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How Well Does This Heating System Work?

How Well Does This Heating System Work?

As the cold moves in for the winter, customers are wondering how well their heating system will work this year. The question is; can you answer that question truthfully? With all the changes coming our way in the industry, it may be time to take another look and redefine what is and what isn’t a working system.

What’s “Working” Mean?
Say your customer cranks up the thermostat, if the fan comes on and there’s warm air coming out of the registers; does that mean its working?

If the furnace cycles on and off because the thermostat is satisfied; is that a definition of working?

What if a service tech completes a 15-point inspection and all 15 points check out; what assurance does that really provide?

If the equipment comes with a yellow sticker with a 21 or a 95 pasted on the side; does that define a working system?

“Working” Used To Be Good Enough
Working has been adequate for most of the industry for a long time, so let’s rephrase the question: Is it good enough for you?

Before you answer, let me say that we’re learned the typical system around the country really isn’t working the way we always assumed it should be. T move forward, let’s take a look at an expanded definition of what constitutes a working system.

An Old and Once Accurate Definition
If we strip way all the efficiency hype and get back to the roots of our industry, we are simply providers of comfort. The best definition of a working comfort system is where the occupants are so comfortable that they are unaware of any need for heating, cooling, or ventilation.

That’s our job. To be effective, however, we must be able to define how we get to this ideal state, or at least something close to it.

Our job is to move heat around and provide adequate humidity control, ventilation, and a little filtration to help clean the air. In the summer, we cause heat to be removed them from the building. In winter, we add heat to the building.

How Much Heat?
Let’s start with the heat we move around. Winter will be arriving soon, so let’s take a look at the amount of heat our buildings need and how we quantify if we have done that part of our job or not. For years a number of contractors participated in a project that measured the amount of Btus that systems actually delivered into the buildings. The results both frightened us and introduced us to some new opportunities.

First, we cataloged the amount of heat the furnaces were rated in the laboratory to deliver. This information is printed on the nameplate data of most furnaces as BTU Output.

Next, we measured the Btus being delivered by the system into the building. It’s much simpler than you’d think, but basically we measure airflow from each of the supply registers and add them together. Then we take the average temperatures in the supply registers and return grille followed by about 30 seconds of simple math.

What we found was the average heating system delivered only 50% to 60% of equipment-rated Btus into the building. These facts excited us though because we saw an unlimited opportunity to improve the performance of systems and that can be extremely profitable.

So, how much heat did that last furnace you serviced actually deliver into the home? Remember, it’s not just the equipment that determines that, but it’s the duct system that makes the biggest difference.

And it’s not just tight ducts -- the ducts have to be sized right and installed right, or the static pressure the fan sees will limit the airflow to a point where a large percentage of the heat escapes before it makes it into the house.

Is a system really working when there’s a 10 degree difference between upstairs and downstairs? Perfection isn’t necessary for most of our customers, but if your customers want improvement, you can give it to them.

Comfort balancing is achievable with a good quality air balancing hood and some simple duct modifications in most cases.

Ventilation is essential, even during winter months. Room-by-room, the right amount of airflow is an essential element of whether or not a system is working. It’s also an issue of air patterns, not just total airflow into a room. In winter, direct velocity of over 100 feet per minute on a person can create discomfort.

Register replacement can be a valuable service above and beyond the call of duty.

Those Filters
Consumers are demanding cleaner air. One way to fulfill their needs is to offer improved filtration systems. In many cases this can also improve the longevity of the equipment and improve the operation of the system.

However, use caution in selecting air filters. Over 50% of the time, technicians are selecting filters that the systems fans cannot afford. Could air filters with excessive resistance to airflow be the cause of your systems not “working”?

So, if a system runs, does that mean it works? Maybe yes, maybe no. The final proof is delivered Btu. If the system can’t deliver the Btus the equipment produces, one of the problems mentioned above needs attention. The entire system, including refrigerant charge and combustion efficiency has to be right to deliver all the Btus. Whatever you do, don’t worry about making every system perfect starting tomorrow. Pick your battles and improve your systems one at a time

Rob “Doc” Falke serves the industry as president of National Comfort Institute an HVAC-based training company and membership organization. If you're an HVAC contractor or technician interested in a free procedure about how to measure system Btus, contact Doc at [email protected] or call him at 800-633-7058. Go to NCI’s website at for free information, articles, and downloads.

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