Charging and manifold gauges...

rsilvers

The last time I had a pro come and charge one of my systems, he didn't seem to know how to use the manifold to charge the system. He quoted me $1600 to try to find a small leak, or $26,000 for a new system. I paid him his $200 diagnosis fee, and then added $30 in stop-leak myself. I never had another issue.

It got me wondering - what percent of AC techs do subcooling and superheat calculations? I asked my neighbor who owns an HVAC company, and he said that in his experience, the techs just bring the vapor line to 40F, and don't do anything beyond that.

How much efficiency are they giving up if they just do that vs do the indoor wet-bulb temp and actually use tables, do the math, or use an app?

mattmia2

It is not just about efficiency, you can cause liquid refrigerant to return to the compressor and destroy the compressor if you have too much charge in it. If you have too little charge you can cause the compressor to not be properly cooled by the returning vapor. It is important for the operation of the system, not just efficiency. Those are the extremes, there is some leeway in a charge where the system will operate properly and it is less critical in a thermostatic expansion valve system vs an orifice system.

ChrisJ

You added stop-leak eh? That's a shame.


I don't know what percentage, but anyone that's installing a TXV system should be checking both SH and SC. Anyone installing a piston system should be at a minimum checking SH. I don't know how anyone could use a number like 40F........ That would highly depend on what the evaporator's doing.

I've seen many braze without flowing nitrogen which annoys the hell out of me.

pecmsg

rsilvers said:

The last time I had a pro come and charge one of my systems, he didn't seem to know how to use the manifold to charge the system. He quoted me $1600 to try to find a small leak, or $26,000 for a new system. I paid him his $200 diagnosis fee, and then added $30 in stop-leak myself. I never had another issue.

It got me wondering - what percent of AC techs do subcooling and superheat calculations? I asked my neighbor who owns an HVAC company, and he said that in his experience, the techs just bring the vapor line to 40F, and don't do anything beyond that.

How much efficiency are they giving up if they just do that vs do the indoor wet-bulb temp and actually use tables, do the math, or use an app?

Professional
Someone that gets paid for their services!

You didn't get a "Professional" you got a sales tech!

rsilvers

ChrisJ said:

You added stop-leak eh? That's a shame.

Because it coats the inside and can reduce thermal efficiency? The system was 22 years old and I wasn't ready to replace it for $26,000 because it is only for one area that we don't use much, and I also didn't want to spend $1600 to have an unknown chance of finding a leak and then get quoted some unknown amount of money to fix it. I was really happy that I was able to extend the life by years.

pecmsg

rsilvers said:

You added stop-leak eh? That's a shame.

Because it coats the inside and can reduce thermal efficiency? The system was 22 years old and I wasn't ready to replace it for $26,000 because it is only for one area that we don't use much, and I also didn't want to spend $1600 to have an unknown chance of finding a leak and then get quoted some unknown amount of money to fix it. I was really happy that I was able to extend the life by years.

Or days!

rsilvers

It is on the 3rd season so far.

SuperTech

rsilvers said:

It is on the 3rd season so far.

You are lucky. In my experience that stuff rarely works and usually causes more severe problems than the one it was designed to solve.  It plugs up metering devices and kills compressors. I stopped using it many years ago. 

It's better to actually find the leak and repair it properly. 

mattmia2

I did use stop leak somewhat successfully in a dehumidifier that had leaks in the evaporator. It worked during the season then over the winter the stop leak wasn't circulating to seal the new leaks and it leaked out over the winter.

rsilvers

"It's better to actually find the leak and repair it properly."

Yes if you can do it yourself. No so clear if you are paying others in an area where they charge by the job but you have found that it works out to $400 an hour.

Since I made this post, I got my certification. Now I would recover the system, pressurize it with nitrogen and trace gases, and find the leak. Repair it. Re-charge the system.

ChrisJ

rsilvers said:

"It's better to actually find the leak and repair it properly."

Yes if you can do it yourself. No so clear if you are paying others in an area where they charge by the job but you have found that it works out to $400 an hour.

Since I made this post, I got my certification. Now I would recover the system, pressurize it with nitrogen and trace gases, and find the leak. Repair it. Re-charge the system.

You said in another post you took your 608 type 1 test.

That's a simple online test for small appliances like dehumidifiers, refrigerators, window A/Cs. I think it was appliances with a charge of 5 pounds or less....

It does not cover central A/C like split systems etc and I do not believe it includes minisplits technically.

You would need a type II for that.

rsilvers

These are below 5 lbs.

pecmsg

608 is minimum and worthless!

vtfarmer

I would strongly recommend doing what I did when I realized that the local HVAC companies would only either rip me off or outright refuse to work on a system that was older than 10 years old:

(This is all on top of having repaired my own automotive A/C systems since I was a teenager, from which I already had a gauge manifold, vacuum pump, and understood the theory behind how basic phase change refrigeration works)

- take a community college course that includes all three parts of the EPA 608 cert and pass the test (I did universal because, why not?)
- buy this text book and read the chapters relevant to the type of system you want to fix: https://www.amazon.com/gp/product/1401837654/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
- buy more tools (recovery machine and tank rated for a high enough pressure to store R410a, if that's what's in your system, micron vacuum gauge, hygrometer, dry nitrogen tank, regulator, and low flow regulator for brazing, then I got fancy and also bought a digital gauge set, nicer hoses, valves, service valve core removers, and a bunch of other small stuff)
- Between my home and my rental I have four heat pumps that I need to maintain, so I started by taking measurements and pouring over that textbook to try and get the theory of what they're doing to line up with the actual superheat/subcooling performance of the system (picture in your head where in the tubing the charge is boiling, how the TXV is moving to regulate this, etc)
- Watched hours of youtube videos by actual AC techs (look for ones from the guy in NJ, I forget his name but he's good) which only really made sense to me once I had done all of the above. This is more to get what I learned in the 608 class to line up with the practical procedures of how to use the service tools and actually carry out repairs. Again, there are lot of videos which are crap so you need to make sure you're watching someone who actually knows what they're doing and is demonstrating competent practices.

Once I got through the above, only then did I attempt the repairs which I had been told were either not worth doing or would cost a lot of money for something fairly small, like a TXV.

Note that I am a fairly accomplished metal fabricator, so I already knew how to braze and have a nice torch setup, but even then I needed to practice brazing small copper tubing before I was confident working in the tight space next to the compressor of once of my heat pumps to replace a TXV. If you have not brazed before then you need to spend a lot of hours practicing doing it before you get a good sense of when the metal is hot enough (but not too hot), how to regulate your torch and not incinerate everything around it, etc.

rsilvers

All 608 are worthless or just T1? There is T1, T2, T3, and Universal. I spent many hours on the Universal questions and it is a lot of stuff.

vtfarmer

rsilvers said:

All 608 are worthless or just T1? There is T1, T2, T3, and Universal. I spent many hours on the Universal questions and it is a lot of stuff.

I believe pecmsg's point, which I would agree with, is that studying the material for the 608 test starts to give you context to learn about what you actually need to know to successfully work on these systems, but by itself does not convey everything you need to know.

Does your local technical or community college offer HVAC classes?

rsilvers

vtfarmer said:

I would strongly recommend doing what I did when I realized that the local HVAC companies would only either rip me off or outright refuse to work on a system that was older than 10 years old: /blockquote>

I will try to pass the T2 test soon. I already passed four practice tests for it, so I expect to be ok.

I have the tools - gauges - manifold. Pump. Recovery tank. Wet-Bulb temp. I am a licensed oil-burner tech and did my boiler install on my own - including the design, soldering, and wiring. Worked great all winter.

clammy

To answer your question about sh and sc calc and service tech ,I know that I personally always check and that just about every installer worth his dirt does the same . I ve really have never heard a owner of a Hvac company state they just look at the suction temp . I ve known plenty of lazy service guys on the residential line who would follow your neighbors mantra but just about any refrigeration / ac installer ,start up or service guys usually always check ,you have to ensure proper charge and operation other wise it’s a crap shoot. Personally I have a couple of leak dectectors and some are better then others . The usually culprits are either outdoor condenser coils and evaporator coils or possible equilizer line on trv s
And some times the occasional braze or sweat joint . Get a Bacharach h10 it will find the leak before you go through reclaiming and nitrogen pressure w trace . The h10 will clearly find the area where your leaking now weather it’s repairable or not and worth repairing is another issue . Being you have put stop leak in it if opened to repair even though reclaimed there nothing to say that any trace stop leak when exposed to air will solidify and cause issue in future operation ,personally I never I use it finding that the ingredients to contain toluene which is harmful to the respiratory System and toxic and flammable and will never permit the reuse of a line set at least by myself .
I guess when you have tech working for you who knows what they will do but when you alone and are help accountable for your actions and cause and effect of it you tend to not use stop leak and those that demand its use can find some one else or like yourself do it all your self and hold yourself reasonable for the cause and effect.
I kninda love it when I come across a old leaky or fairly newer r 22 system in the same shape ,there’s nothing I’m gonna do to really save the day unless something really stupid like leaky shrader valve cap but other wise when it come to leaks .it usually is a money wash and in the long run the wiser money would replace ,that’s not a sales guy just a guy who does not want a pissed customer and does not want to waste everybodies time ,why cause to myself my time is valuable and I usually don’t like to waste it espically for zip in the pocket .
So please spend some money on educating yourself and buying the equiptment and let’s not forget a jug of r 22 or replacement junk and when your done sit on some soon to be totally phased out refrigerant . Truely wishing you the best of luck in your project . Ps if your neighbors in the business and a pro why ain’t he lending a hand possible he already knows the outcome and a wise man may help neighbors but a great way to be a bad neighbor is to take a job for one . I know I don’t do any paying work in my neighbor hood but help a few .
Peace and good luck clammy
Ps nothing last forever including us

pecmsg

rsilvers said:

All 608 are worthless or just T1? There is T1, T2, T3, and Universal. I spent many hours on the Universal questions and it is a lot of stuff.

All 608 does is teach you how to Safely handle refrigerants! It does not teach you basic refrigeration, thermodynamics. and a whole lot more. Most apprentice courses are 4 or 5 years with on-the-job and schooling just to get you started, after the 5 years your real education begins!

rsilvers

"Ps if your neighbors in the business and a pro why ain’t he lending a hand "

He is giving me advice. Also, he does plenty for me. He had his service guys install my pool heater and never billed me for it. He towed his Cat excavator to my other house and spent all day grading my beach himself, and hauled away an enormous truck full of brush. But no, he is not going to come and personally service my AC. He has employees for that.

Also, it wasn't his mantra to only check the vapor temp. He has Testo digital gauges for all of his techs and they do the SH and SC automatically. He said I can borrow the tools. My discussion with him was about the bad tech that came to my house that I could tell didn't know how to use the manifold. I had another one from another company who couldn't fix my thermostat wiring. These two experiences are why I changed to doing these things myself. That is why I am here learning.

SuperTech

If your neighbor was a good friend he would have stopped you from putting that leak sealer junk in your system, or had one of his techs find and repair the leak. Maybe he could have helped you out or given you some advice about the blower in your old hydro air unit as well. 

rsilvers

SuperTech said:

If your neighbor was a good friend he would have stopped you from putting that leak sealer junk in your system, or had one of his techs find and repair the leak. Maybe he could have helped you out or given you some advice about the blower in your old hydro air unit as well. 

I didn't know what was best when I did it three years ago. With what I know now, it may have just been a bad Schrader valve and an easy fix, but I had already consulted professional help - and was given two options - neither of them as good as what I ended up doing.

My rule for asking friends for help is that if it is something they do as their job, I have to pay them. I only ask for free help from friends when it is not what they do professionally. So I would have ended up paying him $160 an hour for the tech.

His advice for the Hydro Air was to replace the full system with a new heat-pump and take the state rebate.

rsilvers

ChrisJ said:

It does not cover central A/C like split systems etc and I do not believe it includes minisplits technically.

You would need a type II for that.

I passed the Type-2 test today, so I am all set with that now.

ChrisJ

rsilvers said:

It does not cover central A/C like split systems etc and I do not believe it includes minisplits technically. You would need a type II for that.

I passed the Type-2 test today, so I am all set with that now.

You found a place open to take the test on a Saturday?

mattmia2

Where did you take the test? Did sanity prevail and it is online now? When I tried to take it 15 years ago i called a few places in the EPA's list and the only one that called back said they didn't have a test scheduled.

rsilvers

Download the free app called SkillCat. You can take the test for free at any time. You have to submit a photo of your driver's license. The app records you taking it on video, and they claim to record your screen. They watch the video to make sure that you don't cheat.

This method has been approved by the EPA. The app also has practice questions in it, but I also took many online practice tests 3-4 times until I could pass them. Some of the questions are stuff one can just know from experience. Others are things no one could know without study because they are memorizing dates of the Montreal Protocol or how many inched of Hg vacuum is needed for various situations. Those are all things that in the real world I would just look up as I needed them, but still - it was useful for them to be on the test because it drilled into me the kinds of things I would need to double-check if I had to recover a system.

Here are some practice tests I used:

https://nationaltradesman.com/building-trades/hvac-techs/epa-608-certification-info/608-types/type-2/high-pressure-practice-test-2/


https://www.escogroup.org/practice/practiceexamsession.aspx?uid=fa8ce666-7049-47cf-9250-90da79b55cd2&q=13


https://www.hvaccertificationpracticetests.com/epa-608/epa-608-free-practice-test-1-type-2-exam/


https://epa.practicetestgeeks.com/epa-608-type-ii-practice-test/