"A lot of people have the perception that a bigger unit is better for the heating and cooling system in their house," Eric Newhouse, systems integration designer at IBACOS, said. "And that's really not the case. A properly sized piece of equipment that's not too large is going to work much more efficiently in maintaining better and more even comfort in your home." Alert: Don't get oversold about systems that are much more expensive than they need to be simply due to their size. "Sizing" means to literally find the right size or cooling capacity of the air-conditioning system for your home. Unfortunately, many homes have systems that are too big or too small for them. This can lead to a loss of cooling efficiency and high electricity bills. There are several components that impact the proper sizing for an air-conditioning unit: Heating and Cooling Hours Windows in the House There are compressor and other component failures that have nothing to do with the equipment, but with improper sizing or installation of the air conditioning unit.

"If you oversize the cooling system in your house, what will happen is that it will only operate in short little bursts," Newhouse said. "And since it's operating for a short period of time, it doesn't have the opportunity to dehumidify the air in your home." When the cooling system is the proper size, it runs a little bit longer every time it turns on, and during this longer period of running, it provides cooling – and it will dehumidify and provide better comfort in the home. So the bottom line is, bigger is not always better. Even the orientation of the house can have a big effect on sizing of the cooling system. The way the windows are laid out, for example. Do they face north or south? This will certainly increase either the heating or cooling load. Because sizing is so important in a home's air conditioning, how that size is determined is crucial. Construction Advice: When sizing a cooling system for a home, keep in mind that it's better to undersize than to oversize.

A smaller system may run a bit more often, but it will cost less to operate. new window ac unit not coolingA larger system will cost more to operate, in addition to being inefficient, which will cost more money in the long run.how to install window ac unit in a wallIf you’re looking for a new air conditioner for your Sarasota-area home, you may be wondering what size air conditioner you need.ac unit in a car If you’re looking for a new air conditioner for your Sarasota-area home, you may be wondering what size air conditioner you need. Hopefully you already know the dangers of getting an AC that is too small or too big. When it comes down to it, you need a professional to help you find the size air conditioner you need.

Here’s how we calculate what size you need. Air conditioner sizes are measured in tons and range from 1 ton to 5 tons. The higher the tonnage, the bigger the air conditioner and the more cooling power it has. But again, bigger isn’t always better. You want the air conditioner that’s right for your home. That’s where a heat load calculation comes into play. A heat load calculation is an algorithm that helps us figure out the amount of cooling your home needs. It takes into account several factors that are unique to your home. To help you better understand why this calculation is important, let’s take a look at some of the factors that go into it. Here are a few of them: All of these factors influence what is called heat gain. Heat gain is the rate at which your home gains heat. That is, the rate heat makes its way back into your home. This matters for air conditioning size because the faster heat infiltrates your home, the bigger your air conditioner needs to be in order to keep up.

Like we said, you need to get an air conditioning company to do the calculation for you. The good ones do this as part of an estimate. (And you should run away from the ones that only give you a rule of thumb estimate and never do the calculation). Professional air conditioning companies know what they’re doing and what to look for, and have specialized software to help them quickly do the calculation. If you want to do it yourself, there are some online heat load calculation tools you can use. But be forewarned: this is a tedious and long process! Give yourself some time to complete it. Need a reputable company to help you figure out the perfect air conditioner for your home? Give us a call at (800) 226-2636 or contact us online today. Cool Today is the leading air conditioning company in Sarasota, Florida and the surrounding areas. AC Unit Maximum Breaker Re: AC Unit Maximum Breaker Is this new construction? Because it is only 5 amps I would look closely at the wire and insure that it is rated for the higher amperage under an inductive load.

It may be wrong IAW the Mfg. but an over current device is there to protect the wire on the branch not the appliance. If the wire to the unit is rated for the breaker size at least you won't have a fire hazzard to the unit. Also a concern is if the breaker is rated for HVAC use. Also consider that the condenser may have internal wiring matched to the Max Fuse/Breaker Rating indicated on the label, and an older oversized breaker may not trip if the compressor motor locks up ... which could complete fry the equipment ... IMO report it as a defect needing evaluation/repair and call it a day ... Consulting Engineer & Inspector LIU CW Post Adjunct Professor I am absolutely amazed sometimes by how much thought goes into doing things wrong ... every HVAC guy and electrician I speak to say it is alright to go to the next 5 amp size. They want to see that the wire size is consistent with the higher size. None of them will change the breaker when called out to confirm this.

At ITA I remember them saying that the wire size can be smaller if matched to the minimum ampacity rating on the dataplate. Being an HVAC tech for a long time that is what would happen. The tech will say no problem. As long as the breaker is correct for the wire size 5 amps isn't a big deal. Start up amps can be in the 60-amp range. I've seen units under this same scenario (25 amp nameplate) that would cause nuisance trips when a 25-amp breaker was installed and when the 30-amp breaker was put in the trips stopped and there were never any problems. It is over fused if a breaker larger than the manufacturer's label calls for is installed. Here is a good explanation I picked up somewhere: A/C condensers contain a hermetically sealed compressor motor as well as a fan to circulate air across the coils. The rules for protection to motor circuits are different than for circuits with simple resistive loads. When a motor first starts , it draws a much higher amount of current than it does after it is running.

The high "inrush" current can exceed the rating of a breaker or fuse sized to protect the wire. The inrush current lasts typically only about 6 electrical cycles, or 1/10th of a second - less time than it would take to damage the wire or its insulation. However, if the overcurrent device is sized to protect the wire against overloads, the device might trip, and the machine would not be able to start. Motor circuits get around this problem by dividing the two separate functions of an overcurrent protection device. "Overloads" are currents that can damage a circuit if allowed to continue for a sufficient time, whereas "short circuits" and "ground faults" are high currents that can cause immediate damage. Large motors and air conditioners separate these overcurrent functions. The breaker or fuse ahead of the air conditioner only protects against short circuits and ground faults. Overload protection is built into the compressor itself. The wire to a condensing unit must be large enough to allow the equipment to start.

The device is therefore NOT sized to protect the wire against overloads. It is not uncommon to see a 50 Amp breaker on a #10 wire. The wire is protected against overloading by a separate thermal protection inside the compressor. How do we know what the motor requires for wire size and proper fuse/breaker protection? It's all on the mfg. label attached to the appliance. If the label calls for fuses, there MUST be a fuse in the disconnecting means, not a circuit breaker. If the label calls for a "HACR" type breaker (Heating, Air Conditioning and Refrigeration), then that is the type of breaker that must be used. If the label simply states "maximum sized over current protection" then any form of overcurrent protection may be used. The HACR designation is not always visible on a circuit breaker once it is installed inside a panel or disconnect. Note on the label taken from a Lennox A/C data plate:FUSE - 25 UL (CSA is a Canadian standard. We use UL in the U. S.)UL - Not allowed in U. S.

All this means is the MINIMUM wire size required is #12 (solid copper); the MAXIMUM rating of a fuse (if a fuse is used) must be 25 amps and the MAXIMUM rating of a circuit breaker (if used) must be 25 amps AND the breaker must be a HACR type.However, if the over current device is sized to protect the wire against overloads, the device might trip, and the machine would not be able to start. "it draws a much higher amount of current than it does after it is running." This is called an inductive load. "The high "inrush" current can exceed the rating of a breaker or fuse sized to protect the wire. " This is why HVAC breakers must be rated for HVAC use. The wire, breaker (to protect the wire), and type of breaker must be correct and is reflected in the "minimum circuit data". Michael MerinoMerino's Home Inspection & Education Inc." IF YOUR INSPECTOR IS NOT USING THERMAL IMAGING, YOU'RE NOT GETTING THE WHOLE PICTURE �Jeff Pope JPI Home Inspection Service

Santa Clarita Home Inspection Originally Posted by jpope I understand that the circuit is over-fused, but the appliance is connected to that circuit. If for some reason it were to draw more than 30 amps (outside of the inductive load) the breaker will not trip. I am confused by the differing opinions. I have been told by inspectors it is OK, and some say it is not. Some say that you can over-fuse the AC up to 40%. I do not seem to be able to find a definitive answer. I am thinking that if the max breaker is supposed to be 30 amp, then the breaker should be 30 amp not 50 amp, even if the conductor is the proper size. Professional Certified Master Inspector In Edwardsville, Glen Carbon, Godfrey, Maryville, Fairview Heights, O'Fallon and surrounding areas of Illinois Metro-East Need a home inspection in South Dakota? listing of South Dakota certified home inspectors. find a home inspector anywhere in the world with our inspection As a Professional Home Inspector, I support the privacy of my clients.