Archive for October, 2009

Going Geothermal Part 2: Finding the right geothermal contractor

To understand what to look for in a geothermal contractor (or what some might call an installer) you first need to understand how many residential HVAC (Heating, Ventilating, & Air Conditioning) contractors work.  As a residential contractor you would spend a good part of your time visiting homes and giving free estimates for your services (which typically include replacing furnaces & air conditioners).  To make the process more efficient most contractors use rules of thumb to determine the heating and cooling loads of your house and therefore size your furnace and/or air conditioner.  And why wouldn’t they when for +30 years all they’ve had to choose from is a handful of unit sizes anyway.  As long as you’re in the ballpark that’s all that matters.  If you’re unsure pick the larger size.  Well that works fine for furnaces & air conditioners where the difference in cost between unit sizes is minimal.  (Granted it’s not good to have things oversized for your future energy bills but that’s another discussion.)  But when it comes to geothermal systems where the cost difference between a 3 ton system and a 4 ton system can be anywhere from $2,000-$5,000 that makes a big difference!

So what is a homeowner to do?  Well first try to do your research and find the most throual HVAC contractor you can.  Ask them how they calculate your homes heating and cooling loads.  Do they use rules of thumb or do they actually calculate them out?  Keep in mind that “rules of thumb” come in many shapes and sizes.  Some rules of thumb are based solely on the square feet of your home while others take into account how much roof and window area your house has.  So as a homeowner your best bet is to just make sure your contractor does a Manual J of your house.  A Manual J is the widely accepted calculation used to determine residential heating and cooling loads.

Side Note: As a mechanical engineer that designs HVAC system for commercial buildings I’m not a big fan of the Manual J since it is less accurate than what we do commercially.  But since it is the standard residentially it’s probably all you’re find contractors use.  Don’t worry in Part 3 I’ll show you how to accurately calculate your own heating and cooling loads.

A good starting point to look for contractors in your areas is to see what contractors are members of your local and national geothermal associations.  The International Ground Source Heat Pump Association is a great source.  Members of this group have taken one or more classes through the association.  Many states also have state groups.  For my fellow Wisconsin readers here’s our state’s association.  Search around!  You may find local groups that do more than recommend contractors to you.  Some organize tours of homes or building that have installed geothermal systems while others have elaborate displays for people willing to learn.  Along the same lines ask around and see if anyone has any recommendations for a mechanical contractor.  But keep in mind that a company that came high recommended by someone with a typical split system may not be good at installing geothermal systems.  And don’t forget to also check out the Better Business Bureau to see how potential contractors compare.

Like most quotes people get make sure you get more than one.  In our experience we found the prices we were quoted to vary a lot from contractor to contractor.  This is due in part to how relatively uncommon residential geothermal systems have been for the last 20 years.  But when tax credit limit of $2000 was removed geothermal systems became a hot ticket item.  What resulted, at least in my area anyway, is that a lot of mechanical contractors have dabbled in installing geothermal systems but few have a lot of experience with them.  Of course ideally you would like to hire someone with a lot of geothermal experience but there may not be anyone in your area.  Instead you might have a number of people with moderate experience levels so how do you choose?  Well the best I can say is do your research and ask a lot of questions.

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Finally, I thought I’d share with you our contractor picking experience.  We had 5 contractors give us quotes.

Contractor 1 has been working on expanding their geothermal department.  They’ve investing lots of money on radio advertisements, fancy websites, custom designed hybrid cars, and even flashy embroidered shirts stating they are the industry leader in geothermal for our area.  As a result they have installed many geothermal systems particularly in the new construction McMansions that were built before the economy turned.  Most people don’t even interview anyone else when they are looking to install their geothermal systems.  They sound great don’t they?  Well when they came to our house to survey we weren’t too pleased with their cocky attitude and the way they treat their clients as if they are stupid.  I could tell in my grilling interview that they weren’t used to dealing with clients who actually knew what they were talking about.  Then we got their quote and were blown away.  They were $9,000 more than the other 4 contractors we interviewed (who were all in very close price range)!  Turns out they used some moderate level rules of thumb to determine our heating & cooling loads.  They said we needed an 8 ton unit where we really only need somewhere between a 4-5 ton.  Classic HVAC oversizing!  On top of that I didn’t like the brand of heat pump they used (I’ll go through these in Part 4) so we crossed them off our list.

Contractor 2 wasn’t a part of any of the geothermal associations I mentioned above but came high recommended to us from someone with a conventional system.  In meeting them Flannel Man was not impressed with their lack of knowledge and when I questioned them about how they came up with our heating & cooling loads they admitted they used rules of thumb.  One more off the list.

Contractor 3 had only 4 geothermal projects under their belt and their quote was a few grand more than Contractor 4 & 5’s bid so we came off our list too.

Contractor 4 specializes in radiant floor systems but also do heat pumps.  They seemed very educated about geothermal systems.  They had installed between 10-12 geothermal systems.  Both Contractor 4 & 5 used one of the brand of heat pumps I like.

Contractor 5 is a family based company that installs more traditional furnace/air side systems than Contractor4.  They had installed a dozen geothermal systems but most of them were horizontal loops (we needed a vertical loop).  They also had a leg up on the competition because they used a software in addition to their hand heating/cooling calculations to size the geothermal loop.  The software was able to tell me our expected electric bills, savings with a desuperheater, and savings versus our current system.  A very handy tool!

It was between Contractor 4 & 5 but in the end we went with Contractor 5 because we felt they were better able to answer my questions and were fast to respond.

Moral of the story: Shop around or you could end up with the pricey Contractor 1.

In fact a few days after we signed our contract with Contractor 5 we saw a house in town was installing a geothermal system with Contractor 1 (we knew this because they put up flashy signs of course).  It took all I had to not go knock on their door and tell them our experience with them but they were already in the middle of drilling so it wouldn’t have done much good.  We found out later that the couple had in fact not gotten quotes from anyone but Contractor 1!

For those of you who made it to the end of this post you have the reward of seeing a sneak peak of our heat pump introduced by our rescue dog Sophie:


Going Geothermal Part 1: How A Geothermal System Works

I’m not going to go into too much detail about this because there are so many websites that cover this better than I ever could (which I have listed below).

Basically a geothermal system is made up of a heat pump, ground loop(s), and either ductwork or a radiant system to heat/cool your house.  A heat pump is just a refrigerator that can reverse between heating and cooling.  If the heat pump is connected to ductwork like a furnace would be it will be able to both heat and cool the air as it is blown over the heat pump’s coil.  If the heat pump is connected to a radiant floor or baseboard system it acts as a boiler by creating hot water but it can’t provide cooling or dehumidify the air.

The heat pump is connected to an underground loop filled with water or a water-refrigerant mixture via a heat exchanger.  A common misconception is that the water/refrigerant mixture in the ground loop is what actually runs through the heat pump but that is not the case.  They are completely separate loops that don’t mix.  Ground loops can come in many styles (which I’ll go through in Part 4) but the most common style today is a vertical bore closed loop system.  The whole system works off the fact that below the surface the Earth’s temperature stays relatively constant.  Because of this the ground loop is able to absorb or reject heat to the Earth.  Even though the temperature difference between the ground and the water/refrigerant mixture might be small heat will still transfer.



Below is a list of websites & a helpful video you can go to for more information on how a geothermal system works:

Going Geothermal: An Eight Part Mini-Series

As I mentioned in my last post we’re converting our house from a traditional fuel oil furnace to a sustainable geothermal ground source heat pump. But instead of just telling you about our system I want to go into depth and do a series of posts about everything you need to know as a home owner if you’re considering going geothermal. When I was researching residential geothermal systems I was disappointed in the quality of info out there about geothermal systems. Yes, there is lots of info about geothermal systems but almost all of it is describing how ground loops work. Go ahead and Google “geothermal systems” you’ll find pretty graphics of cold water/refrigerant mixtures going into the ground and hot water/refrigerant coming out. Once you wrap your head around the concept of getting heating and cooling from the Earth is that all you need to know as a home owner? The answer is NO.
In an effort to help inform others I’m going to write an 8 part mini-series from my point of view as a homeowner and HVAC engineer. I’ll give you every question you need to ask your contractor and calculations you can do to determine the true cost of going geothermal. If you’ve ever considered installing a geothermal system you’ll want to read this!

To follow the series just follow my blog or click on the new “going geothermal” button I created on the right menu bar.

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This is the story of two twenty something newlyweds who are learning to adjust to life in their first house, a 1973 fixer-upper.
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