Choosing a Designer/Installer: Homeowner’s Guide

GSHP failure is most commonly caused by improper design or installation of the system, not by failure of the mechanical equipment. Choosing a designer and installer that is properly trained, has a good reputation in your area and is willing to stand behind their work with a guarantee or warranty is important. Use this guide to help you make sure that the most important part of your system, proper design and installation, is done professionally.

Designers

The sizing and design of a loopfield is crucial to the performance of the system. The loopfield is the backbone of the operation, under or over-sizing are both detrimental to efficiencies and equipment life. Under-sizing systems can lead to excessive dependence on supplemental heat and can cause early equipment failure. Over-sizing equipment will cost more at install and can lead to short cycling of pumps which will shorten equipment life.

To avoid these issues, ask the designer of your system to provide you with the specifications for your loopfield. Don’t trust rules-of-thumb or approximations, improper designs will always cost you more. We recommend making sure the installing contractor used a geothermal loopfield sizing program like LoopLink to design your system. A good designer should be able to provide you with a complete design report that justifies their choices and they should be willing to walk you through that report to ensure that you fully understand everything it says.

Download an example of a design report output by LoopLink.

IGSHPA Certified Installer

As in any technical trade, the best professionals are certified by an authority. For the geothermal heating and cooling industry, that authority is the International Ground Source Heat Pump Association or IGSHPA. Geo-Connections provides training to many of the accredited installers throughout the nation through the aptly named “Accredited Geothermal Installer Course” we provide through our partners at the Heat Spring Learning Institute. Regardless of where they are trained, make sure the person you hire is on the IGSHPA list of accredited installers.

Warranties and Guarantees

A geothermal loopfield is not a cheap thing to have installed. If it isn’t completed properly, at best you won’t make the efficiencies expected and at worst, your system will operate outside the heat pump design parameters until it fails completely. To avoid being stuck with paying twice only use installers that back up their work with a warranty or guarantee.

Always ask “What kind of guarantee do you offer on your design/installation?” and “Do you have any references?” Follow up on the references and take note of how long ago their systems were installed. It is in your best interest to find a contractor with experience that stands behind their work with a written guarantee or warranty. This is a business transaction so never take their word for it-- always get the terms in writing.

Heat Pump Selection: Homeowner's Guide

If you have already started your hunt for equipment you know that there are a lot of options for geothermal heat pumps. What follows are some things to think about to help narrow your search.

There are plenty of good manufacturers and heat pump brands out there, so rather than list every reputable manufacturer, we’ll give you a couple of guidelines to follow when looking for a ground source heat pump (GSHP) brand.

A little known fact about geothermal heat pumps — many GSHP manufacturers use the same or similar mechanical components. This doesn't mean that all are created equal but the wearable parts are usually of comparable quality across the major brands. The primary differences will be the control system and the geometry/effectiveness of the heat exchanger. So, the decision of one brand over another will usually come down to a few key parameters like price, availability, lead time and warranty.

Price

Price is of course of primary concern to any responsible consumer and for heat pumps the advice is the same as it is for any major purchase: The most expensive isn’t necessarily the best and the least expensive isn’t necessarily the worst. Establish your budget and look for options that meet your system requirements within that framework.

Availability

In today’s digital age, it is very common to do most of your research online, make your decision and then purchase. The problem is that not all manufacturers have distributors in all areas. This will make purchasing, as well as installing a geothermal heat pump more difficult and more expensive. In other words, start by finding what is available to you in your area, then research which of those will work best.

Lead Time

Another factor to watch for is product lead time. It is common to see lead times on GSHPs of anywhere from 2-10 weeks, depending on the manufacturer. Always remember that it is never too early to start planning your project. Ordering your equipment sooner rather than later can mitigate problems caused by delays in the supply chain.

Warranties

Often, the warranty is an after-thought, yet becomes really important if you have a problem. Standard warranties can be as short as one year including parts and labor but can also cover individual components for 5 or 10 or 15 years. It is fairly uncommon to have mechanical problems with GSHPs, especially the factory built portion. If problems do arise, it’s most common for the issue to present itself during the first year of operation. Either way, you should read and understand the terms of the warranty before you purchase so that if a problem does arise, you know you are well protected.

In addition to the manufacturer’s warranty there are also installer warranties/guarantees. We will talk more about them in a later article about choosing a qualified and reputable installer. Our next article will go beyond a homeowner's considerations and get into the numbers of sizing and selecting equipment for system designers.

Project Highlight: Construction Details

Instead of just showing you the highlights of the installation of the GSHP system we are installing for our new facility, we decided to take things a step further and turn this into what we are calling a Project Highlight. As the project progresses we will go through and provide you with the full details of the decisions we have made with regard to the project and the reasoning for those decisions. Our hope is that this will shed some light on the areas of design that newer designers are a little uncomfortable with and maybe remind some of the more experienced designers about a nuance or two.

The first installment of the Project Highlight is an introduction to the project with the construction properties of the facility as well as the resulting building load calculations. The 127.5’x60’ slab-on-grade style facility has 90’ of the total length with 20’ side walls with a 24’ peak and 37.5’ of building length with 12’ side walls and a 16’ peak. Other construction details are as follows:

• Metal sheathed walls with 2” x 6” framing and R-19 batt. insulation
• A metal sloped roof/ceiling over a wood frame with R-38 batt. Insulation
• Slab-on-grade floor, heavy dry soil, 2” foam edge insulation 3’ down, tile floor
• Low-e windows with a U-value of 0.410
• Doors will be metal with a fiberglass core
• Occupancy levels of 10 people and 2 appliances

Our home offices are located in Elkton, SD. Elkton is a small town roughly one mile West of the South Dakota-Minnesota state line, and 15 miles East of Brookings, SD. The weather location we chose to calculate the building loads is Brookings, SD. The 99% heating design percentage for Brookings, SD is -11°F, while the 1% cooling design temperature is 85°F. These are the temperature points that the peak heating and cooling loads are based on.

Now that all of the construction details are given, we can determine the peak building loads in heating and cooling using the ACCA manual-J load calculation procedure. The peak loads were determined to be 124,081 Btu/hr and 42,309 respectively.

LoopLink Updated

First things first, we missed a change to the login script on the software page of our site. Sorry to those of you that tried unsuccessfully to log-in through that page over the weekend. We corrected the problem early Monday morning however, you may need to refresh your browser to get the fix to work.

Now that we have that issue sorted out lets talk about some of the updates we introduced this week...

Improved Graphs

One of the most obvious changes you'll notice as you go through the software is that the graphs have changed considerably. We made all of them easier to read and more presentable for the reports. The operating cost and carbon emission graphs now more clearly indicate the values and labels for each bar.

Enhanced Support Tools

Less noticeable changes we made are the backend improvements to help facilitate faster and easier customer support. We have built in access for the LoopLink support team to view your projects with you. The biggest thing you should know about this function is that we will be in a read-only mode while we work with you through your questions and can never alter the specifications that you enter into your design.

We have also expanded our sort and find functions for the user list and simplified the updating for equipment profiles and other system parameters. These are changes that will make keeping LoopLink up-to-date even easier which will help to ensure that you are always working with the most current GSHP design software available.

Read-Only Mode

Besides being a necessary and very cool tool for us, the new Read-Only mode of the software will enable any expired users to view their projects and print out their reports. Of course being read-only, expired users won't be able to change their projects parameters without resubscribing but you will always have access to your information.

System Profiles and Bin Data Values

We have been periodically adding equipment profiles and bin-data locations for the past couple of months. Most of these have been by user request so if you come across an equipment profile you need or a bin-data location we haven't added yet, let us know and we will try to take care of it as soon as possible.

Program Modifications and Bug Fixes

We have made a few key changes to the software that you may or may not have realized needed tweaking.

For those that have tried to make a design with very large loads, you may have run into the cap that we originally placed on LoopLink loads. The reason for the cap was originally to avoid people designing projects that were beyond the bounds of what we intended LoopLink to be used for— residential and light commercial design. We found that for large spaces without complex gains like small warehouses, this was too stringent a restriction. Long story short, we removed the cap and have added in a warning message when loads are beyond typical for residential and light commercial applications.

The NNAGL (Normalized Net Annual Ground Load) calculation has been changed to increase accuracy. The method formerly used was a conservative one so there was no danger of underestimation. The new calculation just brings things a little closer to the true equation for the data curve.

Finally, the carbon emissions graph caused an error when generating reports for systems that had no heating loads. Being from South Dakota, we didn't think of that eventuality when we went through our original testing but some of our southern friends turned us on to this issue.

Practicing What We Preach: Geo-Connections Installs New Loop Field.

Geo-Connections broke ground on the bore holes for our new facility late last week. The system was designed with LoopLink (of course) and consists of twelve, 200' vertical loops on fifteen foot centers. The builiding it will supply is 120'x60' with 20' side walls.

We thought we would share photos as the project progresses. Drilling is going a little slower than planned but the soil contained a lot more gravel than expected from our previous bore fields and we did hit a rock shelf just past 100 feet. The drillers switched out their bit and we are expecting things to move quite a bit faster through out the next couple of days.

LoopLink For Educators Announced

One of the core beliefs of Geo-Connections and our staff is that our success depends on the ability of the GSHP industry to become a mainstream technology. To make that goal a reality, we know that a properly trained workforce coupled with well-designed systems are key. We have had a couple of instructors from universities and trade schools approach us about using LoopLink to help teach their students GSHP design and we realized that the industry was giving us an opportunity to stand by our beliefs.

Geo-Connections proudly announces that we will be offering free LoopLink accounts to instructors and teachers throughout the duration of their GSHP design courses. The software will not be limited in any way the only difference between the student version and the regular version is the price.

To learn more, check out our "LoopLink For Educators" page.

Grouting Practices for Horizontally-Bored (Directionally-Bored, HDD) Loopfields

Horizontally-bored loopfield installations are becoming a more widely recognized viable alternative to the vertically-bored loopfield configuration.  However, designers must be aware of the different aspects and limitations associated with HDD (horizontal directional drills) loop installation to properly design such a system.  Special attention must be paid to the installation depth, soil properties, pipe placement methods, and grouting practices during the HDD loop installation process. 

One major point of debate related to HDD loop installation is whether it is necessary to completely grout the holes after pipe placement.  Arguments against grouting HDD bores are:

• Hole collapse around the pipe
• The presence of heavy drilling mud left in the boreholes

Our response to each of these arguments is:

• There is no way to guarantee that the native soil will collapse around the pipe uniformly and with the density needed to promote adequate heat transfer through system
• Drilling mud and/or drill cuttings are not recognized by IGSHPA or the National Ground Water Association to be adequate grouting materials   

Grouting is the only way to ensure consistent thermal contact between the pipe and the earth to promote heat transfer.  In fact, in Section 7.7 of IGSPHA’s Ground Source Heat Pump Residential and Light Commercial Design and Installation Guide (2009), it is recommended that all horizontally-bored holes be grouted from end to end to ensure contact between the earth and GHEX piping and to protect the integrity of our environmental groundwater supply. 

Our experience with HDD loopfield installations further reinforces this concept.  We have dealt with numerous installations in neighboring states.  The majority of the problematic HDD installations we have encountered have been where the loop contractor did not grout the holes, but left them to bore collapse and thickened drilling mud for performance.  It must be stressed that the ultimate goal during construction is to build a heat exchanger.  Proper performance of that heat exchanger is critical for the performance of the system as a whole. 

In the interest of putting our best foot forward as an industry, best practice principles suggest that we should completely grout all boreholes, vertical and horizontal, and leave nothing to chance.