propane tank as she can afford (propane isn't perishable and thus purchased in bulk when summer prices are low) +
obtain the propane bills past!

Please let us know this mystery ending ....

hillcountryag86 said:

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Who checked her system? Propane company? HVAC company? Home inspector?

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All 3. HVAC and home inspector back when home was purchased. Propane company has been out 3 times in the past few weeks. First time they found leaks, 2nd trip replaced necessary parts and verified no leaks in system/any appliances. 3rd time was because we suspected another leak after it started draining so quickly. No leak found.

The tank is 250 gallons. In 6 days with the heater set to 71, her tank dropped 50%. We turned heat off, looked into a few issues, no problems found. In the 5 days we had heater off, tank reduced by 2-3% I had her turn heater on for 24 hours (starting yesterday) with tank showing 48% going into it. Tank was at 38% this morning.

We know there are a few areas in the attic that need additional insulation blown in. The ducts were cleaned prior to us taking posession. But we did run the AC for a few weeks this summer when we were all out there working, and the house is sealed really well. The AC ran minimally, but the house held temp really well. The house was built in 1991, and is roughly 1900 sq ft.

I guess we need to have the HVAC company come out and look at it. I assume at this point it is likely an issue with the unit?

Yeah. 1900 ish sqft house built in 1991. She lives alone, and doesn't do a ton of baking or laundry. Uses minimal amount of hot water.

How much propane should a furnace use a day?
Here's a rundown of typical propane usage rates for some of the most common home fixtures: Furnaces: 1 gallon per hour. Water heaters: ~1.5 gallons per day. Fireplaces: 1 gallon every 3 hours

Betting myself part of the problem are duct leaks.

Thinking out loud:
1. old thermostats or those located incorrectly may overheat then underheat a house inefficiently but MIL hasn't mentioned artifical "hot flashes" .... then opens a few windows to correct all that

2. rentals we've known in college years didn't have much wall insulation and we added plenty of attic insulation ... to no avail; 1991 build should have state o art wall insulation but if it's not min.wool nor closed cell foam, if it got wet, the R-values drop like a stone in water

3. "sealed very well" only proof is a Blower Door test that sometimes if free via utility co. BUT is she has no complaints about drafts, then may be a dead end ... (blower door tests can also discover duct leaks)

4. without mention of type of foundation, must convey that wood framed floors above grade could be without insulation & good sealing = BTU exit

Brick house, slab foundation, no drafts.

Thermostat is a new ecobee with multiple sensors around home to prevent hot flashes and inefficient heating/cooling (thermostat location is down hallway across from furnace on one far side of home- hence installing the additional sensors).

If it is a leaky duct issue, would we not have noticed it during the summer with the AC? Ductwork runs in attic
New roof installed less than 2 years ago with ridge vents and no damage (my husband is a roofing contractor, so he checked that out).

We had to get into one of the exterior walls when dealing with an issue early on. From what we saw, the insulation is sufficient, and there were no signs or mentions of leaks on exterior walls. Home was sold through estate, and heirs put a substantial amount of work into it prior to selling (not cosmetic updates, but actual work that needed to be done). We have plumbing reports (new septic), thermal wall reports looking for leaks (our inspector), electrical reports (some rewiring was needed for code), new roof, new water heater.

71 is toasty. Especially in Hearne, it's only heating 20-30* most nights so its running a lot or is thirsty...if I had propane in north Texas, I'd have a heat pump with propane backup. Maybe skip the propane and do heat strips backup as far south as Hearne.

I honestly don't think 71 is that toasty. I keep my house at 71/72 and we are comfortable. You also have to remember that she is a 70 something year old woman living alone (with animals). She gets cold easier than younger people.

We went through this a couple of winters ago. We built a 2500 sf house on some land and went with a propane furnace. First winter I was in somewhat of shock of how much we were going through propane. I was convinced there was no way we could sustain this. I think our second night in our house the heat stopped working and we came to realize the tank was empty.

In 2023, we spent roughly $1500 on propane for the year - had our 250 gal tank filled (up to 80%) on 12/26/22, 2/6/23, 4/12/23, and 11/30/23. Peak usage was somewhere between 3-3.5 gal per day. Electricity wise, we spent about $1800 for the year. Total for both Electric and Propane came to about $3300 ($275 per month). This feels like it is on the high side for a new and energy efficient home, but we have some vaulted ceilings and a ton of windows. Our family is also home all day everyday (work from home and homeschool) so there are not many periods where we can just shut the system off for multiple hours per day.

I guess my takeaway is that you need to look at it from the big picture (or entire year) - her electric bills should be minimal right now, and in the summertime, she won't be using any propane. I would at least get through most of the year and reevaluate if you think you really need to switch over.

We have our propane supplier monitor our usage for a nominal fee and they automatically come fill up the tank before it gets too low. They also top it off as the weather changes. Located just south of Fort Worth.

Our usage was about 4.5 gal per day over the last 3 weeks. That is as high as its been since we have been here. Now we look to be having some nice weather the next week or so, so the usage should tail off a bit.

I will say if you're keeping it at 71/72 at night when it's down in the teens, that will keep your unit running like all the time. We are comfortable at about 70/71 during the day and 67/68 at night.

10andBOUNCE said:

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We went through this a couple of winters ago. We built a 2500 sf house on some land and went with a propane furnace. First winter I was in somewhat of shock of how much we were going through propane. I was convinced there was no way we could sustain this. I think our second night in our house the heat stopped working and we came to realize the tank was empty.

In 2023, we spent roughly $1500 on propane for the year - had our 250 gal tank filled (up to 80%) on 12/26/22, 2/6/23, 4/12/23, and 11/30/23. Peak usage was somewhere between 3-3.5 gal per day. Electricity wise, we spent about $1800 for the year. Total for both Electric and Propane came to about $3300 ($275 per month). This feels like it is on the high side for a new and energy efficient home, but we have some vaulted ceilings and a ton of windows. Our family is also home all day everyday (work from home and homeschool) so there are not many periods where we can just shut the system off for multiple hours per day.

I guess my takeaway is that you need to look at it from the big picture (or entire year) - her electric bills should be minimal right now, and in the summertime, she won't be using any propane. I would at least get through most of the year and reevaluate if you think you really need to switch over.

We have our propane supplier monitor our usage for a nominal fee and they automatically come fill up the tank before it gets too low. They also top it off as the weather changes. Located just south of Fort Worth.

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Who do you use for Propane? We live in Benbrook but have a lot off of 30 & 580 on the west side that we may build on eventually. Trying to get all my ducks in a row before we start building.

Yellow Rose

I have converted numerous houses from propane to heat pump in BCS on whole house remodels and so far everyone has liked the results.

What is a rough estimate on that cost?

I'm supposed to work out numbers for a 5ish year forecast to see what is the most cost effective route forward.

Multiple factors in play

Is there only one hvac unit ?

Is there a 200 amp electric service already there ?


Call an hvac guy and get a quote on that end
Marco at aircoole is a good guy for that

Electrical depends on existing breaker box and how long the runs need ro be for the heat pump


If you want a rough guess I would say 10-12k

Is it possible the gauge is faulty and she isn't actually using that much propane?

Nope. It was replaced when we had the leaks addressed and rechecked when they came back out (so in the last week- 2 weeks)

Also depends on how warm she is keeping the house. I know my mom keeps the house a lot warmer than I can stand. It can greatly increase the heating hours over what you would expect.

TexAg1987 said:

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Also depends on how warm she is keeping the house. I know my mom keeps the house a lot warmer than I can stand. It can greatly increase the heating hours over what you would expect.

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And how poorly insulated it may be.

We normally keep our heater on 67. Kind of forgot and left it on 65 last cold snap and realized we were still perfectly fine in our beds. So that's the new setting at night.

If you said she upgraded to an Ecobee thermostat shouldn't it be able to tell you the hours the unit is running a day? That should help with a starting point, if the unit is running all day then that amount of propane usage doesn't seem crazy. So why is it running that much? If it's just a poorly insulated house and she keeps it hot enough that requires to run....you need to be prepared for how much an electric furnace will cost in electricity if running all day also....

If it's an insulation issue, wouldn't we have noticed in the summer with the AC? The house naturally stayed cool, and the AC didn't continuously run. Electric bills were in the $250-300 range.

histag10 said:

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If it's an insulation issue, wouldn't we have noticed in the summer with the AC? The house naturally stayed cool, and the AC didn't continuously run. Electric bills were in the $250-300 range.

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I don't know, I'd say that's high for a 1900 sq ft house. But honestly too many variables to really say. Where does she live, what's her electricity rate, what temps does she set the house at, etc?

But my house is 3,000 sq ft, we like it cold (set to 69 at night) and electric bills were $250 max.

My house is 1500 sqft and we sit around the 200 mark. 2000 sqft house in college station a few hrs ago would run around 600-700 per month in the summers (that's normal for CSUtilities)

She is outside of Hearn on Hearne city utilities.

nm

Any chance you have a natural gas furnace that hasn't been converted to propane? Propane uses smaller orifices. Propane burns hotter. Maybe if using the wrong parts it is running even hotter. That could be the source of cracks and leaks.

Thanks for that suggestion! I'm going to call a heating company to come out and check it, and I'll see what they say to that.

Some basic math. It knowing all the details

Texas Climate zone will give you BTU/ft needed for heating, gives you an idea of expected BTU requirements

BTU input x efficiency rating, or output of furnace will be on data plate, propane is 91.5k BTU per gallon.

Assuming an 100k, 80% efficient furnace, you'll burn 1.1 gallons per hour of run time, to output 80k BTU in the home, doing the math should give an idea on what you're chasing.