On this nice and wintry day here in NC I am yearning to go out to my shop, er garage, and play. It is just a tad too chilly for my liking however. I toyed with the idea of running down to the BORG to buy a space heater. The choices seem to come down to three: electric, propane or kerosene. And yes, I could also buy a nice wood stove but I really don't want to have to fix the heater in one place with a stovepipe, much less take up a permanent spot in my tiny little shop.
So - what have you used and how has it worked for you? Any thoughts on what BTUs are necessary to make 300 sf space comfortable? The garage is over 12' tall - a lot of space to heat up. Strictly based on convenience I am drawn towards electric and I have the amps to spare on the panel. There is one other little thing of importance to me - it can't break the budget of $80-100...
Im in fuquay (just out side of raleigh) about 2 months ago I broke down and got a small propane rocket type heater from the borg. The Reedy Heater - 40,000 BTU one. (Dont remember the price - but it was under 100)
I have a 3 stall garage (1 of which is my shop) all open w/ 14' ceilings. I made it a point when I build the house to insulate the garage and spend the extra $$ for a insulated garage door as well. W/ that heater I can get it up to a toasty 70 degrees and it stays there for a while. I ran it for about 1/2 hr this morning (9:30-10am) it got to about 71 and its at 68 right now (1pm) I let it run for about 45 mins to an hour before I go in then turn it off. The coldest I normally gets is about 50. (last week when it was in the 30s outside - it was 50 in there.) I can work out there confortable for a while - if it gets too cold I guess I just crank it back up again and take a break. But havent had to do that yet.
Anyways - Id recommend that one. It runs on a propane tank. I had an extra one from an old BBQ and have been using that one. Good luck.. _Rob
I live in Kansas City. Our winters get pretty cold at times. I have used a kerosene heater for several years. Home Depot sells them around $100. I love it. After just a few minutes, I have to turn it down or it gets too hot. I think it is 23,000 BTU's if I remember correctly.
Kero and propane heaters put a lot of water into the air. This is ok as long as the shop is warm. As soon as things, like cast iron, cool below the dew point all that water starts to condense.... I like eletric heat or a wood stove.
There's "acquisition costs", and "operating costs"
electric is cheap to acquire, but *expensive* to operate.
kero or propane are relatively inexpensive to operate, but _do_ have significant safety concerns. PARTICULARLY if not vented to the outside. The combustion byproducts also include _lots_ of water. leading to rust, unless care is taken.
"how many BTUs?" depends greatly on the square footage of the exterior walls/ceilings, and the amount of insulation present. Also, 'how cold' you let it get when the heat is off, and 'how fast' you want to get it back to 'livable' temperatures.
Halve the number of BTUs, and it takes somewhat (but not a lot) more than twice as long to raise the room temperature by the same amount.
Running the half-power unit twice as long _should_ cost about the same as running the full-power one. And the half-power one will be cheaper to buy. It's a trade-off between speed-of-heating and price.
"Rob" wrote in news: snipped-for-privacy@comcast.com:
Call around to the locat heating and air conditioning places. Find one that will sell you a used gas heater that someone has upgraded. Mount it ouside the garage. Put one hole through the wall for a return and one through the wall for supply. Enclose the unit in a "shed" with an outside door. Duct the vent through the roof of the shed. It will be sooooooooooo much cheaper than electric. And you won't have to wory about things like paint fumes causing an explosion because the burner isn't in the garage with the fumes. If you do the work yourself then you can probably do it for a couple of hundred or so. Its not the $80 - $100 you asked for but you will save the extra hundred in electric bills the first year.
I bought the HD kerosene heater. Used it two days, and ended up returning it. It gave off a smell that wasn't really strong, but it was noticeable. Also, SWMBO said she could smell it in the house and upstairs ("workshop" is my garage with the MBR over top). It did get the place warm, but it took about 2 hrs. due to not being insulated, etc. I did notice a slight increase in humidity, but it wouldn't have been a problem because I keep my machines coated with Boeshield, and covered. The other issue was the cost of fuel - HD's kero was about $4.50/gal. The directions said to use "high quality", and talked about some synthetic fuel made by Exxon, but that stuff was even more expensive. I didn't figure the $1.50/gal kero from the local gas station was "high quality". Anyway, the Kero unit didn't work for me.
Price and adverse recommendation from my HVAC company discouraged me from trying a natural gas unit.
I'm interested in the propane - does it smell? Any CO problems or issues? If not, (as someone already suggested) I think it would work good to run it, get the temp up, then shut it off. Would someone comment on this? How long does a 20 lb tank last? (about $9 locally)
When my folks built their house in c. 1973 the first stone was the largest. As a Kollage Graduate I know that's not very likely but that's what happened. Don't get discouraged if the backhoe cowers in the first half hour.
This assumes that half the Btu's is adequate to reach the desired temperature. If you desire a 40 degree temperature rise and 30,000 Btus of energy is required to attain it, running a 15,000 Btu heater will not take twice as long, it will never give the temperature rise desired. Heat loss will overcome heat output.
If, however, 15,000 Btu will give the temperature rise required, 30,000 Btu will get you there twice as fast and have a 50% duty cyle to hold the level constant while 15,000 will take a 100% duty cycle. Of course this is greatly simplified as there is little latent heat in the cold shop and a given temperature rise does not alway equiate to comfort. A 40 degree rise is good with 30 deg. ambient, but not so great with the ambient is minus 20.
That is quite true. However, with efficient insulation, it takes a surprisingly small heat plant when speed of heat-up is not an issue.
I can state authoritatively that less than 50,000 BTU will maintain a
90F temperature difference on circa 2k sq ft of well-insulate house. Admittedly, it was running with a near 100% duty-cycle to do so -- but it _was_ maintaining a comfortable 68-70F inside, with outside temperatures at -20 to -25F.
The "rest of the story" The house in question had been seriously remodeled/ expanded. and rather than replace the existent "perfectly good" furnace with one adequate for the whole house, the existent one was used to heat the 'old' space, and a 2nd unit was added for the 'new' space. Some 20+ years later the 'old' furnace gave up the ghost, leaving the new one to carry the entire load. Naturally, this happened in the middle of the winter, during a _vicious_ cold spell. We *didn't*notice* the failure, immediately. EVENTUALLY, it penetrated consciousness that one furnace was running "almost constantly", and investigation ensued.
At about 4:00 on a _Friday_ afternoon, my Mom calls the HVAC contractor and says: "One of my furnaces has just died, can you schedule somebody out to look at it?" (Note: it was -27F outdoors at the time of the call.) The receptionist at the contractor nearly panics; is apologizing *profusely*, and explaining that it is late on Friday afternoon, that all the service people have already left for the week-end, but "We'll have somebody out to see you *FIRST*THING* Monday morning." To which, my mother replied: "I'm sorry, Monday isn't _convenient_, can we schedule something for later in the week?" This was met with _utter_ bafflement and non- comprehension. :) About the third time around, the point got through that (a) we were _not_ "without any heat", and (b) this was _not_ an emergency. (There *were* _significant_ numbers of people who were in that situation -- lots of over-stressed furnaces, particularly in rental house had been dieing; newspaper stories how the heating repair people couldn't keep up with the calls, etc.) For some strange reason, our contractor just was *not* used to dealing with people that had a "hot back-up" furnace installed and on-line. (Really, what we did have was 'separately powered independent zones. -- We _did_ pay for that flexibility, however, when we added central air-conditioning. Had to put in _two_ complete A/C plants, one for each furnace. "ouch"! )
Anyway, had the 'luxury' of getting competitive bids -- and having to ask most of the bidders to "re-quote", or explain _why_ they were quoting a unit approximately "twice the capacity" of the unit being replaced. (Hardly _anybody_ had bothered to 'read the plate' on the dead unit, and were quoting on the assumption the unit being replaced heated the _entire_ house. It was surprising how 'reasonable' the 2nd round of quotes was. ;) We did end up 'going up 1 step in size'; cuz nobody still _made_ ones as small as the one that had died.
Yup. simplified indeed. but still useful points. Thermal losses to 'outside' don't correlate linearly with temperature difference, and then there's the infamous "humidity" issue.
comment: "Gas station kerosene" _is_ probably of adequate quality.
Propane does have less 'smell' than kero.
CO is _always_ an issue with anything that 'burns'.
With 'perfect' combustion, the only byproducts from propane are CO2 and H2O. If there's insufficient oxygen available, there is risk of getting CO.
The "right way" is a 'sealed combustion chamber' unit that is vented outside. These do cost non-trivial money. natural gas fed, or propane.
"Twice as long as a 10 lb one." Not trying to be facetious, but it depends on a -lot- of things -- how big the space is; how well it is, or is not, insulated; how cold it is outside; how much outside air you need to let in for proper combustion; etc., etc., ad nauseum.
If I did my math right, 20 lbs of propane generates 'net' about 411,000 BTUs of heat. And will produce about 32.7 lbs of water vapor. that water vapor condensing will liberate another roughly 980,000 BTUs of heat.
I'm not sure how the water vapor energy is counted, but at 30,000 BTU/hr, it looks like 13.7 to 46.6 hrs.
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