Furnace using excessive propane
#1
12-27-20, 09:33 AM
Furnace using excessive propane
I converted my natural gas furnace to propane, using a kit I bought specifically for my furnace. It seems to use propane unbelievably fast. A 20 pound tank lasts one day. I bought a sniffer to make sure there were no leaks, and I adjusted the gas pressure valve on the furnace way down to see if that made a difference. While the furnace is running the tank gets frost on the outside of it.
My propane furnace is the back up heater for when I’m on vacation, as I heat my house with wood. If I can’t fix it I can’t go anywhere.
Any help would be appreciated. Thx.
My propane furnace is the back up heater for when I’m on vacation, as I heat my house with wood. If I can’t fix it I can’t go anywhere.
Any help would be appreciated. Thx.
#2
12-27-20, 10:17 AM
Member
DO NOT adjust the gas pressure beyond the suggested tolerance lists on the data tag.
This can cause sooting and destroy the furnace.
Your using 1 20 lbs bottle as a fuel source? What BTU furnace?
This can cause sooting and destroy the furnace.
Your using 1 20 lbs bottle as a fuel source? What BTU furnace?
#3
12-27-20, 10:42 AM
Group Moderator
A 20lb tank doesn't last long heating a house.
A 20lb (4.73 gallon) propane tank has 432,804 BTU
The biggest problem is that the liquid fuel cannot vaporise fast enough for a large demand.
A 20lb (4.73 gallon) propane tank has 432,804 BTU
The biggest problem is that the liquid fuel cannot vaporise fast enough for a large demand.
#4
12-27-20, 12:43 PM
Group Moderator
How many btu is the burner in your furnace?
A 20 pound cylinder is likely unable to supply the volume of vapor needed for a full size house furnace, especially in cold weather. The frosting of the cylinder is a symptom of that conversion. Liquid propane needs heat (thermal energy) to make the conversion from liquid to gas. Because the conversion from liquid to gas is consuming heat that heat is coming from the tank and it gets cold. That cold limits how quickly the propane can vaporize and starve your furnace of fuel. A frosting tank is not a good sign and indicates that the tank is probably too small.
Also keep in mind that with the safety valves 20lb cylinders cannot be completely filled. Many bottle exchange sites only fill the tanks to about 75% so you may only be getting a bit over 3 1/2 gallons of fuel.
A 20 pound cylinder is likely unable to supply the volume of vapor needed for a full size house furnace, especially in cold weather. The frosting of the cylinder is a symptom of that conversion. Liquid propane needs heat (thermal energy) to make the conversion from liquid to gas. Because the conversion from liquid to gas is consuming heat that heat is coming from the tank and it gets cold. That cold limits how quickly the propane can vaporize and starve your furnace of fuel. A frosting tank is not a good sign and indicates that the tank is probably too small.
Also keep in mind that with the safety valves 20lb cylinders cannot be completely filled. Many bottle exchange sites only fill the tanks to about 75% so you may only be getting a bit over 3 1/2 gallons of fuel.
Last edited by Pilot Dane; 12-27-20 at 01:04 PM.
#5
12-27-20, 02:50 PM
Member
Those tanks are for bbqs and small heaters.
Get a proper propane supply.
Propane can be very expensive to heat with.
Get a proper propane supply.
Propane can be very expensive to heat with.
#6
12-27-20, 04:52 PM
Group Moderator
I found a chart showing approximately how many btu you can suck out of different sized tanks at a given temperature. Even at warm temperatures you can see that a cylinder that size can't properly supply something like a furnace. If 20lb tanks are the only thing available then multiple ones can be piped together to add up to the size needed.
#7
12-28-20, 02:47 AM
Furnace BTU
It’s 80,000 in, 64,000 out.
I used the 20 lbs tank for a test. I have a 100 lbs tank that lasted about a week with the thermostat set very low.
thanks for the replies.
I used the 20 lbs tank for a test. I have a 100 lbs tank that lasted about a week with the thermostat set very low.
thanks for the replies.
#8
12-28-20, 04:58 AM
Group Moderator
As you can see from the chart you'll be in trouble feeding the furnace enough gas when the tank gets low and the temperatures drop. It will be OK when the tank is almost full and temperatures are warm but I wouldn't count on the furnace running reliably in the winter when your gone.
#10
12-28-20, 08:59 AM
Group Moderator
Take a look at the chart I provided. That will tell you how many btu you can get from a tank of each size and at differing temperatures. As you can see at 10f even a 400 pound tank (120 gallon) will not provide enough gas. I'd be looking at at least a 250 gallon tank. Larger depending on how much gas you will consume.
#11
12-28-20, 11:36 AM
Thank you
Thanks To all who replied. I have my mind around it now.
I bought a 5600w electric space heater for $50 for my vacation heater. You saved me from doing something elaborate and expensive.
Thanks.
I bought a 5600w electric space heater for $50 for my vacation heater. You saved me from doing something elaborate and expensive.
Thanks.
#12
12-28-20, 01:48 PM
Group Moderator
#14
01-04-21, 03:40 AM
Originally Posted by jbeshuk
I’ll unplug the dryer and use that circuit. It has a dedicated breaker.
We have a sunroom / addition with the washer dryer, I added a diverter to the tin ducting, in fall-winter-spring, when doing laundry, it puts the heat / humidity back into the house, (which helps in a cool, dry farmhouse) because a forced air furnace makes it very dry (annoyed cat static comically attracts styrofoam packing peanuts dry).
When somebody in the house has a cold, I skip the puny 'vaporizer' and take a terry cloth bath robe, soak it, then toss it into the electric dryer. Repeat every 20 minutes. Seems to work better.
But, the ultimate question - can you just run an empty electric dryer as a heater? For how long?
#15
01-04-21, 05:18 AM
Group Moderator
Judging by the amount of lint I clean out of my dryer's duct twice a year, I would not feed that air back into the house. Yes, it is nice and warm but it is dirty.
