woman setting a thermostat

Sub Cooling and How to Troubleshoot A Central Air System

Understanding Subcooling …

Let’s go back to basics for a moment to make sure we understand what subcooling is, to begin with. During a refrigeration cycle, high-pressure super-heated gas is converted by the condenser into high-pressure liquid so the evaporator may use it for cooling purposes. It does that by removing enough heat out of the gas in order to cause it to condense into a liquid at the prevailing temperature and pressure (saturated liquid point). Any of the added heat that is removed from the condenser is referred to as “subcooling.” The amount of cooling that may be measured at the condenser’s outlet is a good indication of the performance of the condenser.

man with thermostat

When the condenser is operating in an efficient manner, the process of the refrigerant vapor being converted into a liquid is completed prior to the refrigerant reaching the final several passes into the condenser coil. Those several last passes should be only filled with liquid. Since the coil is transferring heat still, from the liquid refrigerant into the last couple of passages, the temperature will continue to drop and subcooling of the refrigerant occurs.

Subcooling is an accurate measure of the amount of time it takes for the refrigerant to pass through the condenser. This is referred to as “stay time.” The proper amount of subcooling for any specific unit may vary with its application and type of system. Subcooling may fall within the 10 to -20 F range with design air flow, clean coils, and at the right charge.

How can subcooling assist with troubleshooting?

Knowing all of that, how can subcooling assist with troubleshooting? Let’s take a look at a few different situations. When there is an insufficient refrigerant charge in a system (under-charged unit), that will cause the refrigerant to flow quickly through the condenser to attempt to satisfy the load conditions. That doesn’t allow a sufficient amount of “stay time” to let the refrigerant condense and be subcooled properly which will result in no or little subcooling.

A system with a plugged or improperly adjusted valve, on the other hand, will exhibit very high subcooling (perhaps 30 F) due to all of the excessive amounts of liquid backing up into the condenser. The strange part about both of those situations is they have the same effect on the system’s evaporator side: high super-heat, low head pressure, and inadequate cooling.

How do we tell what the problem is exactly and how do we properly diagnose it?

There are 2 different situations here that cause the same problem on the system’s evaporator side. So how do we tell what the problem is exactly and how do we properly diagnose it? The only way to know what the exact cause of the problem is to take a subcooling measurement to pinpoint it without having to rely on trial and error processes. When a subcooling measurement is made, the technician can potentially prevent having to do an unnecessary change-out of the expansion valve.  If there is zero subcooling, the expansion valve cannot close due to a plugged orifice or lost bulb charge.

If super-heat is high and subcooling is low, you can assume there is most likely a low refrigerant charge. In order to double check your assumption, take a measurement of the compressor amp draw. It should be a low reading. There should also be a low-temperature difference across its coil.

ac test gauges

An example of how subcooling can assist with troubleshooting …

The following is an example of how subcooling can assist with troubleshooting.

When subcooling is used properly it can be a valuable tool that can significantly reduce the amount of time that is needed to diagnose system malfunctions. In addition to suction super-heat, it is playing an increasingly important role in maintaining and servicing an air conditioner or refrigerant system. Above I just provided you with a few scenarios – can you think of other areas that it could be invaluable for you in making a diagnosis?

Be sure to look at all sides …

It is important to always keep in mind that an air conditioner is a system. All sides of this system need to be looked at – air flow, evaporator, condenser, etc. All of them deter from or contribute to a system operating correctly. Doing a complete diagnostic will allow you to solve problems.


Is It Time for A New Air Conditioner?

Three signs it might be time for you to get a new air conditioning unit

Summer is right around the corner, and that means the time has come for you to think about your air conditioner. If your AC unit is getting up there in years or just doesn’t use the latest in technology, and it seems you’re calling for an AC repair every year, then the time might have come to get a new one. This air conditioning repair service company in Kingston / Gananoque points out the three signs it might be time for you to get a new AC unit.

air conditioners

Increased Costs and Reduced Efficiency

As with any machine, when an AC unit gets older, it wears out more. Just like with a furnace, a lawnmower, or a car, the increased wear and teary can equate to a decrease in efficiency. In regards to air conditioning unit, this would mean it has to run longer just to get to the same temperature level it might have gotten in just half that time several years ago. Be mindful of your electric bill. Should it keep climbing, you need to contact our air AC company. It might be possible that the unit just has to get repaired. However, if we’re able to trace the issue to the age of the unit, then you need to consider buying a new AC unit.

Repairs Cost More

Even machines built better than others are going to need routine repairs and maintenance in order to keep smooth operating levels. However, as age creeps up on the performance of an air conditioner, it’s possible that you’ll start seeing the very same parts needing repair with a growing frequency. One instance could be the heat pump of the AC unit. If you wind up calling to get service on this particular item multiple times per year, then that’s a definitive red flag. If things get to the point that you start winding up getting repairs for more than one item, it probably makes sense to stop wasting money on individual issues and just buy yourself a new air conditioner. The frequency with which system failures happen goes up with age, which means you’re smart to just deal with things directly instead of continuing to sink money into something that isn’t going to be fixed.

air condioners

More Than 15 Years Old?

At this point, you’re likely wondering what the average lifespan of most AC units is? The short answer is typically 10 to 15 years. This is of course based on the kind of AC unit you have, the frequency with which you run it, and if you clean it periodically or have parts replaced as need be. If you have an AC unit that reaches 15 years of total service and is still running really well, then consider yourself fortunate. Just be ready for what is likely going to be a sudden downshift in its performance level.

You have two choices here, as already alluded to. You can work to get every last minute of service from your AC unit by keeping up with services and repairs. Alternatively, you can invest into a new unit. In the end, it’s a lot more cost-efficient to just buy a new AC unit, although homeowners typically have timetables of their own based just on usage, budget, their current AC unit, and the like. If it makes any sense to you to push your current unit for another few years, then by all means do so. However, don’t flush too much money down this hole, and keep in mind you’re going to need a replacement anyway.

If you want more information about AC installation, repair service, or longevity, then consult an experienced air conditioning professional.

heat pump repair

7 Tips to Repair Your Home’s Heat Pump

Heat Pump Repairs ….

Winter’s is over, so I’m quite sure everyone is looking ahead to the finale of this heating season. Even though the title mentions heat pumps, this could really apply to any equipment that’s out there. It really just boils down to competence, which comes from knowledge and training. You can see how this might apply to nearly anything if you swap out heat pump for whatever kind of equipment you focus on, be it furnaces, packaged units, or what have you.

heat pump

Everyone gets hit with a heat pump which just doesn’t work. It happens sooner or later. The issue might be a defective part, old age, misuse, or just a loose connection.

Are you a service technician?

If so, then you want to try these following techniques. They’re not actually guaranteed to give you results, but they’re certainly going to give you something to do as you figure out how much you’re going to charge your customer 🙂

STEP 1: Approach the heat pump in a confident manner. This will tell the machine, mistakenly, that you know what you’re doing. It should also impress anyone watching, so if the heat pump suddenly starts working, you’re going to be credited with the successful repair. If this doesn’t work, move on to STEP 2.

STEP 2: Wave the manufacturer manual at said heat pump. That should make the heat pump assume you’re familiar with the source knowledge. If that fails, move on to STEP 3.

STEP 3: Forcefully recite OHM’s Law to said heat pump. (Before you take this step, make sure you actually know Ohm’s Law.) This will definitely prove your knowledge to the heat pump. Is the machine still unimpressed? Go to STEP 4.

heat pump repair technician

STEP 4: Slightly jab the unit. That might involve a 3- or 6-lb. hammer. On the other hand, you need to be careful in this step, so you don’t damage the pad.

STEP 5: Wave around a large screwdriver menacingly. This shows the machine that you personally know the fatal short-circuit technique.

STEP 6: Should nothing else work, just add a bit of refrigerant. This will now confuse the heat pump, thereby increasing your advantage.

STEP 7: If that heat pump doesn’t have any sentimental value and you’re just done messing with it, then it’s time to sell a new model. On the other hand, if you’d like to make some last-effort in saving it, then call your preferred factory representative. Also, avoid displaying any further ignorance by giving the customer a bill right now.

electric wall mounted heater

Electric Wall Mounted Heaters

Advantages And Disadvantages Of Electric Wall Heaters

Electric heaters come in handy in keeping your home or office comfortable and especially in cold weather. Electric wall heaters are not only easy to use and convenient but also very affordable, making them a preferred option by many. It’s however advisable to research and look into the features of the wall heater before making an order. Outlined below are some of the advantages and disadvantages of wall mounted electric heaters you ought to know of.

The Advantages

Electric wall heaters come in many shapes and designs. It’s advisable to choose just the right heater for the desired application and preferences. Here are the advantages of electric wall heaters.

  1. Cost: Electric wall heaters are affordable and do not waste energy either. You should notice reduced heating bills after switching to this heater.
  2. Safety and ease of use: Electric wall heaters are relatively easy to operate. You simply plug in and turn it on. These heaters come with two built-in security features to ensure your safety. They have sensors that turn the entire system off completely if an object comes too close to the heater. In addition to this, the heater doesn’t get too hot to cause combustion.
  3. Compact size: The heaters are small enough to fit in the smallest of rooms, including bathrooms and offices.
  4. Instant heat: Once turned on, the heater warms the room fast enough, thus leaving you comfortable. You should, however, keep the door closed for faster heat distribution.


  1. Short cords: The power cords can be a little too short when installing the system. The main idea behind short cables is to keep them hidden.
  2. It’s only efficient in small spaces: Electric all heaters are exclusively designed to heat small areas. This means you cannot use the heater in larger spaces and homes. You’ll need several of these heaters to keep a large room or house warm.
  3. Doesn’t use duct-work: Electric wall heaters do not use ducts to disperse heat. For this reason, it might take longer for a room to heat up to one’s preferences. This is, however advantageous in that; no allergens will be blown in your direction.

Notable Features Of Electric Wall Heaters

  1. Energy efficient heating: These heaters use superior technology to circulate heat in the desired space. The low wattage means reduced heating bills for the heater only uses 4 cents per hour. This translates to 50% less energy usage.
  2. Ultra-Safe Wall Mounted Heaters: This feature makes it possible to leave the heater unattended for hours. The heater comes with an auto shutoff technology which powers the system down on contact.
  3. Healthy Heating: Electric wall heaters run silently, and have an auto-dimming power light that allows you to sleep well at night undisturbed. In addition to this, the hypoallergenic and fan-less design means no allergens and dust will be circulated in the heated space.
ecm motor

All There Is To Know About ECM Motors

Behind today’s high-efficiency furnaces and A/C are higher efficiency motors designed to reduce the total electrical consumption, thereby raising the overall consumption of the system. This equipment also maintains the proper cubic feet per minute, better known as CFM across the various parts of the system, including the condenser coil, the heat exchangers, and the evaporator coils. Airflow is critical for these devices to operate properly. As such, the use of ECM motor technology helps in both these fronts.

What is an Electronically Commuted Motor, better known ECM motors? ECM motors, also known as variable speed motors, are motors that can vary the RPM of their motors. However, variation in speeds only happens when conditions within the system change. In the case of A/Cs and furnaces, the changes occur in an effort to maintain a programmed CFM.

ECM motors have 3 parts components:

1. The motor

ecm motor

The motor does not have windings like typical motors. The motor uses DC voltage and magnetic fields drive the stator. The starting procedure involves the motor rocking back and forth while aligning the magnetic fields in order to drive the motor. These motors can operate with 220 volts as well as 110 volts, depending on the five pin power plug configuration.

This system rarely breaks down and features exceptional reliability. The only instance where failures will occur is when someone drops the module with the motor plugged in, therefore, breaking the wires that connect the motor.

2. ECM Microprocessor Module

This is the brains of the motor. The board send programming information from using a 16 pin harness and thereafter translates it for the motor. This allows the motor to produce the right CFM. As such, it functions as the brain, controlling the relationship between torque, speed, and the airflow the system yields. The module is programmed at the factory for each specific unit. Modules are customized for a specific model and are, therefore, not interchangeable.

You can mount at one end of the motor or install it remotely.

3. Control Board

The control board is the component that stores the desired CFM for the application. As mentioned above, it connects to the module through the 16 pin harness.

OK, so how does it work …

The ECM motor is capable of maintaining a programmed CFM whilst responding to changing torque. When there is a change in torque, the motor increases or decreases the RPM, therefore, maintaining the predefined CFM. I admit it, it can get a tad confusing.

For a better understanding, let’s consider how an ECM motor works on an electric car that has cruise control on. The cruise control is the program that pre-defines how fast the car should move. It set the speed limit in mile per hour.

Obviously, as you set the cruise control, the motors will have a certain RPM. When you get to a hill, the cruise control will sense a change in torque and will rev up to maintain the predefined speed. The same case applies when you travel down a hill. The motor senses less torque and therefore, reduces the RPMs to maintain the predefined speed.

This is the same principles that the ECM motor uses. It functions by tracking the torque, RPM, and CFM (in the place of the mph). In the place of the steering column is the board, which controls the ‘direction’ in the sense that it controls the furnace or AC profiles – delay, heat, adjust, and cool. After programming the desired CFM, the motor and the module will automatically work out what to do.

residential air conditioner unit or central air

Let’s think of a hypothetical AC – 3 ton AC. For the AC to function correctly, we need a total of 1200 CFM or 400 CFM per ton. You program the board appropriately and both the adjust and cool profiles to as close to 1200 CFM as you can. Note that you should always use tables provided by the manufactures when you want to set up the ECM motor.

When you want the cooling function, the motor will start and thereafter try to maintain the ideal CFM as much as possible despite the variety of operating conditions. As the AC runs, the evaporator will naturally get wet, which causes the static pressure to go up. And as the static pressure goes up, the motor will sense some changes in torque. This can be equated to a car going uphill. As such, the motor will start to increase the RPM in order to maintain the ideal CFM expected of the system.

This motor process is experienced when the filter gets dirty. The return static will increase and the motor revs will increase to maintain the ideal CFM.

Under normal circumstance (with a clean filter), when latent heat decreases and there is less water or humidity around the coil, static will reduce. This results in a torque reduction, causing the RPM to decrease, thereby maintaining the predefined CFM. You can expect the system to react in this same manner after changing the filter.

This same process occurs under the heating mode. With heating, you program the board to instruct the motor to maintain the desired increase in temperature for the system. The motor will, therefore, operate to deliver the appropriate CFM to maintain that specified increased in temperature. However, if the filter gets dirty, you can expect an increase in motor RPM to maintain the desired CFM for the predefined temperature rise.

Finally, you can set a “Delay” profile. This function is used for cooling. However, it allows users to further fine tune the motor response when called upon to start to end a cooling call. Generally, you can set Humid, Dry, Normal, or the factory default profile using the control panels.

By maintaining the appropriate temperature increase in heating function and the proper CFM while cooling, you are able to eke out maximum efficiency out of your AC or furnace. Moreover, the ECM motor uses less wattage than the traditional PSC motor, further increasing the energy efficiency of the system. You can now appreciate why the ECM motors are fast becoming the industry standard for comprehensive energy efficiency.


Proper Sizing And Heating Efficiency

I got an email this weekend from my nephew, Joe, in Manitoba. Recently he moved into a house there and they finished the attic and basement. He hired a contractor to come out and he told Joe he needed to have an extra 50,000 BTU bigger boiler for heating his home. He wanted to get my opinion since he knows I retired from the HVAC industry.

old boiler system

The first question that I asked was, “how did your contractor determine you needed an extra 50,000 BTU’s for heating the new areas? I also asked my nephew, “Did the contractor perform a load calculation? Did he base it on the number of feet of new baseboard radiators that he was installing? What is the temperature of the water that the current boiler is operating at?”

The current boiler might be big enough to be able to handle the extra baseboard radiators. I told my nephew that usually basements are not included as part of the load calculations. Therefore, the sizing being suggested by the contractor could be reduced. Depending on what water temperature his boiler is currently operating at, he might be able to g from, 160-degree to 180-degree water in order to handle the extra load.

Joe said, “the contractor just said that I needed to have a new bigger boiler”.

Now Joe’s boiler is a gas-fired hot water boiler. I told him that potentially replacing his inefficient, existing boiler with a new energy smart one may be the best option but there were a couple of things that he needed to take into consideration. So that brings us to this article’s subject – Proper Sizing and Heating Efficiency.

Have you noticed that old spark ignition and standing pilot boilers and furnaces seem to have 80% efficiency ratings? You can check the data plate and it will read 80,000 Btu output and 100,000 Btu input. That is 80% efficiency, right? The answer is, yes and no! Boilers and furnaces in the past were rated by their steady-state efficiency. That means if a furnace was running 24 hours per day over the whole heating season, that it would be at 80% efficiency. That rating never considered milder outdoor temperatures or normal cycling. So, it was 80% efficiency based on that type of rating.

However, today’s boilers and furnace are rated by AFUE’s. That measures the furnace’s annual fuel utilization. To put that into perspective, a 60% furnace is actually 60% efficient since 40% of the heat that it generates goes up and out of the flue. An 80% efficient furnace sends 20% up and out of the flue. And a 90% efficient furnace sends 10% up and out of the flue, and so forth.

It is a truer measure of a product’s efficiency.

Why am I explaining all of that? Well, many dealers are still using the same rule of thumb and size for replacing a boiler or furnaces based on the existing equipment’s input and then get into trouble. They think that since the old equipment had 100,000 BTUs input that they need to replace it with a new 100,000 BTU furnace. However, the problem now is the furnace is much too big.

high efficiency boiler equipment

Some dealers base the new size of the furnace using the existing furnace’s output. It still will be oversized (but not as bad)) due to the fact that in reality, based on AFUE, older furnaces were only really 55-60% efficient. To make things even worse, a 92-98% efficient boiler or furnace is used for replacing the old boiler or furnace, and its size is based on the output or input, so now there is a really major over-sizing problem.

When a heating unit is over-sized, it heats the space, however, the occupants will have to sacrifice both efficiency and comfort. A furnace will blast lots of warm air in the space and over-heat it, then it will be turned off for a long period of time. That will result in bigger temperature swings in the area and occupants will feel warm and then cold and then warm and so forth. Boilers are a lot more forgiving since they heat water that is circulated through radiators or baseboards. The main issue is that it wastes energy to heat an area.

I told my nephew, Joe, the best way to have heating equipment properly size was to have a load calculation. I told him that if he was going to make such a big investment into new equipment that it needed to be sized properly the first time.

When homeowners install weatherproofing, insulation in their walls and attics, and new energy-efficient windows, the sizing of their old boiler or furnace becomes even more out of line, and it is even more absurd to replace it based on old guestimates, rules of thumbs or outdated ratings. It is a real disservice to customers since they are not receiving the true comfort and fuel efficiency that they think that they are paying for.

Keep all of this in mind when you are quoting or replacing a current heating unit. Take the time to perform a proper sizing to give the customers what they are actually paying for. It will also eliminate potential warranty calls caused by erratic cycling, and you will be providing the right comfort level that a furnace is designed to give. This will also provide you with an edge to getting the job by demonstrating to the customer that you are a true professional and concerned about their comfort and needs.