DIY hot air waste oil furnace

[elt]

I built a waste oil heater pretty much following the instructions for the Mother Earth News waste oil heater. I made some changes to the burner; some of the work on that is in my diary.

As a twist, I put the outer jacket from the water heater back around the converted tank and am using it as a forced air heater.

This is my second day of using it.

It was 20F degrees outside today. A 1/4 gallon per hour held the temp in the shop at 55 degrees. Increasing the flow to about 1/2 gallon per hour brought the temp up to 70 in about 20 minutes and the temperature was still going up when I turned it down.

The little fan on the floor is at a little bit of an angle to the opening. I think that helps it swirl around the inside of jacket. With both the oil flow rate and the fan on high, I estimate the air to exit at about 150F. I also use a box fan set on low that is hanging near the ceiling. With that, the temp in the 750 sq-ft shop is nice an even. With the slower drip, I can put my hand on the flue though I wouldn't want to leave it there too long. I'll get some accurate temperature readings tomorrow.

I'm am getting a little bit of oil smell inside. I think that the access hatch could be sealed a little better and I'll work on that.

- Ed.

[dnix71]

If the exhaust air is that warm, you are wasting a lot of heat. Instead of forced air on the bottom, how about adding heat sink fins to the flue and blow air over those to save some waste heat.

That door in the background could be insulated, too.

Even used oil is expensive now. I just did an oil change on my van and a filter and 5 quarts was $20 (on 'sale').

[elt]

> If the exhaust air is that warm, you are wasting a lot of heat.

I don't see the connection. (I'm not disagreeing; I just don't know HVAC.) I saw a formula that, ignoring a small constant, said that

    temp rise = btu / cfm

If about half the air from that fan is exiting the heater, though, I think the numbers are about right. I don't see a term for "efficiency" so I imagine that it's some other consideration that I don't know about...

To say that I "designed" something would imply that I knew even a little bit about what I was doing... but I "targeted" this thing at about 30h BTU/hr based on dripping one quart of oil into per hour. That gives more or less a 30 or 40 degree temp rise. The very high temperature rise is about the maximum that I could get without overflowing my burner.

> That door in the background could be insulated, too.

Good point. I did put the storm door on a few years ago but didn't go farther than that. I just read about using bubble wrap on the glass; what would you use on the door itself?

Thank you,

- Ed.

[fearcityinc]

Looks good!!!! I just realized how old this post is though...LOL....

IF...you still check it, try to move the heater, so you've got that bend out of it.

Straight shot up and out is the best....also, it looks like the flue goes out relatively low on the roof, I've heard that it's best to have the flue exit the roof at the highest point, that way, if a steady breeze comes along, it wont effect your draft.

Something like the air gets turbulent blowing over the pitch of the roof, and makes sort of a "dead spot" If it's down lower on the roof line.....(friend does hvac)

Also, when I get mine installed.....I'm going to pipe the combustion air in from outside, that way the stove's not using air from the room....which, if it starts burning real good, creates a "vaccum" inside the garage, essentially pulling in cold outside air thru the cracks in the building. It'll have all the air it wants from outside, keeping the warm air inside...Plus, you're not burning your breathing o2 as well...

Did you wind up making the burner from pots and pans??? How's that working for you??