Hey Kevin, sounds like a pretty nice setup. Could you fill in a little more info in your profile, so we have an idea where you're located. ( climate and soil vary alot from FL to NH to CA ) It just helps to have a frame of reference.
Hey Kevin, sounds like a pretty nice setup. Could you fill in a little more info in your profile, so we have an idea where you're located. ( climate and soil vary alot from FL to NH to CA ) It just helps to have a frame of reference.
I also have the Water Furnace brand of pump. Noise, as you say is a factor inside. In the future, I will also obtain a unit for domestic hot water. This wasn't in my budget at the time, but do see the need for it. Also, for anyone looking at this type of system, and who have a house larger than 3000 sq. ft, I highly recommend zoning the home. I built a 3600 sq ft 2 story home and did not have it zoned. I do have some problems with temperature regulation on the 2nd floor. Hopefully with some adjustments to the ducts, I will have this problem taken care of, but it would have been simpler to zone it and temperature would be more controlled.
I updated my profile, thanks for pointing that out.
I live in the foothills of the cascade mountains near Seattle. We have about 20 acres of mostly 100' douglas fir trees and beaver ponds. The avg temperature in the winter is about 45 degrees. It will get cold Jan - Mar (somewhere between 25 and 35 for the lows). In the summer, which is Jul-Sep here in WA, highs are usually around 80. The high for the summer was 102.
The house stays pretty warm during the winter. Sudden temperature drops will cool it off. Radiant floor systems don't respond very quickly to temperature changes, so it is a good idea to keep the doors closed!
Kevin
I built my home two years ago. I used American Geothermal Direct Transfer system with blown in cellusose insullation It uses freon through copper tubes placed five feet underground. It is extremely efficient because of the heat transfer properties, and it doesn't require a pump to move fluid, as water systems do.
Mine is a 3500' house, with a finished basement. I have a dual zoned system, with a Trane air handler that constantly circulates the air at very low speed, (unnoticed). When either thermostat calls for air, it comes on at various speeds based on need. I get almost no stratification between the two floors of the house. I also have the hot water option. Very happy with it so far.
jetlag, I'm considering a direct freon-in-the-ground system also for house about to be started. Your the first person I have heard of who has one. I assume you like it fine. I'm still vascilating on my HVAC. Not so sure I can budget for in-floor hydronic AND a complete duct system for cooling PLUS the HRV and so on. I tried to make an end run and thought I could use fan coil units working on circulated water for both heat and cooling driven by a ground sourced heatpump but costs are pretty steep by the time you get the zone controls, pumps, and all the ancilary STUFF. The jury is still out but the freon-in-the-ground looks attractive. Our's is a mixed climate, officially Mixed-Humid having over 20 inches of rain, approx but not to exceed 4500 heating degree days, and average montyhly outdoor temps under 45F. in winter. We don't see 0 deg F very often, even the teens are not prevelant, but get 100 in summer with high humidity. Dehumidification is a real concern. We'll be going for variable speed air
handler and multi speed or multi compressor unit. I was surprised to find the the realy high seer units use two compressors and run the little one until it can't keep up and then run the big one (never both).
Patrick
"I'm not from your planet, monkey boy!"
Dehumidification is the strong point of a geothermal system. Because the cooling coils of an outside, above ground, heat pump system are subjected to ambient air, which is much hotter, they have much less dehumidification capacity than in ground geothermal. Additionally, with a continuous air handler system, dehumidification and filtration is more effective. Can't say enough about the system's ability to dehumidify. It's very obvious when compared the neighbors heat pump system. We typically set 77 degs. for a comfortable summer setting. They set about 74.
Your temp variations sound similar to ours. I'm in central VA.
Jetlag, Sorry but I got lost somewhere in your reply... Probably my fault, thinking you mean something you don't. Anyway you say the cooling coils are subject to ambient air. The coils that get cool when cooling/dehumidifying the home(Evaporator) are usually inside the home and the condensing coils (the ones that get hot during home cooling) are ouitside shedding heat to the environment. This still happens with ground sourced heatpump just more efficiently due to it being easier to dump heat into the ground temp than the ambient air temp. Maybe the inside coils get a little cooler due to this more efficient heat shedding into the ground and promote better dehumidification.
Some of the newer systems run the air handler real slow for a few minutes which lets the evaporator coils get really cold and dehumidify real well, for a little while till they would freeze up. Then the air handler runs faster, still cooling the air but not at such a low temp so the evaporator "defrosts" then they do it again.
A real boost to dehumidification is the application of heat pipes. No moving parts except molecules inside the pipes. No equivalent additional power consumption (minor increase due to two extra sets of fins for air handler to blow through.) It almost seems too good to be true, very much enhanced dehumidification with virtually no increase in operating costs.
A web search on heat pipes will fill you in. Dinh (sp?) in Florida has a line of prepackaged units as well as sets of "U" coils for retrofit. Really clever application of the laws of physics.
I'm still considering a Freon in the ground system with the house side of the system circulalting (heated/chilled) water depending on seasonal requirement) Zoning would be through distributed fancoil units. IAQ would be maintained with an HRV. I'm still struggling with how to ballance the flow vs pressure/vacuum as I will have a rather powerful range hood vented to the outside. So far the best I could come up with is vents to provide ambient air around the periphery of the range and I will probably have to put a fan on that and do some ballancing so I provide as much incoming ambient air as exhaust air is removed. I envision the peripheral vents to work like an "air dam" or air curtain like you have probably noticed at the entrances of commercial operations whose doors stay open during buisness hours while they are conditioning the interior space. This air curtain will segregate the volume above the stove from the rest of the kitchen. Doesn't have to work perfectly to be worthwhile to me. I intend to move 1000-2000 CFM with my rangehood and that would not be good for the function of the rest of the HVAC system.
Pat.
"I'm not from your planet, monkey boy!"
You are correct Pat. The condesnsing coils are the difference. I didn't read my old HVAC pubs prior to posting. Regardless, there is nothing in a geothermal system that's subjected to ambient air, as you know. The system I have disipates the heat into the ground, a relatively heavy clay at 4.5 feet. To ensure the tubing/earth contact is not lost, a rock powder is placed immediately above and below the tubing prior to backfilling. Additionally, a drip system is installed above the system to ensure that even in the most extreme droughts, the tubing/earth contact is not lost. It works real well. Of course, it's a bit more expensive to install, but my savings and comfort level have benefitted. As an aside, I built this exact same house in Illinois with nat. gas and normal central air. The house in central Virginia is much more comfortable with the geothermal, better dehumid. in the sumer/better humid in the winter. I cannot give specs on energy useage, because I have three teenagers, and none of my neighbors are so blessed/burdened. By the way-I have the hot water heat exchanger feature, and have found that to be an incredible deal from a cost/benefit perspective.
Pat,
Check out the WaterFurnace Synergy3 which does exactly what you are thinking. I have two of them in my house, and they work quite well. I have Hydronic heating and forced-air cooling. Where I live, the forced-air cooling ductwork qualified as the IAQ system, so I didn't need the HRV setup.
Kevin
Kevin, Thanks for the URL. Water furnace was on my list of possibles. I'm not as far along as I wish I were in engineering the HVAC. I don't have the practical experience or feel for cost so I can design a while then find out that the idea sucks or is too dificult to do in practice or is just too costly and won't have a payback within the installed life time of the equipment.
I still have a few ideas to check out. I will be pricing an essentially duct free system with distributed air handlers instead of a centralized system with oodles of ducts to breed mold, fungus, mites and other life forms best not raised in captivity.
My idea is to have the output side of the geo-thermal unit heat or cool a quantity of water which in the case of heating the home can be used for an in-floor hydronic system, or distributed baseboard,or whatever will heat the home using circulalted hot water. One of the units I saw that I like is a small fan coil unit designed to take circulated hot water. It is made to mount under cabinets in the toe kick space where it pulls in cool floor level air and puts out warm air. I talked with the manufacturer and for a small non-recuring engineering fee they will add a condensate drain tube and do a powder coat to ensure corrosion resistance. If you circulate chilled water through it and turn its fan on you get cooled air. So it lends itself to a zoned/distributed system and can heat and cool. OF course it can be mounted in the ceiling, wall, or wherever. It does not automatically elliminate in-floor hydronic as they can be compatibly used together. As you know the big problem with hydronic heat is the lack of hydronic cooling and the requirement to have much system duplication to get cooling (two complete circullation systems, one for water and one for air).
Any serious atempt to cool with surface hydronics (ceilings are better for cooling than floors) runs into condensation problems. If surface temps stay enough above the dew point to avoid having a mold farm form, then you don't get enough cooling, at least not where there is any significant relative humidity. Usually, practical dehumidification calls for circulating significant quantities of air.
One scheme I considered was a large metal sculpture and or an ice wall. Consider a large metal sculpture in the great room backed by a wall with lots of artistically shaped and positioned metal plates. There would be a shallow "pool" around the drip zone of the sculpture/wall area. The sculpture and wall plates are the evaporator heatsink for the AC system. When it cycles on, condensation forms on the wall where if forms many interesting water falls as well as dew on the sculpture and drips into the tiled pool to drain away. As the metal chills down below the freezing point, icecycles, frost and ice crystals form in changing patterns until the ice coating gets too thick and the efficiency drops and the unit goes into "defrost cycle" just long enough to weaken/shed most of the ice coating and then revert to cooling cycle where different shaped ice "sculptures" form depending on the random remnants of the previous cycle. This repeats as long as cooling/dehumidification is required. I still like the concept but havent got the inclination to spend the time, effort, and $ to prototype it nor the extra space in the great room to install it. Even if it was way undersized to do a significant job on its own, I think it would be a fascinating object de art and or conversation poiece.
Thanks again for the user report and URL for Water Furnace. I will be contacting them. I am leaning toward the Freon in the ground system as it is less expensive, takes less trenching, doesn't require water pumps for the external circuit and uses one less heat exchanger. If you haven't seen them, they are not particularly special. They just let the compressor circulate freon in the ground loop and elliminate the freon to water heat exchanger, pumps, and associated controlls. Otherwise they work the same except for higher efficiency and lower initial and maintenance costs.
Patrick
"I'm not from your planet, monkey boy!"
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