The main issue I see here is that it will only take about 691 BTU to raise or lower the 38000 cu/ft of air 1 degree. So in the winter even a a modest heat pump for your size living space could be pulling in excess of 48,000 BTU/h out of that air space. Dropping the air temp in there 69 degrees per hour. Of course the air in that room in in contact with the concrete walls and floors that are going to act as a heat exchanger with the earth and heat will conduct into the air from them at some BTU/h rate that would need to be greater than the amount being pulled out or you would get an ice box down there real fast. This gets into the thermal transfer properties of air to concrete along with air flow around that room to make contact with that concrete which is beyond my expertise. I can say based on Fourier's Law 6" solid stone concrete floors and walls of that sq ft should be able to conduct about 112,000 BTU's from one side to the other with a 10 degree difference, but that must end up in the air and blowing over the coil to make up for the 48,000 pulled out otherwise the temp will just keep dropping below usable range. If you do it you might get lucky bascially using a air source heat pump as a ground source heat pump, but if the room can't handle the heat exchange load you will just turn it into a ice box in winter and a hot box in summer without getting enough for you living space out of it.

I am taking your advice and going to do the HVAC on my own. I've had 2 authorized dealers take a look so far. Will have 2 more. I've gotten one proposal back and the second guy will do one but his will be time-consuming and I hesitate to have him put a lot of work into the proposal when I'm still interviewing others. He said he would not be happy if he didn't get the job. I can't promise he'd be the one. NOTE: No load calculations were ever done on this house for heat or AC. I just learned this yesterday - 1 year into the job. The second AC dealer wants to do load calculations but, as I said, we've come so far and have limitations. Would it be worth his time? The first proposal goes like this: Remove incorrect air handlers and install 2 Trane variable speed Hyperion AH 2 Trane 2-stage SL16i condensers install Honeywell control system - digital programmable with WIFI replace all flex ducts on 2nd floor (I believe they're 6 or 7") with new 10" round flex with larger difusers Install 2nd return in ceiling on 2nd floor, redo existing return ducts The total cost of all this is $14,650. He also proposed installing a secondary heat source. We have Viega radiant heat panels in the floors but there is some concern that it will be adequate given the level of quality of the HVAC work and a poor experience with the electrical sub. There are 4 options for supplementary heat proposed: 1. Hot water coils in the AHs: $3400 2. Electric heaters: $700 plus cost of running electric lines 3. Carrier Heat pump (would mean using carrier equipment, not Train) $2900on top of AH price 4. Carrier Infinity 20 greenspeed heat pump - $5400 on top of AH price I have no specific model numbers from him - I suppose he doesn't want me to be able to compare prosals directly. Any reactions?

Please, be very careful about the insulation and vapor barrier placement and type. If you don't get it right, you will have a mold farm. I don' t know the situation details, but this could be very easy to mess up. The most important part of the basement to insulate is between the soil line and the floor of the ground level, the rim joist, and environs. I wish I could be enthusiastic about about the Dryloc paint. If you have water outside the foundation, the only good fix is to lower the water level via better drainage. This usually involves a lot of digging. If it is a soil moisture (vapor) problem OK, but get the vapor barrier/insulation right. Given the oil-powered baseboard, I'll assume that you are in the Northeast. My experience with finished basements in the NE is that when a dehumidifier is running in the summer, you have enough waste heat so that you need little cooling, but two tons, that should be OK for 5000 square feet or more. Oh wait, you have 1000. Keep the humidity below 50%. An efficient dehumidifier would probably be a good investment, but I don't know about the return on investment. As Mike suggested, you can stick a portable unit into a purpose-built plenum located in an unfinished area and run ducts using a small blower and external thermostat for a pretty effective system (see below). I am assuming that the whole basement is half again bigger or twice the size of your 1000 sq ft finished area. If that is the case and you empty even a largish portable dehumidifier 2 or 3 times a week, that is not a lot compared to some other situations. I've seen 70 pint units fill up daily or in part of a day. Add the pump for when you are out of town and it will be so quiet that you will forget it is there. Don't (fully) add cooling until you prove that you need it. It if has been cool while running the dehumidifier and the humidity is an an acceptable level, have a plan and and leave an option in place for cooling now, but you don' need to fully execute it yet if it is going to cost a lot in equipment. There are too many unknown (to us and to you) variables in your plan right now that are going to affect your heat and cooling loads. Insulation will be a two-edged sword. Soil temp is probably in the 50s staring a few inches below the surface. Add insulation and you need heat less in the winter, sure, but you lose a heat sink in the summer that might make you need more cooling. If a typical, inexpensive dehumidifier makes it too warm a Santa Fe or similar will make less waste heat and might be tried before adding cooling. Note that a good engineer might be able to model all this for you and get it correct right out of the gate. A mini split is probably a good option but if you can piggyback on your existing cooling system, so much the better. You might have to install all the ducts, of course and might will be the main investment if tapping into your existing system. On the other hand, maybe a mini split can pretty much be added later with no investment now. As lagniappe, it may provide heat for less cost than the oil burner. Do the math. If you want to use it for heat, location nearer the floor will work better so consider a floor console or setting up a ducted unit with high and low supplies/returns that you switch off seasonally rather than the typical high mount version. They are not as efficient and cost more, but may work a lot better. My experience in finished basements in heating climates is that the floor and feet are always cold. The mini splits in dehumidification mode can take a lot of the load off of a dehumidifier while giving you some cooling at the same time. Make no mistake, however, they are not dehumidifiers. They are always net cooling whereas dedicated dehumidifiers heat as a byproduct. To see some examples of a dehumidifier in a plenum, find these articles, You can probably forget about most of the other stuff found there unless just for interest. Note that this organization might be a good place to look to check or form your insulation plans: Conditioning Air in the Humid South—Creating Comfort and Controlling Cost Research Report - 0214 November-2002 Building Science Corporation Residential Dehumidification Systems Research for Hot-Humid Climates Building America Report - 0505 Feb-2005 Armin Rudd, Joseph Lstiburek, P.Eng., and Kohta Ueno

What year was your house built? What location, climate wise, are you in? We have a similar set up. It runs the full length on the front of the house (about 45'). No tin, just a solid concrete pour, over a foot thick. (Originally for cold storage.) My husband did just what you suggested. He installed 2 layers of foam board insulation, with spray foam to fill & seal the gaps. Totally solved the moisture issue. He waited for the warmest part of the summer, and then ran a dehumidifier to dry it out as much as possible. I think it was late August when he did the foam. Well before any low temps at night. We're in Minnesota, so temps range from 20 below to 100 above. Our house was built in 1965.