LoopLink RLC Update | Variable Capacity Equipment

Thursday, June 23, 2016

Our latest round of updates is focused on the zone and equipment selection options. You can now select variable speed circulators, model variable capacity equipment more realistically and select to use no supplemental heating.

Variable Speed Circulators

Assigning a variable speed circulator allows the system to ramp up and down the amount of flow that is being pushed across the coil and through the ground loop to maintain the target delta-T. For some dual capacity units there is an additional control option that allows you to specify discreet flow rates for high and low capacity operation. By default, RLC assumes the more common control over delta-T.

Variable Capacity Heat Pumps

We additionally implemented full support of variable capacity heat pumps. The equipment has been in the system for some time however, we treated it as dual capacity equipment. Projects in the system that used the original method of variable capacity equipment treated as dual capacity remain untouched. The heat pumps have just been flagged as outdated.

If you would like to go back into your old projects and update them to use a truly variable capacity model, simply open the zones and re-select your equipment.

No Supplemental

There are cases where designers have no intent of using a strip heater or other form of supplemental heat for the system. If the heat pump is sized to 90% or greater in heating, there arguably shouldn’t be very many bin hours where the GSHP system is unable to maintain set point temperature. RLC now gives you the ability to turn off the supplemental so long as you have sufficient heating capacity assigned to the zone.

As a word of caution, just remember that systems without supplemental may have extended run times where the heat pump is simply unable to satisfy the call for heat. This isn’t necessarily a bad thing, but homeowners tend to like their thermostats satisfied.

GSE Power Up

Wednesday, June 22, 2016

GSE is the newest service in the LoopLink® family and it is one we are very excited to have available. If you aren't familiar with LoopLink GSE, it is a web service for companies in the residential geothermal market that estimates the how much a homeowner could save if they switched to geothermal.

Since this is the first GSE update article, you should note the majority of updates and news we report about GSE will be written more for web-developers than our typical audience of geothermal system designers. We will do our best to keep the nerd lingo to a minimum and include information that is of universal interest.

With the basics out of the way, lets talk about what we have been up to.

Units of Energy

You can now access the total number of units of fuel consumed in an operating mode (heating, cooling, hot water) both annually and monthly. In other words, you can report the number of kWh the heat pump consumes in a year for heating as compared to the number of ccf of natural gas the conventional furnace would use. This is handy if you want to apply your own methods for estimating energy rates after you receive your response. Of course, you could always pass that information to us and we will return your cost and savings.

Monthly Outputs

In the first iteration GSE was built to simply provide annual savings, cost and carbon emissions estimates. In our latest update we added the ability to access that information for every month of the year. This is really useful for generating graphs and charts that can really help in making your interface look professional and approachable.

Carbon Reduction

We added a 'reduction' object to the 'carbon' objects (annual and monthly). This is just a convenience addition that offers direct access to the change in carbon emissions from the conventional system to GSHP rather than requiring client side processing.

Backwards Compatible

We haven't discussed versioning since GSE is so new to us but we wanted to make a note that minor versions of the software will always be built to be backwards compatible. It is how we define our major vs minor versions. Simply put, in minor versions, we won't break your existing interface by dropping support for or changing the name of a key etc. We only expand on the existing response. Major versions may not be backwards compatible with your interfaces but when we get to that point, we establish a sunset policy for legacy version support.

LoopLink RLC- Pick Your Pipe

Wednesday, April 27, 2016

This week we introduced the ability to choose between HDPE 3608, HDPE 4710 and PEX-A for loop piping in all ground loop configurations in LoopLink RLC.

You will notice on all of your old projects, that your pipe dimensions are held and that HDPE 3608 (standard issue in residential applications) is preselected. You can modify your materials and pipe sizes on old projects and new. All HDPE pipe sizes assume DR 11 while PEX-A is always DR-9.

Switching materials will properly account for the different resistive properties of HDPE vs. PEX-A. You will notice that HDPE 3608 and HDPE 4710 perform the same thermally. That is because there isn’t a resistive difference between the two. The difference between the two is that HDPE 4710 has a higher pressure rating. For DR11 at an assumed 74°F HDPE 4710 is rated at 200psi while HDPE 3608 is rated at 160psi. Note that PEX-A is also rated at 160psi at 74°F.

A Couple Little Things

As always there were some minor corrections and tweaks that we made in this update.
  1. We now filter comparison technologies in Cost of Ownership to match those selected in Operating Cost. This issue was brought up by a user who deselected all but one comparison option in Operating Cost and was then (understandably) confused as to why they had to choose a comparison technology on the Cost of Ownership page.
  2. Trench width values were not updating correctly on screen for horizontally trenched layouts with only one available option for trench width. The calculations were not impacted by this issue. The problem was strictly visual.
  3. When adding a Hot Water system to a project, it was possible to select ‘None’ for the hot water system type. The page still showed all of the input fields for an On-Demand design so, if you weren’t paying attention, you could generate an error on save. The page will no longer allow you to input data if ‘None’ is selected as the system type.
  4. Print summary checkbox labels are now toggling correctly if you use the Select/Deselect All option.

R.I.P. Deep Earth Temperature Map

Thursday, April 7, 2016

The Project Details page of LoopLink® RLC has just received an upgrade. You can now manually override the minimum and maximum outdoor air temperatures used in your design. Additionally, we created a new ‘Estimate Deep Earth Temp’ button which will apply an approximate Deep Earth Temperature to your project based on the specified Bin Data Location.

Manually Override OATs

This addition is for two types of users.

  1. Those that perform their system sizing calculations using non-ASHRAE weather conditions.
  2. Those required by local rebate providers to document designs at specific temperatures.

In either case, the use of manual values is pretty straight forward. Click the ‘Manually Override OATs’ button and the values assigned are what LoopLink® RLC will use in energy and performance modelling. The values are limited by the local weather data. That said, it is important that you understand the impact modifying these values has on your design before you use this feature.

Estimate Deep Earth Temp

As many users have noticed, the update to the interface included the removal of the Deep Earth Temperature map. Our reasons for doing this boil down to:

  1. The map was dependent on Flash Player and as this article from Wired explains, the internet is actively pursuing the death of Flash Player.
  2. The map had limited utility as compared to the simpler and more effective estimation button that we just added.

The estimate Deep Earth Temperature button is possibly too easy to use… click it and an estimated Deep Earth Temperature is calculated as a function of mean outdoor air temperature. For those performing Open Loop designs, water well temperature has the exact same functionality applied.

You can of course double check the value against the map which (in a non-interactive form) now lives in the help. If you have more accurate data from past experience or in-situ testing, the value can still be entered manually.

Shiny New LoopLink RLC

Friday, April 1, 2016

You may have noticed some pretty major changes to LoopLink® RLC this week like... everything is different. We released our updated interface and now that the dust is settled we wanted to take a little time to explain what we did and why.

The simple answer to the question of why we overhauled the interface is mobility and responsiveness. These have been the buzzwords in web design for the past few years and a trend we waited to follow until a significant number of our users began accessing the software from tablets and handheld devices.

The shift has begun and so we are supporting our user’s natural trend to use the device they have at hand. At the same time, updating the interface allowed us to do some important technical and visual things to simplify LoopLink® RLC and make it lighter weight with respect to data usage which means faster performance regardless of device.

In the end, we have a faster easier to use LoopLink® RLC that will better support new features and improvements as we move ahead.

Simplified Navigation

We stripped out the redundant navigation on the top of the page and moved everything to right hand side of the screen. This streamlines work flows and puts everybody on the same page during support calls.

Additionally, we largely (but not entirely) walked away from image based navigational cues and moved to text based buttons. The removal of iconography is intended to reduce ambiguity for new users and help facilitate faster load times by reducing the amount of data your computer needs to download to render the finished page.

There are a couple of major navigational changes that we should mention as they may be a little confusing for everyone the first time through.

  • You get back to your project list by clicking the logo in the top left of your screen.
  • Click on your initials in the top right corner of your screen to access links to account administration, project list or log out.
  • The save button is always going to be at the top of the page. As always, pressing enter will also save your changes if you are focused on an input.


We completely changed how we create on-screen graphs. The new graphs are lighter weight, faster and interactive. You can now hover over points, slices and bars and read the value directly from the chart.

There are some minor visual differences between the graphs shown on-screen and those in the reports. The plotted data is the same, they just don’t match 100% (yet) because they are built by two very different methods.


The help files have also been redesigned. In fact, we moved the help files to a completely different platform which will make maintenance and enhancement much easier to handle moving forward. The way you get to the help is the same but the new help will be easier to navigate on its own. Plus, it is now accessible without being logged in to your LoopLink® RLC account. Simply go to help.looplinkrlc.com.

Additional Changes

  • Horizontal trench designers, you should note that we no longer ask for the number of flow paths as an input. We ask for flow paths per trench/pit and number of trenches/pits. It is a subtle but important difference.
  • We lowered the fidelity of fixed length mode calculation from ±1 foot to ±5 feet. The result of this is a significant decrease in iterations for the system which means faster responses with a minimal impact on overall accuracy.
  • Soil tables are no longer directly accessible through the software. There has been a lot of confusion related to soil properties (especially for horizontal applications) as a result we moved the tables to the help files and are providing just our calculators in the software.
  • Cost of Ownership is now available for a variable time period (5-30 years) as opposed to a fixed 30 year analysis.

Soil Selection For Horizontally Trenched

Thursday, February 18, 2016

Soil selection has long been a sticking point for a lot of LoopLink® RLC users when designing a horizontally trenched system. For our first try at simplifying the process, we posted the soil selection table from the Residential & Light Commercial Design & Installation Manual. The table is admittedly a bit dense and we were asked to make things a little easier.

So we created, what we thought at the time, was a much simpler method of selecting a soil. We supplied drop downs for soil density and moisture content which filtered the table down to a single thermal conductivity and thermal diffusivity for each soil type. The user then adjusted a slider to define the soil composition. LoopLink® RLC found the closest matches from the table and returned at most three options to choose from.

It was that last part of the interface that seemed to over complicate things. We (I) may have been too interested in creating something neat to look at versus something that did its job well. So, this week we removed the last step. Now you select a soil density and a moisture content and we return the entire table of soil types with just one thermal conductivity and one thermal diffusivity for each.

With this change I thought it might be worth a review of why soil selection matters and generally how to go about it.

Why Soil Selection Matters

Selecting the correct soil for your horizontally trenched installation is important because it defines two key variables in the calculation of loop lengths—soil thermal conductivity and soil thermal diffusivity. Both variables are a function of soil composition, density and moisture content.

Soil Thermal Conductivity
How fast heat moves through the soil given a specific temperature difference.
Soil Thermal Diffusivity
The measure of how fast heat moves relative to the capacity of the soil to store heat.

Determining Soil Composition

Soil composition is the single most important component of soil identification and it is also the one that tends to be the most intimidating. There are hundred page books on soil classification systems or we can point you to a very simple and direct explanation from Colorado State University Extension.

The page is written with gardeners in mind but the concepts are universal. If you are after more depth, refer to the IGSHPA Soil & Rock Classification Field Manual. We do also cover this topic thoroughly in our IGSHPA Geothermal Installer Certification Training which we offer through HeatSpring.

Once you determine your soil composition, you need to determine its density and moisture content.

Determining Soil Density

The density of your soil as it relates to the tabled values in LoopLink® RLC is determined as a dry bulk density. To find the dry bulk density, you extract a known volume of soil using a bulk density soil sampling kit. Dry the sample completely and then divide the weight of the dry sample by the volume extracted.

Practically speaking, if the soil density test is skipped you should know that in general lower soil density tends to correlate with lower thermal conductivity and diffusivity. So assuming low density is more conservative.

Determining Moisture Content

For LoopLink RLC we have reduced the moisture content selection to values of dry, typical and wet. Where dry soil is at the wilting point, wet soil is at field capacity and typical soil is the average of the two.

To understand these terms a little better you should know that wilting point is the level of soil moisture at which plants can no longer draw water through their roots and thus begin wilting. Field capacity simply means that the soil can absorb absolutely no more water because it is saturated.

The dryer the soil the worse it will perform with respect to our thermal properties. It should be noted that unless it is known that droughts are prevalent or the formation has a tendency to dry out, it is rare that 6 feet down the soil will dry out to the wilting point. It can however be overly optimistic to assume that a soil will always be at field capacity.

You Can Look It Up

The USDA maintains very detailed soil maps for the entire United States. If you are unsure about your soil composition reach out to your county USDA office to get this information or look it up through the Web Soil Survey. A quick search of the internet should also result in a few other tools that will help you in your pursuit of determining the correct soil properties.

Introduction to LoopLink PRO

Tuesday, February 16, 2016

Introduction to LoopLink PRO presented by Doug Carruthers on Vimeo.

Learn about the features and basic navigation of LoopLink PRO commercial geothermal design software. This video is a recording of a webinar held on February 5th, 2016.

In the interest of time, participant questions during the presentation and the Q&A session from the end of the presentation have been redacted.