Friday, July 26, 2013


     Before doing any work yourself or talking to any HVACR technician it is important to get your HVACR technical terminology right so you can at least communicate. The following are some common terms with not-so-technical explanations:

Condenser is the outside unit which consists the condenser fan motor, compressor and some electrical components like contactor, capacitor etc.

Evaporator Coil is the unit that sits on top or on the side of your furnace that connects to the condenser.

Furnace is the heating unit that uses natural or LP gas to heat your home. It consists of a blower motor, gas components (pilot, gas valve, flame sensor etc.) and some electrical components (control board, relay, capacitor etc.). It is located in the garage or attic most of the time.

Packaged Unit is an a/c unit that has all the components within the unit instead of having a split system like a condenser and evaporator separately. Packaged unit will simply blow hot air or cold air into the house.

Gas/Electric is an unit that runs on electricity to provide cooling (compressor) and gas to provide heating (combustion).

Heat Pump is an unit that runs on electricity (compressor) only to provide both heating and cooling.

Liquid line is the copper tubing with the smaller diameter that runs from the condenser to the evaporator coil. It is where the liquid refrigerant travel from the condenser to the evaporator coil.

Suction line is the copper tubing with the larger diameter that runs from the evaporator coil to the condenser. It is where the gas refrigerant returns from the evaporator coil back to the condenser.

Thermostatic Expansion Valve or TXV is a metering device that forces liquid refrigerant into gas refrigerant according to the temperature sensed by its probe. Usually it is located in the evaporator coil.

Basically how a typical residential split system work is like this: When calling for cool, the compressor runs and compresses the low pressure/low temperature gas refrigerant into a high pressure/high temperature gas refrigerant. The condenser coil then cools it so it becomes a high pressure liquid refrigerant and travel thru the liquid line to the evaporator coil. Then the TXV restricts how much refrigerant can go thru and thus high pressure liquid refrigerant will become gas refrigerant and in the process will absorb heat thus cooling the evaporator coil. The furnace blower forces air thru the evaporator coil into you house so you have cool air out from the registers. Low pressure gas refrigerant then goes back to the condenser thru the suction line and starts the process again. When calling for heat, the furnace simply turns on the gas valve and ignites the combustion process while blower force air thru the chamber so you have warm air coming out from the registers. Both condenser and evaporator coil are not in use when system is calling for cool. Well, this should be enough for one day, now that you know the basic names lets talk about common a/c problems next week. Have a great weekend.

Questions? Suggestion to write? Leave us a comment!

Wednesday, July 17, 2013


     We've answered this questions hundreds of times, there is no simple yes or no answer as it depends on what kind of part you are talking about. Before going any further, let's first understand what is considered OEM and what is considered Aftermarket. Basically OEM means this part is the same or it is made or supplied by the manufacturer who original made the equipment as a replacement part. Most of the time it will look and work exactly the same but sometimes it won't. We will go into detail more later on. Aftermarket, on the other hand, means this is a replacement part not made or supplied by the manufacturer who original made the equipment. It is just what it is, simply a replacement that will work. So what is the difference?

     The first difference you will notice, unless you are not paying, is the price. OEM tends to cost a lot more than aftermarket parts. If your unit is still under warranty then you can probably claim the OEM part for free. By using aftermarket parts you will most likely void your warranty so there is no reason not to use OEM if you unit is still under warranty, except that it may take longer for the claim to go thru. Now if your unit is out of warranty, then you got a totally different ball game. OEM parts can be 2-3 times or even more expensive than aftermarket parts so you can really have a hard time deciding which to get unless again, you're not paying or just so rich and don't care.

      In General, for simple parts like capacitors, contactors, fan blades etc it won't matter much as long as the aftermarket one is with the same specification. In fact, these parts may actually come out from the same factory with different brand name printed on it afterwards so there is no reason to spend extra money. However, when it comes to control boards, motors, sensors etc you may want to stick with OEM since they are just more complicated and fine tuned parts. Of course, if you are a pro or have no trouble doing some modification here and there to make stuff work then more powers to you. For a lot of DIYers it is a pain in the butt when they find out even though the aftermarket motor has all the same electrical spec but the shaft is just a little too long or too short and they have to make changes on the bracket or mounting.

     Now that you decide to go with OEM, does that mean the OEM part you ordered will be exactly the same as your old one 100% of the time? The answer is NO. Manufacturer has the right to make changes to their design and replacement parts anytime so if they say this is the part for your unit, it won't matter if it looks totally different. They might have an adapter kit to make it work but if not, you have to make the changes and make it work. Also manufacturers can discontinue any parts or models that they made anytime and when that happens you can only go with aftermarket or buy a new unit. One more thing to bear in mind is that your unit's performance data is based on all OEM parts when it was tested in the factory and according to most manufacturers their authorized parts are also tested in the same standard as their unit so it will work better. Bottom line is, for simple parts OEM will work just as well but when it comes to better tuned parts going OEM will save you more time and hassle, unless you are a pro and knows how to deal with making some changes or adjustment on your own.

Monday, July 8, 2013


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