Dealing with Wintertime Dryness Ways to Improve Indoor Air Quality Climate Zones for HRVs & ERVs on Apr 06, 2013 My home is heated and cooled with a geothermal heat pump – also known as a ground source heat pump.  I was sold on the idea of geothermal heating and cooling for the same reasons that I suspect most homeowners are: The promise of lower energy costs The attractive renewable energy tax credits, which make it easier to come to terms with the rather exorbitant cost The belief that this is truly a more environmentally responsible choice since geothermal heat pumps do not rely on combustible fuel The “cool factor” associated with owning a geothermal system (This was not a major driver for me, but I do get a warm glow when people are impressed that I have a highly regarded technology in my home.) I now question (and with good reason) the validity of the first and most significant incentive for purchasing a geothermal heat pump:  Lower energy costs.

Energy Performance Not What I’d Hoped The fact is, the utility costs in my all-electric, Energy Star, LEED-certified, geothermal heated and cooled home is not drastically better than my neighbor’s homes with far less expensive heating and cooling systems.  Now, the reasons for that are probably quite complex and have to do with numerous application and lifestyle matters that can make or break the efficiency of any type of heating and cooling system. But none of those matters came up in that first, fateful meeting with the geothermal distributor.  No – that conversation was filled a lot of confusing yet highly persuasive information about why I should choose geothermal, including an estimate that projected a lifetime savings to me of nearly $40K! Suffice to say the distributor offered a pretty compelling case for geothermal.  You may wonder if, after 4 years of living in my home, I find I’m on track for that type of savings. I’d be lying if I said I thought I was.

The truth is, I suspect there was much in that conversation that would be terribly, terribly misleading to the average homeowner.  A building scientist might have called the distributor out on a lot of those details.  But neither I, nor most homeowners, go into these decisions with that level of expertise. I open about this not because I am disappointed or disillusioned with geothermal technology.   Rather, I am disappointed and disillusioned with how the industry conducts itself, and I am concerned with the fallout to well-meaning homeowners.  Many homeowners will never see the true the advantages of geothermal energy because of misapplications. Disadvantages of Geothermal Energy Reside in the Industry, Not the Technology I got a hard dose of reality after the first cooling season in my home.  My system needed to be replaced because the original system was oversized—grossly oversized.  I went to a lot of trouble to confirm this fact and basically had to go through a six-month arm wrestling match to make those who were responsible bear the expense of the replacement. 

I eventually won – but not before I got this depressing peek at the dark side of the geothermal/residential HVAC industry.air handling unit maintenance schedule Were my experiences unusual?  prices for commercial air conditioning units, which confirmed much of what I already suspected.  ac unit on but not coolingHere’s is the gist: The high cost of geothermal systems is not necessarily attributable to the cost associated with installing the ground loop (that is digging or drilling the holes or trenches that make it possible to transfer heat to and from the earth for the purpose of heating and cooling your home).  Over the last few decades, it is the cost of equipment, not the drilling, that has skyrocketed, making geothermal cost-prohibitive to most homeowners.

The cost-savings frequently touted by geothermal manufacturers are generally unrealistic and inflated, partially due to the nuances of how efficiency ratings are calculated.  One expert compared these ratings to scoring the fuel efficiency of car based on the car’s performance while coasting down a hill.  Sure, the savings estimates are based on mathematical data, but data that isn’t necessarily relevant to real life. Manufacturers are more interested in selling more and bigger equipment than they are in the energy performance of your home.  This inherent conflict of interest undercuts the homeowner’s chances of getting the best bang for their buck when installing a geothermal system.  There are many factors that impact the efficiency of a geothermal system but the manufacturer and/or the installer is typically concerned with just two things:  (1) selling the equipment and (2) avoiding callbacks.  Neither of these have much (if anything) to do with actual energy performance.

Here’s the funny part.  I am still a fan of geothermal technology, as are many of the experts intent on “calling out” the industry for its…. shall we say….imperfections. The best homeowners can do is be aware.  If you are considering geothermal you owe it to yourself to get the “big picture” before you dig into your pockets with your fingers crossed. Sizing A/C Units and Ducts Notice how "square footage" is never mentioned. Important Warning to Home Buyers! How to Recognize a "Soft" Home Inspection Report. Need a home inspection in Tennessee? listing of Tennessee certified home inspectors. Re: Sizing A/C Units and Ducts He does a good job of explaining oversizing but I stay away from calculation. opps watched the wrong one first but Similar. Originally Posted by jbushart If you are designing a new system, that video applies. When you are just changing the condensing unit/air handler, it is a different matter. The existing duct work will dictate what sized unit can be used efficiently.

A home built in 1970 with with inefficient windows may require a larger, 1 ton larger according to the guy in the video, won't work as the duct work was not designed for it. The square foot method is a basic guesstimate for certain regions and when it is all said and done, in most instances, once you add in all the variables, isn't that far off. I recall doing an inspection on a 900 sq ft condo. The guy installed a 5 ton unit! I told my clients that it should be replaced to a properly sized unit. During the inspection, the unit came on for five minutes and shut off. It did this all through the inspection. That is what is known as short cycling! Magnum Inspections Inc Website Originally Posted by evandeven The dynamics of heat loss as opposed to the loss of cooled air are quite different. What might be the rule of thumb in Florida is folly in Maine. To further prove my point, our home is 1,700 sq ft. The rule of thumb is 1 ton per 600 sq ft. That is roughly a 3 ton unit.

When you factor in all the variables, the total cfm required comes to 1200, which is a 3 ton unit. Our duct work was designed for a 2 ton unit, which is why it was replaced. The 3 ton unit was installed to compensate for the, at the time, insufficient attic ventilation and insulation, no "drops" in the bathrooms or laundry room,etc. Originally Posted by jbraun We did that on our home along with installing a ridge vent and a radiant barrier,along with the new duct work. The ridge vent/radiant barrier brought the attic temperature down significantly, and then, by planning out the duct work properly, it is now balanced. If I were to put a flow meter in front of the vents, it would probably be very close to equal on every vent. A 1000 sq ft home with lots of single pane windows and little insulation may need a larger sized unit than a well-insulated home twice that size Originally Posted by jhugenroth Take two homes with 1500 sq ft on the same street. One sits on a hilltop with no trees or wind barrier, 150 sq ft of single paned windows facing north and west, 75 sq ft facing south and east, R-19 attic with 80% of the ductwork outside of the thermal boundary (no mastic at the seams and joints and uninsulated).

Second sits in a valley, fully shadded on the south and east, Low-E windows facing south and east (150 sq ft) and regular double paned facing north and west (75 sq ft), R-38 attic with all of ductwork inside of the thermal boundary (no mastic at the seams and joints and uninsulated). How many contractors (and home inspectors) would walk off the 1500 sq ft and apply their "rule of thumb" to determine the adequacy of the cooling capacity of the a/c? I think most, and for at least one of these two units....they would be wrong. Air Conditioner or Heat Pump Sizing Chart Preparing your sizing chart:Print out this page. Leaving the page intact, carefully cut out the holes on the dotted lines. For operating instructions see bottom of page. 1 1/2 to 2 ton 2 1/2 to 3 1/2 ton 4 to 5 ton Sizing Chart Operating Instructions Stand on the curb.* Hold the sizing chart approximately one foot from your face. Look at the house through each hole.

If the house fits in a hole, that's the size unit to use. *If the curb is not available - ask the homeowner where a curb would be if there was one. Would you like a little more accuracy? Or see our Table of Contents Un like some that has never accomplished anything but sit behind a desk its hard for them to comprehend that when someone has done that same thing day in and day out for most of their adult life that one simply has the ability to walk through a home view the windows, doors and insulation based on SQ footage that is typical for the local area and determine the exact tonnage required . There are always unusually designed homes that will require the J program but by all means not every home as some would lead to believe. Oh BTW Bushy tell me the foot print of your house SQ ft the type of windows and age how much insulation and type in the attic and I will tell you how many tons of A/C your contractor is going to install and I have never seen your house