I live in a concrete block home in SE Florida. The air in the house stinks and I am well aware of indoor pollution. The house is 2 years old and we have lived in it one year. The first year the house was vacant BUT the AC (2.5 T) was kept on. We AC 1800 sq ft with insulated ductwork in the attic. I talked to 2 contractors. They want to stick an outdoor duct into the supply and leave it open. Yea right. I want an electronic damper that I can open say 12 to 4 AM (lower temp and humidity) I want them to exhaust the air from the return located at the other end of the house. They look at me as though I have 3 heads. They want to bring in air all the time and not exhaust any. I say not possible with tight CCB home and few windows. How do I size and buy the necessary stuff so I can hire some one to do the labor. Am 71 and tired of cleaning up other peoples messes!
DIY fresh air intake
hvac
Related Solutions
The problem you describe is considered normal performance for many residential A/C units. By design, these only function correctly if the outdoor temperature is warmer than mid 70s and the indoor temperature is above 68F. Below these temperatures, the evaporator coil gets colder than freezing, becoming worse as the coil accumulates frost, eventually causing the system to become covered in ice and stop cooling until the unit is manually shut down and thawed.
In a situation such as yours where A/C needs to perform even during cool temperatures, it is necessary to install three accessories which will enable the unit to operate under these conditions:
(1) A compressor crankcase heater (sized for your compressor)
(2) A head pressure control (such as Totaline p251-0083h, approx $35 new, Ebay)
(3) A evaporator control limit (ECL) switch or Freezestat (approx $20 new, Ebay)
Calibrating the head pressure control perfectly requires a set of gauges, but it usually works correctly if the temperature probe is placed anywhere near the discharge of the condenser coil. Other than that, these are electrical items only, requiring no refrigerant expertise. This setup is sometimes referred to as a "low ambient kit with freezestat." An experienced tech should be able to install all these within a couple hours.
Better idea: flip things on their head
You need hot water to run a hydronic heating coil efficiently, far hotter than you'd ever set your water heater to (water heaters struggle to reach 180°F which is the standard temp a hydronic boiler is set to). However, your hydronic load probably pales in comparision to your domestic hot water load most of the time, and your current gas heater is not all that and a bag of chips regarding efficiency (EF=0.50).
So, the solution I propose is to use a hydronic boiler to drive an indirect hot water heater tank in addition to the coil in the air handler. An indirect tank the size of your existing heater with a 150kbtu modulating-condensing boiler can give you practically infinite hot water, will have far fewer standby losses (~350-400Btu/hr for a Bradford White SW-2-80-L based on the AHRI figures of 0.6°F/hr and a 71 gallon potable capacity) compared to the kBtu/hr range standby losses of a conventional gas heater, and will be more efficient than your existing heater overall with a computed EF in the 0.7 to 0.8 range depending on the thermal efficiency you can milk from the hydronic setup (good modcons get into 95-96% thermal efficiencies, and indirect tanks are quite efficient as well), comparable to a good condensing gas tank-type heater.
Atop that, you'll be running the coil in the air handler more efficiently due to the improved delta-T available over what a domestic hot water heater can produce, and you have a solid platform for future desires (such as zoned air handling or radiant heat).
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Best Answer
I use a charcoal filter ahead of the regular filter. My wife has a nose that can smell anything even a football field away. They work great, I buy mine at Home Depot or lowes for around $10.00. Look for the WEB Absorber, ask an attendant in the heating/ ac section. It is a cut to size and comes in 20x25 size. I only had to cut the plastic piece once and reuse with each change. Mine last 6 months.