Friday, January 14, 2011

Propane Heaters


Introduction


There are two classes of propane-powered heaters: vented and unvented. Your rig's standard furnace is vented; that means its combustion gases, including poisonous carbon monoxide (CO), are sent outside. That makes it very safe, but not very efficient, because about half of the heat produced goes outside with the flue gases, instead of warming your coach. As you know, the furnace is also noisy and uses a significant amount of battery power. LP has an energy content of 90,000 Btus per gallon, so a 30,000 Btu input furnace would consume a gallon in three hours running time - at maybe 70% net heating efficiency (21,000 Btu/hr of heating capacity). Our cat heater is at least 95% efficient in delivering the heat from the LP, and does so at a rate that avoids the cycling the furnace undergoes. Thus your LP supply lasts a lot longer, as well as the batteries.

For all these reasons, many of us have sought out alternatives: various kinds of unvented radiant heaters. The majority of catalytic, "blue flame," and "brick"heaters belong to this class of unvented propane heaters. Because these heaters are not vented to the outside,all the heat generated stays in the coach, so they're quite efficient.

Most unvented heaters are primarily radiant. That is, they don't have blowers to move the air around; instead, they heat the objects directly in front of them, just as a fireplace does. No blower means no noise and no battery drain, but less effective distribution of heat. The heated objects do heat the adjacent air, so eventually the overall air temperature increases, but the main effect of a radiant heater is localized--it won't do a good job of heating your whole coach, any more than a fireplace will heat your whole house.
In short, none of these unvented radiant heaters is a complete substitute for your furnace. They are, however, useful as secondaryheat sources in mild weather, especially because they are silent, efficient and draw no battery power.


Unvented radiant heaters fall into two categories: catalytic and non-catalytic.






The most popular catalytic heaters are made by Olympian, which offers 3,000, 6,000, and 8,000 BTU models under the Wave 3, Wave 6 and Wave 8 product names. When used on low, the Wave 3 consumes about 1/16 lb/hr of LP. The consensus of this group is that the Wave 3 model is most appropriate for Lazy Daze owners; it is available for about $200.




Another catalytic heater is the Coleman 5053A751 ProCat Perfectemp Catalytic Propane Heater. It includes a fan for better heat distribution. Retail price is about $110.








Non-catalytic heaters include "blue flame" heaters, "brick" heaters (the Mr. Heater Buddy Portable Heater is one example), heaters commonly described as "radiant" or "infra red," etc. The Mr Heater Buddy heater is is an open flame infared radiant heater. It burns at a much higher temperature than a catalytic such as the Olympian. This is an advantage because it radiates the heat much further. The downside is that it is more dangerous in that it can set stuff on fire more readily. Also the Buddy only has a high and a low setting. This relates to 4000 and 9000 btu. It does have a pilot setting which holds the pilot light only on and that puts out quite a bit of heat. As a note the instruction say not to try to set the control dial between the high and low settings. Also, Buddy is not designed for connection to the propane system; it uses the small canisters. Buddy sells for about $80.

In normal operation catalytic heaters are safer because they emit no carbon monoxide, and they run at lower temperatures, so they present less risk of accidental skin burns or fire. But they cost more, because they use a small amount of platinum to catalyze the propane's low-temperature combustion.

Safety Caution: Non-catalytic unvented heaters such as the "Portable Buddy," "brick," and "blue flame" types cost about half as much as comparable catalytic heaters, but must be used with extreme care because they constantly emit poisonous carbon monoxide.

Always open a vent or window to provide fresh oxygen and let carbon monoxide escape. (Since CO is lighter than air, it heads for the ceiling, so opening a vent is better than opening a window.) And never leave the heater running while someone is sleeping. Even though catalytic heaters don't normally emit CO, most of us who use them follow the same rules: open a window or vent at least an inch, and never run the heater overnight. Any fuel-burning ventless appliance needs adequate air exchange to replenish Oxygen and remove products of combustion. Standards require at least a 1 square inch fresh air opening for every 1000 BTUs of propane used by any appliance. Replacement air (oxygen) is provided best by two vents, one low on an outside wall and the other high on another outside wall.

Cat heaters produce moisture in the air as a by-product, so expect condensation issues when it is cold and damp out. The condensation is mostly on the window frames and glass, but it pays to keep an absobent chamois or such handy. Running the furnace doesn't create this problem, and can help reduce it. Running the Fantastic Fan on low will reduce heating efficiency, but can cut way down on condensation.

Installation


The Olympian Wave heaters can be permanently installed on a wall in the RV or can be used as a "portable" heater. In either case, you'll need a propane source to fuel the heater. If permanently mounting the heater, you would undoubtedly use a permanent connection into the LD's propane system. For a heater not permanently mounted, you can use either a quick-disconnect fitting or a permanent connection using a length of flexible hose long enough to allow you to place the heater where you'd like.

Permanent Gas connection

To install the heater permanently it is recommended to mount the heater on a metal (steel?) plate with a couple of inches of margin beyond the heater body all around, and that in turn is screwed to the wall. You can also put a small metal plate on the floor just underneath the heater, to protect the rug.

The propane connection basically involves locating a propane line, inserting a T-fitting, installing a shut-off valve between the T and the heater, and connecting a rigid or flexible line to the heater. It's usually easiest to tie into the propane system somewhere near an existing gas appliance, such as the fridge, stove, furnace, water heater of furnace. Unless you are experienced working with propane, it is advisable to have the installation completed by a professional. You sure don't want any propane leaks.

Note that the gas flow required by the heater is less than any appliance except the fridge. You can therefore tap it in anywhere without affecting the performance of any appliances.

Quick-Disconnect Connection
If you opt for the quick-disconnect, you should use a quick disconnect approved for interior use that is double acting, i.e., it cuts the gas off on the source side and also on the hose (heater side) so propane does not escape from the hose. You'll need at least one length of flexible hose long enough to reach to where you plan to stand the heater.

Other Installation Information

"Where do I get the hardware and hose for proper hook-up?"

You can get the quick-disconnects/hookup kits from RV Solar Electric. Call them direct for the best information and to custom tailor your order.

http://www.rvsolarelectric.com/index.php?route=

The flare brass fittings, used for natural gas and propane, are available at any home center or plumbing supply house.

http://www.flickr.com/photos/lwade/sets/72157602104740401/ http://www.flickr.com/photos/lwade/sets/72157602095131438/

You will need to have and properly use a tube flaring tool and tubing cutter.

http://tinyurl.com/5vhonea http://tinyurl.com/638nxb9

Make sure to install a gas-rated shut off valve and to leak test the entire system with a good leak detector.

http://www.homedepot.com/buy/cleaning/drain-openers/rectorseal/8-oz-better-bubb\ le-gas-leak-detector-65796.html

If you are not 100% comfortable with doing this, have a pro install it. Propane leaks are nothing to fool with.

And finally this alternative
While the experts here duke it out over who's going to have the last word on the CO debate, I just wanted to offer this: For the last 30 years or so, my wife and I have relied on unvented Cat heaters to help keep us warm on cold nights, and we're still here to tell the story. True, there have been a few unpleasant spontaneous methane emissions, along with the inevitable maintenance headaches, hairballs, shedding, etc., but our experience has overall been very positive. Our current Cat heaters are our favorites so far. We've nicknamed them "Penny" and "Joe", and we've grown very attached to them. There may be newer models of Cat heaters out there, but P and J do just fine for us.

Penny and Joe are high-capacity, high-output Maine Coon models, and they do an admirable job of keeping us warm on a cold winter's night, and, by the way, keeping us entertained and busy the rest of the time. You should definitely research your options, but we can heartily recommend one or two unvented Cat heaters for anyone seeking a primary or auxiliary source of warmth for cold weather camping, or at home, for that matter.


Contributors: Andy Baird, Jonna, Les, Bob and Carolyn, Norm, Lorna, Joanne, WxToad, Larry Wade

Revised March 24, 2011

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