Please note: While I feel comfortable doing most of my own work there are some things which are inherently dangerous, and working on any combustible-based heater or furnace is one of them. I do not recommend a homeowner attempt these repairs or ones like them. I expressly deny any liability from damages should one attempt these repairs or ones like them. This blog in its entirety is for entertainment and information purposes only, and no guarantee or warranty is implied or expressed on the contents herein as to the correctness, fitness, adaptability or usability of the ideas, contents or directions set forth herein. 

Okay, for obvious reasons, I needed to get that out of the way.  All right, here’s the problem.

Several years ago I had a flood which inundated the crawlspace of my house and most of my garage. It was devastating in many ways. I had no flood insurance and tons of things were hopelessly damaged. Chief of them was my old old furnace.

This furnace is what is known as a floor furnace. It literally sits in the floor in a central location of the house and warm air reaches most places in the house quite easily. It has but one duct, and a blower forces fan over the hot heat exchanger and up into the room. Given the house is only 1000 square feet, it works quite well.  The entire furnace, duct, heat exchanger, blower and burner are all house in one 24″ by 36″ compact unit with only a 2-wire thermostat, fuel and 110 volt power hookups.

Over time, I learned how to reset the primary control and bleed the line when it ran out of fuel. It functioned well in the 2 years I had it prior to the flood.

Some people might grimace at the thought of oil heat. Messy! Yucky! Expensive! Not clean burning! I’ve heard it all.

The truth is, oil is one of the most efficient fuels out there. It contains more BTU’s per dollar than any other fuel, and runs hotter than natural gas or propane, meaning it doesn’t have to run as much. Right now it runs about once an hour, set at 68 degrees, for roughly five minutes, with the outside ambient temp at 50.  That’s pretty darn efficient!

This is what it looks like…

I got a few paint splatters on it the grate so I need to do a thorough cleaning at some point.  Anyway, with the unit non-functional, I crawled under there and assessed the damage. Right away, I could see the control board wasn’t working. There ‘s a green light that flashes if the unit isn’t working, but that light was out even though I had the thermostat all the way up. The transformer was warm so I knew it was getting power. So, I ordered a new one.  It cost $69.00 plus 10.00 shipping.

Two weeks ago I went under there to replace that control. It relays the signal from the thermostat to turn on the burner. It worked, sort of, once I replaced the control. But it would not stay running. The motor was nearly frozen and took a long time to free up, with me patiently moving the fan back and forth until it moved, but it was clear, this unit was toast.

New control board being installed.

Ok, then, I started assembling what I needed. First, a new flue pipe. I purchased all I needed for $70.00 at Lowes, including elbows, 4-foot lengths and a male coupler.

I found one problem: the collar where the flue pipe attaches was severely rusted. I suspect this was less a result of the flood than rain coming down the chimney. (My next project will be a good chimney cap!)  Nonetheless, I had serious doubts as to whether this was a viable project.

I removed the old pieces of flue pipe and inspected. The firebox or heat exchanger was actually in decent shape, made of heavy-gauge steel which had little rust except some surface rust. The collar was a different story, though; the bottom third was gone.

I decided to try something, unsure if it would work. I took the connecting male coupler, normally used for joining two pieces of female flue pipe and cut a 2 inch slit in it with my tin snips. This allowed it to narrow slightly. I then inserted it in the damaged collar which was a very tight fit: the collar is also a male fitting designed for the female end to slide over it. So being the same size (except where I slit it) it wasn’t going to go in easily. The slit enabled me to get it in and started, and I took a block of wood and a hammer and gently hammered it in until it would go no further.  I tried to pull it out and could not, it was in there very securely! I felt if there was any chance of this repair to leak, I would abandon the project. But once I examined it, I was very confident it would not leak at all, nor pop loose.  Then I assembled the rest of the flue pipe. I didn’t get good pics of those, but here’s one I was trying to pop together earlier…

Assembling flue pipe requires pushing down while aligning the ends so they slide in together, then pushing back to round once they pop together

So then it was time to buy a new burner. I looked on eBay and found a nice used one (used only 2 years, per the seller, who is an HVAC guy) which looked perfect. I bought it for 159.99 with free shipping.

It arrived 6 days later and I was ready to get rolling. I gathered the tools and worked my way under there. Important note: ALWAYS wear a face mask under an old house. No telling what you will breathe in!

Three bolts hold the old unit on, on the back where the black flange is. It also requires disconnecting the 110v line and turning off the valve on the fuel tank and disconnecting the fuel line.

Old burner. Beckett Type A, AF

This is the old one, above.  I got it out and examine it, actually in good shape save for the motor.

The new one had arrived, a more modern Beckett Model AFG, very similar. And here’s where it gets complicated. I have never done this kind of work before but I did a lot of online reading and studying and asking some questions.

The most important thing was this: never, ever alter the manufacturer’s settings. These things can run on a variety of settings but that depends on the furnace manufacturer’s construction specifications. I examined mine and found the air adjustment on the new one was precisely the same as the old one. But one big item was the nozzle and blast tube, where the fire actually shoots out.  These were as different as night and day.

The new one, as it arrived (below) had a 3.75 inch blast tube and .60 nozzle. The old one had a .70 hollow nozzle and a 7 inch blast tube. I couldn’t tell the blast tube length until I removed it.

Almost new Beckett AFG burner

So the first thing I did was remove the blast tubes. Just four screws and it slides off. Inside the igniter and nozzle are housed.  They are all one unit, and detach easily.

So I made the swap, and thus my new burner was now configured like the old one.  Here’s what it looks like after the swap.

New burner with old blast tube attached.

Though the old blast tube looked rusty, it was just light surface rust. It had no defects or issues. So I assembled the entire thing and it was ready to go.

One last issue was the fitting for the fuel line. The old line had a straight fitting but the new one was L shaped, and pointing straight up, meaning I couldn’t just screw the line in. Ok, a quick trip to NAPA and I had a one-foot length of 3/8ths  inch tubing and a new compression fitting.

Making compression fittings is pretty easy, you just cut the length of pipe with a pipe cutter, then place in the flaring tool. Leave about an eighth of an inch above the tool and use the flarer to expand it. It’s important to put your compression nut on the pipe before you flare it, otherwise there’s no way to get it on.

Flaring the pipe

Then it’s ready to attach. I did this on both ends and added a connecting piece so I could screw the old line into the connector, the connector into the new one-foot line, and the new line could be bent at a 90-degree angle to meet the connector on the new burner.

Flared end with nut.

Finished fitting

Then it was time to attach it to the burner. This was done quickly and it was time to get back under and start assembling everything.

Replacing the burner, once all the details were done, is nothing difficult. Simply make sure you have a good or new gasket, place it in place and bolt it on, then make your connections.

This is the hole where the old one was removed. As seen here, the white gasket is in great shape.

Then I was a matter of getting it in place, securing the 110 v line, attaching the thermostat (2-wire, white and red, and color coded to it’s impossible to make a mistake, and attaching the fuel line.

So finally, I got it in place. I turned the power back on, started the fuel running again, checked the flue pipe to make sure it was still seated, and crawled back under.

Moment of truth.

I couldn’t get it to fire, but I was ready for that. No doubt air got in the line when I opened it, so it would be necessary to bleed it first. No sweat. Second attempt. I open the valve, let the line bleed and heard a nice roar, and it caught.  I turned the bleeder valve shut again and waited, and listened. The furnace continued to run and within a minute, the blower kicked in, scattering dust, leaves and my cats all over the house! No kidding, my cats had never heard it run so it took them a day to realize this thing wasn’t going to hurt them!

The installed unit is shown here, with the green light on above the red button, and the new copper line coming out of the left side.

And lastly, from the inside, a view from the topside. There is a window on the heat exhanger which allows HVAC guys to evaluate the flame and I opened it to see how it looked. Nice hot fire blowing into the firebox.

Fire in the hole!

There was only one scary moment or two. After I got it running, I smelled a pretty strong smoky smell. I wasn’t sure what it was, so I shut it off. I did smell fumes, like diesel fumes, a bit, but it didn’t smell quite like it, either. I checked to see if the fumes were going up the chimney and they were, quite a strong flow. I shut it off for the day, and tried it again the next morning. Still some fumes but I noticed a bit of smoke on the firebox. Then it hit me, it wasn’t fuel or fumes, but dust and grime from five years of non-use burning off. I’d vacuumed and cleaned it before firing, but the vacuum could only reach a few areas, not all. After three days, the smells were gone and it’s just been nice, warm air blowing out.

I’m totally happy.  🙂

Old total:                                                                                          $369.96

New total: (including $600 for yard work earlier)         $918.99