Be Part of the Solution

My father lost his battle with cancer early on the morning of December 21, 2015. When someone dies there begins a very busy period where family and friends come together to take care of all the details associated with final arrangements as well as to figure out how everyone whose lives were closely knitted to the deceased will regroup and continue with the business of living. In a peculiar twist, a house that has just been overcome by the shadow of death overflows with life. A neighbor called in the midst of this activity. I answered the phone and was mistaken for dad. The neighbor did not know dad had died, and I did not correct her. Instead, I just listened because I could tell she was upset and needed help. The mail carrier had already been by her house and had not come up to the house to bring the mail. She had two letters she needed to mail and feared that she had missed her chance. She is legally blind, and so tries to void walking down to the street. I explained that I was not dad, but his son. However, I said that I would be glad to take her letters and see that they were mailed today. I walked down to the neighbor’s house, got the letters, found the mail carrier, and handed over the letters. You see, dad’s neighbors had gotten used to turning to him when they needed a solution. One of dad’s mantras was “be part of the solution, not part of the problem.” I was glad to help dad be part of the solution one more time.  

Funky Flames

Funky flame patterns may be an indication of a dirty or restricted secondary heat exchanger in 90% furnaces. Most furnaces today use draft inducer blowers which draw the vent gasses through the heat exchanger. In the case of furnaces with efficiencies of 90% or greater, there are two heat exchangers – a primary and a secondary or recuperative heat exchanger. The secondary heat exchanger condenses water out of the flue gas. Most secondary heat exchangers look something like a tube and fin coil made out of stainless steel. Many have turbuators inserted into the tubes to increase the heat transfer by making the gasses swirl as they pass through the tubes (see photo). Flue gasses could never make it through without the induced draft blower drawing them through.

If the water does not drain properly out of the secondary heat exchanger, flue gases cannot travel though easily, and the combustion gases back up. This causes the flue gas created by the flames to find another exit – usually out the front where the gas and air entered. The errant flue gasses disturb the flames creating yellow coloring, dancing, extinguishing and relighting, or rolling out of the combustion chamber. The resulting flames often create a lot of carbon, which can further clog up the heat exchanger.



If you see these symptoms BEFORE the indoor blower is energized, you should first check to see that the induced draft blower is operating and that it is actually producing a draft. Sometimes the blower wheel comes apart or slips off the shaft – causing the motor to turn without actually moving any air. Next, you may want to inspect the secondary heat exchanger for obstruction. This varies between units, but most often you will need to remove the draft inducer to see the secondary heat exchanger. If the secondary heat exchanger is filled with water – you need to solve the drainage problem.

If it is clogged with black soot, the secondary heat exchanger will need to be changed. If that is the case, you will also need to look for the cause of the soot. Double check the orifice and operating manifold gas pressure. An oversized orifice or incorrect manifold pressure can cause soot. If the furnace is located more than 1000 feet above sea level, remember that it must be de-rated – which can mean a lower manifold pressure and/or a smaller orifice. Check with the manufacturer for orifice and manifold pressure recommendations. If the furnace uses sealed combustion (combustion air coming in through its own pipe) check to see that the combustion air pipe is not restricted. Birds and rodents are common problems. If the flame pattern is fine up until the indoor blower comes on, and THEN the flames get wacky, you probably have a cracked primary heat exchanger. In this case, the primary heat exchanger definitely needs to be changed.

A Nutty Furnace Problem

A common fault in condensing furnaces is a draft switch shutting down the furnaces. Before changing that switch, check to see if the switch is just doing its job. Most draft safety switches are open before the draft inducer fan starts. The ignition board looks to see that the switch is open before starting the inducer blower. If the pressure switch is closed before the draft inducer starts, the process stops right there and the board will flash a diagnostic code or report a fault in the case of communicating systems. Disconnect the tubing and wires going to the draft switch and check resistance between the two electrical connections, usually labeled “common” and “NO” for normally open. You should read infinity (OL). If you get any reading besides OL, the switch is bad. Assuming the switch reads open (OL), you want to check to see if the switch is closing, and at what pressure.  Put a tee and short piece of tubing in line with the tubing connected to the draft safety switch and connect a magnehelic or digital manometer to the branch on the tee. Remove the wires connected to the pressure switch and use alligator clips to connect meter leads to the switch connects and set the meter to read continuity. A meter with a continuity beeper works best so you don’t have to watch the meter. Start the furnace and observe the pressure reading when the meter beeps. You are trying to determine the pressure where the switch closes. Once you have that, compare it to the rating on the switch to see if the switch is opening at the right pressure. The correct pressure is usually on the pressure switch.    This can be pretty tricky because it happens quickly. Connecting the pressure switch to a tool that provides a controlled vacuum works better, but involves another tool.  There are electronic vacuum tools as well as simple rubber bulbs that can be used to produce a vacuum. If the pressure switch does not close and the pressure reading shows a vacuum of at least the pressure switch rating, the switch is bad. If the switch does not close but the pressure is not at the rating, the problem is that you don’t have enough draft. This can be caused by leaking vacuum hoses, bad inducer fan motors, loose or rusted induced blower wheels, or stopped up vents. Recently I learned about a condensing furnace whose vent was stopped up with acorns and plants. Squirrels were hiding acorns in the vent, which was discharging horizontally out of the house. When the acorns got wet from the furnace vent gasses they started to sprout, so the vent was stopped with plants and acorns. One way to prevent this would be to add a large mesh screen over the vent outlet. However, many manufacturers recommend against using a screen over the vent. They are worried that water will condense on the screen and freeze, causing an obstruction. In areas with a lot of squirrels, you may still want to add a large mesh screen (1/4” between wires) over the vent pipe because it is easier to remove an obstruction on the vent outlet than down inside the vent pipe. Removing the squirrels also works, but is easier said than done in some areas. There are more squirrels than people in my neighborhood.  

Practicing Responsible Behavior

Irresponsible behavior can cost you an opportunity for the job you really want. A bad driving record can affect your employability as an HVACR tech. Whether installation or service, it is common for HVACR Technicians to drive company trucks. The company pays dearly for insurance to cover these trucks and drivers. The first thing many employers do when considering a new tech is to turn their name into the insurance company for an investigation. The insurance company looks up your driving record for the past seven years. Too many problems and the insurance company will refuse to insure you. Obviously you won’t get the job if the insurance company won’t insure you. I know a local contractor who has had a particularly frustrating experience with this. They hired three people who the insurance company would not insure. Particularly troublesome are DUI/DWI and multiple speeding tickets – especially if the speed amounts are 20 mph or more over the limit. Before you complain that this is unfair, remember these are actions you can control. It is logical for the insurance company to avoid obvious risks. As for the HVACR Company, they really must be insured. Further, the behavior and driving record of their employees can affect their rates – which are already quite high.

While we are discussing controllable behaviors, you should know that many companies require drug testing these days. Again, this goes back to avoiding risk. So even though a number of areas are making some recreational drug use effectively legal, this can keep you from being hired. A local company told me that they have a six week hiring process. At the beginning of the interviews they inform the job applicants that they will have to take a drug test if they make it through all the interviews. Half of the people who clear the interview process fail the drug test. This means they could not stay clean for six weeks even though they were warned up front. So do yourself a favor: don’t use recreational drugs; if you drink, don’t drive; slow down when you drive; and follow the rules of the road. You will most definitely will be expected to do these things AFTER you get a job, so you might as well start practicing now.