There is a great deal of confusing and misleading information being circulated as "airflow data." Sometimes the airflow is stated as "free air" or is given without reference to the static pressure (SP). Both ignore the flow restrictions imposed by vacuum hose, filters and other system components. Other published rates have never been tested or verified using established industry testing protocols.

I have an obsolete 34 ton Carrier, rooftop, multi-zone, direct expansion unit that I virtually can't get replacement parts for. I need a comparable change out, preferably not a Carrier. Can someone recommend a good substitute, brand, and model number? Also, I have the same scenario with a 20 ton Carrier. We recently bought another home and moved. This home has two dual fuel heat pumps that are zoned. Can you explain exactly how dual fuel heat pumps work. See similar questions...

A 4 cylinder engine requires about 1000 cfm (1700 m^3/h), a 6 cylinder engine requires 1700 cfm (2890 m^3/h) and a small V8 about 2100 cfm (3570 m^3/h). To reach the minimum cfm required you may need to install two or possibly more fans. See similar questions...

Hello, I have 7 air handling units, 2 of which are supplied by 100% outside air. There is a set of primary, secondary and hepa filters. Both of these units run 24-7. The one units pressure is normal the other one the pressure is always max. I know it is not the gauge because I have 2 different measuring devices. Any ideas or comments. Thanks in advance G.E. We are installing HVAC ducts in a Substation Building. See similar questions...

When number of clients is defined by CLIENTS_NUM_MAX tag, number of CAPS (call attempts per seconds) is resulting from the clients number and load duration for each cycle, comprising from url time for each url with possible redirections, intervals betwee urls and after url interval. The actions and time intervals are configurable in batch file, whereas url retrival time is server and network dependent and not always easy to predict. See similar questions...

This is a short name for "heat loss and gain calculation". This is something that every HVAC contractor should do at the very beginning of every job, but in reality there are very few that will even mention it to you, and if you even ask them about it, they will try to convince you that it is either very expensive or completely unnecessary because there's a "rule of thumb", or press you with their alleged experience and tell you how many thousands of people they have made happy. See similar questions...

Consult the HVI Home Ventilation & Indoor Air Quality Guide for assistance in determining how much airflow (cfm) is appropriate for the room you wish to ventilate. There is also an HVI Certified Home Ventilating Products Directory that lists manufacturers of HVI Certified products with their specifications. Be sure to check your local building code requirements as well. See similar questions...

Just add the power requirements for all the equipment being powered, these details will be in the datasheet for the product under power supply. Then follow the steps described in the APS Configurator on the website. It couldn't be easier. See similar questions...

Web space requirements should be calculated keeping in mind the quantity of html pages, graphics, audio and video content and database requirements. You should generally opt for a little more space than you originally calculated as the same may be required to accommodate customer responses and database size growth. See similar questions...

The aim is to give the simplest explanation of the calculation of the winnings in case of a dead heat. The example will be taken from a real and recent race: Prix du Bourbonnais of December 10th, 2005. First, we have to remember that we are talking about parimutuel bets: there is no creation of money, the money of the stakes is distributed after deducting the charges, the taxes.. See similar questions...

This is tough to display here... It is the result of the gross model weight divided by the rotor disk area. Radius squared, times 3.14, divided by 144, will give you the square feet. Then take the weight of the model in ounces, and divide this by the square feet, and the result is the disk loading in "ounces per square feet"........... See similar questions...

Yes - WISP contains glycaemic index values for a large number of foods and automatically calculates glycaemic load from food intake records and dietary glycaemic index. See similar questions...

The CFM (Cubic Feet per Minute) is the measurement of how much air passes through the unit. For the HealthMate, the HealthMate+ , and the Allergy Machine™ the fan CFM is 400 cfm on high and 75cfm on low. The HealthMate Jr™ is 200 cfm on high and 50cfm on low. See similar questions...

It varies on wind speed but is equal or greater than the required exhaust vents on the market when used at the soffits. CFM is very hard to compare apples to apples because of all the different variables. Everything would need to be exactly the same for the tests: Outside and Inside Temp., Pressure, wind, same ridge vent, same shingles, same inside living space conditions, same sun rays, etc. etc. etc……..That is why we feel that the industry has chosen NFA to compare products. See similar questions...

Cubic feet per minute - a unit of measure used in air infiltration testing, e.g., "maximum .10 cfm per square foot of window area." See similar questions...

Yes, our TS-400-24 24 VAC/VDC/VAC half-wave recitified digital time switch contains a form C relay to interface with low voltage systems. See similar questions...

No. Filtration testing measures the percentage of dust retained before the filter reaches a terminal test pressure, often 10” of restriction above initial restriction. We use airflow as a simplified term to explain a more complicated physical process. The more precise description is restriction: K&N air filters create less restriction which helps an engine run better. An engine will only use the air it needs and our air filters do not result in an engine using more air than necessary. See similar questions...

No, an engine can only take in a fixed volume of air depending on the engine’s size. The more restriction that an air intake system (filter, air box, and tubing) causes, the greater the potential is for power and mileage degradation. See similar questions...

CFM stands for “Cubic Feet Per Minute”. It is a measure of the blower’s air movement performance. The CFM performance of all Tempest Blowers is tested and certified by a third party organization, Air Movement and Control Association, called AMCA. This ensures that our customers receive accurate performance information. See similar questions...

A complete listing of the CFM ratings for all Tempest blowers can be found on our web site. Go to the main page and click on the product link that says “Blowers”. This information is also available in the current Tempest product catalog and can be requested by calling Tempest Customer Service. See similar questions...