Tigerdunes brought up demand defrost versus timed defrost. For the past 18 years, I have dealt with my Lennox defrost scheme. The only times I heard it go into defrost mode were when the unit was first running in heat mode. The unit would switch over from heat to defrost, the defrost cycle would complete and everything would turn off. I never heard it run a defrost cycle when it was not first heating. I rarely heard it go into defrost. I never heard it defrost on a fixed cycle such as every 90 minutes. Am I to understand that a Carrier will just go into defrost mode every X minutes whether it needs it or not and is not in a heating cycle; just turn on and defrost itself? I found this information in the Carrier 25HNB6 heat pump installation instructions: AUTO defrost adjusts the defrost interval time based on the last defrost time as follows: When defrost time When defrost time 3-5 minutes, the next defrost interval=90 minutes. When defrost time 5-7 minutes, the next defrost interval=60 minutes. When defrost time >7 minutes, the next defrost interval=30 minutes. The control board accumulates compressor run time. As the accumulated run time approaches the selected defrost interval time, the control board monitors the coil temperature sensor for a defrost demand. If a defrost demand exists, a defrost cycle will be initiated at the end of the selected time interval. A defrost demand exists when the coil temperature is at or below 32_F (0_C) for 4 minutes during the interval. From that description, if the time interval elapses and the coil is not at 32 degress, then no defrost will take place. That, to me, sounds like a form of demand defrost. Is Baldloonie saying that the coil could be at 32 degrees or less without frost and, therefore, a defrost cycle would be unnecessary? What kind of ambient sensor detects presence or absence of frost? Neohioheatpump asked, "When your old A/C would run, was it producing water?" It was producing water and I saw it dripping from the condensate drain. One weekend I went out of town and came back to find water on the floor around the return box that the fan coil sits on. I opened up the access and found the interior insulation of that box soaked. Turns out the condensate line was plugged. Took awhile for that to dry out. On the other hand, this past summer I did not see water dripping from the condensate drain. The drain line was not plugged and the drip pan seemed dry. I thought it was because I had dried out the air so much with the two dehumidifiers that there wasn't enough remaining for the A/C to remove. Cooling was normal. Running the fan on manual started with the installation of the Lennox and an associated Honeywell Electronic Air Cleaner. The house suddenly became dusty and I blamed the EAC for not doing its job. The Honeywell zone representative came to my house, sized up the situation, and told me to run the fan on manual so that the dust would remain suspended in the air and available to be captured by the EAC. I did that and it was of no help for the dust situation but it did help reduce the temperature differential between the first and second floors during cooling so I kept doing it as a matter of routine. Thus, I cannot say that not running the fan reduced the humidity. Though I complained about humidity, the heat pump contractor never told me that I was humidifying the house by running the fan (on orders from the Honeywell rep). I will continue to run at least one dehumidifier in the completely below grade basement during the summer because I want that area to be warm and dry to avoid mold and mildew. I've been in the basements of other houses in the area that don't use dehumidifiers and they stink. Mike Home said, "You stated in an earlier post that you run the fan in the summer because the upper floor is 2-3 degrees hotter than the lower floor. I think adding the attic insulation will help this." I agree that adding attic insulation could help. But, having a Dutch Colonial house with a barn-like roof that is covered in dark shingles on the east and west sides causes a lot of heat gain through the second floor walls. I'm not keen on opening the walls to determine the amount of insulation or add to it. Changing to a light-colored roof would make the house look out of character with the neighborhood. There are newer shingles that reject heat gain that I will investigate. Mike Home also said, "You could also zone the first and second floors, but this is expensive and probably not feasible with your current duct work." There is but one main feed duct and it runs through the basement. There is no way to segregate the room feeds in this scheme without doing each one individually. I'll leave that expense to the next owner.

I just rerouted the condensate from one of my two A/C evaporators (the other was too far) and an Aprilaire dehumidifier. PVC pipe painted to match a downspout brings the condensate from the 2nd floor attic to a rain barrel I've set up to catch it. Hose connected to the rain barrel faucet allows me to empty the condensate into the pool--and then hide the hose when I need to. My hope was to have enough to keep the pool topped off with 7.0 pH water (pure water is 7.0; our city water is 8.2; ideal pH for plaster pool is 7.2-7.8). Initially I collected the condensate in a 5 gallon pail for testing. Turns out the water has a pH of 5.8, which I learned is due to carbon dioxide dissolved in the water from the air. That's not a problem. In fact the small amount of 5.8 water will barely raise the pH of the 15,000 gallon pool. Right now, I'm getting only about 8-10 gallons a day, but this is fall, and the AC runs less than summer. I should get 12-15 gallons in the summer. I don't know if that will keep the pool topped off, but it will help with both quantity and pH. My other water tests showed, not surprisingly, -0- chlorine, -0- calcium hardness, -0-total alkalinity, -0- salt, and -0- cyanuric acid. CDC recommends treatment of AC condensate if used for other than watering plants and other applications that don't require potable water, as the AC evaporator can carry in-home viruses and bacteria. Well guess what? A swimming pool has built in water treatment: chlorine. I use a salt water chlorine generator and keep the pool at 4-6ppm chlorine level, which is well above CDC's recommended minimum of 2-3ppm (CDC is only concerned with health issues, while pool owners also want to prevent algae.) Reuse of AC condensate is likely to become more important in the future. Consider in Houston, there are about 2 million "housing units" and 110,000 business in Harris County according to the Census. Just consider how much water is created by AC units and then piped right into the sanitary sewer system every day at 10 gallons per household. 20 million gallons--and that's just Harris County Texas. I know a few people who capture the condensate and use if for gardens (5.8pH is perfect for most flowering plants.) There are 82 million single family homes in America. Do the water math and see how much we're throwing away every day. The cost of routing AC condensate out to a container instead of into the sanitary sewer would be almost zero for new construction. It cost me $150 for the AC guys to do it. I know I won't live long enough to get my money back in savings on my water bill and reduce use of muriatic acid for pool pH. I just wanted to know if it would work. I'm doing a tiny bit to save water.

So, if I do not use bleach to clean the drain, how to you recommend that I should keep them clean? One way: use a good quality filter and change them at regular intervals. This method is not perfect. Second way: pitch drain line to a minimum 10-15 degree angle so that it empties fully, into a single trap if possible --- trap placement is just as important. Flat piping runs and elbows should be avoided as much as possible. (Don't forget about first step.) IE: gravity works for you just as much as it can work against you. It all comes down to the design of the drain system. Third way: wait until it clogs and then clean it out / or pay to have it cleaned out. Which way do you suppose most service companies are counting on? So by now you clearly see the 'two sides to every coin'. If something is billed as being perfect --- it is an out right lie, merely to swindle you. Drain line could still clog given the second way, but you cut the risk to fraction of what was possible with other methods. It's not always possible: architecture was built for beauty, not for how the HVAC system condensate line is to be run to prevent drain clogs. In some situations it may be better to level the home and start over. Ah the reasons why someone sells a home these days... it will boggle your mind. It should be noted that bleach does not clean the drain, it merely treats it by killing bacteria and algae growth. To keep bacteria and algae growth in check the drain has to be treated continually, because as you run the AC the bleach is eventually diluted and flushed down drain with condensate from the AC. The problem with retreating is that bleach is corrosive. If not flushed down the drain completely the fumes come up the drain and attack anything metal. Your all aluminum coil is no match for bleach. It will attack the heat exchanger as well. The more you treat the drain with bleach the more less likely you have drain clog, but at the expense of system damage due to the corrosiveness of the bleach you use to treat the drain.

I'm disappointed that what had at first seemed a very balanced comment was followed by what seems to be misinformation and misdirection. People buy ground source heat pump equipment because they want to and can afford it. Or decide they need to in their locations. They're hugely more expensive than alternatives, which is why they're still not very common. "When’s the payback on a Tesla? People still choose to buy them for reasons other than the ‘bottom line’." Not a comparable. A false analogy. "I would not choose natural gas or propane for reasons relating to the environment, safety, IAQ & paying for yet another utility hookup for an energy source that might not even be used for months on end during the year." What effect having a gas furnace has on indoor air quality. Another hookup? Most people prefer gas cooking appliances and besides, the OP is talking about an existing home, he either has gas service or he doesn't. "Rather than spending perhaps tens of thousands of dollars on a Solar Array, I would sooner invest that same money, hopefully less, in a ground loop for a Geothermal system." Sure you would, that's the business you're in. The ground source heat pump market is not growing as expected by those in the industry, which suggests that your opinion isn't widely held or easily sellable. In many parts of the country, solar panels can have a quick payback. Not so ground source heat pumps. "I often hear about Solar Panels when geothermal is mentioned, as an alternative way to save money by creating energy." In a place like Texas, where electricity is cheap (other than during cold weather crises as they just experienced) there's likely no payback from a solar panel installation. People do it as a personal statement, call it for environmental or other personal reasons. Like buying the Tesla, not a financial decision. An HVAC system blows warm air when it's cold, cool air when it's hot. It's one of those things people don't care about - either it works or it doesn't work. Spending extra money for an exotic system doesn't equate to extra payback when the home is sold. Neither owners, nor visitors, nor people passing by, nor anyone else, concern themselves with what's doing the work. It's equipment that doesn't produce an experience for someone in the house if it's working. In the US, there are vast areas where electricity is cheap. It will remain so for some time. People don't spend money today to potentially save money 10 years out when market conditions may or may be different. I suspect you could build a house with mahogany or teak framing. Or you could paint the framing bright colors. Why bother, you can spend less money and effort and get something else that will do the same job. "We almost never use setbacks at our home - even when going on vacation for weeks on end with no one home, our geothermal just runs." You're combining two different things to produce confusion. Thermostats that have a setback feature ALL are set up to provide lower overnight temperatures to have more comfortable sleeping conditions and then a recovery in the morning before wakeup time. As sleep specialists recommend. That in demand comfort features isn't possible with ground source heat pumps because the warm up period from a setback is too slow to be convenient to use, absent triggering a secondary heating source (like a furnace) to help. THAT'S why you don't "believe" in setbacks with a heat pump - they don't work. Turning down a thermostat during heating season when the home will be unoccupied is not a "setback" as that word is most commonly used. It's done to save money, why heat a vacant house? No setback thermostat is needed, even a dumb 50 year old analog thermostat can be turned down.