| Author | Message | ||
| John Ferguson (Jarlaxle)
Registered Member Username: Jarlaxle Post Number: 40 Registered: 7-2006 Posted From: 4.174.70.41 Rating: N/A |
Does anyone make a 12V->120V inverter that is capable of running an electric heater (~12-1500W), without costing as much as a small car? | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 184 Registered: 7-2006 Posted From: 68.205.196.248 Rating: N/A |
Not too sure about running a full resistance load, but I bought one of these $149 deals for our "Class B". I haven't had a chance to hook it up yet... But one of the workers at HF said he runs his roof AC unit and the TV, etc., in his van with one, without a problem... (I was witness to it) http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=92464 If it works for me, and I can ever get back to working on my bus, I'd buy two for the bus as well... | ||
| Pete/RTS Daytona (Pete_rtsdaytona)
Registered Member Username: Pete_rtsdaytona Post Number: 307 Registered: 1-2005 Posted From: 72.40.15.147 Rating: N/A |
2500 $179 http://www.theinverterstore.com/2500gp01.html 2000 watt - $189 http://www.donrowe.com/inverters/vector_2000.html PepBoys Vector 3000 watt / 6000 surge inverter #vec051d - $319 Pete RTS/Daytona I've been using a smaller vector to run my Tv and phone chargers & my son's CPAP for years also try your local thruck stop - lots of truckers out there use big inverters too - sometimes they have real bargins at LOVES/FLYING J/ETC | ||
| Pete/RTS Daytona (Pete_rtsdaytona)
Registered Member Username: Pete_rtsdaytona Post Number: 308 Registered: 1-2005 Posted From: 72.40.15.147 Rating: N/A |
Think John - MC9 has the BEST solution - Harbor Freight - why didn't I think of that If it doesn't work - return it Thanks JOHN | ||
| James Stacy (Jimstacy)
Registered Member Username: Jimstacy Post Number: 33 Registered: 1-2001 Posted From: 71.150.86.63 Rating: N/A |
12 amps at 120 volts is 120 amps at 12 volt assuming 100% efficiency of inverter (not likely). That's a pretty heavy constant load on a battery bank. Better keep the alternator running. | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 186 Registered: 7-2006 Posted From: 68.205.196.248 Rating: N/A |
Yeah James! I'd use mine for "down the road" with the AC unit(s), or while stationary with the engine running, for the AC, Microwave, or other heavy draw... I don't (or didn't) plan on a BIG battery bank.. And I'd sure as hell need one, if I wanted to run the big stuff totally off battery power.. It's great to have the genset for all that, but it's nice to have the redundancy, too... And if the engine's going to be running anyway, why not use the power (and fuel) to produce AC power as well.... (was just my planned way) | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 82 Registered: 8-2006 Posted From: 207.231.81.154 Rating: N/A |
John, Have you done the amperage calculations, and the amp-hour calculations for what you propose? If an inverter were 100% efficient, a 1500 watt electric heater will draw !! 125 !! AMPS out of a 12 Volt battery. If the inverter is 90% efficient, which is a reasonable number, the current draw on 12V goes to 138 Amps. The electrical/heat engineering constant is 3412BTU/Kilowatt hour. What this means is that a 1500 Watt electric heater will produce 5118BTU per hour, which isn't squat. (my term) The next point which MUST be considered, is that the inverter will put off A WHOLE LOT OF HEAT WHILE INVERTING 138 AMPS! Do you know what size of battery cables you will need to do this? The next point to consider is the percentage of the amp-hours of battery capacity that you will ACTUALLY get out of a battery. I don't have that figure off the top of my pointed head, but I wouldn't figure on having more than about 2/3 available. The expensive inverters have low battery protection, the cheap ones don't. Before I make the next comment, I want to be very clear, I am trying to HELP, I don't get any satisfaction out of raining on somebody elses campfire, or doing something else to it, (humor)! I also don't post where I am not qualified, and I will not stop when a dangerous post is made. Nothing dangerous to this thread, except the inverter can't be in a non-ventilated compartment, heck, put it in with you in the space you are trying to heat! Now, after doing the math, please look at the above posts again. "I haven't actually hooked it up... but one of the workers at HF said..." SEER (Seasonal Energy Efficiency Ratio) which measures air conditioner power usage is BTU/Watt. So, a 10 SEER 1/2 ton roof air will use 600 Watts, a small TV, 150 or so, for 1/2 the total consumption of your proposed electric heater? The other problem with keeping his campfire lit, is there is no mention of how long his A/C runs with the engine off. I know he said he witnessed it, just not for how long. We don't know what your proposed application is, so fess up, and we'll try and help! Sorry to be a grump, George | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 83 Registered: 8-2006 Posted From: 207.231.81.154 Rating: N/A |
My above post was started before the two posts now immediately above it. It just took me longer to get mine out, and edit it the way I wanted it. The two posts immediately above my first are exactly correct, and said the same thing in less words, and are NOT what I was referring to. Apologies, George | ||
| John Ferguson (Jarlaxle)
Registered Member Username: Jarlaxle Post Number: 41 Registered: 7-2006 Posted From: 4.174.70.145 Rating: N/A |
"John, Have you done the amperage calculations, and the amp-hour calculations for what you propose?" Well...I have a 250A alternator on my noisemaker, and it will happily run for many hours before needing fuel.  I'm not planning to run anything like this off the batteries. It's just that, well--my heating system needs a boost for winter camping. | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 85 Registered: 8-2006 Posted From: 207.231.81.154 Rating: N/A |
Good evening John, Could I suggest a (or another) propane heater? By noisemaker I assume you mean a generator, and if so, why not use the 120 ac straight? If you are only generating 12VDC, go right ahead with an inverter. Be aware that it will take #3 minimum copper cable between the alternator and the inverter, and the generator fuel consumption will increase dramatically. Watch the heat put off by the inverter, it will be a lot. Now a point to ponder, alternator output directly into an inverter? Most alternator output looks like 3-phase full wave rectified, but it still has "ripples." I don't know what an inverter would think of that, so, put a battery in the circuit for a buffer/filter. Whew... HTH, and don't HTAM (Hesitate To Ask More) Ha! George | ||
| James Stacy (Jimstacy)
Registered Member Username: Jimstacy Post Number: 34 Registered: 1-2001 Posted From: 70.254.119.35 Rating: N/A |
At risk of starting an avalanche of comments on dripping walls, instant death by suffocation, etc., etc, I would suggest you consider a propane, catalytic heater sold for decades by reputable RV suppliers, and used by many thousands of RVer's for many years. They require no electricity, are silent, portable, and dependable. I am only speaking of the Catalytic heaters that are rated safe for sleeping areas, not the "blue flame", "ceramic" or other models sometimes recommended by board users (who may well have had good luck with these), but I prefer something officially recommended for sleeping areas. If you have propane on board, a couple of quick disconnects plumbed in and a couple of flex hose equiped heaters will amaze you with the no draft comfort and 100% efficiency. We keep a front roof vent and a rear window slightly cracked whether using the heaters or not. The heaters do consume some oxygen as do occupants. IMHO | ||
| Christy Hicks (Christyhicks)
Registered Member Username: Christyhicks Post Number: 17 Registered: 1-2007 Posted From: 65.77.66.1 Rating: N/A |
So, which Catalytic heaters are approved for sleeping areas? Curious minds. . . .Christy Hicks | ||
| ChuckMC9 (Chucks)
Registered Member Username: Chucks Post Number: 1090 Registered: 10-2003 Posted From: 66.167.61.139 Rating: N/A |
I agree that I wouln't dream of using the inverter for a heater because of battery capacity... ...but if some of the earlier posters are looking for a testimonial on the 2K HFT inverter, you've got it. I went through three Vectors, one Xantrex, and have been peachy pleased with my HFT 2K inverter since then. The very one in JohnMC9's link. Because I was gun shy after the earlier failures, I got the extended warranty, (which I normally never do) and the warranty expired a year or so ago with no need to even think about needing it. It will definitely do until I get my 'grownup' inverter. | ||
| John Ferguson (Jarlaxle)
Registered Member Username: Jarlaxle Post Number: 42 Registered: 7-2006 Posted From: 4.174.70.116 Rating: N/A |
The genset isn't a commercial one--it's a 1.5 VW engine spinning a big alternator. As for propane...I have one propane heater (vented outside), and would rather not use another due to propane capacity. The only catalytic heaters I can think of that are vented outside are the (no longer produced) Platinum Cats. I'm not a fan of catalytic heaters, due to moisture & safety concerns. I know the inverter will get pretty warm...I was planning to use a small 12V fan blowing across it to cool it off, and also not putting it anywhere enclosed. Good call about using the batteries as a "buffer". (I have a bank of T-105's.) | ||
| Harmer (Dave_4104_in_victoria)
Registered Member Username: Dave_4104_in_victoria Post Number: 2 Registered: 2-2007 Posted From: 24.64.223.203 Rating: N/A |
Hi guys, Dave here, I have used the older style Olympian catalytic/propane heaters and actually still have a smaller (6000btu's)one in the bath/bedroom rear area of the coach, nice to be warm when you get out of the shower when it is icy outside. I went from a 9000 btu platinum (Sunburst, made in Alberta)catalytic heater up front to a 18000 btu fireplace/blueflame. As like any propany appliance/non vented, like ovens/stoves, heaters etc. The rule is 1 square inch of air for every 1000 btu's of heat. So if you are using your oven, like I have seen people use in the past, with all of their vents closed and windows closed and they were getting a little nauseated or tired, lack of oxygen is the likely problem. Replace the air.. A number of other friends who own buses and rv's/trailers also use this type of heater. These types of catalytic heaters were and still are installed in tent type trailers. I also have three thermostatic reversible fantastic fans on the bus with covers so that they can be left open even in the rain. Overall once the heat has been on for awhile, we find minimal condensation on the inside of da bus. We do see a bit more when the weather is colder, like -5 or so | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 88 Registered: 8-2006 Posted From: 207.231.81.154 Rating: N/A |
Good morning Dave, I don't want to be crabby, or start a fight over ventilation, BUT. By your comment of "the rule is 1 square inch for every 1000 btu's of heat." I assume you are talking about Table 7-1 of the Uniform Mechanical Code? That table is for combustion air supply TO A VENTED APPLIANCE! I know, we have all sorts of posts saying, I've done it for years, etc., and I appreciate your comments about people being nauseous or tired from lack of oxygen. Actually, it is more likely carbon monoxide poisoning. People absorb carbon monoxide much easier than they do oxygen, with deadly results! I am a licensed HVAC contractor, and am aware of four fatalities this year in the greater Sacramento area due to CO poisoning from improperly vented wall heaters in houses, (read a much larger space than a bus.) Yes, all of the fatalities, three kids and an adult were in a rental house which had the heater disconnected by the gas company due to improper operation, and because it was cold, and the landlord wouldn't fix it, the tennant re-connected it, turned it on and killed himself and his kids. That aside, this is something that you just can't play with, the odds are against us. I wouldn't trust my life to the oxygen depletion sensor on a cat heater certified for indoor use. George | ||
| Harmer (Dave_4104_in_victoria)
Registered Member Username: Dave_4104_in_victoria Post Number: 9 Registered: 2-2007 Posted From: 24.69.65.204 Rating: N/A |
Hi George, no offense taken, i think it is important remember the basics and the rule that I put forth regarding one square inch, was not taken from my code book as i do not own one. I defer to numerous certified propane appliance installers and one certified provincial propane/gas inspector. This is where I have heard this rule from. The reason i remember it is because it is simple to remember. Having said that, i think you would be hard pressed to find anyone who is not aware of the dangers of propane appliances. Having said that if there were such a person in the group, they should definitly ask questions. I personally ensure that i have more than one square inch per 1000 btu's of heat when operating my propane appliances, and i would recommend the more fresh air the better. I definitily appreciate your added information though as i am sure everyone else does. Cheers Dave out | ||
| joe padberg (Joemc7ab)
Registered Member Username: Joemc7ab Post Number: 83 Registered: 6-2004 Posted From: 66.38.159.33 Rating: N/A |
George I Have posted before about finding a vented 20KBTU nonpowered heater, Is there such an animal available anywhere? Joe. | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 92 Registered: 8-2006 Posted From: 207.231.81.154 Rating: N/A |
Joe, I don't know of one off the top of my head. It would be a slick solution to boondocking. My whole concern was and is carbon monoxide poisoning. We all have to learn, and this kind of knowledge doesn't come instinctively. The "square inch per thousand BTU" mentioned previously is the combustion air opening requirement for a gas appliance in a closet in a building of normal construction. There is a more stringent requirement for buildings of tight construction. A bus is tight construction. This code section inherently requires ALL combustion products to be vented to the outside! People absorb carbon monoxide MUCH more readily than oxygen. So, when that table gets corrupted into one 4 X 5 inch opening in a bus with a 20KBTU non-vented (catalytic included) heater, the results can be deadly. Proper gas combustion produces a lot of carbon dioxide(CO2), quite a bit of water vapor, and a little carbon monoxide.(CO) This is why there are all of the comments about "dripping walls, etc." Thanks for giving me the soapbox, I'll get off now. HTH George | ||
| joe padberg (Joemc7ab)
Registered Member Username: Joemc7ab Post Number: 84 Registered: 6-2004 Posted From: 66.38.159.33 Rating: N/A |
Thanks George . That is Exactly my thinking, that it would be the ideal for boondocking. Yesterday the day after I posted to you I found two 10K used gravity heaters. Both appear to be good useable shape with one missing the outside vent/chimney grill. Price for both 120 canuckies. I was a happy camper yesterday. I am thinking of putting both right at the front and a regular at the middle rear for extra capacity for a total of 55KBTU. It does get cold up here at times. In my work I carry a CO monitor and I know exactly where you are coming from, and as far as I am concerned keep preaching on that soapbox about the danger that most people dont seem to understand or appreciate. Joe. |