HVAC (residential) questions

[andrew whicker]

Fan speed is right on (unloaded). 1080 rpm vs nameplate 1075

[Bill George]

Working fine for 10 years then starts freezing the coil? Adding the defrost Coolbot thing is Not the answer. You could find the problem with temps and pressure readings I gave you. Airflow or charge, keep guessing?

The TD (Delta T) across the Evaporator would tell you a lot about the air flow rate. Superheat would tell you the state of the charge, as would the low side pressure reading.

[andrew whicker]

I keep forgetting my temp gauges when I go to the house... anyway, washed out the evap cooler with my hose this time. Didn't get any real dust or anything. Water came out pretty clean.

Here's something interesting though: If you Google R22, you can buy it for $300 / 10 lbs.. am I missing something? I thought this stuff was liquid gold pricing? Am I getting completely ripped off at $ 300 / lb?

Example: https://abilityrefrigerants.com/prod...4aAsGfEALw_wcB

[Bill George]

R22 is no longer made.... in this country and I am not sure if it can be legally imported. You could have purchased the MO99 stuff at a local HVAC supply house for about $500 for 25 lbs, or less if your CFC certified.

[Maurice Mcmurry]

The gentleman I learned from would advise that this is an end of life situation for the equipment. My advice is to replace the entire system rather than trying to eek a little more life out of obsolete equipment. That unit looks like it is 30 years old maybe older?

My certificate allows me to buy R22. I always advise residential people to think carefully before spending much on equipment that is over 20 years old. I can't make out the serial number on the A-coil. Part of that number will be a date code.

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[George Yetka]

R22 is black label. You can still get it with a license for maintaining existing equipment. cost to a license holder is 1200 or so for a 25lb can. It is bad practice to reuse refrigerants as no one truly knows what it was you put in your recovery tank to begin with. A tech may have pulled it from a 22 system but someone may have dumped something in the system to top it off that wasnt 22 or very dirty 22. We scrap a few hundred lbs of 22 and "AGAS" the guy we scrap it to can measure purity. we very rarely get above 90% 22. Usually in the 85% range. My guess is that doesnt mean its mixed or anything like that its probably just has moisture or particulates from brazing.

Like Bill said its either charge or airflow. Usually airflow. You can have your tech sniff the joints and coils to eliminate the charge.

If you decide to swap condensers 407 will work well. Line sizing and system pressures should be about the same. If you want to pull the charge and put in a new gas you have to get all the oil out to use 407. Other wise you can pull the 22 and put in M099.

Techs charge a lot per lb on refrigerant to cover all the other stuff they cant charge for. Nitrogen, brazing rod, and not to mention the pile of tools they need. Its a vehicle for charging. If he showed up and gave you an itemized list for depreciation on each tool used, his truck, gas, and consumables it would look bad. So generally they charge refrigerant/parts/labor

[George Yetka]

We have many clients with r22 equipment that hold on to and reuse r22. If you know where it comes from for sure and have it well marked go for it.

[Maurice Mcmurry]

Check that serial number. Charge, Airflow, and Old Age all contribute. Here is a snip from the web that repeats my instruction and experience.

Your Evaporator Coil Problems Might Be More Than Just That

When it comes to the performance of your air conditioning system, the condition of your evaporator coils plays a crucial role. Air conditioning services are based on maintaining these components to ensure seamless cooling and comfort in your home.
The more you know about these components, the better you can maintain them and save yourself time and money. Read ahead to learn about the lifespan of evaporator coils, factors that influence their lifespan and signs that it may be time for a replacement.
What Are Evaporator Coils?

Evaporator coils are an important component of your air conditioning system, responsible for absorbing heat from the air inside your home. Often located within the indoor unit of your AC system, these coils contain refrigerant that evaporates as it absorbs heat, cooling the air that is then circulated throughout your home via ductwork.
As the air passes over the evaporator coils, heat is transferred from the air to the refrigerant, resulting in cooler air being distributed throughout your living space. This process is essential for maintaining a comfortable indoor environment, especially during the hot summer months.
How Long Does An AC Coil Last?

The lifespan of your system’s coils isn’t set in stone, but factors such as the quality of the coils, the frequency of use and the level of maintenance they receive are all relevant. On average, evaporator coils can last anywhere from 10 to 15 years. However, certain factors may cause them to wear out more quickly.
What Affects An Evaporator Coil’s Longevity?

Many homeowners make the mistake of assuming that the lifespan of their HVAC components is out of their control. In truth, there are plenty of factors that influence their life expectancy. Some examples include:

• The quality of materials used
• How often the coils are used
• Whether the coils are maintained regularly through cleaning, inspections and other methods
• Unprotected exposure to environmental factors like high humidity and pollution
• Whether or not the unit is installed by a professional technician

The expected lifespan of your evaporator coils can be altered even on day one, when your AC unit is installed. That’s why it’s so important to make sure yours is installed by a qualified technician, such as those at Deets.
Warning Signs That Your Evaporator Coils Need Replacement

As these components near the end of their lifespan, they may exhibit signs of wear and deterioration. If you notice that your air conditioning system is struggling to cool your home effectively, it could be a sign that the coils are not functioning properly. If you inspect your unit and notice signs of corrosion, rust or other damage, it may be time to replace them.
Additional signs include bad odors and signs of airflow trouble. Foul odors emanating from your air conditioning system could be a sign of mold or bacterial growth on the evaporator coils. Excessive ice buildup can indicate a problem with airflow or refrigerant levels, both of which may necessitate coil replacement.
Delaying replacement can allow even small problems to grow into costly damages. You don’t need that kind of stress, so be sure that you respond to these signs early to minimize the impact on your daily life.
Is It Worth Replacing An Evaporator Coil?

Your evaporator coils may seem like just one small part in a larger machine, but that doesn’t change their importance. Delaying a replacement can lead to a range of issues, including:

• Decreased cooling efficiency
• Increased energy costs for the same amount of cooling
• System breakdowns across your AC system
• Poor indoor air quality, filling your air with pollutants and bacterial growth

Putting off a simple replacement job can cost you money and potentially even your entire AC system. Why put your cooling system at risk when you don’t need to?

[Bill George]

Well speaking to just anyone... the temperature and pressure readings I gave are from over 30 years in the trade and are also well documented. The OP can do as he pleases or not, the MO99 / R438a is made by Dupont and its not a fly by night company. Test as I outlined long ago and do what you want.
Guess and whatever.
https://www.freon.com/en/products/refrigerants/mo99

[Jack Frederick]

Perhaps I missed it Andrew, but is this a heat pump or condensing unit to a gas furnace? An old R22 condenser is a max of 10 seer I believe. You can do far better with the current 410a inverter systems. I’d check to see if there are any rebates on new gear. My daughter’s house just upgraded to an 18 seer Gree inverter condensing unit and air handler. I was happiest that they got rid of the 30 yr old gas furnace. I’ve done their work on their other houses. This one, my wife gave me the old finger shaking, “don’t you dare do this one…” Woulda been a piece of cake.
I appreciate a troubleshooting challenge, but I’d suggest doing the research on what your new options are so you are prepared.

[Bill George]

Perhaps I missed it Andrew, but is this a heat pump or condensing unit to a gas furnace? An old R22 condenser is a max of 10 seer I believe. You can do far better with the current 410a inverter systems. I’d check to see if there are any rebates on new gear. My daughter’s house just upgraded to an 18 seer Gree inverter condensing unit and air handler. I was happiest that they got rid of the 30 yr old gas furnace. I’ve done their work on their other houses. This one, my wife gave me the old finger shaking, “don’t you dare do this one…” Woulda been a piece of cake.
I appreciate a troubleshooting challenge, but I’d suggest doing the research on what your new options are so you are prepared.

My R22 unit condensing unit is 13 SEER, my gas 2 stage furnace is a 96% and with a variable speed ECM motor. If I was to spring a repairable leak on the condensing unit I would repair and recharge with MO99/R438a rather than spend $6000 - $8000 for a new system! Testing the OPs system instead of trial and error and guess is the smart way to go. Yes and do the research R410a is going away also. https://www.lennoxpros.com/news/tran...p-refrigerants

[andrew whicker]

That website looks very legitimate to me.. so it looks to me like I can order 10 pounds for $375. Is it common practice to upcharge 10x the cost of refrigerant?

R22 is no longer made.... in this country and I am not sure if it can be legally imported. You could have purchased the MO99 stuff at a local HVAC supply house for about $500 for 25 lbs, or less if your CFC certified.

[Bill George]

That website looks very legitimate to me.. so it looks to me like I can order 10 pounds for $375. Is it common practice to upcharge 10x the cost of refrigerant?

I would rather you do the temperature drop across the coil same distance either side and make sure its in the range of 18-22 DegF, unit doors closed and normal operation for 30 minutes or so. IF its greater than say 22 deg you have an air flow problem. Less than you have perhaps a charge problem that can be double checked doing superheat. IF you have low charge level again or still, you have a leak. You can use liquid soap watered down a bit to check all the fittings and access valves. If that does not turn up anything usually the A coil has a corrosion leak on the copper to steel and if so its time to R&R the entire unit. This is not guessing but testing, I made a very good living for many years fixing problems others could not or would not find.