How dumb is an indoor LPG furnace..?

WTF is he heating his anvil? That's a new approach to blacksmithing. Good for keeping heat in thin pieces of metal.

 

My setup can be seen here:

http://www.alloyavenue.com/vb/showt...eversing-this-motor/page6&highlight=vent+hood

I used an active blower setup as you can see. Most garages are not too well sealed so I would not be too concerned unless yours is really tight. It is hard to know exactly now much CO your furnace might produce. When cooking it is common to have 4 LPG burners running for hours with no ventilation at all. Then again you hear stories about malfunctioning LPG heaters causing CO poisoning. I would say, go for it with some type of passive chimney. Buy a CO detector (or 2) and run it near your work area as a precaution.

Robert

 

That's a fancy schmancy setup.

Pssst Robert.... >>>>>>>http://forums.thehomefoundry.org/index.php?threads/members-with-youtube-channels.188/

 

AL203 QUOTE My initial reaction even with electric was a little apprehensive. For fuel fired furnaces, carbon monoxide would be the concern but ya-know, every house I have lived in has had a natural gas furnace and hot water heater. Those are vented of course. Other gas fired appliances included stove and dryer. So why couldn't a small LP or NG furnace be similarly vented safely? The volume and temperature of exhaust gas may be a bit different but I would think double walled vent duct would stand a chance of keeping temps down on the inner tube. I would think it just needs to be sized properly on the exhaust side, and a reasonably good seal at the furnace lid, and fresh air source available to easily make up for what you are pushing out. I would think most garages would naturally do the latter and with enough chimney length you might achieve plenty of additional updraft....chimney affect. Ever heard of a fireplace?

Bear in mind that vent piping is designed to handle no higher then about 600 F temps, you cant direct our furnaces exhaust at 2000f direct into a vent, even water heaters and furnaces dilute the exhaust stream with room air before venting up the double wall or triple wall pipe. you can vent fairly close to the ventilation fans opening which will dilute the exhaust air stream and cool it down enough. the discharge air temp is a ratio between the volume of fuel air mixture and the exhaust air stream if the exhaust stream is 2000 cfm and the room temp is 75 and the furnace stream is 200cfm the 1/10 ratio of the cfm and the absolute temp ratio is 2460/535 2460 +(535 x 10)=7810/10=781 absolute -460 = 321F discharge out the exhaust fan. I hope that makes since

some how the calcs got cut off when i originally posted this

Art b

 

What a fantastic set up Robert. Waaayy better than what I had envision for myself.

I just remembered that I snagged a squirrel cage blower from an estate auction last year. That would be perfect for this application. I doubt it would keep up to my brute/bouncy castle blower, but there's nothing stopping me from building a propane burner that would run on way less combustion air. Might take a bit to heat up my current furnace (even though it's "low mass" by Pat's perspective ), but just building a burner and fab'ing up a hood vent is more doable than a whole furnace build.

Can't agree more Kelly. I think what gets lost in the conversation is the current use of the variables within my home (or anyone else's) already. I have several appliances that run on NG. Although only one isn't vented to the outside (stove). I don't batt an eye at using a torch within my garage without circulating the air. I don't concern myself with maintaining the condition of my garage floor.

I had an electric furnace swimming around in the back of my mind mainly to avoid the potential open flame of a burner. I didn't give the off gassing of the molten material much thought, and that's a something I believe is greater concern than the other variables. It wouldn't take much to construct a large enough catch try to melt/pour within to remove the hazard of spills out of the equation, or at the minimum make them no worse than a spill outdoors. If I kept my efforts within the realm of aluminium pours and used material I've already made ingot stock with, I think that should keep unknown off gassing hazard risk low.

Something else that keeps this option alive in my mind that I think I mentioned earlier, I'll recant now.... The byproduct of constructing an actively venting "casting area" within my garage, is also using the same location for welding and/or spray painting. I have some HVLP spraying equipment that has been in storage since I left a former employer (who had a hood vent I used to control vapours and over spray). Having a actively vented area would give me back the ability to use that equipment in an controlled environment. Although my garage would be too cold for painting on any level during the winter months. I could also fabracobble a snorkel for collecting grindings and welding whatever.

Ok... I think I've reached the point where I'm just trying to sell the idea to myself...lol. I'll ponder it for a bit and see if I can justify adding this to the ever growing project list.

 

I don't think I'd bother attempting to paint in the winter months. At least not with the HVLP rig. Too cold most days to maintain required temps even without venting. My garage space has zero climate control.

It probably sounds frivolous to not use the HVLP gun without a hood vent in the warmer months. However, for me at least..., dust control is a must. Nothing worse than going through the effort to lay down a nice paint job and have it end up with lousy finish because of dust and insects looking to take a bath.

A buddy of mine built a collapsible paint "booth" out of some 2x4's and plastic sheet. Uses a furnace filter on the inlet of a blower and pressurises what's probably better described as a tent. I'd love to one up him

 

Ron who used to post on AA recounted a story of knocking an aerosol paint can off the shelf, It split and the home heating furnace caught it. He lost the entire house to the fire. Make of that what you will in this context.

 

Accidents happen...?

 

Is it not a case of a furnace will consume a fair amount of o2? In an enclosed space that may be bad. What if blower feed is piped from outside?

 

Well if I went through with setting up a actively vented area, I'd have to also cut in a passive vent to allow make up air from the outside. Although knowing how drafty my garage is I doubt I'd need a make up vent...lol. Regardless, a vent up system would compensate for any burnt up O2 from the burner.

I don't really have much in the way of experience concerning gas based burners. However I really don't think they use much combustion air. At least no where near a drip oil burner would.

 

My point was, be cautious with the materials around an area you might plan to run a furnace. Not meant in a way to question the common sense that prevails here. As far as CO and such, I've had CO poisoning and it hurts (Car exhaust bent through a broken boot floor) I agree with jag a perfect flame should negate the problem, the reason home heating boilers seem to kill people is a stuffed up flue leading to a bad burn. Not sure I would cast 'indoors' in anyway but my shop is attached to the house. (Checks insurance policy....)

 

the difference between our furnaces and any other combustion appliance that we are familiar with is that our furnaces exhaust temps are typically at flame temp which is above 2000F all the other appliances have stripped out the heat through some form of heat exchanger and the leaving temp from the appliance is typically under 500F 500 F vented into a 6" pipe from a 4 " flue drops the temp below 400F 2000F vented under the same conditions is still going up the 6" pipe at well over 1000F, in order to get it to work you would need to vent into at least a 10" vent and probably through combustion exhaust fan. to get enough additional air.

 

The problem is that our furnaces would be considered the firebox in a heating appliance like a furnace or boiler, The BTUH that is still in the exhaust stream of a furnace or boiler is about 20% of the input firing rate, in our furnaces the BTUH in the exhaust stream is close to 90% of the firing rate. if you can vent 20% through 6" flue then it would take a flue 4+times that size to vent the 90% that we have to vent from our furnaces.

Doubling the size of a pipe = a 400% increase in area. So if 6" is required to vent a normal furnace it would take a 10 to 12 " to vent a foundry furnace of the same input firing rate. I hope this helps to see what we are dealing with when are are looking at ventilation requirements.

Art B

 

Combustion air requirements are more a product of the BTUH input of the fuel, so if the BTUH of a burner whether it is propane Ng or oil is the same the burner will require the same amount combustion air. The only difference being the amount of air required to vaporize the oil. When the oil is vaporized through a pressure nozzle the combustion air required is the same. If it is vaporized in a system such a s a Hago or Delevan nozzle the amount of compressed air used can be subtracted from the combustion air, as the work required was provided by the air compressor in generating the pressure lost to vaporization, when it is vaporised as in a drip burner, the additional air required is used in generating the heat to vaporize the fuel. but once it is vaporized the secondary combustion air required is the same.

Art B