Tag Archives: Mechanical

Variable Speed ECM Blower Motors | HVAC Heating & Cooling Systems

ECM Variable Speed Blowers

Variable Speed ECM Blower Motors

An ECM Variable Speed Blower Motor in a squirrel cage blower

Variable Speed ECM Blower Motors - 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 ECM Blower Motors

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.

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Closing Off Part of the House To Save Energy on HVAC | HVAC Efficiency

Closing Off Part of the House To Save Energy on HVAC

Closing Off Part of the House To Save Energy on HVAC - 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.

The Answer:

Closing Off Part of the House and HVACHello 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 - Closing Off Part of the House To Save Energy on HVAC

Closing Off Part of the House To Save Energy on HVACRichard 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.

Closing Off Part of the House To Save Energy on HVAC – Conclusion

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

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Closing Off Part of the House To Save Energy on HVAC

Variable Air Volume Box with Hot Water Reheat | Commercial HVAC

Variable Air Volume Box with Hot Water Reheat

Variable Air Volume Box with Hot Water Reheat

Variable Air Volume Box with Hot Water Reheat - 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.

Variable Air Volume Box with Hot Water Reheat

 

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 set point 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 and is controlled by a building automation system or DDC. Building automation systems are capable of being linked to the internet for remote control and monitoring which adds many beneficial factors for managers and technicians of commercial property. A single building can have several hundred VAV boxes and with a DDC system managers can quickly see where problem areas are or change control set points with a few clicks.

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Variable Air Volume Box with Hot Water Reheat

Air Conditioning and Heating Sizing | HVAC Technical

Air Conditioning and Heating Sizing - How many tons of air conditioning and heating do I need per square foot?

Air Conditioning and Heating Sizing

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 Conditioning and Heating Sizing - 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.

Air Conditioning and Heating Sizing

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.

For other resources you find them here.

 

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Air Conditioning and Heating Sizing

Types of Boilers | HVAC Heating and Cooling

Types of Boilers

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 boilers and those two categories are steam boilers 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 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?

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TUESDAY, AUGUST 26, 2014