As warmer weather taxes aging air-conditioning systems, the decision whether to repair an older rooftop unit or replace it with a newer, higher efficiency system may loom large for some commercial property owners.Most light-commercial HVAC products are for a life expectancy of 15 to 20 years. However, factors beyond the control of the original equipment manufacturer dictate the actual reliability and cost effectiveness of operating the equipment during its useful life period. That’s why it’s important to carefully examine each piece of equipment before reaching a decision to repair or replace a system. Understand the History of Your SystemA careful examination begins with the collection of all available information regarding the system, including records of the original installation, periodic maintenance, and repairs. If you do not have this information, contact servicing contractors and let them know you are evaluating your equipment to determine whether or not you will be replacing it.

Cooperation will usually follow, and you will have the opportunity to “size up” the contractor for consideration when doing future maintenance, repairs, or replacement.If you do not have a file on each piece of equipment, start one. In addition to the records you collect, be sure to include the manufacturer’s model and serial number, individual unit or site reference numbers, installation and operating instructions, warranty information, and factory- or contractor-backed service and maintenance agreements.Overall appearance of each unit will provide valuable information about the quality and attention to maintenance provided the unit. Inspect the equipment (or have a qualified technician perform the inspection), following the manufacturer’s instructions and safety warnings before removing any access panels.The cabinetry should be intact and fastened properly to minimize any air (or weather) leakage into or out of the unit. Filters, too, should be clean. Clogged or restricted filters reduce a system’s efficiency markedly, increasing the internal negative air pressure and pulling dust, dirt, and debris into the unit’s air circulating system.

Check the condition of the coils as well, looking for evidence of dirt, debris, or physical damage to the coils. car ac repair winnipegBent, damaged, or restricted coils restrict air flow, reducing unit efficiency and increasing operating costs.do ac window units need freonArrange for a professional contractor to inspect each unit to assess its operating condition. harga ac portable semarangIf you can tie this to a periodic maintenance or repair call, you will save some expense. The inspection should include a complete operating review of the and portions of the equipment and an assessment of the airflow, temperature rise, and temperature split to be certain they are within the manufacturer’s specified ratings. Be present for the inspection and request that the technician review the findings with you, including the identification of problems and recommendations and quotes for corrective actions.

Include this information in the unit files you have started.Review the Information You Have CollectedAt this point in the evaluation process, you likely have learned a lot about each system. As you review the information you have gathered, determine and confirm the applicable manufacturer and contractor-supported warranty coverage that remains on each unit. Based on the records you have and inspections conducted, assess the condition of each unit. Equipment improperly maintained and serviced is likely to be less reliable and less efficient, resulting in increased operating costs and premature failures and repair costs. Consider the age of the unit, warranties or service contracts that apply, and the condition of the unit. Has it been well-maintained and what repairs are needed in the short term and the long term?Make the Decision to Repair or ReplaceStudying current operating expenses as well as projected repair and operating expenses better equips you to make the decision to repair or replace existing equipment.

Compare these expenses to the operating costs of new, high-efficiency equipment. Most manufacturers can help you make this comparison by estimating operating costs based on unit efficiency and local utility costs. In many cases, if your equipment is aged, new high-efficiency replacements will provide significant utility savings that can be factored as a “payback” in a decision to replace.A firm quote from your contractor will help you estimate the future costs associated with restoring a unit’s operating performance. Finally, as you make your decision to repair or replace, consider applicable utility rebates for the installation of high-efficiency equipment. Your local utility can provide rebate information that applies to your area.You should also consider potential savings that new equipment warranties will provide compared to out-of-warranty repair estimates. The purchase of extended warranties and scheduled maintenance programs offer additional savings worthy of your consideration.

Often these warranties can be negotiated into the initial purchase price for new equipment and offer an affordable approach to future maintenance and repairs.Select a reputable local contractor who will offer future support or backup of their workmanship. Work to define a maintenance and monitor program for the existing or new installation. This program should cover all aspects of the equipment, be performed regularly with accurate recordkeeping, and include basic system performance measurements to assure each unit remains in peak operating condition.Be certain to keep accurate records. These records will help you estimate operating expenses and, in the event of future problems, guide your contractor in proper repairs. And as your equipment ages, these same records will prove useful as you again consider the decision to repair or replace.I got a question this weekend that's often asked—and, I'm sure, wondered about—by homeowners: "Will my household AC system run more efficiently (perhaps cycle on/off fewer times, or the compressor won't have to run as long when it cycles on) by shading the compressor?"

I've written about the outdoor unit of air conditioners and heat pumps a few times, but I've never tackled this question directly. Let's change that now. First, a little explanation about air conditioners. That metal noisemaker that sits out in back or on the side of your house is called the condensing unit for air conditioners. The compressor is one component in that box, but the condensing coil and a few other parts are there, too. (To understand how an air conditioner works, see my article, The Magic of Cold.) The condensing coil's job is to dump the heat picked up inside the home to the outdoor air. (If you have a ground source heat pump, that heat gets dumped into the ground rather than the air, and you won't have an outdoor unit like the one shown above.) The hotter it is outdoors, the harder it is to dump that heat and the more you'll spend keeping your house cool. Hence the question, can shading your air conditioner's outdoor unit provide significant savings? And the answer is yes and no.

It depends on what type of shading we're talking about, but for the type of shading most people are thinking about when they ask that question, the answer is no. Shading the outdoor unit with a structure as shown below will reduce the direct solar gain from insolation but won't do a whole lot for the air temperature around the unit. That photo is from a study done the Forida Solar Energy Center on the effectiveness of shading air conditioner condensing units. Caution: The unit below exhausts from the side so the shading structure doesn't interrupt the air flow. Most AC outdoor units exhaust from the top and that structure would reduce the air flow and perhaps cause serious damage to the unit. Don't try something like this unless you have a good understanding of air conditioners. In the Discussion section at the end of their report, the FSEC authors give the big reason why small scale shading like this doesn't work. The temperature of the surrounding air has a much bigger effect on cooling efficiency than direct solar gain, and the volume of air pulled in by an air conditioner is huge.

A typical 3 ton air conditioner condensing unit might pull in 2800 cubic feet per minute (cfm) of outdoor air. If it ran continuously for an hour, 168,000 cubic feet of outdoor air would move through the outdoor unit. Since your air conditioner is probably oversized, it won't run the full 60 minutes. My oversized AC, for example, runs about 30 minutes an hour at design conditions. Even at 30 minutes per hour, though, the outdor unit pulls in 84,000 cubic feet of outdoor air. To put those numbers in perspective, 84,000 cubic feet is about three times the volume of a typical house being cooled by that 3 ton AC. It would take a lot of shading to cool that much air. The FSEC study sums it up this way: We conclude that any savings produced by localized AC condenser shading are quite modest (<3%) and that the risk of interrupting air flow to the condenser may outweigh shading considerations. The preferred strategy may be a long-term one: locating AC condensers in an unobstructed location on the shaded north side of buildings and depending on extensive site and neighborhood-level landscaping to lower localized air temperatures.

A related question to shading the condensing unit is about saving money by spraying a mist of water on the unit, especially with the recent launch of the Mistbox. I wrote about that topic a couple of weeks ago, and again, the answer is that you're better off looking elsewhere. If you really want to improve the efficiency of your air conditioner, your opportunites are much greater if you look to your duct system. By fixing disconnected ducts, flacid flex, uninsulated boots, and more, you may be able to cut your air conditioning bill in half, depending on how bad your particular ducts are. And they most likely are bad. 9 Uncommon Tips for Keeping Cool with a Struggling Air Conditioner Does a Heat Pump or Air Conditioner Condenser Need to Go Outdoors? An Easy Way to Save Money — Let Your Air Conditioner Breathe!I'm an Air Conditioner Compressor Killer Is Evaporative Cooling the Answer to High Air Conditioning Costs? Top photo by Energy Vanguard. Bottom photo from Florida Solar Energy Center's air conditioner shading study.