What is the HVAC component? What’s its function? What condition would make this component a defect or safety hazard? How would its condition affect the entire HVAC system’s performance or safety?
What is the HVAC component? What’s its function? What condition would make this component a defect or safety hazard? How would its condition affect the entire HVAC system’s performance or safety?
What is the HVAC component? What’s its function? What condition would make this component a defect or safety hazard? How would its condition affect the entire HVAC system’s performance or safety?
What is the HVAC component? What’s its function? What condition would make this component a defect or safety hazard? How would its condition affect the entire HVAC system’s performance or safety?
Describe this type of system? What component could indicate to you whether this system is installed upside down?
ANALOGY: Understanding how the condition of one defective shingle relates to the performance of the entire roof system is equivalent to understanding how the condition of one defective component relates to the performance of the entire HVAC system.
You desire to know more about HVAC…
You want total confidence about HVAC…
You want to know more than just how to turn on the thermostat…
Many heating technicians around here, including the heating techs that I eat with on Fridays, call it a condensing unit. A more accurate word and I would think acceptable word is condenser unit. They both basically mean the same - compression - but when discussing things here, I think you were indirectly saying this is not the correct type of word to use. If I am correct on what you were indicating, I agree with you.
When I lived in Kentucky, it seemed like everyone in the area I lived in called a bathroom exhaust fan a Fart Fan. Even though that name was easy to leave behind when I moved to Indiana, there were those few times it slipped out.:shock:
A little off the subject but go to www.dumblaws.com and click on Tennessee. I love it that there is and was laws in Tennesse that reads “You can’t shoot any game other than whales from a moving automobile.” or “Driving is not to be done while asleep.”:|.)
Ok I am back caught up until tomorrow morning. It appears that Ben has added some advertising since my last visit/post. In my last post we talked about switches caps and the low voltage circuit starting the compressor.
Lets continue with the basic refrigerant cycle starting with the smaller of the two lines extending out of the compressor this is the hot gas discharge high pressure vapor line (250) PSIG that is discharged into the condenser coils. One of the heat transfers occurs at this point in time the higher temp of the hot gas vapor transfers its temp to the air moving across the condenser fins thus condensing the hot gas to a high pressure liquid. This high pressure liquid (250) PSIG exits the condenser and becomes the high pressure liquid line that you observe on the exterior of the unit and travels to the A-coil. This high pressure liquid can not enter the A-coil at 250 psig so we have to add a metering device to control the amount of refrigerant allowed into the A-coil. The metering device is the dividing line between high pressure and the low pressure side of the system. Once the refrigerant is metered into the A-coil as a liquid this liquid refrigerant flashes back into a vapor at approximately 65 PSIG within the A-coil. This is where the next heat transfer occurs. The refrigerant within the A-coil is colder than the return air temp thus the heat transfer from 75 degree return air temp to the refrigerant temp within the A-coil approxinmately 50 to 55 degrees keeping in mind that heat is always transfered from a higher temp to a colder temp. The large line protruding from the A-coil and visible at the condensing unit is the suction line or refered to as the low side. The compressor is the dividing line between high and low pressure at the exterior condensing unit. The compressor draws the low pressure vapor from the A-coil and starts the cycle all over again.
Another item to remember is that some oil from within the compressor crank case always travels with the refrigerant through out the system but should also return to the compressor if the lines are installed properly. Anytime the exterior condensing unit is installed higher in elevation than the A-coil. (Examples) 1. Roof top unit with the A-coil on the first level. 2. Condensing unit ground level and the A-coil in the basement. It is good engineering practice to install a P-trap in the refrigerant suction line on the exterior side of the A-coil box this ensures that the oil is returned to the compressor and does not become trapped within the A-coil decreasing efficiency of the coil. An A-coil that has a good amount of oil trapped within does not have the proper amount of refrigerant within the coil to have good heat transfer.
One last statement this evening for those that think if you operate an A/C unit when the ambient temp is below 60 degrees that the unit is going to disappear in a cloud of smoke and you will have to buy a new unit. Fear not these units are tougher than most can imagine especially now with scroll type compressors being used. No I am not telling you to operate the unit when the outside ambient is below 60 degrees just follow your SOP. But I can tell you that if playing with the thermostat you accidently turn the A/C on it will not make it disappear;-). Questions please
Charley, do you think some might want to know how this draft check for the old furnace worked? I know I would. It was located next to the thermostat in the dining room.
Good question but it appears to be before my time if I was to take a wild guess I would say some sort of counter balance weight to see if the barometric damper was operational just a guess???
Charley, I thought that different refrigerants operate at different pressures and temperatures. R-22 operates at that pressure/temp while the newer 410 operates at higher pressures and temps.
And that’s why it is called an evaporator. It refrigerant squirts through the metering device; it spits. It sprays into the evaporator just like a warm beer shaken does when you barely pry open the cap. It then absorbs so much heat from the house interior air passing over the coil that it boils, or vaporizes. And that’s why it’s called an evaporator.
Let’s say you are driving your car in the hot summer time with the ac on, you turn off the car, get out, and you hear a “hhissssss”. That refrigerant gas passing through the metering device - spitting.
Question: If the refrigerant in the coil boils or vaporizes because it is absorbing so much heat, then why is the suction line coming from the evaporator cool to the touch?
As a QUALITY Home Inspector you SHOULD be able to IDENTIFY EVERY COMPONENT of a home. And quit REFERRING it to a QUALIFIED TRADESMAN.
If you don’t KNOW what your inspecting as a “HOME INSPECTOR” maybe you should call yourself a “LIMITED” or “NOT KNOWLEDGEABLE HOME INSPECTOR” and continue YOUR EDUCATION about EVERY COMPONENT of a HOME until you are KNOWLEDGEABLE about the WHOLE HOME.
Understanding howone part of an HVAC system can affect the performance and safety of the entire HVAC system…
is equivalent to…
…understanding how one defective shingle can affect the performance of the entire roof system. Or how one defective floor joist can affect the performance and integrity of the entire floor system. Etc.
It’s not that complicated (or expensive) to become thoroughly knowledgeable and competent in the duty of inspecting HVAC.
It’s an inspector’s ethical duty (as well as a requirement according to SOP) to inspect the HVAC equipment. And you can’t inspect the system without understanding the parts that make it up.
Understanding the parts that make it up…Hmmmmmmm…Well as far a Home Inspection Goes there are about …what 4 parts to most AC systems…Compressor (Heat Pump), Evaporator (Air Handler/Furnacce), Thermostat and duct work…sure filter and maybe humidistat falls in their too…sometimes there is an energy conservation unit for the water heater…Should we go further and do I really want to know more? Then where does it stop? What about the inner workings of a Wash Machine, Dishwasher, Oven, Range, Microwave…KNOWLEDGE is POWER…thats for sure…but sometimes TOO much knowledge is dangerous in the wrong hands…I love the info Charley is offering and it appears to be great and I hope he keeps it up…For me…all we have is Simple Split systems with heat strips…NO GAS furnaces in SW Florida…makes like easy…
Very simple Ben wrong theory refrigerant doesn’t boil because it is absorbing heat it boils because the pressure is lowered (pressure/temp) relationship. Refrigerant absorbs the heat as a result of the pressure/temp being lowered.
Ok lets talk a bit about metering devices and the A-coil. Metering devices can and are of various designs and or makes. The old standard for many years was the capillary tube but were actually numerous copper tubes extending out of a common header from the liquid refrigerant line these tubes were attached to different points of entry’s on the A-coil for equal distribution of refrigerant into the coil. The TXV (thermal expansion valve) again is attached to the liquid refrigerant line and moniters refrigerant into the coil based on the temp of the suction line leaving the A-coil. The TXV has a detachable head filled with the same type of refrigerant that the system uses as part of the valve assembly this head has a diaphgram type metal disk that expands and contracts thus opening or closing the valve plungers controlling the amount of refrigerant into the A-coil. This head assembly has a small capillary tube extending from the top of the head to a bulb that is attached with two clamps to the suction line. The attachment point on the suction line can be inside the A-coil box or external to the box depending on the MFG. This attachment point is very critical the suction line must be clean of all corrosion and the bulb must make 100% contact with the suction line. This bulb is simply sensing the refrigerant temp of the suction line only and must be insulated from any surrounding ambient temps that could effect the bulb such as air flow across the A-coil or the ambient from the exterior of the coil box if the bulb is mounted exterior to the box.
AXV (Automatic expansion valve) would be very uncommon to find one of these on a split system A/C unit. AXV’s have no removalable head or remote bulb they are like a regulating valve designed to keep a constant pressure within the A-coil. Mostly used on very small refrigerant systems.
Piston type flow raters are probally the most commonly used with new system in todays market. They are just a small piece of machined metal plug with different sized holes to match the tonnage of the coil. These flow raters are not very noticable as they are held in the liquid line by a brass nut that gives the appearance of a compression fitting.
Concerning refrigerants basically 3 class only HIGH, MEDIUM and LOW temp classes. Now of each class there are many different types R-22 and the 400 series are both a high temp refrigerant used in residential/commercial HVAC. Puron is another high temp refrigerant that is commonly used today operates at very high pressures and I think the score book is still out on Puron has not been tested long enough high pressure = high temps= equipment failure. Just my opinion.
It was located next to the thermostat in the dining room.