Condensation!!!

[Dana G.]

I am heating my new shop with a ventless propane heater. The problem is condensation. I live in the Detoit area, so it is pretty cold here in the winter and I only heat it when I'm using it. So my question is what is best way to deal with my dripping walls? The condensation is so bad that the lower power outlet cover plates actually drip! About half way up, the walls remain dry. As for insulation, I used R13 in the walls and R30 in the ceiling.

Thanks in advance for advice or solutions!

[BILLG]

Don't ever use a ventless heater in a sealed building if you value your life.
Condensation is the least of your problems, I would be much more concerned with what you can't see like CO.

[Dana G.]

Supposed to be approved for indoor use (99% efficeint). Do you think that is still a problem?

[jhill3264]

Your life is probably not in danger, but your cast iron surfaces might be. ;-)

Most of the ventless heaters have a CO detector that is designed to automatically shut the heater down if the level of CO gets anywhere dangerous. At least designed that way, never really tested it myself.

You really should pay close attention to any warnings about fresh air requirements, etc., but as to the condensation, there's not much you can do about it. I have the same problem in my Minnesota garage shop. I haven't noticed much condensation on the walls (R13), but the garage doors (not insulated) and the concrete floor sure collect alot. And worse, all the cast iron tools get a nice "dew" on them until they warm up enough to "burn-off" the moisture. If you're not out there long enough for the condensation to burn off, expect to have a lot of issues with flash rust on your cast iron surfaces. Just like a cold can of pop on a warm summer day.

It's a simple chemical equation. Oxygen + (carbon based) fossil fuels = C02 (Cardon Dioxide) + H20 (water). No getting around it. In fact, the more perfect the combustion, the more water vapor that is produced. Without a vent for all that stuff to go outside, it just sits in the air. Your own personal cool-temp sauna.

The only real way to deal with this is to have some kind of positive air exchange with outside air, or maybe a dehumidifer running full. But the real answer is to discard the notion of a "ventless" heater. Go with a power vented heater that sends all the burned gasses and all that water vapor outside. That's what I'm doing next year. 75K BTU for about $400-$600. Natural gas is also cheaper for the same amount of heat ouput (at least around here).

One step better would be a real "direct-vent" heater, where the air used for combustion is actually taken from outside, burned in a sealed combustion chamber, then exhausted back outside again. That would be even better for some of our dusty environments, but those will run an additional $300-$500 though.


Jim

[wbrooks]

Dana, for every pound of propane you burn you actually put about a pound of water into the air. Propane makes for quick heat but the cost is moisture. I was in the same boat until I insulated (13 walls, 20 ceiling, 10 garage door), now I just use a 4800 watt construction heater on a thermostat to heat. I leave the temp at about 40 and it only takes 30 min to get to 60. better to pay a bit more for heat than spend hours getting the rust off all your tools

[HVAC HAWK]

wbroks is wright , propane gives off a lot of moisture.
the best way to cure this is to keep the heat on all the time

keep it at about 40 to 45 when not in use

try not to heat it above 55 to 60 when you are out there

or you have to get the room hot enough to dry the moisture 75 to 80 ?or hotter

i hope this helps i will ask around at work to see if there is a better way

[HVAC HAWK]

i checked with others at work and like wbrooks said is true .

the reason it is 99% is that there is no heat going out a chimney.

thats Wye when its coled out you see all that white smoke coming out of chimneys , this is the water vapor from the fossil fuels.
you can try opening a window a little or get a dehumidifier .

or try to returning it and get one with a vent.

[Dennis/Ohio]

Originally Posted by HVAC HAWK

wbroks is wright , propane gives off a lot of moisture.
the best way to cure this is to keep the heat on all the time

keep it at about 40 to 45 when not in use

try not to heat it above 55 to 60 when you are out there

or you have to get the room hot enough to dry the moisture 75 to 80 ?or hotter

i hope this helps i will ask around at work to see if there is a better way

Hawk,
Once the water vapor is in the building, making the building hotter won't make it disappear. You have to remove the moisture somehow. I learned this washing cars in the garage with a direct vent furnace. I wasn't changing the air in the garage.
Best, Dennis........

[HVAC HAWK]

i now that in my garage if i got it hot enough that it will dry it out .

now i guess this may not work for all ?

[Dana G.]

Thanks for all of your input! A dehumidifier is on the way. Or maybe I should have just cracked the windows.