Just two things in your ducts are responsible for giving the blower in your furnace or air handler a hard time. They make the blower push against more pressure, thus reducing air flow or increasing energy use, depending on blower type. They cut the amount of air that gets delivered to the rooms. And they can be reduced but not eliminated. Do you know what they are? Maybe you're thinking it's flex duct that's not pulled tight or not using rigid elbows or maybe even the dreaded ductopus. Those things are related, but we need to go back further. We want the root causes. This is basic physics I'm talking about. Maybe looking at the image below, a view through a piece of flaccid flex duct liner, will give you an idea of what's to blame. The first cause of reduced air flow is friction. When air moving through a duct rubs against the inner surfaces of that duct, it loses energy. The more it rubs, the more those things happen. It's like walking down a busy sidewalk with your shoulder rubbing against the buildings.

The amount of friction depends on the nature of the material the duct is made of, how it was installed, how dirty it is, and how fast the air is moving. The photo above shows flex duct that's not pulled tight at all. Even though you can't see it all that well, you can tell that there's probably going to be a lot of rubbing when air moves through that duct. The same flex duct pulled tight is shown below. It still looks a bit rough but is much better than the one above. A piece of rigid metal duct would provide a much smoother surface. The other primary cause of reduced air flow is turbulence. This one is a kind of friction of the air rubbing against itself. The main cause of turbulence within ducts is turning the air. When you send air through a 90° turn, the type of fitting you use to do so can make a big difference. The diagram below is from ACCA's booklet Understanding the Friction Chart. In both of the 90° elbows, the air enters nice and smoothly. When it makes the turn, however, notice that the air in the elbow with the curved inside edge (the throat) results in less turbulence.

The elbow with the square throat produces more turbulence. Pick your fittings carefully! Friction rates and pressure drops The result of friction and turbulence, as I said above, is that you get a drop in the pressure. As air moves through a supply duct, the pressure created by the fan behind it keeps it moving. The farther it travels down the duct, though, the more that pressure is reduced by friction and turbulence. Surf Brand Car Seat CoversThat's true in good duct systems as well as bad.Nike Cycling Shoe Parts Both of these causes, friction and turbulence, are included in the friction rates given for various types of ducts and fittings. Toshiba Laptop Fan Replacement CostAs the word 'rate' indicates, the friction rate doesn't tell the whole story.

You've got to combine it with something else to figure out what the whole pressure drop is. That's where equivalent length comes in, and I'll save that for a future article. Or you can skip ahead and go read Manual D. When designing and installing ducts, you've got to know about this stuff. Friction and turbulence play a big role in whether a duct system does what it's supposed to or not. We've got this stuff quantified. If you're not using Manual D or a ductulator or some other method that quantifies these effects, you may well end up with a system that no amount of commissioning can save. How to Install Flex Duct Properly Keep Your Elbow Rigid — A Lesson in Flex Duct Installation Don't Kill Your Air Flow with This Flex Duct Disease NOTE: Comments are moderated. Your comment will not appear below until approved.At Shortys HVAC Supplies our parts and service specialists have been actively involved in the HVAC industry since 1973 and are dedicated to providing you the best parts and customer service available anywhere.

Click here for more information about us. Click here for shipping information God Bless our Military men and women. We extend a heartfelt THANKS for the sacrifices you are making! Shortys HVAC Supplies LLC. Air Filters, Humidifier Pads PTAC Equipment and Parts Rheem, Ruud, Weatherking Parts***OBSOLETE- NO LONGER AVAILABLE FOR PUCHASE*** Carrier 1/30 HP 3000 RPM 115 Volts Inducer Blower Mo Call For Pricing and Availability 1 H.P. Carrier OEM Furnace Blower Motor & Circuit Board.In Stock 1/12 H.P. 1-Speed 1100 RPM 208/230 Volt Condenser Fan Motor.In Stock 1/15 H.P. 208/ 230 RPM 3000 Rotation C.W. (FASCO)In Stock 1/15 H.P. 208/230 Volt Inducer Blower Motor 3450 RPM.In Stock 1/15 H.P. 115 / 230 Volt RPM 3000 Rotation C.C.W.(FASCO)In Stock 1/15 H.P. 115/230 Volt RPM 3000 Rotation C.W. Factory Direct Upgraded Replacement Motor (Fasco)In Stock 1/15 H.P. 2-Speed 1550 RPM 115 Volt Window A/C Motor (FASCO)In Stock 1/15 H.P. Inducer Blower Motor 460 Volt RPM 3000 Rotation (C.W)In Stock 1/16 H.P. 3450 RPM 208-230 Volts Inducer Blower Motor.

In Stock 1/2 H.P. 1-Speed 1075 RPM 460 Volt Commercial Condenser Fan Motor.(Universal 460 Volt Replacement MoIn Stock 1/2 H.P. 230/460 Volt OEM Commercial Condenser Fan Motor.An oil-burning furnace is essentially a blowtorch in a fireproof box. Electrical ignition sparks a high-pressure mist of oil and air, heating the air in an adjacent chamber. A blower pushes the warmth throughout your home.Despite its complexity, problems with an oil-burning furnace are rare. The good news is that many common problems can be addressed easily by a home owner. However, some repairs call for an HVAC professional.If Your Heat Is OutIf the family is already getting chilly and anxious, take immediate steps to preserve the safety and comfort of you and your family before you venture into furnace analysis. Start Out EasyCheck the thermostat. Is the fan mode set to “automatic?” Is the thermostat set to “heat?”Check your fuel oil supply. Don’t just rely on the gauge — it’s as prone to failure as any component.

Unless you just had it filled recently, check the fuel tank itself. Use a dipstick to determine how much fuel you have. By the way, it’s never a good idea to let your fuel level get low; that’s when sludge and sediment get sucked into lines and plug up filters.Can you hear it running? Is the cabinet warm to the touch? The air filter may simply be so dirty it’s blocking the flow of warmed air. Install a clean filter ($3-$30, depending on make and model furnace) and bask in your good fortune.In rare cases, clogged ducts can restrict air flow sufficiently to reduce the performance of your furnace. Duct cleaning is dirty work that’s best left to professionals. Related:Increase HVAC CirculationHVAC Maintenance ChecklistStill Not Working? Try These StepsIf the furnace isn’t running, go back to the thermostat and crank it up by 5 or 10 degrees. Does the furnace start? If not, switch the fan setting from “automatic” to “on” or “run.” If air isn’t moving and the furnace fan isn’t running, check your circuit breaker.

If the circuit breaker is tripped and resetting it only causes it to trip again, have an electrician check the wiring and circuit capacity.If the fan is running, your circuit is fine. Next step: Look for the “reset” button on the furnace control module. Your problem may be fuel-related — either a lack of supply or an obstruction in its flow. Press the reset button and check your oil tank and in-line filter. Clean or replace the filter ($4-$7) if it’s gunked up. Don’t hit “reset” more than twice. The process pumps oil into the burner chamber, where it can accumulate if you have no ignition. Then when the furnace finally does start, it can do so explosively. So if the button won’t reset, or quickly pops up again, it’s time to call a professional repair service. As you examine your furnace system, watch for two potential culprits: Leaks in oil lines and soot in the burner chamber. Leaks let air into the system, which can hurt performance. And soot indicates inefficient combustion that can lead to other problems.

Either condition should be corrected by an expert.When It Sounds Like TroubleKnocking sounds: You likely have air in the lines. Purging the air — called bleeding the lines — isn’t difficult, but it can frustrate a beginner. If you’re not confident, have your system checked over by a service pro.Clattering sounds: Check the access panels on the furnace itself. They can work loose and rattle, with the annoying sound carried through the house on warm air from the furnace.Squealing sounds: Probably indicate problems with a belt or the blower motor. Shut down the furnace, check the belt, and put just a few drops of electric-motor oil in any oiling ports on your firing assembly fan (some sealed units run oil free, so you may not have ports).The furnace sounds like it’s running intermittently: Check the air filter first. Then check your oil supply and filter. If the tank is full and the filters are clean, it’s time for a service call focusing first on the burner nozzle and electrodes that ignite the fuel.