Wet tools!!

[David Keller NC]

"I think the proplem you are having is more the fact that the cast iron and by that mater the whole shop was so cold and then you warmed it up with propane. I think the water you found was more a matter of condensation than a by product of the propane burning. The propane burning will give off some mosture but not the amount you are talking about."

From the standpoint of someone that has a couple of Chemical Engineering degrees, I can assure you that open-flame combustion of any organic fuel (propane, kerosene are common ones) will dump a huge amount of water vapor in the air. Moreover, if you heat the air in the garage by an indirect or non-combustion source, the relative humidity will drop like a rock, usually far, far below the condensation point at above 50 degrees or so.

Propane heaters and kerosene wick-type heaters are great things to have in a garage where you want to change the oil in the car, but definitely not so good for a Woodworker's shop.

From the standpoint of energy efficiency, electric resistive heat is nearly at the bottom of the scale. That would include baseboard and overhead, radiative-type heaters. Slightly more efficient are forced-air electric resistive heaters. Enclosed-oil type electric heaters are about as efficient as forced-air electric resistive heaters. Moving up the scale, electric heat pumps are considerably more efficient than the resistive types, though considerably more in initial outlay than a resistive heater.

Finally, currently one of the most efficient heat sources you can buy is a condensing natural gas furnace. Not only is the natural gas combustion very efficient (these units, by the way, don't vent the combustion directly to the heated space, so they don't contribute to increased humidity), but the unit uses a small heat pump to remove the heat of condensation of the water vapor in the combustion gases, and re-cycles that heat back to the heated space. They're nearly 95% efficient, but fairly expensive for the installation - I think I'd only do something like that if I had a very well insulated space that was going to be my permanent shop.

[Wade Lippman]

I left my lathe in an unheated garage one winter and it rusted. Not badly, but enough.
So there is certainly more to it than either heat or propane, since I didn't have either.

The cars bringing moisture and salt in can't be good.

I moved enough of my wood to the garage so I now have room in the basement for my lathe. No rust!

[Steve Leverich]

Propane produces a LOT of water - from this document

http://www.engr.uga.edu/service/exte...01/vol13n2.pdf

"burning one gallon of propane requires 850 cubic feet of air and
produces 108 cubic feet of carbon dioxide and 0.8 gallons of water."

I have one of the "jet engine" type propane heaters but stopped using it in the shop for just that reason.

Now, I keep individual 100 watt bulbs up inside major power tools so they stay warm, will eventually change these to hard-wired with "rough service" bulbs so they can stay put.

I also modified a dead LARGE upright freezer into a "warm box" by running a power cord thru the drain and into a "keyless" light socket and box, installed a 50 watt bulb, drilled a 3/8" hole in the top of the freezer (warm air/moisture escape) and keep all the measurement, router accessories, saw blades, planes, chisels, etc, in that. Works really well, it's 32 degrees here right now and the box is about 75 degrees inside and DRY and dust free.

To keep the chill off the shop itself I use a couple small quartz heaters spread out.

I have another dead reefer that's slated for the same treatment, running out of room in the first one... Steve

[Larry Edgerton]

Jim, I have baseboard heat in my shop and it works fine. However, if I were doing it again, I would combine some of the overhead radiant heaters. You see them in places that are open to a lot of air exchange - lumber yards, etc. I think I could work in a cooler environment with that type of heat.

John, if you are talking about the radiant tube heaters, don't. I had a couple in my last shop and they were awesome to work under, economical, and not all that expensive to buy, but....

They would warp a board in 10 minutes! I really got tired of setting everything up so that wood was never under the heaters. If you left it 10 minutes under the heat it would be so cupped that you couldn't fit it in a rabbit until you turned it over and heated the other side for 5 minutes, but then you would get busy and ........

I had 10 foot ceilings in that shop. They were great for heating you lunch though. Put a sandwich in tinfoil on a ladder and in five minutes it was toasted golden brown!

I would use them in a finish room to speed curing. There would be no open flame in the room, and they cure finishes fast.

Oh yea, propane. When a house is drywalled we use propane heaters to keep it from freezing, but it will not dry without dehumidifiers in the house as the propane adds so much water to the air. Even in a dry house, when you turn on a propane heater the windows will almost instantly bead up on the inside. You need to vent somehow, or go electric as suggested.

[Tom Esh]

From the standpoint of energy efficiency, electric resistive heat is nearly at the bottom of the scale

I think you're confusing efficiency with how well or evenly they distribute the heat within a space. Essentially all types of electric heaters are 100% efficient. Even the tiny amount that escapes as accoustical energy (fan noise) or light (element glow) is converted to heat as soon as it's absorbed by something.

[Steven Hardy]

Besides the various suggestions of covering with oil shields,waxes etc...the best thing you can do is to slow down the heat up cycle in your shop and cover your tools with an old blanket while it is heating up.I would allow at least two hours of constant temperature before uncovering.

[John Keeton]

No doubt Jim's original post had more to do with the propane heater and the moisture vapor produced.

But, on the expanded topic, the only times that I have had difficulty with condensation are when I have allowed warm, moist air to enter my shop after a cold spell and my tools are cold.

My shop is well insulated and tight. In the winter, I do not let outside air in unless I have heated the shop. I keep my tools waxed and rarely have an issue with rust.

It seems that air exchanges would be difficult to control in a garage shop, and I think that is a real problem for most in that situation.

On the topic of baseboard heat - it certainly is not the cheapest, but I am a hobbiest, and it works well for me. I can heat my shop to 55 deg (a comfortable temperature to work in for me) within about 30 minutes. It will hold that heat for several hours - possibly overnite if it doesn't get too cold.

Were I to use my shop on a daily basis my choice would be a wall mount heat pump - although I would love to have a wood stove. It just seems fitting!

[Jeffrey Makiel]

I doubt that propane caused the problem. Even though its primary combustion bi-product is water vapor, when you heat air that is very cold, its relative humidity drops like a rock and becomes very dry. The humidity in the propane would actually make things more comfortable for short periods but is very unhealthly due to other dangerous bi-products that are present.

My guess is that your garage is kept cold most of the time. Therefore, when a warm, moist winter day comes along that is common in early and late winter, all that cold iron is like a glass of sweaty ice tea on a summer day.

The best defense against condensation:
- Keep your garage as sealed as possible (i.e., a good garage door gasket),
- Consider electric heat with a minimum setting around 50 degrees when you are not there,
- Add insulation/vapor barrier if possible, apply a good quality garage floor sealer,
- Paste wax what you can, and cover with a cotton drop cloth what you can't.

Keeping it warmer is the primary goal.

Sorry, it's not an easy fix.

-Jeff

[Jim Kappel]

Thanks folks! Although I only get into the garage a few times a month at most, this information will go a long way in helping me.

I am planning to tighten things up in the attic, as insulation is still needed in most of the garage ceiling. The garage doors are also not insulated. The only fix I have for that, short of new expensive doors, is to put pink styrofoam insulation in them and hope that helps. I'm also thinking of going with a Modine Hot Dawg natural gas heater. I've got natural gas in the house so that's the easiest and probably cheapest fix for me.

[David Keller NC]

"Essentially all types of electric heaters are 100% efficient. Even the tiny amount that escapes as accoustical energy (fan noise) or light (element glow) is converted to heat as soon as it's absorbed by something."

This is actually not correct. The reason is that for an electric resistive heater, the amount of power that flows through the circuit is determined by the voltage and the resistance through the circuit. The electric heater would, in theory be nearly 100% efficient if the resistance was infinite, because all of the energy flowing through the circuit would be dissapated as heat. However, virtually no current would flow through such a system. Because the resistance (technically, impedance for an AC circuit, but for the sake of simplicity, let's just stick with resistance) must be at some reasonable level to have power flow through the circuit, a fair amount of the energy is routed out the neutral wire back to the source (the circuit box, and eventually, the grounding rod outside the house).

It's for this reason that electrical resistive heat is not the choice for a heat exchanger in a whole house HVAC system - they use a much more complex heat pump to do the heating because in most locales it's more energy efficient. Electrical resistive heat is, however, very effective at putting out very high heat output per unit time, and they're often installed as auxillary heat in heat-pump based HVAC systems to boost the output on very cold days, and when the demand for heat is high (when the house is very cold).

[John Callahan]

Jim, as previous posters have mentioned, moisture is a byproduct of combustion ......... see it all time in winter in new construction with natural gas, kerosene, and propane fired space heaters-windows sweating etc. Long term, if it isn't already, insulating the garage is a good place to start. Might be enough to get by with a 120v electric space heater or two. Gas (propane or natural gas)- at the very least I'd want a vented unit so the exhaust gases (and moisture) exit to the outside. Better still in a dusty shop environment would be a vented gas unit with a sealed/separated combustion chamber that takes in outside combustion air.

[Jim Kappel]

The Modine Hot Dawg has two options with both being vented outside of course. One has the separate combustion but runs about $1400. The cheaper model is $550.

[Curt Harms]

but there's an (questionable efficiency) fix available--used/garage sale dehumidifier. Buying propane then buying electricity to remove the combustion byproduct isn't elegant but the initial investment could be pretty reasonable. Just another thought.


Curt

[John Callahan]

How big a unit (BTU's)? The price for the HDS (separate combustion) unit seems a bit high. I've not dealt with them but DJ's Online Modine prices are as good as I've seen- $949 shipped for the HDS 45 45,000 BTU unit. You'll have to add sales tax (they're a MN company) and you'll need the vent kit and thermostat. Might be worth a look.

[Jim Kappel]

I was quoting the HDS60 stainless steel. The normal HDS60 is $1158.