Why We Use Dry Nitrogen

We are gearing up for the air conditioning start up season and you know what that means: more AC installations. As the number of installs increase, so does the workload. Let’s not forget one critical part of any AC installation—the use of nitrogen while brazing.

Why do we use nitrogen? Nitrogen is an inert gas, meaning it is not chemically active. By using nitrogen, we prevent oxidation inside the tubing. But what causes oxidation, and why is important to us? When we are brazing copper, we use a lot of heat. This heat can cause the oxygen to react with the copper and cause oxidation. Have you ever noticed a black residue on the outside of the copper lines after brazing? Without nitrogen, this happens on the inside of the tubing also. Externally, this looks bad. Internally, this can cause harm. The black residue can break free and circulate with the refrigerant throughout the system. This can plug strainers and cause bearing damage to the compressor.

Over the years, I’ve seen a number of installs that were done without nitrogen. I have seen many plugged strainers, bad TXV’s, and ruined compressors. This is not something that we want to see on any installation, let alone a brand new one. This is a warranty call waiting to happen.

So what is the proper method? Once the piping is all fitted together, remove the Schrader cores from the service valves. Hook up the nitrogen to one of the service valves and add nitrogen. The pressure should be just enough to push the oxygen out. Allow the nitrogen to purge through for a few minutes (or longer if the line sets are long). Once this is done, release the pressure but keep a small amount of nitrogen owing through the tubing. This will keep nitrogen in the system without causing so much pressure that it will blow the braze out. Now the line can be brazed together. Once done, the nitrogen is already hooked up for a pressure test.

Using nitrogen while brazing will ensure no oxidation occurs in the system, which will reduce warranty calls. As always, if you need any technical assistance please call the Famous Supply Tech Support Team.

Jeff Rosenblum
Technical Support
18 Years Industry Experience
Cell (330) 962-2491

Cold Weather is Coming!

Sorry to break it to you, but cold weather is coming. Before you start throwing tomatoes my way, this is only some advice to help you be prepared.

So what do you need to be prepared to brave the cold weather? I’m not talking about long johns and snow boots. I’m talking about tools! Unfortunately, we get so wrapped up in the heat that we often times forget to get our tools ready. Below is a partial list of tools you should have ready to take on the majority of problem calls.

  1. Combustion Analyzer (fresh batteries and professionally calibrated)
  2. Oil test kit (smoke test papers, etc.)
  3. Draft gauge
  4. Hygrometer (used to test humidity levels)
  5. Multimeter
Dual port manometer (to test static pressure and diagnose pressure switches)
  7. Typical hand tools

If you need any tools to help you get through this heating season, feel free to stop by your local Famous branch to see our selection. If you need any advice or tech support, please call our Famous Tech Support Team.

Jeff Rosenblum
Technical Support
17 Years Industry Experience
Cell (330) 962-2491

14 SEER Heat Pump System Replacements

We’ve had numerous questions over the last few weeks where a heating contractor is replacing a heat pump system for a homeowner and they want to use the existing air handler and just replace the coil inside. There are various reasons why you can’t or you shouldn’t replace only the coil. Instead, replace the entire air handler.

  • The minimum efficiency is 14 SEER, it’s practically impossible to find a coil that will t in the air handler that AHRI matches to the heat pump.
  • If you decide to use a non-AHRI matching coil, the system is not going to work properly and will have significant operation issues.
  • Replacing the entire system gives the homeowner a brand new system warranty on ALL parts.

We’ve seen the negative side effects when trying to match up a coil or selecting the wrong coil. We have seen liquid slugging back to the compressor in AC mode and head pressure issues in heating mode. Both of these issues can reduce the lifespan of the equipment.

It is fitting to also talk about airflow. Proper airflow must be set and verified before the charge can be checked. I always tell people that if I purchased a 3-ton system, I want 3 tons of air! Why sell a 3-ton system but only deliver 2 tons? Incorrect airflow can cause several issues like:

  • Incorrect superheat and subcooling
  • Poor humidity control
  • Head pressure issues in heating mode
  • Inefficient operation
  • Nuisance lockouts
  • Excessive use of backup heat, and more

As always, if you need any help with your heat pump, feel free to call the Famous Supply Tech support department at 330-962-2491.

BY JEFF ROSENBLUM – Training & Technical Support
& COLLIN MURPHY – Armstrong Air/Concord Equipment Specialist

Mitsubishi Electric Updates and Applications

Hello Everyone! As the HVAC industry changes so does the Mitsubishi Electric line- up. I would like to take a moment to introduce some of the newest Mitsubishi units.

PUY-6 P series cooling only unit: Mitsubishi released the -6 cooling only P series unit. This unit has the ability to run in cooling mode down to -20 degrees outside (with the use of the 3 piece wind baffle). This makes it a great option for server rooms where non-critical cooling is needed.

MXZ Multi-Zone Hyper-Heat units: Yes, that’s right! A multi zone unit that is hyper heat! This has the ability to provide heating down to -13 degrees or lower. They can provide 100% capacity at 5 degrees.

MVZ Air Handler: Mitsubishi has finally released their air handler. This is available in 12, 18, 24, 30, & 36 KBTU’S. This unit must be teamed up with their multi zone unit. This can be used to replace an existing air handler, and match to a Mitsubishi outdoor unit.

Thermostat interface: The interface allows the usage of a conventional 2 heat 2 cool thermostat. The homeowner can then use a thermostat that they are comfort- able with, or one they prefer the look of.

Kumo Cloud: The Kumo cloud is Mitsubishi’s wireless app-based interface. You can download the app and control your equipment by your phone or tablet.

6,000BTU one to one Hyper-Heat Heat Pump: When a 9,000 is just too big, Mitsubishi has released their 6,000 BTU hyper heat system.

MFZ-KJ floor mount 1 to 1 Hyper-Heat system: An excellent option for the home where a wall mount system won’t t. Available in 9, 12, 15 & 18 KBTU’s

That sums up the new releases in the land of Mitsubishi. These systems can be ordered if it is not in our current inventory. As always, feel free to contact the Famous Supply Technical Support department if you have any questions.

Jeff Rosenblum
Technical Support
17 Years Industry Experience
Cell (330) 962-2491

Sizing Equipment

We often get asked, “What size furnace/AC do I need?” The answer is not as simple as just knowing the square footage. There is a lot that goes into figuring out the right size.

So, what information is needed to figure out the right size? First, we recommend you use the Manual J sizing program. Second, you will need to know some key points.

  • House/building square footage      •  People load
  • Number and size of windows          • Additional load (lights, computers etc.)
  • Outside exposures 
                            • Unconditioned Spaces
  • Amount of insulation throughout the house • Weather info for the area
  • Number and type of doors 
              • Solar Gain
  • Amount of infiltration air 

               • Ventilation
  • Which way the house faces 
             • Humidity

This may seem like a lot of info in order to size equipment, but figuring out the design load is very important. If the system is too large, it can have a very short run time, may not humidify or de-humidify correctly, and the system will be inefficient. If it is too small, it may never satisfy the load of the building, which leads to being uncomfortable, and it is also inefficient. Either way will reduce the life of the equipment. Guessing the size is never the answer. Size the system the right way and keep your customers comfortable and happy!

Jeff Rosenblum
Technical Support
17 Years Industry Experience
Cell (330) 962-2491

Choosing the Proper Mitsubishi Electric System

I have received several questions regarding which Mitsubishi system would be appropriate for their application. Since Mitsubishi systems can t in a wide range of applications, selecting the right one can sometimes be a daunting task. There are a few key things to consider when selecting the right system.

Where is this unit going to be used? If it is in a commercial system, we recommend using the P series system. This system gives you the ability to link up to 16 systems to a common control. The P series is also the unit to use for non-critical server rooms because of its low ambient cooling capability. If it is a residential home/sunroom/ addition, an M series may be the better choice.

What size system do you need? A load calculation must be done in order to decide which size is best.

Is this going to be a multi zone system? Look around and see if there are other areas that can be covered. Usually, a simple question to the homeowner of “are there any other areas of concern?” will point you in the right direction.

Unit location is a key thing to look at. Where is the indoor unit going to be mounted? Will you need a condensate pump? How long is the line set going to be? Where will the outdoor unit sit? We must nd out where everything will be located to avoid potential setbacks.

Do you have enough power for the system? A quick look at the main breaker panel will tell you.

These are just a few of the things to pay attention to when considering a Mitsubishi system. Once you have all the necessary questions answered, then you can have a better idea of what system will be best for your application. If you need assistance in selecting the right Mitsubishi system please feel free to call the Famous Supply tech department at 330-962-2491

Jeff Rosenblum
Technical Support
17 Years Industry Experience
Cell (330) 962-2491

Proper Start Up

The summer is in full swing and I’m sure you are staying busy. With that being said, please take time to do a proper start up on that brand new AC unit you just installed. As I have said many times, we don’t live in the age of just hooking up an AC and letting it run. Things have changed! We must pay special attention to the process we use to install and start that new equipment.

When doing the initial install, you need to flow nitrogen through the line set as you braze to prevent oxidation on the inside of the lines. Then when pulling a vacuum, use a micron gauge to make sure you have reached the correct level of dehydration. Now that the system is installed, the job is not done yet. Make a point to check and adjust the cooling speed for the correct CFM per ton. Typically use 400CFM/ Ton. The static pressure should also be verified to ensure that the ductwork is delivering enough air to the conditioned space. Then and only then connect the gauges to verify the refrigerant charge.

By following these steps, you can feel comfortable that the system will perform as expected and deliver the comfort your customers expect. By installing a system that makes your customers not just happy, but ecstatic, you will have a much better chance of that customer giving you rave reviews to prospective buyers.

If you need any assistance in the start up process, please call the Famous Supply HVAC Tech Support Team at 330-434-5194

POE vs. Mineral Oil

As many of you have already noticed, all Copeland, R22 compressors are now being shipped with POE oil instead of the standard mineral oil. This has made many question installation practices for new compressors, and refrigerant usage for dry charge units.

When installing a new compressor in an existing unit that was previously using mineral oil, the entire system (outdoor coil, line set, indoor coil) must be flushed. There must be NO mineral oil remaining in the system. We recommend that you follow the same flushing procedure outlined in our installation manuals.

Even with the use of POE oil in R22 compressors, allied does not recommend or allow the use of any “drop-in” R22 replacement refrigerants. Use of any refrigerant other than R22 will affect the system capacity and efficiency, and will void the manufacturer’s warranty.

Check with the manufacturer to distinguish between compressors and units with POE and mineral oil.

Jeff Rosenblum
Technical Support
15 Years Industry Experience
Cell (330) 962-2491

Heat Pump Basics

One of the often-overlooked aspects of installing a heat pump is the location. As a heat pump runs in heating mode it tends to build frost on the outside coil. When the frost gets too thick, the efficiency drops. Because of this, it is necessary to put the heat pump into defrost mode. We do this by reversing the flow of refrigerant. So in heating mode, hot refrigerant is sent to the indoor coil to provide heat. In defrost mode we send the hot refrigerant to the outdoor coil to melt the ice and frost that has built up. When the ice melts we must make sure that the water created can safely drain away. This means, be careful where the unit is located. If it is near a walkway, the water created can drain onto the walkway and refreeze. This poses a danger to the homeowner. Another thing to be aware of is to install the outdoor unit above the snow line for the area. This will help keep the coil clean and the heat pump operating efficiently. This is done through the use of pump-ups or stands. As always, if you need any technical assistance with a heat pump you are working on, feel free to contact the Famous Supply HVAC Tech Support Team.

Jeff Rosenblum
Technical Support
15 Years Industry Experience
Cell (330) 962-2491

Codes and Changes

You may have noticed a few recent changes when placing orders for HVAC related material with Famous Supply. The Ohio Revised Codes have recently changed and there are a few things that you need to be aware of. Here are some brief highlights of the changes.

  • All new air conditioning systems must now be equipped with locking-type tamper-resistant refrigerant caps
  • CO detectors are to be installed on all new fossil fuel furnace installations
  • Condensing units and heat pumps are to be installed on a minimum of 3” high pads
  • Programmable set back thermostats are now required

As always, review the most recent local and state codes to make sure your installations are up to date in order to avoid potential code issues. If you have any questions or need assistance, please feel free to contact Famous Supply HVAC Technical Support.

Jeff Rosenblum 
Technical Support Manager 
14 Years Industry Experience
Cell (330) 962-2491

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