Why does TPD use an “assumed CFM” to evaluate system performance?

Anyone who does not measure CFM every time, on every job, assumes CFM. If you prefer to measure CFM in the field then TPD ceases to be an evaluation tool and becomes a system commissioning tool.  With TPD, you can have it both ways. By using either the “CFM Override” feature when measuring CFM, or using the system default settings when assuming CFM.

Some quick notes about “measuring and/or calculating” CFM.

1)  Just because measuring CFM is possible, doesn’t mean it is always practical.

2)  CFM is meaningless with out being converted to “air mass flow.”  Click here

3) What is commonly referred to as “measuring and/or calculating” CFM is, more often than not, just “estimating” CFM.  Tools that claim a 7-9% accuracy will still distort system performance by 7-9%.  Even extremely accurate tools are subject to errors due to system duct design problems, procedural errors and technician errors.  If you are going to estimate CFM in the field, we suggest you take your time and do it right.  We further suggest that you get paid, and paid well, for your time.

4)  Better yet, run a TPD system evaluation first and then check CFM on those systems with obvious faults – faults that you can quantify and your clients will be happy to pay you to repair.


How exactly does TPD work?

    We like to say that TPD works by you entering in the information and TPD giving you the answers.  But if you’re looking for a more technical explanation, TPD is a unique combination of three components:

1)  A modified psychrometric calculator for measuring current system performance.

2) A unique set of algorithms that model the expected system performance based on the information contained in the technicians input fields and the system administrators preference fields.  (note: Since TPD first became publicly available, both Florida Solar Power and NREL have published technical studies validating the veracity of system performance modeling)

3) A separate set of algorithms that perform a regression analysis in order to report information in a consistent format that is comparable, over time and over different system operating conditions.  The regression analysis also allows TPD to report information in a manner that is consistent and easy for both clients and technicians to understand.

And that’s all there is to it.

How can I make money from a technical program?

 1)  TPD is designed to allow technicians to identify potential system performance problems quicker than any other method. TPD is also designed to aid technicians in communicating that information quickly, easily and effectively to clients. This equates to finding and selling more repairs in less time. But that’s only a small part of the money you can make with TPD.  If you look at TPD solely as a technical solution, you will miss more than half of its value.

 2) Your clients are using tablets and smart phones every day, and they are wondering why you don’t.  Call it client relations,  client confidence or improving your professional image. HVAC companies pay large consultantion fees to help their company identify a USP (unique selling proposition) to stand out from their competition.  You are looking at the best USP the industry currently has to offer.  But like everything else, you not only have to buy it, you have to use it. You also have to use it for more than just the “technical stuff” that TPD does so well. You can move you company into the 21st century in they eyes of your clients, or remain where you are.

3) Service Managers can use the TPD reporting platform to hold technicians accountable and identify training opportunities.

    Sales Managers should use the TPD reporting platform to identify potential sales opportunities and to use in sales presentation to validate the advantages of equipment replacements and the performance deficiencies of existing equipment. TPD doesn’t calculate SEER and estimate annual operating costs just because we thought it would be a fun thing to do … we did it so our clients could use it to make money … by making their customers aware of the true cost of continuing to operate low efficiency equipment..

     Scheduled Maintenance Managers should make TPD the central focus of their maintenance program.  There is no better or more comprehensive maintenance report (from a client perspective) than TPD.  Retain more clients with less advertising.  TPD can help solidify the loyalty of the maintenance client and free up advertising and promotion dollars for attracting new clients.

4) TPD is much more than just a “bolt on accessory” for any HVAC company. Properly implemented TPD should touch every area of your business profitability.

How do I cancel or “unsubscribe” a technician from TPD?

Log in to your account using your existing user name and password.

Select the “SETTINGS”  tab,

Select the “MANAGE USERS” tab


Scroll down the page and select the arrow next to under the “SUBSCRIPTION PLAN”  and select the “UNSUBSCRIBE” option.

Then select the “NEXT” button and follow the directions.

Our payment provider requires a credit card in order to make any changes.  The credit card charge to unsubscribe is $0.00 dollars.  There is no charge to unsubscribe but the payment provider does require a credit card number be entered in order to process any transaction.

Once you have unsubscribed your account … TPD will retain your user information and reports and still allow you access for up to 12 months.  Should you decided to renew your membership you can do so by using the same menu options  and then selecting an active plan.  Your user information and users settings will also be retained.

This process allows our users with multiple technicians to add and remove individual technicians on a seasonal basis while retaining one or more active technicians.

What is the difference between the residential and commercial TPD programs?

TPD residential calculates SEER and is designed only for single phase systems.

TPD commercial calculates EER and is designed for single phase, three phase and mixed phased systems.

Why do my technicians rarely get a 100% report?

Check out our blog “Cooling Capacity Dynamics”.  Take a good look at the MFG detailed cooling performance chart and you will discover something that is true of almost every system manufactured … systems rarely produce the rated nominal  BTUs under design conditions.  This 60,000 nominal BTU system only produces 59,000 BTUs …  or 98% of rated nominal capacity.

Since field technicians rarely have access to such detailed information in the field, TPD uses “rated nominal tons” (since this information is readily available on the equipment label) as a base reporting platform.

Any recognition of real world field conditions and equipment performance, demands the use of  … acceptable ranges of performance.  This is commonly recognized in CFM measurements of 350 to 400 CFM per ton.  Mfg charging instructions commonly designate a range of +- 3 degrees.  This is why TPD permits system administrators to select and establish a company wide acceptable range of performance.  Our recommendation is that this range be kept no lower than 96%.

Anything “out of range” should prove profitable to investigate.  However mismatched equipment, incorrectly sized line sets, extra long line sets, smashed condenser fins, and a host of other conditions may make bringing a system into … an acceptable range … either impossible or cost prohibitive.

 Your client only has three choices,  Fix it … Replace it …or Live with it.  But they can’t even make those choices if your company doesn’t first make them aware of the problems.

     The engineers and educators I have talked to tell me that it is not possible calculate EER or SEER in the field.

The word “calculate” is a “loaded” and misleading term. I find it is most often used to create arguments and justify positions than to create clarity.  This short story best explains the idea.

 Driving down a country road one day with an engineer, a man happened to draw the engineers attention to a herd of sheep and remarked that the sheep had recently been sheared.  The engineered corrected the man … “all we know for sure,” he said “is that one side of each sheep has been sheared”.

Many engineers and educators are still woefully behind current technology and/or committed to protecting their own little corners of their world.   This is the year 2014 …  and any engineer and/or educator that is not familiar with HVAC system performance modeling is at least  five years behind the technology.  EER and SEER can be estimated in the field with a high degree of accuracy using performance modeling and retrogression analysis. A failure to understand the technology on their part does not limit the technology … it only limits them.  You may want to read  “Revolutionary Ideas”.

The way we look at things is :  “Just because something is complicated, is no reason to make it more complicated than it is.”