Vented gas heaters

[PassnThru]

I've been reading about vented gas heaters here lately - I currently have a non-vented gas wall mounted heater and I have always regretted that decision. It's the usual reasons - it dumps a lot of moisture in the garage and always seems to smell. Also, if I leave it on the lowest setting it wants to keep the garage around 55 or so. I just want to keep it above freezing when I'm not using it. Of course, this is often a moot point because it will usually shut itself down after a few days thinking the oxygen level is too low. So I've been looking at the vented heaters. But I have a few questions:

1. Does the vented heater really produce that much less humidity?
2. Is there an efficiency loss versus the unvented?
3. What happens when the power goes out? My current heater requires no power to work. Most of the ventless that I have seen would require power to work. Any way to work around this?
4. With an external thermostat, how low can you go on temperature? IE - will they hold a temp like 40 degrees?

Thanks in advance for the advice

 

[HoosierBuddy]

1. Yes. The vented heater produces NO humidity in the heated space. Gas and air are mixed and burned and that heats a heat exchanger that actually heats the air. The products of combustion, Carbon Dixoide and Water, are vented out of the structure through the flue pipe. Ventless heater are fine for occaisional use, or for emergency backup heat, in approved spaces that DO NOT contain any solvents or airborne contaminants as these are burned up and blown back into the heated space by ventless heaters. IMHO, they are a terrible solution for a garage.

2. Yes there is a loss in efficiency. A standard hanging heater or furnace with metal flue will burn at about 80% efficiency vs 100% for the ventless product. A high efficiency furnace or space heater (fully condensing) utilizes a plastic "flue" and those typically are rated between 90% and 95% efficiency. However, by utilizing a thermostat that can set the garage temperature at the level you really want, (lower) you should actually use less gas and have much greater control over your comfort level.

3. When your power goes out, a standand furnace or space heater won't run and neither will a high efficiency unit. They all require power to run the blower that pushes air past the heat exchanger and the high-efficiency units also have a fan for the combustion air/exhaust gasses. Neither will run without power. The work around is to have a ventless heater as a backup OR have a backup power supply such as a standby generator that can supply the requried power to the furnace/space heater.

4. Most of the new digital t-stats can be set that low, but you should check the specs on the t-stat to be sure.

Phil

 

[PassnThru]

That pretty much answers that. Thanks for the input. It all sounds great except for the no power - no heat situation. I could leave the old heater in there but I'd rather reclaim that wall space that it is currently taking up. Emergency heat will have to take the form of kerosene. I have two kerosene heaters already but they would be in the house if the power was out. Keeping it above freezing isn't all that critical now that I think about it. It's detached with no water supply in it so there would be very few things that could freeze anyhow.

 

[ishiboo]

That pretty much answers that. Thanks for the input. It all sounds great except for the no power - no heat situation. I could leave the old heater in there but I'd rather reclaim that wall space that it is currently taking up. Emergency heat will have to take the form of kerosene. I have two kerosene heaters already but they would be in the house if the power was out. Keeping it above freezing isn't all that critical now that I think about it. It's detached with no water supply in it so there would be very few things that could freeze anyhow.

A forced air furnace will easily run on all but the very smallest generators, you should be able to pick one up to run it for $100-200 easy on Craigslist. I wouldn't worry about it.