HRU - Not what I consider the best value especially for a homeowner. I'm a 57 year old retired , at 46, scientist who worked for many years in the field consulting in analytical materials labs. I worked with lots of instrumentation and it all had various systems to move heat or do various things with materials and electricity. I also was exposed thoroughly to developing methods to test how plants who make things run their production lines. Anyway I say this kind of product doesn't look like a good value to me for a couple of simple reasons. 1. The initial cost . If it's $100 or less well I can't complain. It's only a box with a tube basically. So what you pay is money that's out of service for you and not working elsewhere. 2. The freon has to be plumbed into the unit. This is more cost and introduces something I would never do in a laboratory unless it had more gains than this ... A leak would ruin the A/C unit and cause downtime plus the cost of the A/C unit. This isn't a good plan. If the unit came with the A/C mfg design I would consider it a part of the method the plant uses to build the entire unit. But aftermarket just does not ever make much sense to me unless .. there is no other way. I think there's another way. 3. The efficiency ratings I read are 10%. That is exactly the gain I got when I water cooled my coils on a home refrigerator unit. I got a similar reading when I cooled a regular home A/C unit with water. The amount of water to cool my parent's 4 or 5 ton , 1935 (it's still running) A/C unit is about 6 gallons / hour. The amount of water usage is very low. So I say this: Use water to cool your coils. You'll lose the heat energy to the water if the water's thrown away but assuming it's at home the water can be used so it's not wasted. And if you want some heat that's in the water then plumb a regular $50 heater core or small radiator on the cooling coils of your A/C unit. If the size doesn't fit .. yes you'll have to reconsider the design. Maybe you can only run 1/4" copper tubing firmly attached to the coils .. But you'll be running water through the secondary coolling system .. not freon. And a failure of that system won't affect the safety or even the operation of the A/C .. as long as you haven't blocked the air flow. If not for the probable high initial cost . I'm guessing $400 and the plumbing into the freon line I would be positive towards a unit like this. Which I am via the design ideas above. 4. Another method to cool coils without putting water directly on them is to use a 'swamp cooler' design around the coils where air comes in to pass over. I realize this won't work as well in Houston or Florida. However air that is 90F and wet will still carrry away more heat than air that is dry and at 90F. Any gain of humidity with pads and a bit of water over them will give you some gain of efficiency. And there is the fact that your compressor will run longer.. ours has been running in 100F Summers since 1935. And I personally know it's been running since 1975 without any maintenance or downtime and the costs of running it are low. This will occur with both plans of my idea or the HRU. One things I don't quite get in the marketing is the absolute heat temp of the output of the HRU. If the compressor is to run cool it 's going to need cool water. The outflow from the unit we have , from 1935, is at about 15F above the incoming temp. While this would help to preheat water I would not expect hot water nor would I want hot water. I 'd want my compressor to run as cool as possible. You decide. I have not run extensive testing. I'm using mostly experience but not any calculations on the HRU except the specs I've seen. I have an idea. Seriously. Why not put a 100 gallon tank of water in your car and use your engine to heat it to about 180F as you drive around? Then when you get home you'll have a day's worth of very very hot water 'for free'. Seriously. This is the exact design used for carpet cleaning vans which use engine heat to heat the steam either preheating or fully heating. I don't know how they can get to 212F without the engine overheating but they do , for about $3000, offer a heater that runs off the engine and heats the clearning water. why not do the same and then 'plug in your water tank' when you get home for an whole night's worth of hot water ? There are ideas out there. They're not dumb. Just weigh the cost and risks. Andre

Or the humidity could be VERY high, or you have an open window or three (combined with high humidity). Or the drain from the evaporator could be blocked. Turn on the fan, but leave AC off to melt ice off the evaporator and make sure all of your windows and doors are closed. Some newbies (myself included) have left a few windows open before while trying to get the heat out, and turn on ac to get the temp down. That combo doesn't really work well :) Make sure you see water trickling out of the drain. If not, thats a problem. If the piping feels lukewarm (not hot or cold, depending on where you touch it) something ain't right.

To put you in perspective you're somewhat north of North Dakota LOL..I lived in Calgary for many years where there were so few days one even needed a/c because it was so arid and really hot days so few. I don't think Regina is all that much different. A number of years ago, about 11 now, I came back east to the Windsor/Detroit area where it's extrememly muggy sometimes to help my elderly mom get some quotes on central air and we ran into the same thing, nobody did any detailed sizing. They just sort of sat at the kitchen table and said "you need this" Sears was the worst but I finally got the Carrier agent to pay attention a little. First off, mom didn't want her house freezing cold inside like some people do, old ladies don't like it like that. He quoted on a new then hi-efficiency furnace and an a/c that was 2.5 tons with a 2 ton coil or vice versa. The idea was that it would run longer thereby dehumidifying better without freezing her out. She's very happy with it's performance but we can't say the same about the Carrier furnace which has had numerous problems, replacement hi veolocity blowers etc. Fortunately mom swung for the 10 year extended warranty but last winter, the first since that warranty expired, that blower blew again and got noisy and it cost her $800. I'll never buy a Carrier product for myself.

All that tells you is the AC is providing some amount of cool air in the home. Basically is saying the AC is operational but gives no indication of the condition of the system and if it has fundamental problems. You can't turn on the AC is your looking at houses in the winter. In addition most people look at houses with their realtor when the homeowner is not home. It is unlikely the realtor is going to let you turn on the AC without the homeowner present. If it were me I would do a visual inpsection to estimate the age of the AC. If it is realtively new, I would review the quality of the installation and inspect any visual duct work. If the AC is running I would walk around the house to see if there is an even temperature distribution in all rooms.