RSES-Long Beach Chapter: Proper Furnace Clean & Check Tips

No contractor likes to receive a no-heat call in the dead of winter on a weekend night, for example. For infants or the elderly, having no heat may even be a health hazard. Additionally, emergencies make it tough to plan business.

One of the easiest ways to level out emergency calls is to encourage your customers to have their gas furnaces cleaned and checked in the early fall, before overnight temperatures fall. Performing this service not only gives your customers peace of mind that their furnace will operate properly throughout winter, it also reinforces your company as the heating and air conditioning experts and helps generate referrals for future business. A real win-win!

Here are some of the many suggestions to help you, your customer, and your company through the chilly nights ahead...

1. Ask for information
When you check in with the occupant, you should ask how the system is performing and if they have any concerns. Ask if there is anything they feel might have been out of the ordinary. Their responses can sometimes clue you into a potential problem, saving you time in diagnosing an issue or preventing you from missing over an intermittant issue altogether! You can even ask for service history if this is your first time to this site.

2. Check the thermostat
Check the general condition of the thermostat. Remove the thermostat and check the condition of the contacts between the subbase and the thermostat itself for oxidation or fatiqued contacts. Check for tight connection of conductors to wire terminals and that the wire is in good shape. Check batteries of thermostat and replace if needed. Check programming and date and time are set properly. Perhaps suggests they actually have you set a schedule into the thermostat. (What a concept, I know!)

Identifying components of a non-condensing furnace - Note that some terms are incorrect above

3. Clean the surrounding area of the furnace
We gotta do the housekeeping too! Assuming the furnace is in a closet, you should use your vacuum to clean the area immediately around the furnace, below the gas train (burners), the blower section, and if on a raised wooden plenum platform, remove the return air grille and clean the void behind it. While its open, verify there are no air leaks from non-conditioned areas or signs of rodent activity. Wipe down the cabinet if necessary. Remember: this is what the occupant "sees" and does make an impression!

4. Inspect flue piping and ventilation
Make certain the flue piping is in tact from the furnace to the roof cap. Crawl into the attic if necessary. Is the flue pipe rusting through? Is there double-wall piping where there should be? Is there a proper gap between the flue pipe and any combustibles such as penetrations through wood? Is the pitch and routing of the flue piping okay? If a flue pipe is routed through a chimney, is the proper type of liner installed?

For condensing furnaces, is the piping installed to allow condensate to slope back toward the furnace? Is the proper PVC line size being used? How many elbows were installed that may negatively affect proper airflow? Is the piping terminated outside properly? Are condensate lines internal to the furnace free and clear of debris?

5. Inspect gas line to furnace
Ask yourself if the line is properly sized. How about the flex line size? Is there a nipple on the gas valve so the flex line terminates outside the furnace enclosure? Is there a hand-operated shut off valve readily accessible? Is there a drip leg installed? Is supplied pressure while furnace is running acceptable?

Micro pleat filters - Strongly not recommended.

6. Check the filter
Find the air filter. Verify it is large enough for the airflow it must filter. If the occupant is using a 1" micropleat filter, such as the type shown above and purchased at the local hardware store or Target, coach them as the how severely these filters restrict airflow and can damage the furnaces heat exchanger due to the resulting overheating condition they cause the furnace to try to operate with. Sell them a filter that is much less restrictive.

If the filter is an electronic type, wash the pre filters and cells, using a mild detergent if necessary. If a media type, replace the media. If the homeowner changes their own filter, set them up on a filter program using sources such as www.filterfetch.com where you place a sticker with web site and filter ID number information on the furnace. When they order the filter you've specified, your company gets a small piece of the sale each time!

7. Inspect the blower assembly
Remove power to the unit and remove the blower section door. Reach in and give the blower wheel a spin to verify free movement and bearings are not tight. Wiggle the shaft too. Check for debris in the wheel and dirt buildup on the blades.

If your are working on a condensing furnace, this is a great time to remove the blower section completely from the unit and look at the secondary heat exchanger. Remember this exchanger is just like a tube and fin coil and can suffer from a buildup of lint and dirt that gets past the filter and blower wheel. Clean as necessary.

Silicon-Nitride
Ignitor

Steel wool is a better choice for cleaning flame sensors...

8. Inspect and maintain burner section
Lubricate the induced or forced draft motor, if necessary. Use a flashlight to check the heat exchanger for cracks while the exhanger is both cold and hot. Better yet, if you own a seesnake or equivelent, use it for an even better inspection.

Measure the ohms of the ignitor and compare to the normal ohm range of that particular ignitor (see manufacturers data). Be sure NEVER to touch the ingitor as the oils from your skin will cause the ignitor to fail prematurely. Check the flame sensor which, on many systems, is located on the opposite end of the gas train from the ignitor. These need periodic cleaning. It is recommended to use non-detergent infused steel wool. Using sand cloth or emery cloth can cause deep scratches into the sensor surface. This adds additional surface area to the sensor and increases the milliamp reading sometimes beyond the normal range the ignition board is looking for, causing nuisance lockout conditions.

Lastly. Check the in-shot burners for a nice beautiful flow into the volutes. Verify no flame wavering occurs when the blower kicks in. Does the burner have the proper "cone" on it? The cone is the different dark blue, light blue, and yellow-white colors. Does the gas train have the proper pressure leaving the gas valve? Most manufactures like to see 3.5 inches.