Thought energy from the people at Virtjoule

From the Blog


It’s hard to imagine where control of our indoor environments would be without the lowly thermostat. Programmable thermostats have been a mainstay of both commercial and residential heating and cooling.  But like the VCR “Blinking Twelve Problem”, the proliferation of thermostat interfaces has caused many to be completely misunderstood.  Property owners and tenants ignore the thermostat to their own detriment.  

This article discusses a client who was heating and cooling 24/7 on two of their Carrier HVAC units for a retail store in a small strip mall.  The cause was mis-programmed Carrier Debonair thermostats.  They had no idea.  Without the HVAC monitoring capability of Virtjoule, this condition may have gone unnoticed for years.

Upon properly programming the thermostat, the units are now running just 12% of the time they were running before.

Carrier is a big and trusted name in HVAC, without a doubt.  But that hasn’t solved the problem of complex programming interfaces for mere mortals.  I have a 29+ year career working with computers and the interfaces on most thermostats can still be mind boggling.  This store was using a Carrier Debonair thermostat.  Within the Debonar lineup there are no less than 10 models to choose from.  The model our client had was similar to this one:

Carrier Debonair thermostat

Carrier Debonair thermostat

Since this client was very close to where I live, I took the opportunity to go check on it myself.  First thing I did was to go on the Internet and find the owners manual for this model.  I was able to find it here:

As is often the case, I was expecting that there would be some schedule problem or perhaps a misunderstanding about what happens when the fan mode is set to “On”.  After all, we’ve seen that there is no predicting what the blower is actually doing when the heating and cooling mode is set to “Off” or even “Auto”.  We’ve seen blowers continue to run when the thermostat mode is set to “Off” and it is thermostat dependent.  Very counter intuitive, but who is going to go on the roof or hold a tissue in the air stream to notice if the blower is running after you shut down for the night?

What I found on this thermostat is that it has three different occupancy programming modes.  The first and default mode, Occupancy 1, has the unique feature that the occupancy schedule can be overridden by a light sensor.  That was a red flag to me as that means the thermostat was depending on yet another sensor which might or might not be working, rather than the building schedule that it also contains.  It could also be getting confused by other inputs like street lights through windows and start times would change radically depending on what time of year it was.  Why would you want that if the building hours are nearly identical throughout the year?

Without enough time or a good way to determine if the light sensor was working, it was clear to me that a retail establishment like this should not be depending on light to control its space.

Switching the thermostat to “Occupancy 2″ mode allowed it to be controlled by the occupancy schedule.  On this thermostat each day has occupancy times and unoccupied times.  Luckily there is a feature that allows you to copy one day to the next, but how you do that is completely inscrutable if all you had was your eyes on the thermostat.  It took some careful reading of the owners manual to figure that out.  By the way, where do you think the owners manual was on site?  I don’t know either.

Besides the occupancy mode issue, both thermostats had their time and day set wrong.  In the case of this seven day a week establishment, having the day set wrong was harmless.  But here in February, both clocks were still set to daylight saving time.

Let’s take a look at the results.  During this time the temperatures here in Colorado were temperate with daytime highs in the 40′s and 50′s and lows in the mid-20′s.  The first image is a typical daily runtime graph of one of the units before the thermostat change.  The blower was running 24/7 punctuated by cycles of heat.  There was simply no schedule on this unit and it was always running.

Runtime before thermostat change

Runtime before thermostat change

The “after” chart is one that is much easier on the eyes.  You can see some periodic runtime during the night when the setback temperature of 58 was hit.  But by late morning there was no runtime at all.  So not only was the tenant saving night time and after hours runtime, the majority of their savings was actually achieved during business hours when outside air and activity in the building was working for them.

Runtime after thermostat change

Runtime after thermostat change

 Across the two units, I was able to compute that total runtime after the thermostat change was just 12% of what it was before.  That’s what you call saving money.  Without HVAC monitoring of these units, this money would have been wasted month after month.

[Randy Cox - CEO and co-founder of Virtjoule - He is the software designer and analytics engineering for Virtjoule Sense sensors. He studied Chemical Engineering and Petroleum Refining at the Colorado School of Mines. You may contact Randy at: randy at virtjoule dot com]


As a young company, we’re still learning the range of things that are possible with the Virtjoule solution.  In the last year and a half, we’ve discovered that not only has the technology met our original vision of functionality and price, the types of projects that can be accomplished are even more varied than we thought.  The Virtjoule solution has been installed on everything from beverage coolers to a 6,000 ton cooling system on a major Las Vegas hotel.

We often get asked, “What kind of projects can you do?”  In the earlier days of the company, the answer was in the form of suggestions of what we ought to be able to do.  After all, we had a device that could pick up vibration and the ability to track that vibration over time and see patterns emerge.  

These days, the answer is educated by field experience with the problems and the economics of solving those problems for our customers.  At the highest level, the answer is “If it vibrates, we can monitor it.”  As a company, we’ve done work in the various segments you’ll see in the list below.

To get a handle on the range of applications, perhaps it’s useful to take a scan across the types of units that we’re currently tracking.

Function Model
Beverage Coolers Micro Matic MMPP4301
Walk-in refrigeration Numerous models of Harford Duracool
Harford Duracool – H1984A8
Trenton – TEHA025L6-HS2A-F – 2.5 hp
Trenton – TEHA006E6-HS2B-B – .6 hp
Air conditioning – Split systems Ducane – 2AC13L60P – 2A – 5 ton
Package units Trane YSC048A3EMA2U – 4 ton
Trane YSC060A3EMA3 – 5 ton
Rheem RKKA-A073CL10E – 6 ton
Carrier – 48TCEA07A2A5A0A0A0
Bard PH13062
Bard PH1060-B – 4.6 ton
York D1NA042N05625C – 3.5 ton
York D1EB048A25B – 4 ton
York D2NA060N09025D – 5 ton
York DM090N10A2AAA4B – 7.5 ton
York BP090C00A2AAA4A – 7.5 ton
York D1EB060A25B – 5 ton
Johnson Controls – J05ZJN10D2AAA1C – 5 ton
Johnson Controls – J07ZHN15P2AAA4B – 7.5 ton
Johnson Controls – J10ZHN20S2AAA4B – 10 ton
Johnson Controls – J25ZJN32S2BZZ10001 – 25 ton
York ECO2 50 ton
Carrier 48P5 Horizontal VAV 100 ton
McQuay 40 ton
McQuay 70 ton
Heat pump packages and split systems Heil Tempstar – NHP060AKC1 – 5 ton
Coleman/York – HP060X1021A, 5 ton split system
Goodman CKL60-1 – 4.75 ton
Goodman CPLE60-1 5 ton
Goodman GPH1324M41AB 2 ton
York 20 ton
CRAC-(Computer room air conditioners) Liebert
Evaporative Coolers – Water pumps Can’t divulge manufacturer at this time
Air handlers Goodman AH120-00
Commercial Refrigeration Compressors Copeland Copelametic 4RA3-100A-TSK-800
Copeland Copelametic 6RA4-200A-TSK-800
Copeland Discus 3DB3F33KE-TFC-800
Copeland Discus 4DL3F63KE-TSK-800
Chillers York – 18 ton
Carrier 30GTN090 90 ton
Cooling towers Baltimore Air Coil, 125 hp electric pump and 100 hp VFD fan – 2,000 ton

One of the most satisfying things that we’ve seen is that this is a huge range of equipment, all being monitored by the same Virtoule Sense technology.  

If you’re familiar with some of the pieces on this list, you’ll know that some put off so much noise and vibration that you need ear protection.  Other pieces are so quiet and smooth that it’s very difficult to tell if they’re running when standing right next to them or even putting your hand on the machine.  I’ve been particularly impressed with the Trane series (YSC060A3EMA3) as very smooth operators in package units.

Because the Virtjoule sensor is self-calibrating, once it’s installed it can start off as a very sensitive device and self calibrate to the point where it can handle large magnitude vibrations.   This self-calibration means that the installation is roughly the same for all of these installations, stick it on, power it up, and start getting data.  An operating signature will always emerge that can be analyzed, reported on, and alerted on.

Customer and facility types

The table above is specific to equipment and equipment applications.  But what sort of customers and markets does this represent?  Here’s one look at the type of facility and customer:

  1. Executive office buildings
  2. Restaurants
  3. Strip malls
  4. Small market and convenience store refrigeration
  5. Data centers
  6. Hotels

Some are very high energy users where control problems or equipment degradation can cost thousands of dollars a year if the problem isn’t corrected. Some have equipment that might not burn a lot of energy, but the unit is serving high value contents. Food, pharmaceuticals, and computers are good examples of high value contents that need to be protected from catastrophic loss.

In a recent example, Virtjoule was able to give the owner of a walk-in refrigerator days of notice that their unit was degrading. The customer was able to get a refrigerant leak fixed before they lost control of the temperature of the cooler. One of my upcoming blog articles will discuss this “catch”.

If I were to sum up our results since we started, I would say we’ve helped customers save money by identifying control problems or system degradation that were racking up extended hours and energy bills. And we’ve helped some customers avoid serious loss of high value contents that were being refrigerated.

What new applications will we see this year? I can’t wait to find out.

[Randy Cox - CEO and co-founder of Virtjoule - He has been the software designer and analytics engineering for Virtjoule Sense sensors. He studied Chemical Engineering and Petroleum Refining at the Colorado School of Mines. You may contact Randy at: randy at virtjoule dot com]