Vented or Ventless?

[Jarnotski]

Building a fish house this fall and trying to determine what type of heater to put in it. I would like a vented heater but from what I hear vented heaters require a 100lb cylinder, I would like to go with a 30lb cylinder. Sounds like the ventless heaters would work on a smaller cylinder. Wondering what you guys have in your fish house and what your opinions are? Thanks

[TooBusy]

I would definitely recommend using the vented. You do not need to have a 100 lb cylinder. I have a vented heater in my house and use standard 40 lb cylinders. Vented heaters put less moisture into your house and the dangers related to noxious are certainly less. Vented heaters generally cost more, but if it fits your budget I think it is worth the extra cost. This is especially true if you plan on sleeping in your house.

[Kylersk]

I've got an Empire direct vent heater in my house. It runs great off of my 30#'ers.

[Pikeslayer]

Im going with a wood stove,safe,dry heat that you can cook on!

[federline]

Whether a 100# tank (or multiple smaller tanks ganged together) is needed depends on how cold you want to be out in and how many BTUs the heater is. Give us that info and we can tell for sure. There are certainly situations where some commonly sold vented and unvented heaters will need a 100# tank in MN.

The required cylinder size depends on the combination of:

- BTU draw

- tank temperature

- size of the tank

- how full the tank is

This is due to a physical property of any liquid turning to a vapor, called vapor pressure. The propane in the tank is pressurized into liquid, and we burn the fumes off it.

Propane does not evaporate below -44 deg F, it stays as liquid. As you get closer to -44, less and less liquid evaporates to vapor, thus, less pressure. And that vapor pressure drop off FAST below 30 degrees!:

30 deg = 40% of 80 deg pressure

0 deg = 20% of 80 deg pressure

-20 deg = <10% of 80 deg pressure

Both the vented and unvented heaters, if not supplied with enough pressure (read: BTUs), may not run reliably or safely with too low of a pressure - because if the heater is not getting enough propane for its BTU rating and design, the thermocouple may not get hot enough and the heater can shut down.

Example: If you have a 35,000 BTU heater, and run it off a 20# tank at 0 degrees, you are probably going to have some problems. Like wise for a 75,000 BTU heater and a 100# tank - you would need two 100# ganged together for -20F to push that amount of BTU for more than a couple hours.

And to make things worse for us all, as you draw down the propane tank, you get less and less pressure, too. Here's a BTU chart of temp and fill level for a 100# tank - its proportionally less for smaller tanks. This means that the colder it is, the less usable propane there is, even in a full tank!

As you can see below, 0 deg F and a low 100# tank brings low BTU outputs into play that approach the BTU outputs of common BTU-sizes of vented and unvented heaters. Halve those 0 deg F numbers on the left side (approximately) for -20 deg F.

-----snip!------

VAPORIZATION RATE - 100 lb. Propane Cylinder (Approx)

Pounds of propane in cylinder Maximum continuous draw in BTU/hr

at various temperatures in degrees F.

Code:

---

pounds

of

propane 0° 20° 40° 60° 70°

100 113,000 167,000 214,000 277,000 300,000

90 104,000 152,000 200,000 247,000 277,000

80 94,000 137,000 180,000 214,000 236,000

70 83,000 122,000 160,000 199,000 214,000

60 75,000 109,000 140,000 176,000 192,000

50 64,000 94,000 125,000 154,000 167,000

40 55,000 79,000 105,000 131,000 141,000

30 45,000 66,000 85,000 107,000 118,000

20 36,000 51,000 68,000 83,000 92,000

10 28,000 38,000 49,000 60,000 66,000

---

This chart shows the vaporization rate of containers in terms of

the temperature of the liquid and the wet surface area of

the container. When the temperature is lower or if the container

has less liquid in it, the vaporization rate of the container is

a lower value.

-------snip!-------

Also - Smaller tanks' behave differently than you would expect, too. I.e., A full 30# tank DOES NOT put out 45,000 BTU at 0 deg F like a 100# tank with 30 pounds in it does - it is actually less. This is because there is less liquid volume below the liquid-vapor interface.

That's it from Dr. Science - remember, he's not a real doctor, he's just a kook.

[cold one sd]

I have never had problems with my 15,000 btu Empire Direct Vent heater as of this time. I kind of think that as long as the combustion chamber is vented to the outside and my propane tank doesn't leak it may be ok to bring the tank inside to keep it warmer. I sometimes warm it up in my driveway and set the tank inside while it is lit. Probably not the safest way to do it, but it would be better than freezing on the ice if your propane isn't vaporizing fast enough to keep you warm. I know that they make electrically heated blankets that can be wrapped around these tanks for those that have generators.

[iffwalleyes]

Empires are great and I think they are really good heater. But I think almost everyone but me on this site must run these . I personally have a veltless heater and love it. The think is even though it is ventless it doesn't mean your stucture can be ventless you need to provide decent venting for it to be safe. If you install it with the proper venting that is listed in install manual you will be ok. The other thing is many of the new ventless heaters have low oxygen shut offs. If the heater starts to get starved it will shut off. As with any heater if you are planning to sleep in the house you should have CO2 sensors in the house. The great thing about ventless is you never worry about wind blowing out a pilot lite like they sometimes will on vented heaters.

One thing about the size of tanks they will run on most any tank but you might not get all the propane of a tank before it won't run anymore. Personally I have a 100 lber on my house and it is really nice you pretty much can run most of a season without having to refill.

[papabear]

I have ventless and like the performance. I have a co monitor in the house for added safety. It is not much diffeent than using a mr buddy heater in a portable. The moisture is my only concern. H2O vapor is a major by product of combustion and it collects in the house. Proper air exchange through open door, windows or vents should help this.

[DuluthMedic]

does the shack still stay warm with windows cracked? We've got one of those crank style vents in the roof of the camper. Do you think this will be enough? Or will I have to open a window? Do you have to run the heater constant?

[Shack]

I also run a vent less heater with the porcelain cells. I placed a window right above it and have it cracked when heater is on. It sucks fresh air and heat rises outward!

I like it a lot! Throw in a cycling fan and an elec. power vent in bathroom and a carbon dioxide detector; I sleep very well at night!

Also it acts like an open fire place. It is nice to sit in easy chair and watch a movie with the warmth of a fire place hitting your face and body, waiting for the sound of a rattle reel!

What I would like to upgrade to is a t-stat for these things. I know they sell them and I would like to get one this year! Currently I run heater untill desired warmth is gotten and turn down of off.

[Pikeslayer]

When you return to your fishhouse after it has been sitting cold for a few days is it frosty in there from shutting down your propane and the temp. in your house dropping so fast?

[heiman507]

We have the ventless in both houses. An 8x6 and 8x10. Both keep the house warm. We have a 2" hole in the wall with a plastic floor drain cover on it for ventalation. Both houses have circulating fans above the heaters. We have never had problems of odor and CO detectors read fine.

I can't recall the manufacturer (been too long since ice) one have a high medium and low, while the other has 5 heat settings (when desired temp is reached, burner goes out to just the pilot, then reignite the burner when temp falls)

Houses are always warm!

[fishinalot]

The empire direct vents pilot will not go out if you use the extended vent box to keep the wind draft down.

Most the time if you use those cheap BBQ single stage regulators, they will not push enough LP thru the tank if it gets cold.

I have a 15,000 Empire with the extended vent box on the outside and a good Dual 2-stage Regulator hooked up to 2- 20 # cylinders and it has never failed me yet.

I have had the heat on for 6 weeks in a row without the pilot ever going out.

I like the vented over the ventless not only for safety issuses, but for moisture reasons.

[hanson]

Quote:

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When you return to your fishhouse after it has been sitting cold for a few days is it frosty in there from shutting down your propane and the temp. in your house dropping so fast?

---

In my house... No.

I run a 15,000 BTU Empire Direct Vent. I have the vent extension box on my house as well.

For those building houses or installing these furnaces, remember to provide some kind of air relief in the house (a couple 4" round vents to the outside or something).

What I have learned is that there is an air pressure difference between the inside and the outside of the shack if you don't have some sort of vent, or crack a window open a little bit. I know there are holes in the floor but when the house is banked in, it doesn't matter. This pressure difference causes a draft through the furnace which makes lighting it a nightmare.

In my house, I have to crack a window open about 1" and the draft through the furnace disappears. My house is built so tight that it causes a big air pressure difference. I should have put a couple small vents in the house to solve the problem but haven't. Cracking the window 1" has worked great and I can run the furnace for the entire weekend in all sorts of nasty wind and it keeps running.

Just something to think about.

Vented all the way!

[Pikeslayer]

I used to run a vented propane in my perm.angleing house and when I would shut it down for a few days it was all frosted up when I returned.After I switched to wood and stoked the fire and shut it down so it would slowly burn out after I left(dropping the temp.slowly)that seemed like it was alot less frosty when I returned the next time!

[Kylersk]

I set my thermostat to 45 when I leave for a day or so. I picked up a digital programmable thermostat for it.. so I can even program it to warm up the house to 72, 20 minutes before I get there.

[Pikeslayer]

I always shut mine off when I left because I never knew when I was going to be able to go back.Im one of the unlucky ones with a bad back and I never know from one day to the next if I can go outside to play!

[rocki]

if you leave it on when your gone, what would happen if the pilot blows out? does it continue to run propane when pilot is not lit? might be a dumb question, but never owned a empire.

[Shack]

It shuts off with most newer heaters!

When I shut down and come back I never have a frost issue. I do vent my house very well and it is very tight and when shut up for the week, is very tight and insulated well enough to slow cooling down.

I just never trusted leaving heater run on auto or low when not up at shack! First off it sucks alot of fuel, second is like stated above (my luck). I figure I would get a call from resort that my shack burnt down or blew up!

Most resorts for an extra fee or just asking, will go and start heater for ya before you head up. So when you get to lake, your shack is nice and warm! Punch holes and use box fan to suck exhaust out window and the shack heats back up quick! This entails giving resort owner a spare key or giving comdo for lock!

Good luck!

[blueroof]

Quote:

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I set my thermostat to 45 when I leave for a day or so.

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My brother-in-law left his heater running while unattended, sadly last year it caught fire somehow out on Minnetonka. A volunteer fire-fighter from Orono was on the lake and saw it was on fire. He hooked it to his truck and drug it to shore to be put out. Brave soul.

LB

[Kylersk]

That's would suck. But If these heaters (empire direct vent) are meant for you to be able to sleep without fear, and they are also designed to be installed in a home. I'm not too worried that it'll burn down my fish house.

[Mike L]

Just have to remember that burning propane produces about 3.75 gallons of water per a 20 pound cylinder. That water plus moisture from respiration has to be exhausted from the fish house in some fashion, be it a vented heater, an open window or wall vents.