ProCom Unvented Propane Heater
If you have an unheated outbuilding or basement and you want to warm it cheaply with minimal installation hassles, the ProCom "Blue-Flame" ML300TBA is an interesting option. A combination radiant/passive-convection heater powered by propane, the ProCom burns cleanly and needs no vent or chimney. A bit more civilized than the brute-force, rocket-engine-style of the previously-reviewed, portable Dyna-Glo workshop heater. Granted the Dyna-Glo has the raw power to bring a very large, cold space up to a comfortable temperature within a minimum amount of time, but it is relatively expensive to run and does make a distracting amount of noise. The Procom, on the other hand, just simmers almost silently in the background.
Those who live in the boondocks may already have a propane tank in the yard. Otherwise, you can buy a cylinder of the same type that you would use with a barbecue grill, and refill it from a propane dealer or by using the cylinder-exchange service at Wal-Mart. To run the heater from a small cylinder you will need a pressure regulator that screws into the top (with a sneaky left-hand thread), plus a piece of hose with 3/8" female connector on each end, and a male-to-male 3/8" brass adapter (known in the trade as a "nipple") to attach the hose to the heater. All of this stuff should be available at your local hardware store, together with Teflon tape, which you wrap around the threads before assembly. Make the joints tight, then squirt a solution of dishwashing liquid on them to check for leaks (which will blow bubbles). If you have any doubts about this, naturally you should consult a plumber. Personally, I had no problems.
Building codes and commonsense advise you to keep propane cylinders outside in case a cylinder leak occurs, which you may not notice since propane is heavier than air and collects at floor level. I made a hole through the wall for the hose and stood an 8-gallon tank outside on the deck. The only problem I found using this size of tank is that the heater's pilot jet sometimes doesn't relight easily when the heater is warm and the propane tank is cold (the tank gets colder during use, because of the loss of internal pressure). The instructions do recommend a full-size tank of 150 gallons or larger.
During use, the heater creates virtually no odor detectable by my nose, and because no heat is lost through an outside exhaust, it's super-efficient. Just to be on the safe side I bought a carbon monoxide detector from Home Depot for around $20, but it has not registered any hazard. Of course any flame will consume oxygen, and for this reason alone you should crack a window a little if you keep the heater burning for prolonged periods. The heater is not recommended for very small spaces, bedrooms, or bathrooms. Be sure to follow all the instructions in the manual.
Initial setup only took me fifteen minutes. It hangs on a single (supplied) bracket, which you fix to the wall with two screws. Model ML300TBA generates up to 28,000 BTU of heat and warms my office area comfortably within about fifteen minutes, starting from 55 Fahrenheit. Since the combustion of propane unites hydrogen in the gas with oxygen in the air, the heater liberates more than one-and-one-half pints of water per hour at its maximum setting, in addition to some carbon dioxide. The water is a bonus for me, as my sinuses prefer some humidity. The heater is silent unless you buy the optional (overpriced) circulation fan. Personally, I prefer to use a ceiling fan to spread heat around more actively.
Is it really safe?
Well, consider the alternatives. A wood-burning stove is generally regarded as benign, yet can emit significant carbon monoxide through incomplete combustion if you use it in "slow burning" mode. Fragrant wood smoke is rich in tars that may be carcinogenic, some escaping into your living room while the rest circulate through your neighborhood via that convenient device, the chimney -- which is not only horribly inefficient but becomes a notorious fire hazard as residues accumulate inside it.
You can see where my bias lies. For those who don't want to install a chimney, or don't have a municipal gas supply, or don't want to pay a plumber to extend an existing gas line to an additional location, an unvented heater is a convenient option. Propane is not an irritant, does not cause sensitization, and has no known teratogenic or mutagenic effects. Also, unlike a wood stove, the ProCom heater contains an oxygen depletion sensor that will shut it down if necessary. Of course if you allow it to become very dirty, it may burn less efficiently, creating some carbon monoxide, like a kerosene stove, which is why you may find a carbon dioxide detector reassuring.
Your only problem may be in finding this item. A large local hardware store refused to believe that such a thing could exist. Ventless gas heater? You mean -- without a chimney? "Impossible," they told me. Even a local plumbing/heating specialty place was skeptical. But my local propane supplier told me to mail-order one from Northern Tool, known to many of us as an indispensable source for cheap Chinese hardware, which sells the ML300TBA model heater for $170, excluding external connections. Similar heaters are available from Amazon, but they're more expensive.
-- Charles Platt
ProCom Unvented Propane Heater - ML300TBA
$170
Available from Northern Tool
Or $203 from Amazon
NOTE: Northern Tool also sells a natural-gas version of the ventless gas heater, which I have not tried -- Charles Platt
Favorite (15)
Randy
These are great heaters for garages, etc. As for finding them, Harbor Freight Tools has three different models ranging from 10,000 to 28,000 BTU ($70 to $159 and sometimes on sale cheaper.) We have a Harbor Freight store in my town, but you can also find them at: www.harborfreight.com.
No - I am not in any way affilitated with Harbor Freight, I just like the "toy store for boys."
Jennifer
Also check out the Mr Heater brand "Buddy" heaters. The do both portable ones (Little Buddy, BIG Buddy), and permanent installation ones. Sometimes the magic words to use when searching for them are "catalytic heater".
Stephen Le
I follow Cool Tools regularly, and this heater really piqued my interest, as I'm a chemical engineer employed in combustion safety and control. ProCom links to a trade group website that explains the safeguards included to make vent-free heaters safe for indoor use, while noting that some states have banned their use. That latter detail stood out, and a Google Scholar search reveals research showing "significant pollutant accumulation indoors when the fireplaces were used for extended periods of time. In one case, CO concentrations greater than 100 ppm accumulated in under 2 hr of operation; a person at rest exposed for 10 hr to this environment would get a mild case of CO poisoning with an estimated 10% carboxyhemoglobin level." (Dutton, Steven J., Indoor Pollutant Levels from the Use of Unvented Natural Gas Fireplaces in Boulder, Colorado). Thus, it seems like these heaters are really only safe for very durations.
Tom Sackett
Yikes. The study that Stephen Le cites scares the hell out of me. We use a "Buddy" heater to heat a one-room cabin at night while we sleep. It's supposed to be safe, as it uses a low-oxygen sensor. However, the indoor fireplaces studied in the indoor pollution study have the same sensors, and this did not prevent them from creating significant levels of carbon monoxide. We always leave a window cracked, but I'm no longer sure this is enough. Another point made in the study is that the CO detectors available to consumers are not always reliable.
Mark Ross
When I was looking for an indoor heater a couple of years ago, there were enough reports of problems with the unvented heaters to scare me off of them. I'm not sure I want to bet my life on a 2 dollar oxygen sensor. Or even two 2 dollar sensors. In addition, my wife has mild asthma and is very sensitive to air pollutants, so I would much prefer to vent these outside.
I ended up going with a Rinnai vented heater and have been extremely happy with it. It was more expensive than most of the heaters I looked at, but it really has operated flawlessly, with a fantastic thermostat. Set up your heating schedule once and never worry about it again. The venting was really easy - just drill a 3 inch hole through your wall. Everything required to connect and seal the vent was supplied. Took about 2 hours because I work slowly. I know this looks like spam, but I have no connection with these guys, I'm just a happy customer.
I think the unvented heaters are well-suited for drafty areas like a garage, but they are now being marketed for indoor use. If you really cannot find a way to vent your heater, then at least buy a high-quality unit from a respected manufacturer like Rinnai or Monitor or Empire. Don't go with the cheapest unit made in China, as you may be betting your life on this decision.
Greg
We have used these O2-depletion sensing heaters for years with good success and no problems. Of course, smoke detectors, c.monoxide detectors are a good idea as well....but, with an n of one observer, we've had more problems with older "well-maintained" gas and oil furnaces than ever with these heaters.
Alistair
One additional thing to consider, water vapour is also a product of combustion here. Makes a good 10 minute exercise, to calculate the grams of water produced for each gram of propane burned.
Joe Hooker
I've used one for a couple of years as a backup for my heat pump now and like it. It will heat the whole central portion of the house (800+ ft2) with no problem, even in cold weather. Also a nice boost for the heat pump on really cold days.
I have a very sensitive CO sensor (a chain saw outside set it off one day) and have had no problems there. It does put out water vapor but in winter this may be a feature & not a bug. The only thing I don't like about it is the built-in thermostat, which is on the rear and not very sensitive to temperature changes. Hence, hard to adjust for a steady temp. Would really have liked the ability to use a separate wall theromostat.
Andrew S
Let's examine the cost versus an electric resistance heater.
Propane burns about 91600 btu/gallon. The gas station where I get my gas grill tank filled charges $4/gallon (Tank exchange prices are slightly higher). 91600/4 = 22900 btu/$.
Electricity can be converted 1 kWh to 3400 btu in a resistance heater. I pay $.12/kWh (PG&E, bay area).
3400/.12 = 28000 btu/$.
If propane cost per gallon is more than 27x the electricity price per kWh, then the electricity is the better deal. In other words, if you don't already have cheap propane (from a large tank), it's worth considering an electric heater in this case.
Electric heaters have a safety advantage, and are generally more portable and more directional, which usually means you can live with lower output. On the downside, for very large output, the electric heaters require a 240V connection and are larger, so they really are not portable.
Fire is fun, but be careful!
David
If you are using hose make use it's rated for propane, or over time it will break down.
"R" rated hose, for acetylene only. Alternative fuel gases, like MAPP, Propylene, Propane, LPG, and Nat Gas are not suitable for "R" rated hoses. If you are using the alt fuels, please use a "T" rated hose.
Peter
Never use teflon tape with propane fitting! It will break down quickly. There is a yellow tape for this purpose- ask at the hardware store.
Tech News
One additional thing to consider, water vapour is also a product of combustion here. Makes a good 10 minute exercise, to calculate the grams of water produced for each gram of propane burned.
John
Please rethink using unvented heaters..I drive truck and to prevent idling my truck I used coleman unvented catalytic propane heaters and now I am suffering from asthma. I was very healthy before and now every time I go out in the cold air my lungs start weazing and coughing. I did some research and found out propane after burning emits Nitrogen oxides and can irritate the lining of the lungs, causing asthma. If you have a choice, it's better to use electricity for heating .I also used a co2 alarm with a lcd digital display and it never registered any co2 and that is after mounting it near the ceiling...I now change to an outside generator with electric heat... But please don't take the chance it's not worth the risk!
R.Tuttle
I have been using the ProComm with the built in electric fan for 2 years now.
You need to clean the dust out of the Pilot orifce and Clean the dust particles
from the burner. At least 2 to 3 times a heating season. If you see a yellow or white tip on the pilot flame, you need to clean it. It will return to blue. I have the
big unit, it is 60000 btu and it has preformed flawlessly. I have 2 O2 dectors
one High in the room one low. As a former fireman i was not sure of this unit.
It heats the back half of the house and the Pellet stove the front half. When the
propane forced air furnace was working I used 3 500 gallon (420) usuable each
year. This year I used 380 gallons total, the savings more then paid for the pellets. I have had a warmer house now then the furnace ever was able to do.
If the ProComm ever go's bad I wil buy another one.
Remember it is important to clean the orifice on the pilot tube and to keep the dust cleaned out. There is nothing really to go bad, just get dirty. Watch your
pilot, it will tell you when it is time to clean the unit. Takes about 15 min.
As far as the one comment I dont think o2 can cause Asthma, However the added moisture and the oxides could possible attribute to this. I had Asthma
when I was young, Dry air was the cure. I would guess that the humid output of the heater caused his problem. I have not had any recurence of Atshma from using the heater. The only set back I have found is on outside walls that the additional moisture can cause mold to appear. You must keep it cleaned. I found that adding a fan to help circulate the heat better took care of the problem.
As for the person with the Asthma, You may have had a little mold build up in your truck cab in an hidden area, Mold spores will trigger Asthma. That is the reason we make sure to check for it regurlarly.
gerald
I read on the box at a store it say's thermonstat control:: Does that mean when it gets a certain temperature it shuts off.