Joined on February 12, 2004
Last Post on April 14, 2011
@ April 14, 2011 12:03 PM in Professor Siberstein- Suffolk County Community CollegeThanks for the kind words. You are always welcome to come visit.
@ April 3, 2011 10:33 AM in sodderlessA few years back, I picked up a sample of a product that claimed to join copper piping without soldering or brazing. I brought it to the lab at my college and had my students perform a number of lab tests on the product. We found that, as long as the joint did not vibrate or shake, it held well. I contacted the company via this forum as well as by e-mail to inquire about the product and its performance during our tests, but received no replies. This product came in a red plastic bottle and the company was located in College Point, NY.
@ April 3, 2011 10:24 AM in Balanced Port TXVJust to clarify for those who would like to know:
The balanced port TXV is intended to maintain refrigerant flow levels during low ambient conditions. This allows the evaporator to operate at or near design conditions, even when the ambient temperature is low.
We typically use a balanced port TXV when the head pressure of the system varies greatly, when there are varying pressures across the TXV, when the evaporator load varies greatly or when there are very low liquid line temperatures.
By the way, the balanced port TXV looks just like any other TXV. You have to look up the part number to identify it as a balanced port TXV.
Carry on gentlemen!
@ April 3, 2011 10:16 AM in HOT WATER COILUse the sensible heat formula, which will get you very very close. Here goes...
With the blower operating, determine the temperature of the air before and after the coil to establish your delta-T across the coil. Next you need to determine the air volume through the coil. You will need a velometer for this. To get an accurate reading of the velocity, you will need to take a traverse, which is basically the average of multiple air velocity readings. The third thing you need to know is the area of the coil, or the duct, in square feet. I know this all sounds complicated, but it's very straightforward.
Now that you have the area, velocity and the delta-T across the coil, your heat output can be found by:
Qs = 1.08 x velocity (feet/min) x Area (Square feet) x delta T
Have fun and let us know how you make out!
@ March 29, 2011 12:39 PM in ac install colonialThe straighter the duct run, the better. Addition elbows to any duct run greatly affects the operation of the air distribution system. Adding an elbow to a duct run can have the same effect as adding an additional 10 to 90 feet of straight duct to the run, depending on the elbow used.
@ March 29, 2011 12:33 PM in evaporator questionYou guys have all of our videos on hand as well as bunch of resources. Ask your instructors. Also, ask about "coursemate". For $10 a year, you can access all of our videos and a bunch of other items on your comuter at home!
@ March 28, 2011 11:05 AM in evaporator questionWhat school are you attending and what textbook are you using? There are likely many resources available for use in your class.
@ March 27, 2011 11:45 AM in evaporator questionAre you preparing for an exam?
once all of the liquid in the evaporator has boiled off, any additional heat added to the refrigerant is referred to as superheat.
@ March 27, 2011 9:56 AM in evaporator heat loadIt depends on the metering device the system is operating with. If the system is equipped with an automatic expansion valve, the low side pressure will remain constant. This is because the purpose of the AEV is to maintain constant evaporator pressure regardless of the load on the system. If, however, the system is operating with a capillary tube or a thermostatic expansion valve, the suction pressure will increase.
If the system has a capillary tube, the suction pressure will increase and so will the evaporator superheat. If the system has a thermostatic expansion valve, the suction pressure will increase but the evaporator superheat will remain constant.
Hope this helps.
@ April 22, 2010 11:48 AM in Aw jeezeYou recovered the refrigerant as you should have, since it is the property of the building owner. The carcass of the unit was sold to a scrap delaer, right? You do not have to keep any records regarding the disposal of the capacitors, oil etc, since you sold the dead system AS IS to the dealer.
@ April 17, 2010 4:02 PM in Leak LocLeakLoc contains Ethanol (Ethyl Alcohol) which is sensed by many electronic leak detectors.
@ April 14, 2010 12:54 PM in Fan CalculationsYou will need the specifics on the blower you are using to determine the amount of air volume (in cfm) that the blower moves at a particular speed.
In the meantime, you can get a good starting point by using the following:
Drive Speed (Motor RPM) X Drive Pulley (Diameter) = Driven Speed (Blower RPM) X Driven Pulley ( Blower Pulley Diameter)
For example, you can determine the speed of the blower if you know the speed of the motor and the diameter of the motor (drive) pulley and the diameter of the blower (driven) pulley.
Example: Let's say we have a motor that is turning at 1000 rpm with a 3 inch pulley connected to it and a blower that has a 4 inch puley attached to it.
The speed of the blower can be determined by:
Blower Speed = (motor RPM x drive pulley diameter) / driven pulley diameter
Blower Speed = (1,000 rpm x 3) / 4
Blower speed = 750 RPM
Now, if the blower pulley is changed to a 5 inch pulley, we get
Blower speed = (1,000 rpm x 3) / 5
Blower speed = 600 RPM
Remember: If you increase the diameter of the drive pulley or decrease the diameter of the driven pulley, the blower will turn faster.If you decrease the diameter of the drive pulley or increase the diameter of the driven pulley, the blower will turn slower.
I hope this helps!
@ April 14, 2010 9:40 AM in water and electricityThanks for the kind words. Glad you enjoyed it. We are working on a new one that stresses the geothermal end of the business a lot more.
Thanks for posting!
Here's to a great summer!
@ April 13, 2010 7:21 AM in water and electricityThe truth of the matter...
Water itself is NOT a conductor of electricity, but the stuff that comes out of the tap is...
What makes tap water a conductor is all of the impurities in the water. If you try to complete an electric circuit with distilled water, you will find that water is, in fact, a very good insulator.
Water from the tap will conduct electricity, but not as well as metallic substances. If you were to set up a flashlight-type circuit and use various substances to complete the circuit, you will find that items such as paperclips will cause the buld to burn brightly, but tap water will only cause the bulb to burn dimly. Distilled water will not allow the bulb to light at all.
Sounds like the makings of a great sicence fair project!
@ March 23, 2010 5:54 PM in epa stuffWe are working with the Refrigerant Transition and Recovery Certification Program Manual for HVAC Technicians, 5th Edition.
As always, I offer training and testing... Call me at 917-428-0044
@ March 3, 2010 10:53 AM in Central A/c sizing questionSince you are changing out your system, you owe it to yourself to do it correctly. Rules of thumb no longer cut it! Have a professional come in and do a complete Manual J on your home. This will give you both the heat gain and heat loss of your home.
As Terry (Techman) mentioned, bigger is definitely NOT better. Put in what you need... nothing more, nothing less.
@ February 18, 2010 9:54 AM in Heating Haiku?With Dan at the helm
Who can go wrong with haikus?
Watching bird feeders!
@ February 18, 2010 9:48 AM in Heating Haiku?How to heat my house?
The ground source heat pump will work.
Time to trench... and trench
@ February 17, 2010 8:42 AM in high compression resetThe control you are referring to is the high pressure control and will open if the pressure on the "high side" of the system reaches unsafe levels. When your heat pump is operating in the heating mode, the indoor portion of the system is the high pressure side. The most common cause for the opening of the high pressure switch is improper airflow through the indoor coil. You mentioned that you replaced the air filter, which is the number one cause for excessively high pressure on a heat pump system. Be sure to check for closed supply registers, blocked return grills, dirty indor coil or anything else that might impede airflow in the duct system.
Keep us posted.