CIBSE publishes several guides to HVAC design relevant to the UK market, and also the Republic of Ireland, Australia, New Zealand and Hong Kong. These guides include various recommended design criteria and standards, some of which are cited within the UK building regulations, and therefore form a legislative requirement for major building services works. The main guides are:
Air conditioners can create a lot of water because they remove moisture from the air. To get rid of this, they have a [usually plastic] drain pipe that comes out of the side of the air handler. Over time, algae can block this pipe and, when it does, the AC won’t work. In fact, some condensate drains have a float switch that won’t let the AC run if water backs-up. Water can also puddle around the unit or flood the area. To deal with condensate problems, please see Air Conditioner Leaks Water, below.
Clean air delivery rate is the amount of clean air an air cleaner provides to a room or space. When determining CADR, the amount of airflow in a space is taken into account. For example, an air cleaner with a flow rate of 100 cfm (cubic feet per minute) and an efficiency of 50% has a CADR of 50 cfm. Along with CADR, filtration performance is very important when it comes to the air in our indoor environment. Filter performance depends on the size of the particle or fiber, the filter packing density and depth and also the air flow rate.[30]

PickHVAC Tips: Oil burns dirty, so it is important to have your plenum and ducts checked to see if they should be cleaned when replacing an oil furnace. If you don’t clean the plenum and ducts when replacing the furnace, the new furnace might not run as efficiently and comfortably as possible due to restricted airflow. This can also reduce the oily smell sometimes associated with oil furnaces.
Humidifiers/Dehumidifiers: Humidifiers add needed moisture to the air in winter and very dry climates. Dehumidifiers remove dampness any time of the year. Central air conditioners dehumidify too, but in very humid climates, you might want to remove humidity without also cooling the air. You have a good range of options for both of these HVAC accessories. Whole-house humidifiers cost $350 to $800 installed, while dehumidifiers are $1,250 to $2,000 or slightly more.
These are the prices for a proper installation from a professional – as a word to the wise, HVAC systems require fine tuning and the custom fabrication of parts during installation to work properly, otherwise they will likely fail prematurely. But there are plenty of people who will do it for cheaper than this, using substandard, used, or stolen equipment (stolen from construction sites and new housing developments). Or, they are using unskilled laborers with no experience, etc. But HVAC is not a “we’ll figure it out trade;” there is a right way and a wrong way to do things. There are just too many predatory companies out there, so be careful. I’d highly recommend not skimping on your HVAC contractor. If you go cheap, you will typically pay more in the long run...and in California, that will be a lot!
Multiple inventions within this time frame preceded the beginnings of first comfort air conditioning system, which was designed in 1902 by Alfred Wolff (Cooper, 2003) for the New York Stock Exchange, while Willis Carrier equipped the Sacketts-Wilhems Printing Company with the process AC unit the same year. Coyne College was the first school to offer HVAC training in 1899.[12]
BIG THANK YOU for being honest, and advising us that for some reason the fuse/switch was in the reverse position so the AC unit would not properly turn on.   The unit turned back on immediately, and began cooling the house.   And then providing advice that the AC/Heating system needed some TLC, and giving us options to save money by purchasing a maintenance plan that included the filters plus cleaning services since we were already being charged for the service today.
Multiple inventions within this time frame preceded the beginnings of first comfort air conditioning system, which was designed in 1902 by Alfred Wolff (Cooper, 2003) for the New York Stock Exchange, while Willis Carrier equipped the Sacketts-Wilhems Printing Company with the process AC unit the same year. Coyne College was the first school to offer HVAC training in 1899.[12]
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Many homes have a forced-air HVAC system. Both the heating and the central air conditioning units share a ductwork system where they either push in or pull out warm or cooled air. There are also heating and cooling systems that don’t require ductwork — such as ductless mini-splits — but work on the same principles of heat exchange. The national average to hire an HVAC specialist is $2,920-$3,670, with costs varying depending on the work you need done and the equipment you are installing.
So, whether you need an AC repair or you’re in search of a new heating and air conditioning system—or you need a new water heater now–you can count on our team in North America. We’re experts in AC and plumbing repair, and offering top-notch AC and plumbing service is what we do best. Call Service Experts 24/7/365 at 866-397-3787 or request an appointment online today, and don’t forget to check out our coupons page for savings on your AC or plumbing repair service.
Because an air conditioner moves heat between the indoor coil and the outdoor coil, both must be kept clean. This means that, in addition to replacing the air filter at the evaporator coil, it is also necessary to regularly clean the condenser coil. Failure to keep the condenser clean will eventually result in harm to the compressor, because the condenser coil is responsible for discharging both the indoor heat (as picked up by the evaporator) and the heat generated by the electric motor driving the compressor.
We bought 2 top of the line Lennox HAC for $29,000 less about $3,500 rebates, thinking they would at least last 10 years. Well, after 6 years, the system leaked. We are paying $1,700 to fix that leak. We thought at least it is still under warranty - yes BUT - the warranty covered $15 & the rest we were up for ,even though they advertise 10 year warranty. We are trying to sell & move out of high cost southern Calif & have looked at 20+ places in Arizona. Most of the houses we looked at were built from 1998 to 2005. We asked if the HAC was original & in most case it was - even though the highs were 115 to 120 & the lows 90F - versus where we live the highs run 85 to 95 & the lows are in the 60s. I asked the repairman WHY ours went out at 6 years. He replied that they just do not build them the same anymore. In Arizona, I did not see any Lennox - mostly Trane or Carrier. We had Fujistu in Australia which were fantastic - nothing went wrong in the 9 years we had them. Also, they had full induction motors not like the energy consuming 2 stage motors in Lennox. Maybe the Japanese built Fujusita still builds quality & the warranty is meaningful?
Pro Tips: Before you buy one of the learning thermostats available, you should beware of their shortcomings. First, many require a c-wire to work properly. A common problem is that the old thermostat might not use a c-wire, and this makes it confusing when swapping wires to the new thermostat. Secondly, if you change your thermostat setting often, you might become frustrated with a nest thermostat or other learning thermostat. It will be constantly trying to learn patterns in your random setting changes, and will therefore change your home’s temperature when you don’t want it to. If you have a fairly consistent schedule or don’t mind overriding the unit either manually or via the app on your way home or when leaving, then you won’t experience this issue.
But Tim, doesn’t this mean that a less-than-honest air conditioning company can just charge what he wants and say that it’s a difficult job? No. You see, dishonest contractors, typically, aren’t the brightest people (I figure if you’re still reading this, you’re warming up to me so I’m taking off the training-wheels). They aren’t smart enough to take difficulty into account, and will probably get confused if you ask them about it. They will tell you things like, “that’s how much the unit costs,” or “California has a new law that magically adds $5,000 to the price.”  Trust me, follow your gut, and you’ll be able to tell who the honest contractors are...or just use one of our ASM-approved contractors.
If your AC doesn’t turn off when room temperature reaches the temperature set on the thermostat, the problem is generally occurring either at the thermostat or in the electrical system that runs the outside condensing unit. You can use the AC’s circuit breaker to shut off the unit, but that should not be a permanent solution—circuit breakers are not designed to be used like light switches.
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