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j3l2404
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Posts:5
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| 08/04/2008 12:59 AM |
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I own a one acre lot (165x265) in an unincorporated area within LaSalle County, Illinois. I plan to build a new home on the lot with construction to start in the spring of 2009. The house we decided on will be approximately 2,150 square feet. The house is a two-story design with three bedrooms and a full bath on the second floor; and a master bedroom and all other living space on the main floor. The basement will be unfinished and approximately 1,400 square feet. The exterior walls will be 2x6 and we plan to put in energy-efficient windows. The home will be served by a private well and septic system.
After doing some research, I found good reviews of WaterFurnace systems and found a reputable local installer that is a WaterFurnace dealer. The installer I found is IGSHPA accredited and works for a respected company that has been in business for 40 years. I still need to verify the company's track record for actual installations though.
It appears that we will have plenty of room for a horizontal loop. From my research, it appears that a horizontal loop is both less expensive and more efficient. Is this correct?
I want to zone the system from main floor to second floor. I want to make sure that the second floor bedrooms get enough cool air in the summer, that is the thought process behind the zones. Should I have one larger unit for the zone system or two smaller units? This is not a giant house, so I am thinking one larger unit will do fine, but I may be wrong on that.
On a side note, we are thinking of using spray foam insulation in the walls. Any thoughts on this?
Does anyone have recommendations for geothermal contractors in north central Illinois? Does anyone have a bad experience with a geothermal contractor in north central Illinois to share? |
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engineer
Registered Users
Posts:397
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| 08/04/2008 8:29 AM |
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If you are willing to spring for sprayfoam in the walls, why not go all the way and consider ICF - great insulation and thermal mass and great sound supression
A tight 2k SF house should work fine with a single unit with a zone on each floor.
Ensure contractor does detailed ACCA Manual J, D and S calculations. Beware sizing for heating may oversize for cooling, reulting in poor summer dehumidification. You don't want that. Consider a two stage unit and don't necessarily rule out occasional backup operation (heat strips) on coldest days
Horizontal is generally cheaper to install but LESS efficient than vertical. Vertical accesses the most stable deep soil tempes for most efficient operation |
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Without data, you only have an opinion. |
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TechGromit
Registered Users
Posts:225
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| 08/04/2008 10:29 AM |
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Posted By j3l2404 on 08/04/2008 12:59 AM
From my research, it appears that a horizontal loop is both less expensive and more efficient. Is this correct?
I want to zone the system from main floor to second floor. I want to make sure that the second floor bedrooms get enough cool air in the summer, that is the thought process behind the zones. Should I have one larger unit for the zone system or two smaller units? This is not a giant house, so I am thinking one larger unit will do fine, but I may be wrong on that.
On a side note, we are thinking of using spray foam insulation in the walls. Any thoughts on this?
Does anyone have recommendations for geothermal contractors in north central Illinois? Does anyone have a bad experience with a geothermal contractor in north central Illinois to share?
Actually since your installing a Well anyway, an Open loop system would be the least expensive method. Although horizonal loops tend to be slightly more efficent. You would have to check on the water quality first before making that determination. I would think if you could get a glass of untreated water (something that wasn't run thru a water softener system) from a neighbor for testing would be good enough. If the water doesn't have too much iron in it, all you would need then is a return well.
Spray foam Insulation is great stuff. It's a full vapor barrier was well as insulation.
Qouted from Engineer
"Consider a two stage unit and don't necessarily rule out occasional backup operation (heat strips) on coldest days"
I'm not sure I understand this statement, why would you ever want to use the backup heat? I think having it installed is a good idea, if you well pump takes a dump, you could at least have some heat until you get the well pump replaced, but I wouldn't think during normal operation you would ever need it.
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a0128958
Registered Users
Posts:183
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| 08/04/2008 12:13 PM |
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Posted By j3l2404 on 08/04/2008 12:59 AM
... I found good reviews of WaterFurnace systems
... I want to zone the system from main floor to second floor. ... Should I have one larger unit for the zone system or two smaller units?
I too have WaterFurnace equipment (Envision series). So far, after one year of use, it's performed very well, and to the advertised claims.
I believe, for a 2000+ sf home, that's well sealed and well insulated, you'll want just one unit, not two, regardless of zoning decision. In the WF line, for example, the smallest GSHP size is 3 tons (which I would think would be fine for the sf / construction quality level). Two units automatically puts you at a minimum of 6 tons.
If you zone using a WF Envision model, if you go with a 2-stage option, then you'll need to accommodate at least 750 CFM of air per zone. This shouldn't be difficult if implementing just 2 zones on a 3 ton system, and duct sizes for 750 CFM is not all that large.
Best regards,
Bill |
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engineer
Registered Users
Posts:397
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| 08/04/2008 2:21 PM |
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TG -
In a heating-dominated climate I caution against sizing so as to never ever have to run backup because the result is often a system way oversized for cooling. Inefficiency and discomfort result during cooling season, especially if humidity is a concern, which it is in Illinois.
If a bank of electric strips has to run for 100-200 hours during the coldest part of winter the cost is low, maybe an extra $100 per year. If allowing for that causes system size to be able to drop by a ton or so, the result will almost certainly be lower first cost, smaller, quieter ducts and more efficient operation the other 8600 or so hours of the year. I'll even venture a guess that the efficiency gained during those 8600 hours partially or even completely overcomes the incremental cost of running strips for a couple hundred hours.
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Without data, you only have an opinion. |
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richntiff
Registered Users
Posts:28
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| 08/05/2008 10:48 AM |
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| Not a criticism - but some well intended advice. You seem to be putting alot of thought into the geothermal aspect, which is great, but I would strongly advise you to put a lot of effort into the building envelope itself. You mention 2x6, w/"energy efficient" windows, maybe sprayfoam, etc. IMHO, stick building is a dinosaur, I don't care how much spray foam and pinkboard you put on it. Put your time/effort/money into either a SIPS or ICF shell, high grade windows, etc. and reap the benefits of a smaller overall HVAC system, be it geo or what have you. You only get to build the shell once - do it right :-) |
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joe.ami
Registered Users
Posts:372
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| 08/07/2008 10:49 PM |
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I'm with engineer, $100/yr for aux. heat trumps several extra thou. in installation and is quite common in your area.
unless you have a pond I'm not a fan of open loop as injection wells cost 1/2 as much as 4 tons of horiz loops, however a 1 acre lot if you have a well and septic can be tight for a horizontal field/ vertical loops are nearly twice the price of horizontal (in MI).
I suggest to everyone to zone their ductwork (upstairs/downstairs trunks) with manual mainline dampers and use 1 appliance. Electro-mechanical dampers can be added later if not satisfied. Variable speed blowers do a great job of even distribution and it's never to late to spend more money (tough to get back money spent though).
Again I concur with engineer, horizontal less efficient (due to less stable temperatures closer to grade), but way more cost effective.
A 40 year old company is usually not run by the founder, worry about the last 10 years (I've owned a 50 year old companny for 18 mos, a 25 year old company for 10 years and my corp. for 12).
Most important, go geo the rest might cost you a hundred or two per year while geo saves you thousands.
Good Luck,
Joe |
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j3l2404
Registered Users
Posts:5
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| 08/11/2008 2:47 AM |
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Posted By engineer on 08/04/2008 8:29 AM
If you are willing to spring for sprayfoam in the walls, why not go all the way and consider ICF - great insulation and thermal mass and great sound supression
A tight 2k SF house should work fine with a single unit with a zone on each floor.
Ensure contractor does detailed ACCA Manual J, D and S calculations. Beware sizing for heating may oversize for cooling, reulting in poor summer dehumidification. You don't want that. Consider a two stage unit and don't necessarily rule out occasional backup operation (heat strips) on coldest days
Horizontal is generally cheaper to install but LESS efficient than vertical. Vertical accesses the most stable deep soil tempes for most efficient operation
Thank you for the reply. We are not going to do ICF due to cost and lack of contractors with experience using the product. We spoke with several reputable general contractors and not a single one has done geothermal.
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j3l2404
Registered Users
Posts:5
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| 08/11/2008 2:50 AM |
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Posted By a0128958 on 08/04/2008 12:13 PM
I too have WaterFurnace equipment (Envision series). So far, after one year of use, it's performed very well, and to the advertised claims.
I believe, for a 2000+ sf home, that's well sealed and well insulated, you'll want just one unit, not two, regardless of zoning decision. In the WF line, for example, the smallest GSHP size is 3 tons (which I would think would be fine for the sf / construction quality level). Two units automatically puts you at a minimum of 6 tons.
If you zone using a WF Envision model, if you go with a 2-stage option, then you'll need to accommodate at least 750 CFM of air per zone. This shouldn't be difficult if implementing just 2 zones on a 3 ton system, and duct sizes for 750 CFM is not all that large.
Best regards,
Bill
Thank you for the information.
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j3l2404
Registered Users
Posts:5
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| 08/11/2008 2:53 AM |
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Posted By engineer on 08/04/2008 2:21 PM
TG -
In a heating-dominated climate I caution against sizing so as to never ever have to run backup because the result is often a system way oversized for cooling. Inefficiency and discomfort result during cooling season, especially if humidity is a concern, which it is in Illinois.
If a bank of electric strips has to run for 100-200 hours during the coldest part of winter the cost is low, maybe an extra $100 per year. If allowing for that causes system size to be able to drop by a ton or so, the result will almost certainly be lower first cost, smaller, quieter ducts and more efficient operation the other 8600 or so hours of the year. I'll even venture a guess that the efficiency gained during those 8600 hours partially or even completely overcomes the incremental cost of running strips for a couple hundred hours.
I spoke with the sole "accredited installer" in this area and he says the oversized for cooling issue is not as much of a concern as it used to be due to the modern dual stage systems. The majority of what I read to this point seems to indicate that oversizing is bad for cooling, but no mention of dual stage systems.
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j3l2404
Registered Users
Posts:5
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| 08/11/2008 2:57 AM |
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Posted By joe.ami on 08/07/2008 10:49 PM
I'm with engineer, $100/yr for aux. heat trumps several extra thou. in installation and is quite common in your area.
unless you have a pond I'm not a fan of open loop as injection wells cost 1/2 as much as 4 tons of horiz loops, however a 1 acre lot if you have a well and septic can be tight for a horizontal field/ vertical loops are nearly twice the price of horizontal (in MI).
I suggest to everyone to zone their ductwork (upstairs/downstairs trunks) with manual mainline dampers and use 1 appliance. Electro-mechanical dampers can be added later if not satisfied. Variable speed blowers do a great job of even distribution and it's never to late to spend more money (tough to get back money spent though).
Again I concur with engineer, horizontal less efficient (due to less stable temperatures closer to grade), but way more cost effective.
A 40 year old company is usually not run by the founder, worry about the last 10 years (I've owned a 50 year old companny for 18 mos, a 25 year old company for 10 years and my corp. for 12).
Most important, go geo the rest might cost you a hundred or two per year while geo saves you thousands.
Good Luck,
Joe
I have also seen many businesses fail when passed from founder to new owner or father to son. We are finding that very few HVAC contractors in this area have any experience with geothermal. The one company just happened to have an "accredited installer" on staff.
What do you mean by variable speed blowers and spending money? I am a little confused on this point.
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joe.ami
Registered Users
Posts:372
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| 08/11/2008 9:21 AM |
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Regarding the variable speed blowers and spending money, you originally asked about zoning and 1 larger unit vs 2; in one of my frequent not so articulate moments, what I hoped to express is this:
I personally almost always prefer 1 appliance vs 2; usually lower operating and installation cost.
Most imbalance problems are the result of poor duct design. Variable speed blowers (DC drive fans that start at low rpm's, ramp up higher in mid cycle, then drop back to lower rpm before shutting off or stay low untill next cycle) do a great job of evening out house temps regardless of the duct system. The main benefit of zoning is to get temps where you want them when you want them and (since we know that dialing down is not advantageous to geo) I try to do that with sheet metal not appliances or zone dampers. So with manual mainline dampers and independant upstairs/downstairs trunks if I get the temps of both zones where my customers want them then there is no need to spend the extra money on electro mechanical dampers, control boards or additional thermostats. However if they do want the additional control of an upstairs thermostat later, it's a piece of cake to install a zone damper system in one of my manually zoned duct systems.
Your installer is correct in that 2 stage systems solve the over-cooling/humidity problems there are other ways to address humidity as well (such as reduced blower speed). Your heating on one of these systems would actually be 3 stage (1, 2 and auxillary). Not oversizing is still king. In my area we try to protect our customers from diminished returns. If an extra ton only saves a few % of aux. heating hours then you might be spending 2 or 3 thousand to save <$70/yr. This is where local experience is important as well.
As far as finding local installers contact Climatemaster through their web site (www.climatemaster.com) and they should help you find a competitor for your local guy. Nothing wrong with Waterfurnace, but understandably, they are going to be less enthusiastic about finding competition if your guy is a big dealer. You are also very close to a large Earthlinked distributor (www.earthlinked.com) if you want to explore DX.
In the absence of another local geo dealer, you might be able to get competitive bids on the duct system for cost comparison. Make sure to make a fair comparison, though, as the heat pump duct work may be larger.
Finally, in my area, someone who pays 6K too much for a 5 ton system, probably adds less than 2 years to his/her payback vs propane. So if you want to be sure you are not paying too much, don't use propane.
J |
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