Sunday, May 26, 2019

Air Conditioning Season

It's that time of year. Is your air conditioner ready?

In more and more parts of the country, air conditioning is becoming a necessity for modern living. May be part of this is due to global warming, I'm not sure. All I know is when we lived in central New York in the 1970's we didn't have air conditioning and it very rarely was hot. There might have been two or three days in the summer where it was hot during the day but it was always cool in the evening.

When we moved back to Central New York and bought our lake house near Ithaca, it was very warm and the house had only one split system in the kitchen area. We quickly added three more split systems plus two portable air conditioners to keep the house cool.

The original owner who built the house didn't even plan for air conditioning, thinking incorrectly that air conditioning wasn't needed in central New York. Well, that was then, this is now. And it gets hot even up North.

In the South, it's not even an option. Temperatures can rise into the 90's and even over a hundred and you need to have A/C in order to just be comfortable.  For some folks, it could be a matter of life and death.

This time of year, they turn on the Georgia furnace, as I call it. The pretty green "realtor grass" that I plant during the winter dies almost overnight and turns into a crunchy mass under foot. When the first 90 degree day comes, the grass all dies in unison.

Central air conditioners have a design life of about 15 years or so.  You can get more life out of them, and sometimes less, depending on how well they're made and how well they're treated. It's not a bad idea to have a service contract with your local HVAC contractor. They'll come out twice a year usually and check the system to make sure it's working properly before heating season and before cooling season begins.

They will check the functionality of the unit, either by checking the charge level with a manifold gauge or, increasingly, by using a temperature sensor in the discharge of one of the air ducts. Both techniques can tell you the level of charge and how well the machine is functioning.  Generally speaking, the discharge temperature of the ductwork should be 16-22 degrees less than the return air temperature.

Generally too, they will check to make sure the condensate line is draining properly and if you have a condensate pump that it's functioning properly. And usually they change the air filter as well.

Some of these things you can do yourself, and you should do them in addition to having the service contractor do it. We generally change our air filter about once a month or so if we've been using the air conditioning or heat. Sometimes we leave the fan in the "on" position to circulate the air more evenly throughout the house. Also, during pollen season this tends to draw the pollen out of the house and into the air filter.

We purchased HEPA type filters online and buy them by the box load.  Thus, its inexpensive to change out the filters once a month and throw the old ones away. And the old ones definitely turn gray and collect a lot of dust and pollen. If you don't change these filters frequently, they can get clogged and restrict the airflow to the air conditioner.

Some air conditioners or furnaces come with fiberglass filters and these filters are also sold in retail stores. These don't perform as well in filtering out dust but they do have less resistance to airflow. One problem with the HEPA type filters is they can restrict airflow to the air conditioner,  which is why they should be changed frequently as they can clog more easily.

It is tempting to buy a super HEPA filter with a very high filtration rate, but these usually create more restriction to air flow. If the air flow is restricted across air conditioning coil, the system might not cool your house as well, and it might short cycle on and off which might not be good for the air conditioner.

In humid climates such as on the East Coast, when air flows across the evaporator coil in the air handler inside the house, it goes below the dew point and water condenses on the coil. This water drips down into a pan and drains out through a condensate drain. In some applications this drains to the outside of your house using gravity flow. In other applications, a condensate pump is used to pump water out of the drip pan.

If the condensate drain backs up or the condensate pump fails, water may accumulate. If this water overflows the pan, it may spill out and ruin your carpet or flooring. It is a good idea to make sure the drain is flowing properly and/or the condensate pump is working properly.

In our house, we have a condensate drain which uses gravity flow. There is a removable section of pipe that can be pulled out so that warm water or soap or other materials can be poured in to clean out the condensate drain. Over time, the slow drip of condensate water can cause an accumulation of mold, mildew, and bacteria which sometimes clogs this pipe.

We pour hot water down the pipe using an electric kettle and sometimes soap to clean out the bacteria, mold, and mildew.  One reader suggested pouring a small amount of mineral oil down this pipe as it lubricates the pipe and prevents the formation of mold and mildew.

A washing machine lint trap on the outside is a good way of keeping bugs and snakes out of your condensate line.

If you have a condensate pump, I would be careful with trying these techniques as hot water or aggressive cleaning agents could damage the pump. Talk with your HVAC contractor and ask him the best way to clean the condensate line. as well as the pump itself.

If you have a thermometer or temperature sensor, you can monitor the output temperature of your air conditioner and  get a rough idea as to the charge level and performance of the machine. Again, the discharge temperature should be in the range of 16-22 degrees less than the return air temperature, when it is functioning properly.

We've noticed on very hot days, our attic gets very warm and the ductwork passing through the attic tends to heat up the air from the air conditioner.  Thus, on a very hot day sometimes the air conditioning system doesn't work very efficiently.  Attic fans are one way of cooling down your attic, but they can either start fires in your attic, or of one starts, fuel the flames by drawing more oxygen into the fire.   There are no easy solutions, it seems.

One of our goals is to replace the ductwork in the attic, which is eight inch round ductwork covered with fiberglass insulation that was installed in 1969.  No doubt this ductwork is also filled with dust and God knows what else. There are companies that, for a fee, will clean out your ductwork by removing the registers and running various sorts of vacuums and cleaning devices through the ducts. It is possible to clean these ducts yourself if you have a long vacuum hose and a lot of patience. I was able to clean the ducts in our house on Washington Road by attaching a piece of sump pump hose to the vacuum cleaner and slowly feeding it down through the ducts, after removing the registers.  The house was built in 1949 and you can only imagine what I vacuumed out of there.   Disgusting!

After 30 or 40 years though, you might want to think about replacing some of these ducts if they are readily accessible.  More modern ductwork might be better insulated than the stuff that was installed in 1969.  I plan on looking into this shortly.  We might take this opportunity to add a register in the kitchen area, as it gets warm there.

Most air conditioning systems have two components.  There's an indoor component which comprises an air handler with an "A" coil, known as the evaporator coil.  The compressed refrigerant evaporates in this coil (after going through an expansion valve) and cools down the air which is circulated by the blower fan.  The cooled air then passes through the ductwork throughout your home.  The outside portion contains the compressor, which receives the expanded gas from the evaporator and compressors it back to liquid, which heats up the refrigerant.  The hot refrigerant is then cooled off, using an outdoor coil and fan to remove the excess heat.  The net effect is to pump heat from your house to the outside.

Many air conditioners are indifferently installed.  Our air conditioner was placed on a plastic pad which itself was placed on top of a concrete pad, which had supported the air conditioner that was installed when the house was built.  Over the years, this concrete pad had sunk to more than six inches below ground level and also took on a tilt.  As a result, dirt was getting into the air conditioner and causing problems.  It also made it a pain in the ass to work on the unit, as it was "down in the dirt" quite literally.   I managed to jack the pad up using hydraulic bottle jacks that I found in a dumpster at the campground.   I used concrete pavers wedged underneath the pad to hold it in place and back filled with soil.  The air conditioner is now above ground level and level as well.  I put some pavers around it, as well, so I no longer need to mow so close to the machine (which causes it to suck in grass clippings).  I also added a piece of lawn edging on one side to try to divert at least some of the water and pine needles away from the unit.

The inside of the air conditioner was filled with pine needles which I vacuumed out.  This is probably a job for professionals as it involves shutting off the power and removing at least a portion of the casing, in this case the fan housing, to access the interior.  It's very easy to damage the equipment if you're not careful.  If you break the refrigerant lines or cause a leak, it means an expensive service call or even damage to the compressor.   So while I do this sort of thing myself, I don't recommend it to others.

For me, it was just embarrassing, as a former HVAC technician, to have a condenser unit sunk into the mud looking like trash.  I took this opportunity to paint the service disconnect box (which was getting faded and rusty) and replace the pipe insulation on the suction line (which had rotted off) and paint the "filter/dryer" whose paint rusted off long ago.  The main power conduit was also sad looking, so I split a section of sump pump hose lengthwise to cover that.   And yes, I even waxed the cabinet with some car wax.   It looks neat and clean now, and maybe the HVAC tech will do more than merely glance at it, when the service call us due.

One problem I still have is that the refrigerant lines (and condensate line) are below grade.  The house has settled over 50 years, as most houses do, and these lines exit right at ground level.  If I had it to do over again, I would have mounted the unit on a platform off the ground, which would protect it from flooding (should that ever occur) and install new refrigerant and condensate lines (perhaps with a condensate pump) well above ground level.

Another issue is that our air conditioner was placed under the eaves of the house and the rain was flying off the roof and into the air conditioner, bringing with it pine needles from a neighboring tree. One of the HVAC techs recommended placing a "C" channel underneath the edge of the shingles on the roof to divert this stream of water as well as the stream of pine needles.  This has cut down on the amount of pine needles entering the air conditioner.

All that being said, these things only last so long, as they are usually designed for 15-year design life. Some of the older units were more robustly made.  We had a York air conditioner Virginia which had solid copper coils and fins and lasted well over 20 years.  Our current unit has aluminum tubing with what's called a "spiny fin" coil which looks like Christmas tinsel.  The spiny fin coils are very delicate and you can literally blast the fins right off with high pressure hose . However the spiny fins are very efficient when they're new, but as they clog with dirt over time they lose efficiency.  They can be cleaned - carefully - with special cleaning solutions.

The big problem is corrosion.  Particularly in saltwater environments, the salt attacks the aluminum and eats through it, which causes refrigerant to leak out.  Trying to repair or patch these things is problematic.  Usually it's a good idea to just replace the entire unit at this point.

And in that regard, it pays to shop around.  Several contractors have quoted outrageous prices for replacing air conditioners.  Down here in the South they tend to look at Yankees as being clueless ignorant fools.  I think also there is a mindset that they need to get revenge for the loss of the Civil War, and taking money from Yankees as one way of doing this.

So it pays to shop around and think carefully before you jump.  When your air conditioner breaks during the middle of a heatwave, it may seem like a panic mode situation - that you have to immediately replace it.  However, being in a panic situation is never advantageous to the consumer.  It might be worth your while to purchase a small window unit to keep your bedroom cool while you think about what your options are replacing the main HVAC unit.

Hopefully, we don't have to do this for many years.  But given that our unit is 13 years old, it probably will be need to be replaced in the next 5 to 10 years at the latest.  And we have budgeted for this eventuality, along with the eventual replacement of other appliances in our house, as well as the roof and driveway, floor coverings and paint.

I have thought about perhaps replacing the unit with a series of split-system units, as I could install these myself and they would provide zoned cooling to each room in the house.  They are also quieter and more efficient.  Since the air doesn't go though the hot attic, they tend to be a little more efficient.  But the overall cost of such an installation would be daunting, and having a half-dozen condensate lines to check and clean would be quite tiresome as well.

Owning a home is so much fun!