Propane Insert

[oskar470]

My house is a 2 storey building approx. 3000 sq.ft, slab on grade, built in 1987 and well maintained. The main heating is electric baseboards and on the ground floor where my 30’x15’ family room is located I also have a Regency wood insert installed in 1998. The insert is rated at 67K Btu/hr with a 72% efficiency and I burn 6 cords of wood per season which cost me $522 delivered and keep this room quite warm, perhaps hot at times with some heat escaping to upstairs. I’m very happy with this fireplace but as the years passing by the wood maintenance is getting to me and have started thinking to change this wood insert and go for a propane one (no natural gas in my area).

I have calculated the heat losses of the family room to be approx. 20K Btu/hr with a temp. difference of 70F inside and -10F outside. I would say in Montreal, Canada, average winter temperature is about -10F but in January we often have days with -30 or more. I have also estimated the operating hours of the fireplace to be approx. 1500 hours per season.

Shopping around I noticed that most propane inserts are in the 20-30K Btu range and I wonder if one of them would be sufficient to keep the family room warm. My other concern is the operating cost which I’m sure is going to be much more than I pay now for the firewood but I wonder how much.

Does anyone live in a northern climate and have a propane insert who would like to share his experience or perhaps someone would be able to help me calculating the operating cost. I was told that the current propane cost in my area is $0.75/liter

Thanks

 

[Ashful]

Our house had a Mendota D40 installed in one of our fireplaces by the prior owners. I ripped it out and replaced with a Jotul Firelight, but I can say that Mendota was a pretty capable heater, at 40,000 BTU/hr. In the little reading I did on gas fireplaces, before tearing it out and selling it, it seemed to get very favorable reviews.

I think I paid $2.12 per gallon for my last fill of 400 gallons, but that probably doesn't mean much, in terms of your local pricing. Good luck!

edit: I can post the cost comparison when I get to a real computer.

 

[DAKSY]

You don't indicate which Regency wood burner you have, so I can't guess at the size of your fireplace opening.
Regency also makes one of the higher rated (38K BTU) GAS inserts in the E33, & it's a great heater.

http://www.regency-fire.com/Products/Gas/Gas-Inserts/E33-(1).aspx

I just don't know if it'll fit your configuration.
I switched from wood to gas for the same reasons you are citing,
& while I miss the nice toasty heat from the wood, my back thanks me for the ease of operation.
LP prices have fluctuated so much over the last 10 years, & the fact that I added another gas fireplace & a gas waterheater
makes the cost of operating only our insert tough to isolate. I know I'm spending more money for my heat,
but I'm comfortable & doing a WHOLE lot less work to achieve that comfort, so I guess that counts for something.
I will say this: you will never get that same feeling of warmth from a gas unit as you do from a wood burner.
You may have to wear a sweater to keep AS warm, but you won't freeze.
As far as calculating the fuel costs, you know how many BTUs you got from the wood insert & you know the efficiency.
Calculate the same number of BTUs, multiply that by the efficiency of the gas burner & then multiply THAT by the price per unit.
There are approximately 92K BTU in a gallon of LP. You will have to convert that to liters to complete the calculation.
Hope some of this helps in your endeavor.

 

[Ashful]

Costs:

Cord wood at $522 / 6 cords, 83% eff = 172 - 277 thousand BTU/$ (dep. species)
Propane at $2.05/gal, ventless 95% eff = 42 thousand BTU/$
Propane at $2.05/gal, direct vent 70% eff = 64 thousand BTU/$

Any time I post numbers like this, folks seem to get hopping mad about incorrectly assumed efficiencies, etc. There surely is a lot of variability in these numbers, but they're the best I have at the moment, and the math is correct.

 

[Fsappo]

Don't pigeon hole yourself into a 20-30K btu insert. Get a good sized one. Nicer flame, plenty of heat if needed and you can turn down or run on thermostat

 

[oskar470]

Checking my records the Regency insert is an I3100 model, 75000 BTU/hr, 71% efficiency. What I wrote before was by memory, sorry.

Based on the info provided which I thank you, I came to the following

(75000 BTU/hr) x (0.71) =53,250 BTU/hr

Divide the above by 92000 BTU/gallon = 0.578 gallons/hr or 2.2 liters/hr

(2.2 liters/hr) x (1500 hrs per season) =3,300 liters per season at $0.75/liter = $2,475 cost of propane / season.

Are the above calculations correct?

BTW if I go for a propane insert I'm looking at the Mendota FV44i, 40K BTU/hr, 86.3% efficiency. That is the largest I can get

 

[DAKSY]

Your numbers are a little off, because you figured the efficiency into the wood to get your OUTPUT.
The INPUT is 75K for wood.
You need to know the INPUT for a particular gas burner to determine the LP usage.
For example, the 40K BTU unit will burn a gallon of LP in 2.3 hrs (92/40),
but at 86.3% efficiency, it will OUTPUT 34.52K BTU/Hr.
With those numbers you can plug in your BTU/Hr costs...

 

[oskar470]

You are right Bob, now the cost went down to $1,623 / season from $2,475 (I like these mistakes, lol)

But I was thinking something else which I don’t know if it is applicable; when you start a fireplace I will assume you start her at full blast to warm up the place fast but after some time she will go down by a certain ratio and then she will cycle on/off to maintain the set temperature. This means that the 40K we calculate is not constant and therefore the $1,623 may not be the correct number

Is there a ball part number to compensate for this fluctuation? I was thinking perhaps a 0.7 multiplier which will bring the $1,623 down to $1,136. Do you agree?

 

[Ashful]

I think you're looking at the wrong numbers, oskar. I mean, you already decided you want to move away from handling firewood, and switch to gas. So the only remaining question is whether it makes sense to burn propane for heat, in which case you really want to compare the cost of heating via propane to the cost of heating with your electric baseboards (not wood), or if you want to reserve that propane fireplace for just evening ambiance fires.

 

[oskar470]

Joful you might be right but please let me explain. Electricity where I am is the least expensive in North America and have no intentions to replace it not only because of the cost but also for the convenience it offers. The fireplace as you mentioned is for evening ambience and as a bonus will reduce my electricity bill too. But on top of these reasons the fireplace (wood or propane) it is kind of a necessity here because a few weeks back we had a 5 hours black out due to an ice storm and this happens often in my area.

What I try to do is twofold; first I would like to compare out of curiosity my present firewood cost with my future propane insert cost and second I would like to find out approx. how much the propane will cost me per season. I’m retired now and on fixed income so I don’t want to invest $5K for a propane insert and then find out later that I can’t afford to enjoy it.

I’m not familiar with this type of calculations and if I have done something wrong I will be glad to hear back from you