An ECM Variable Speed Blower Motor in a squirrel cage blower
Variable speed blower motors have become increasingly popular in residential air conditioning and heating systems and for good reason; these motors increase efficiency of the systems and offer a whole range of other benefits that help the system and the consumer.
Variable Speed Blower Motors first offer a higher efficiency for air conditioning systems based on the manufacturers set up of the control with the ECM Variable Speed Motor. Each manufacturer calls it a different thing such as Trane calling it the Comfort R and Carrier calling it Infinity Control. Despite what the manufacturer calls it helps efficiency with air conditioning by starting the blower slowly and letting it run at a 50% speed for the first few minutes (up to 7 minutes) to remove more humidity. This increases comfort and efficiency by removing more moisture from the air. The lower the humidity in the cooler you will feel so the variable speed blower with this type of control will enhance comfort.
ECM variable speed motor manufacturers include General Electric and Emerson with Emerson offering their very own packaged control and control program to meet various control sequences to meet efficiency and comfort for any manufacturer that uses the Emerson ECM variable speed motors for their equipment.
Other benefits include:
Soft start capabilities which reduces high inrush current like conventional blower motors.
Precision control to deliver a set amount of CFM’s for whatever the HVAC equipment manufacturers need for their equipment for airflow control.
High efficiency which reduces energy bills.
Very quiet operation
Better comfort as described above
One of the disadvantages include a high replacement cost if something happens to the motor or controls. ECM variable speed motors need the attention of a qualified HVAC technician if something goes wrong as special diagnostic tools are needed to diagnose any problems which may arise with the motor or controls.
These motors are typically offered in the medium to higher end models of air handlers and furnaces so you will have to pay a little more for the initial cost but the benefits will give you a pay back in the future with increased comfort and higher efficiency. Here at High Performance HVAC we always recommend going for higher efficiency models because the cost of energy is not going to go down in the future and the high efficiency models will help reduce the cost of energy so your utility bills will be reasonable in the future. The bonus this air handler or furnace component also adds comfort while increasing efficiency.
Troubleshooting ECM Blower Motors Basics
Never assume the blower motor is bad. Always perform a cursory look at other components and inputs before condemning the ECM blower motor. Check the air filters and duct work integrity before beginning component checks outlined below. The system needs good air flow to function properly.
Check the main control board in the air handler. Wiring connections including the thermostat wire coming from the thermostat. Always perform these checks with the power turned off. Check for loose connections, corrosion, and burned spots on the board. Some HVAC equipment has an additional control board for control of the ECM blower motor in the air handler. Also check all the connections going to the motor including pins inside the molex plug connection. A bent or loose pin will cause problems.. A plastic molex plug should make the connection between the motor and the control board.
Next check the input voltage for the board. Restore power and use a volt meter to check both the main line voltage and the control voltage. The control board should use 24 volt for the control voltage and all voltage ranges should be plus or minus 10%. Make sure that the safety circuit is good. Switches in the safety circuit will keep the system from running.
Using the manufacturers instructions, check additional settings on the control board. Many have dip switches that will control RPM’s for the proper air flow for the sizing requirements of the system. Ensure these are set properly.
Ensure when you start the system that you wait for the programmed delays. An ECM blower motor, properly programmed, will start off very slow and then ramp up to a low speed according to what the program calls for. After a specific period of time, usually around 7 minutes, the blower will ramp up to 100% of the program according to where the dip switch settings is set for RPM’s or CFM’s.
If this doesn’t work then and you still have problems check with the manufacturer for a ECM blower motor troubleshooting flow chart or guide. Some manufacturers have a diagnostic tool that will confirm specific problems and can indicate if the motor or the controls are bad. If the motor is turning too many RPM’s or not enough RPM’s and is causing issues with the air conditioning or heating system because of improper air flow then it is a good idea to check the dip switch settings on the board. Good luck.
17) I have a Heil gas/electric package unit in my home. I, particularly, want to know, if I can close off a section to save on heating. Heating dealers have not been helpful as they hedge on whether and how this can be done with the system still running at it’s most efficient. I have closed doors to seal off area. Then closed floor registers. Should I also close air return in that area? I just read this should not be done at all as it decreases units efficiency? Will you please advise. I am thinking of closing off part of the house to save energy on HVAC. Thank you.
Hello and Thank you for emailing High Performance HVAC, Dorothy, Your registers should not be closed off as it is bad for the unit. The unit was installed based on the size of your home and the needed airflow for the house. This is designed airflow and requires all registers to be open to get the designed airflow through the unit and all the ducts. Closing off registers restricts airflow and is the same as a dirty filter which restricts airflow and causes problems with the unit. I have seen this before and I cover this on the HVAC filter page. In a gas pack it will cause excessive heat build up inside the unit and cause the unit to trip on high limit safety if you close off too many registers as the required airflow is not moving across the heat exchange so the heat continues to build up in the heat exchanger and eventually trips this high limit safety. Leave all your registers open and make sure you have a clean filter to maximize the unit. The best way to get the most efficiency out of the unit is to get a programmable thermostat and run the unit only as necessary. For more information on this see the thermostat pages concerning programmable thermostats and there use. Additionally, making sure you have good windows and doors to minimize heat loss will also help. Adding insulation to your attic space and other areas will also help reduce the amount the unit runs will result in savings and additionally having a humidifier installed will also help you remain comfortable in the winter time. For more information on why a humidifier will help you remain more comfortable in the winter see the humidifiers page.
Thanks for emailing High Performance HVAC. Hope this helps you.
Richard High Performance HVAC
Richard Many thanks for your very prompt response! What you say ties in with what I read regarding stress on the unit. However, this Victorian “cottage” is 3,000 sq. ft. w/ 12 ft. ceilings is now too big for only my husband and I. Is there not a way we can isolate the unused space and save on heating without stressing the unit? We have done all that you suggested. Storm windows, doors, etc., except for the attic insulation. The company that installed the unit is no longer in business and the man that I got to service it after that died. last fall. I’m in a very small town and the nearest Heil dealers seem to be 40 or more miles away. I did print a list of those I found. Haven’t called any yet as I ran across your webpage. My final question is, given the size of the unit, could I convert to 2 zones somehow? And, only heat the occupied part in winter? Thanks for you patience and help.
No unless you installed a whole new system (two new systems for zoning) or de-rating your current unit and buy another smaller unit. Also it doesn’t have to be a Heil dealer to work on the unit. Many gas packs are very similar in design and functionality. Any qualified HVAC tech should completely understand your unit and how to repair it. Not many would know how to de-rate it though. This would likely need Heil involved to give you the engineering data for derating and exactly how to derate the equipment. We are talking about a 2 ton system (I think) so you can’t derate too much. Generally the tonnage is the size of the air conditioning and doesn’t refer to the heating because the system is designed for airflow for air conditioning. You don’t want to derate the air conditioning but you can derate the gas heater side of the equipment. If the unit is older than 5 years I don’t recommend this. Richard
Closing Off Part of the House To Save Energy on HVAC
The variable air volume box or VAV box is a commercial solution to adding multiple zones to large buildings. VAV boxes offer zoning solutions so that separate zoning demands or temperature selections can be maintained in different areas of the building. If the president of the company wants the temperature in their office to be 70 degrees Fahrenheit but the vice president wants their office to be 74 degrees Fahrenheit then it is possible with the VAV zoning system as long as their VAV boxes are on different zones. This particular VAV box in the picture is not fan powered. It relies on the main VAV air handling unit to provide all the air. Generally, when a fan powered VAV box is calling for heat the damper inside the VAV box closes down so that minimal CFM’s are coming through the primary duct from the air handler. The fan turns on an pulls air from the plenum space above the ceiling. This plenum air is normally warmer than the air inside the occupied space. The heating system kicks in and adds heat to the air until a setpoint is attained. The heat for a VAV box can typically be a hot water coil or electric heat strips. The VAV box in the picture has hot water reheat. Continue reading “Variable Air Volume Box VAV Box Hot Water Reheat” »
How many tons of air conditioning and heating do I need per square foot?
Rules of Thumb
It is not uncommon for HVAC estimators or HVAC contractors to use various rudimentary techniques which are generally referred to as rules of thumb. Some will say on the low end you need 1 ton of cooling for every 500 square feet. On the high end you will need 1 ton of cooling for every 700 square feet. These rules of thumb will also generally take into account a basic heat gain calculation for the kitchen and the number of people who will occupy the structure. At best these rules of thumb are educated guesses and may not give you an accurate calculation of what you really need. Unless the contractor used software based on the above mentioned manuals it would be to your advantage to actually do a proper load calculation for the structure based on Manual “J” or Manual “N” whichever is appropriate for your HVAC application.
Air Conditioner and Heating Ductwork
Manual “D” is used for sizing residential ductwork for the appropriate amount of airflow. For each ton of air conditioning you will need 400 cubic feet per minute (CFM) of airflow. It is imperative that this amount of airflow (400 CFM) be provided to the air conditioner evaporator coil of the air conditioning system. If the ductwork is too small it will restrict the amount of airflow crossing the air conditioner evaporator coil and this will likely cause big problems. If the ductwork is too big the system may have a problem generating enough static pressure to maintain designed airflow across the coil. The proper design and construction of the air conditioning and heating duct work is important for the proper functioning of the system. Using the proper techniques, software, and skilled personal will ensure that the HVAC job is accomplished correctly and will provide many years of reliable and efficient comfort to you.
Using good and time tested methods to size air conditioning and heating systems for your home or business is a smart thing to do. Using an HVAC estimator who is going to employ a rule of thumb for something that will be attached to your home and provide you with comfort for 15 to 20 years is not so smart. Use proper HVAC sizing methods and you will be better off and comfortable in the future.
There are many different types of boilers in the boiler room today in a variety of heating applications. There are two main categories of boilers among the different types of boilers and those two categories are steam and hot water boilers. Either of those categories can be fueled by oil, gas, or electric (although electric is uncommon for steam boilers). They have different designs and piping configurations as a steam boiler system is designed to turned the water into steam and uses gravity and pressure to deliver the heat and the hot water boiler systems are designed to simply make hot water to be circulated (by a circulator or pump) through a piping system to provide heat. Typically, hot water boilers are more efficient than steam boilers for a few reasons. First, there is less heat loss throughout the hot water piping and the shell of the boiler because the hot water boiler operates at a lower temperature than the steam boiler. This means there is less heat loss throughout the entire boiler and piping system. Secondly, because the hot water boiler operates at a lower temperature, it requires less fuel or energy to convert into heat. What kind of boiler do you have in your boiler room?
The National Electrical Code (NEC) and HVAC: The Basics
Chapter Two of the National Electrical Code (NEC) covers Wiring and Protection and starts at Branch Circuits, Feeder circuits, GFCI requirements and protection,. An HVAC installer may want to pay attention to branch circuit requirements. Article 220 in Chapter two of the NEC includes calculations for branch and feeder circuits including service calculations. (Table 220.3)
Specific branch circuit requirements for HVAC can also be found in Chapter 4 Article 440 – Air Conditioning and Refrigerating Equipment Branch Circuit Conductor Sizing
Article 424 – Fixed Electric Space Heating Equipment Branch Sizing
An entire chapter on motors including feeder circuits for motors
This damper is part of a free cooling system for a rooftop economizer. It is part of an economizer damper system which allows free outside air cooling when the outside air temperature and humidity are ideal. This economizer also works on CO2 control so that if the CO2 levels inside the space rise above a CO2 set point the economizer damper opens allowing fresh outside air into the space while venting the air laden with CO2 to the outside. Continue reading “HVAC Rooftop Economizer – CO2 Control” »
Unit heaters are used in various places to protect equipment and provide comfort to occupants. This hot water unit heater provides protection for a mechanical room where there is a large air handler and other associated equipment in the mechanical room. This hot water unit is controlled by DDC. A thermostat on the wall detects the temperature of the mechanical room. The DDC system will maintain a temperature set point by energizing the hot water unit heater fan and modulating the hot water valve open on the hot water piping. The actuator and hot water valve can be seen in this photo on the right lower half of the hot water unit heater. The valve is a two position valve so it is either open or closed with no modulating the valve on the unit heater. Other unit heaters for heating mechanical rooms or providing comfort include electric units heater when hot water is unavailable, gas fired unit heaters when gas (either propaneor natural gas) is available, and infrared unit heaters typically found in large garages or warehouses for basic comfort of workers in those spaces. There are also steam unit heaters that utilize steam and a steam coil for heating spaces where steam is available. Most unit heaters are forced air unit
This ceiling fan keeps the air moving in a large garage where repairs are made to heavy machinery. In addition to providing a level of comfort by keeping the air moving in the shop the ceiling fan also helps to keep noxious fumes at higher elevations and moving towards the exhaust fans so the noxious fumes from heavy equipment can be removed from the shop area. The black metal you see hanging from the ceiling of the shop are baffles to keep the noise levels to a minimum. The whole shop is designed to keep noxious diesel fumes from the vehicles being repaired from affecting the occupants of the shop. The shop is also equipped with a carbon monoxide sensor and a sulfur dioxide sensor that automatically activates the ceiling fans and the exhaust fans so the air will always remain safe inside the garage. HVAC has a “V” in it and that “V” stands for ventilation. This ceiling fan in the garage facilitates the ventilation process. Continue reading “Ceiling Fan in a Garage” »