Air-source heat pumps in zone 6
jackson28
6 years ago
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mike_home
6 years agojackson28
6 years agoRelated Discussions
Geothermal heat pump vs air source heat pump vs gas
Comments (27)Air source heat pumps don't make sense in areas where winter temps frequently fall below 32 degrees. Once you get below freezing, you will be running the auxillary heat a lot. If you decide to go the air source route, you will want a second stage gas fired auxillary heat. I live in the mid-atlantic region in the mountains and selected GT. That choice was coupled with a blown cellulose insulation package. My other choice was a propane heat/electric AC with a foam insulation package. Both options were roughly the same install cost. Both would have provided similar energy efficiency. At the time we selected, propane was 3.75 a gallon and rising (with no end in sight) so we went with GT. The delta cost for the GT system (above the cost for a HE propane heat and electric AC system) was $15,000 for the heat pumps and loop plumbing (including pumps) plus $17,000 for digging the pit. The pit excavation should not have cost as much as it did but it is a 12 ton system and the hole was gigantic (120' x 48' x 6'). We live on a mountain and hit a bunch of boulders that required special equipment to get out. Rocky soil also required a 1' base of stone dust to cover the loop piping. The total cost for the GT HVAC system including all ducting was $50,000 plus the pit excavation cost of 17K. It is a large investment and I would only recommend it if you plan to live in the house a very long time. My heating bills are great - maybe 300 dollars maximum a month during peak winter for an 8500 square foot home (5900 living and the rest a condiitoned but unfinished basement). Make sure that whatever equipment you choose can be maintained by more than 1 very qualified HVAC company who has many years of GT experience. In my area there is only 1 GT company who has over 20 years of experience but I am stuck with them for maintenance. There have been times when I wanted to fire them but cannot. Local competition is a good thing. Also - if you build a tight home make sure that you consider ventilation and dehumidification in the HVAC design. I wound up adding both a whole house dehumidifier and energy recovery vent after we moved in becuase we had basement moisture issues as well as stale air in the winter. Tight homes are great for energy efficiency but can create health issues too. It is easy to deal with as long as you plan for it. Good luck with the build....See MoreWater Cooling Air Source Heat Pump
Comments (3)Thanks for the info regarding the volume requirements, the 1.5 gpm/ton did seem rather low to me as well. I have been looking for a curve or equation based on factors such as source water temperature and even ambient external temperature and insulation efficiency but so far no luck. As for the cooling by spraying with water, I'm not clear as to why you suggest that it is not a good idea. It is exposed to the elements after all (e.g. rain). My biggest concern would be scaling due to the content left behind after evaporation but maybe there is a way around that (e.g. descaling or reducing/removing hardness, I have considered looking into a softener system to make use of my existing sand point for household use and reduce or eliminate the need for city water but am not sure if that would remove enough)? As for the sand point, you should not be mislead by the pictures or experience of the Muskoka's and assume that all of northern ontario is exposed rock, not to mention the fact that I am not in the Muskoka area. In fact, as I mentioned in my previous post, we have a significant water source at about 10 feet below the surface and myself and a number of my neighbors have sand points into this water (which is primarily used to water lawns and gardens), with my own at about 16 feet deep on a 2" pipe. The soil is rather sandy and boulders do not appear to be an issue though i am sure an occasional one could be hit which would result in abandoning that hole. The bigger issue, as verified by a local installer, would likely come again from the same issue I pointed out above, namely hard water build-up, though this time it would occur in the exchanger itself, leading to reduced efficiencies and emminent failure if it cannot be controlled. This variable itself will likely make the project a no-go, again however leaving the question of how effectively a softener system would work around this and provide a controlled heating/cooling fluid, and then at what cost. On a slightly different topic, in a closed loop vertical system, what is the typical bore size for the wells? In other words, how much separation is there between the supply and return tubes? This post was edited by Dave_Gillingham on Wed, Feb 12, 14 at 19:11...See MoreEstimate comparison and pro help: Geo vs. air-source heat pump
Comments (6)The $3346 difference between option 2 & 3 is primarily for the desuperheater - thatÂs a lot of money! System #1 SEER equivalent is 24 compared to TraneÂs 15.75. System #2 equivalent SEER is 26.5 vs. TraneÂs 15.75. They have to offer you at least a 1-year warranty (5-years on the compressor). So, what I would do is negotiate a better price for the system (#3) with the desuperheater and a fixed period of say, 3~4 months (say till spring) to decide on an extended warranty. If the system is trouble free all winter, chances are you donÂt need the extended warranty. Bottom line is if you can install a geothermal system for less than $20k  itÂs a no brainer! Last piece of advice; insist on the Waterfurnace with the highest COP (5). BTW: R-22 is at least 5% more efficient in heating mode & closer to 10% more efficient in cooling mode than R-410a from what IÂve seen, but donÂt let that sway you. Go for 2-speed compressor & ECM variable speed blower. IMO SR...See MoreAir Source Heat Pumps
Comments (26)The windows were not part of the energy audit, nor were they funded through my office of clean energy rebate. I had windows with broken seals and a window with a broken sash so they needed to be replaced. The original windows were not insulated very well around the framing (not even a barrier underneath) either so having these new construction windows installed fixed that. I also had an uninsulated drafty door from the kitchen into my garage replaced with an exterior door. My home energy audit got me into the Tier 4 category for ~20% improvement. The work included air ceiling of the entire attic, 10 inches of blown cellulose in the attic flats, 2" poly iso on all knee walls, and a new heatpump water heater to replace my 15 year old electric water heater. When they did the blower door test at the end apparently the house was too tight and they needed to add a fresh air intake. Also it turns out I have two 7.5 kW heat strips for a total of 15 kW. Apparently the original installer ( for the previous owner) who told me he installed a 20 was misinformed. When I look up the model number the associated heat package could be anywhere from 5 to 20. Unfortunately the new contractor that did my HVAC work was unable to wire two strips as separate stages. So it's still only operating in one stage in auxiliary. Would having that wired as two stages provide me any improvement in energy savings?...See Morelittlebug zone 5 Missouri
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6 years agojackson28
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6 years agojackson28
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6 years agolast modified: 6 years agojackson28
6 years agoNia Obara
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6 years agosktn77a
6 years agoionized_gw
6 years agoNia Obara
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6 years agolast modified: 6 years agomike_home
6 years agoionized_gw
6 years agoNia Obara
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6 years ago
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