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Servicing Denver, Arvada, Westminster, Northglenn, Thornton, Wheat Ridge, Sheridan, Lakewood, Englewood, Centennial, Littleton, Aurora, Castle Rock, Highlands Ranch and surrounding communities. Counties served are: Douglas, Arapahoe, and Jefferson Counties.

REPLACING A FURNACE BECAUSE OF A CONDEMNED HEAT EXCHANGER.

The following photos will show the importance of proper maintenance on a gas furnace.

We were called to a client's home since another company had condemned the horizontal crawl space furnace because of a cracked heat exchanger. It is actually NOT cracked to the point of causing a problem, the problem that is created with this furnace is one of air leaks. In reality, seldom do we find actual cracks in the Denver area. We however, spent many years in Georgia where the high humidity caused MANY large cracks in heat exchangers that were 10 years plus old! When we get a good photo of an actual crack in a heat exchanger we will post it on this page. There are also several things that lead to finding cracks. Some heat exchangers such as the Lennox Duracurve heat exchanger are almost impossible to visually see the middle of the heat exchanger since it " curves ". This is why we not only rely on a visual inspection with a mirror but also test with a Carbon Monoxide Test meter. The Gas Co. in our area also does a third test which is called an Inert Gas Test. This third test involves putting a mixture of nitrogen and propane in each heat exchanger segment. If there is an air leak between the furnace cabinet and the heat exchanger it will NOT pass this test. Because they use this test we have replaced furnaces in our area that we didn't condemn because of a carbon monoxide leak but because of the rusted cabinet and codes in our area.

In the shot below you will see a discolored side panel. This discoloration is from the burner flames actually " rolling out " of the burner compartment when the furnace blower starts. This heat exchanger has a couple of small cracks inside but this flame roll out is actually being caused from air being blown out through a weak spot between the side panel and the heat exchanger. This air is then blown down on the burners while they are lit, causing the flames to be blown in several directions. Obviously this is dangerous in several ways. Carbon monoxide could be spilling out under this clients crawl space. If you look to the right of the discoloration you will see the furnace gas valve. If the flames were to hit this valve there would most likely be either an explosion or a fire! We will move on to other pictures to show what led up to this happening.

Below is our Head Service Technician removing the old furnace flue pipe. It is a single wall pipe and should never have been installed in a crawl space. The codes say this pipe needs to be a double wall flue. The reason is a crawl space or attic is cold and will condense moisture causing poor venting of the flue gas. All modern furnaces have an inducer motor that will help the furnace draft better, but we are educating our readers on what the codes call for.

Below our Installation Technician is removing the sheet metal supply plenum to get ready to remove the old furnace.

Below the furnace is detached from the ductwork, the electrical supply line has been removed as well as the gas line. We will haul it out to our truck after putting carpet protection down on the client's flooring.

Before leaving the crawl space we want to show you another problem. Notice the water heater flue pipe on the left top of this picture? The next shot will show you a bad situation!

Below is the same flue pipe. Notice the pitch of the pipe is to the left of the water heater? The flue gases can't rise this way! This appliance is supposed to have 1/4" per foot pitch toward the main flue that exits your home. As you can see it is the opposite way! This is another code violation and is unsafe!

The problem for the home owner is this - in order to get the water heater pitch right someone will need to lower the water heater and it is sitting on a poured concrete floor!!! We aren't here about the water heater but we will advise the client of the unsafe condition.

Below we have the furnace sitting near our truck and are showing the point that the flames were rolling out of the cabinet. Also notice the rust on the side of the furnace? This may be from the water heater dumping corrosive by products under the crawl space, or it could be from the flame roll out of the furnace.

We have loaded the old furnace into the truck. Where our Service Manager's hands are, is the heat exchanger. Think of the heat exchanger like the engine of your car. It is the most expensive part of the furnace. Most people will change the furnace rather than try to install a new heat exchanger if the furnace is over 10 years old. But here is the first problem! The manufacturer gives a 20 year warranty on the heat exchanger. However, the side panels which are rusted badly will not seal well to the new heat exchanger. Additionally new side panels and gaskets are usually not available. We could cut a new gasket and install it to the old panel but most homeowners in our area would not want to pay the labor involved to do this since in our area the rust itself is a reason to condemn this furnace. We are not saying we agree with this but it is the way it is in OUR area. It may not be that way in your area???

Below is the dismantled cabinet with the burners leaning on the right.

Below is the furnace blower motor. It is FULL of dirt as is the blower wheel. The furnace needs a clean filter at all times or this is what is going to happen. As the burners run a while and the blower motor can't provide enough air flow through the furnace, the heat exchanger gets red hot. At 200 degrees a limit switch ( the small silver box on the bottom end of the side panel in the picture above) shuts the burners back off before there is a fire! At least we hope the limit switch works!!!! This is a PRIME REASON TO HAVE THE FURNACE CHECKED EACH HEATING SEASON. Also, the motor can't cool itself since the cooling vent holes are covered. This will lead to motor failure.

Below is some more rust on the side panel. In the following photos we will show you why we won't warranty our work if you want us to install a new heat exchanger in an old furnace. 

Below we have removed the side panel and the burners. The heat exchanger has been slid out partially. Notice the torn insulation gasket on the heat exchanger? We would now need a new gasket if we are replacing the heat exchanger!

Below you can see the heat exchanger has turned blue from the overheated condition, probably for years judging by the dirt in the blower wheel. It is no wonder that most Home Warranty Companies won't pay for a replacement furnace when this is encountered. If the furnace had proper maintenance it probably wouldn't need replacement to begin with. But the most important issue here is of your family's safety! Change your filter at least every 2 months and have a reputable HVAC Service Company check the safety controls, heat exchanger, flue etc. at the beginning of the heating season!

Below is a better shot of the torn and worn out insulation gasket. Remember how rusted the side panel was? How can you expect a rusted panel to seal to the new heat exchanger? If it doesn't seal we may as well not have bothered changing the heat exchanger in the first place. There is nothing cheap about changing a heat exchanger to begin with since you can see how labor intensive it is -  just put in a new furnace. Of course if the panels weren't this rusted it could be more reasonable to do. But don't forget the new furnace will have much better efficiency and the warranty will be much better. The heat exchanger change will only have a 1 year warranty from the manufacturer and no warranty on labor from us because we KNOW there will most likely be a problem.

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