What do you mean always on fan? Like the furnace (air handler) blower is always running? Do you have a fresh air intake for ventilation of some sort?
Where are the cold spots? Are you getting drafts from doors and windows? Are there exterior walls that feel cold (poor insulation)? Are some rooms just colder than others (unbalanced system)?
I would think an HRV/ERV would be more for a scenario where the whole house is cold and having trouble keeping the air warm that's coming in for ventilation. I think they're more common when homes are "tight" - the trend towards eliminating air leaks and making houses more efficient also eliminated natural sources of fresh air/ventilation, so it introduced the need for mechanical ventilation. Do you have outside air being introduced into your central forced air system?
We had an HVAC guy in - he pretty much said there wasn't much to do. We could go the AeroSeal route at ~2.5k or Arzel multi-zoning for ~4-5k. A cheaper alternative a friend of mine mentioned was the Honeywell Prestige thermostat which would allow multi-zone temp sensing and keep the furnace on longer with the colder rooms.
We are having an energy auditor out next week to see if theres any problems with the windows in those rooms, check insulation...etc. We'll see what he says.
If there's something wrong with the house the builder is going to find out what happens when you try to pull a fast one.
I had to Google AeroSeal. That could probably be helpful in overall performance, but wouldn't really do much for an imbalance unless the cold rooms happened to have the most ductwork leakage. Are the joints in the ductwork sealed and taped? If it's a new house I'd expect that to be done - so if you have leaky ductwork I'd definitely be upset with the builder and try to get them to foot the bill to remedy, whatever the solution is. No excuse for leaky ductwork in new construction these days.
If you can't even out temperatures in all spots/rooms through manually adjusting the registers and dampers in the ductwork you could look into retro-fitting a zoning system with automated dampers and multiple thermostats. The benefit there would be you could also heat/cool certain rooms more than others, so it's more flexible/customizable. How practical or expensive it would be to implement would depend on the house's layout. For example, I've considered converting two a 2-zone system as our ductwork T's off above the furnace going left to all the bedroom and to the right for the rest of the house, which is pretty ideal.
Funny you mention the Prestige system as I've been looking at it recently. I actually just put in Honeywell's Wi-Fi Smart Thermostat and am pretty happy with it. I'm not sure if I can actually build off it or not if I want to incorporate their zoning or accessory controls, but I didn't want to invest in the whole solution yet as we may be doing some major renovation that involves reconfiguring ductwork anyway.
Anyway - regarding the thermostat - it's great and all to read temps from multiple rooms, but without setting up separate zones really all you're doing is setting a minimum temperature - so if the bedroom is 68 when the house is 72 but they're not separate zones, to get the bedroom to 72 you might bring the rest of the house up to 75-76. So it's really just effectively the same as setting your thermostat higher, I think. I think the Ecobee3 thermostat does this as well... or maybe it takes an average of all the readings...
In regards to the fan used for circulation/evening the heat, our old cheap-o thermostat had 2 fan settings - "on" or "auto". "On" would run the fan non-stop (sounds like your setup), "auto" kicked in on only when the furnace (or A/C) ran. The Honeywell has a "circulate" option which runs the fan sporadically through the day... like 1/3 of the time I think is what the manual said. Enough to provide a little more evenness, but not so costly as running the thing non-stop. Haven't used that feature yet, but I've only had this t-stat a few days.
The energy audit will help for sure... you can also do smoke/feather tests near your windows and doors to check for drafts, or if you can get your hands on a temperature gun you can go around looking for cold spots in walls, etc. If you're adventurous you could carefully pull back a couple trim pieces around windows and doors to see if the space between the jambs was insulated - again, these days it should have low-expansion foam filling the gap, but lazy/old methods involved stuffing newspaper of fiberglass in, if anything.
Another thing to check would be how your rim joists are insulated. Check the article on Fine Homebuilding's website - "Insulating Rim Joists". Again, that's more of an overall efficiency thing rather than your ductwork being balanced, but it may give you an idea of whether your builder took shortcuts.
Before the audit, take a IR thermometer and walk around the room and find those cold spots, then check insulation. I see a lot of tier ceilings that are uneven insulated and sometimes the exterior sides near the soffit, there is very little.
If you close registers you may increase the static pressure on the blower. The HVAC tech should have taken an anemometer and checked the cfms at the registers and return and adjusted based on readings. Also he should have checked static pressure on the blower/furnace. Having blower always running just isn't right, if the ducts are in the attic, there going to cool down when the heat isn't on and blow that into the rooms. In summer when the AC turns off, all of that moisture on the coil is gonna get blown right back into the rooms, so no dehumidification. In AL R-38 is code minimum for insulation, I don't know about MN but I thought it would be 50+. Also check around all of the window on the exterior, Fill any gaps, except weeps, the slits at the bottom, with at least GE 100% Clear Silicone.
As with most homes the builder only really did the code minimum, so they didn't tape ductwork. This isn't a cheap home either, just corners cut and our first home, so it's a learning experience. Most people in our development are in the same spot.
I agree on the temp increase, but then I was going to shut down vents in the different rooms that are hotter to try and even things out a bit.
Our thermostat (Trane z-wave) only has auto/on, so the honeywell may be a little better there.
One of the neighbors retrofitted their house with 4 zones for $10k (incl. system and fixing knock-down). We're not willing to spend that much. I looked at this...
http://www.thisoldhouse.com/toh/video/0,,20810706,00.html
Interesting approach, just not sure on longevity (sharp edges, duct screws, duct cleaning...etc). Also a friend of mine brought up the issue of having too much pressure if too many zones are shut down, burning out the motor.
We might end up insulating the attic better (r-46 now).
Really hoping the home energy audit with IR camera shows some damning evidence. Most HVAC guys in this area build for the big national builders (incl. ours) and don't want to start stuff with them lest they lose out on huge contracts.
Before the audit, take a IR thermometer and walk around the room and find those cold spots, then check insulation. I see a lot of tier ceilings that are uneven insulated and sometimes the exterior sides near the soffit, there is very little.
If you close registers you may increase the static pressure on the blower. The HVAC tech should have taken an anemometer and checked the cfms at the registers and return and adjusted based on readings. Also he should have checked static pressure on the blower/furnace. Having blower always running just isn't right, if the ducts are in the attic, there going to cool down when the heat isn't on and blow that into the rooms. In summer when the AC turns off, all of that moisture on the coil is gonna get blown right back into the rooms, so no dehumidification. In AL R-38 is code minimum for insulation, I don't know about MN but I thought it would be 50+. Also check around all of the window on the exterior, Fill any gaps, except weeps, the slits at the bottom, with at least GE 100% Clear Silicone.
The kid that was out did some CFM readings but overall didn't do shit, only checked at the registers and such. I didn't find out till afterwards that his company is another contractor for the builder... I might talk to the other guy from the company and see if he can do something more for me.
If not, I might try to find somebody else. The energy auditor is from the power company so I am hoping I get a little more of a honest answer.
As far as I can tell, R-46 is the minimum here, I am a bit surprised, but that's the area. I'm not sure if they went around and did the caulking or not. Anything I should pay attention to in particular?
Another thing I noticed is a small draft coming through our basement outlets. Not sure whats up there.
This house wasn't cheap...
Power Co should be about as unbiased as you're going to get. They'll likely do smoke tests to help locate drafty windows and doors. It sounds like a pain but if they find issues there you can carefully pull back the casing (cut the paint/caulk where the trim meets the wall) and do a better job insulating those gaps w/ low-expansion foam. The caulk outside will help with sealing from the elements as well - but the focus is probably more on preventing water infiltration.
The draft coming from the outlet is similar to the gaps between the framing and doors and windows - there's probably either loose or no insulation around the outlets. They make these little foam covers with outlet cut-outs that you can put behind the wall plates - that might help a little. The wall will still be cold in that area but you shouldn't feel a draft anymore. Actually getting some insulation back there would be a little trickier, but it can be done.