Page 8 of 8 FirstFirst 12345678
Results 92 to 104 of 104

Thread: PM time

  1. #92
    Join Date
    Mar 2015
    Location
    Medford, N.Y.
    Posts
    5,176
    Post Likes
    Quote Originally Posted by Fender60 View Post
    Let me ask rookie question. First an observation. My instructor has diligently tried to instill in us that we should "NOT" automatically install gauges first thing. He said we should think about what if anything is not as it should be. Check amp draw, airflow, etc before jumping in with gauges. One reason he said was some systems are critically charged for one and you need to understand the whole system, not just refrigerant.
    Check out this article by Testo Tools & Jim Bergmann. They talk about "no gauges" in this "AIR-CONDITIONING APPLICATIONS GUIDE,,,A Measurements Reference for the Advanced Technician".

    It is a Good Read.

  2. Likes Fender60 liked this post
  3. #93
    Join Date
    Dec 2011
    Location
    Maryland
    Posts
    499
    Post Likes
    Quote Originally Posted by Core_d View Post
    Yea guage up every time, what if you have low airflow and also low on charge? Temp delta is good, enthalpy delta is good, discharge line temp is normal. Yet total capacity is low and more easily diagnosed with a pressures/ sh,sc

    There are exceptions like if you were just out and checked the charge. But those that have low airflow are also low on charge...js


    Sent from my iPhone using Tapatalk
    Maybe check airflow? Lol

  4. #94
    Join Date
    May 2014
    Location
    Bay Area California
    Posts
    21,188
    Post Likes
    Well, a PM is just that. What we do are things to find problems before they take the unit down. Like check bearings, grease bearings, look for leaky capacitors, cracks in the fan blade, oil on the piping, inspect electrical, etc.

    If a unit has poor air flow and is low on charge, then there won't be cooling going on. And that's a service call.


    Quote Originally Posted by Core_d View Post
    Yea guage up every time, what if you have low airflow and also low on charge? Temp delta is good, enthalpy delta is good, discharge line temp is normal. Yet total capacity is low and more easily diagnosed with a pressures/ sh,sc

    There are exceptions like if you were just out and checked the charge. But those that have low airflow are also low on charge...js


    Sent from my iPhone using Tapatalk
    If you were a real tech, you'd solder a relay on that board and call it good to go.

    I do a triple evac with nitro to remove non condensables.

    I use 56% silver on everything except steel.

  5. Likes Fender60 liked this post
  6. #95
    Join Date
    Dec 2012
    Location
    columbus, OH
    Posts
    6,447
    Post Likes
    I do check airflow in a round about way, by checking the refrigerant charge and temp split.

    Heres another example this unit is cooling like a champ yet the charging chart says it should have a head of 258 and 7degrees sc. how you gonna spot that without slappen a gauge on it?


    Sent from my iPhone using Tapatalk

  7. #96
    Join Date
    Dec 2011
    Location
    Maryland
    Posts
    499
    Post Likes
    Quote Originally Posted by Core_d View Post
    I do check airflow in a round about way, by checking the refrigerant charge and temp split.

    Heres another example this unit is cooling like a champ yet the charging chart says it should have a head of 258 and 7degrees sc. how you gonna spot that without slappen a gauge on it?


    Sent from my iPhone using Tapatalk
    It's low because you're gauging up every time

  8. Likes Core_d liked this post
  9. #97
    Join Date
    Dec 2011
    Location
    Maryland
    Posts
    499
    Post Likes
    Do you work on any "rooftop farms?" If so, you still gauging up?

  10. #98
    Join Date
    Dec 2012
    Location
    columbus, OH
    Posts
    6,447
    Post Likes
    No, i think the most rtu’s at one place is 8 or 9


    Sent from my iPhone using Tapatalk

  11. #99
    Join Date
    Mar 2015
    Location
    Medford, N.Y.
    Posts
    5,176
    Post Likes
    Oh Boy,I am tired.I did a 8 hr PM on 2 LuxAire 5t RTU and 1-2t Fujitsu. Washed all 3 evap and cond coils.Replaced 1 cond fan motor/cap, replaced a 55/440 run cap on 1 unit. 1 RTU low on freon,found leak,repaired,added freon....Darn. I forgot to mention anything to the customer about what I did.Except for saying to them,at the end of the day"here is your bill for what I did".

  12. #100
    Join Date
    Feb 2004
    Location
    New Mexico
    Posts
    8,583
    Post Likes
    A PM shouldn't be sold w/o going over the units first. Otherwise it's like insuring a burning house. Once a unit has been commissioned or gone over I see no reason to check air flow as nothing has changed.
    If something had changed the shop probably would have heard about it. Same with some other things like a loss of refrigerant and other performance trouble.
    The touchy/feelie method of refrigerant testing makes sense for a seasoned tech. Even a temp test of sub-cooling can tell a good tech a lot. There s also refrigerant loss with most gauges unless the hoses aren't emptied or a stubby is used. While there won't be precise numbers most techs can tell if there is a refrigerant problem.
    I've seen guys strap on gauges first thing. Look for a genie to pop out and whisper what's wrong. It also assumes the refrigerant is the problem when it's more likely something else.

    I could guess that because PM's are so boring for experienced techs they might want to just make it more interesting by testing stuff.

    As with much of the work we do, probabilities need to be considered if a PM is going to not be a $$$ loss. What's important and what's just going through the gears.

    I do remember a pm a buddy was doing at a restaurant (occupied). He was testing a high limit on a RT unit. He took the belt off the blower and fired it up. He didn't know (yet) that the high limit had failed. Before he could respond he had filled the restaurant with thick smoke. He swore he would never test another high limit.
    Unforeseen events.
    Like an old boss that was checking for gas leaks in a crawl space with his Zippo. A sand cast hole in an elbow taught him how to crawl very fast and also what they call them crawl spaces.
    Give me a relay with enough contacts, and I'll run the world!

    You can be anything you want......As long as you don't suck at it.

    USAF 98 Bomb Wing 1960-66 SMW Lu49

  13. #101
    Join Date
    Dec 2011
    Location
    Maryland
    Posts
    499
    Post Likes
    Quote Originally Posted by hvacker View Post
    A PM shouldn't be sold w/o going over the units first. Otherwise it's like insuring a burning house. Once a unit has been commissioned or gone over I see no reason to check air flow as nothing has changed.
    If something had changed the shop probably would have heard about it. Same with some other things like a loss of refrigerant and other performance trouble.
    The touchy/feelie method of refrigerant testing makes sense for a seasoned tech. Even a temp test of sub-cooling can tell a good tech a lot. There s also refrigerant loss with most gauges unless the hoses aren't emptied or a stubby is used. While there won't be precise numbers most techs can tell if there is a refrigerant problem.
    I've seen guys strap on gauges first thing. Look for a genie to pop out and whisper what's wrong. It also assumes the refrigerant is the problem when it's more likely something else.

    I could guess that because PM's are so boring for experienced techs they might want to just make it more interesting by testing stuff.

    As with much of the work we do, probabilities need to be considered if a PM is going to not be a $$$ loss. What's important and what's just going through the gears.

    I do remember a pm a buddy was doing at a restaurant (occupied). He was testing a high limit on a RT unit. He took the belt off the blower and fired it up. He didn't know (yet) that the high limit had failed. Before he could respond he had filled the restaurant with thick smoke. He swore he would never test another high limit.
    Unforeseen events.
    Like an old boss that was checking for gas leaks in a crawl space with his Zippo. A sand cast hole in an elbow taught him how to crawl very fast and also what they call them crawl spaces.
    Your mistake is assuming the unit has been properly commissioned.

  14. #102
    Join Date
    Feb 2004
    Location
    New Mexico
    Posts
    8,583
    Post Likes
    Quote Originally Posted by GorillaTight View Post
    Your mistake is assuming the unit has been properly commissioned.
    I was talking about a PM bid. The contractor might have commissioned the equipment or gone over it. Point being the contractor should be confident things are ok. Keep the faith.
    Give me a relay with enough contacts, and I'll run the world!

    You can be anything you want......As long as you don't suck at it.

    USAF 98 Bomb Wing 1960-66 SMW Lu49

  15. #103
    Join Date
    Dec 2011
    Location
    Maryland
    Posts
    499
    Post Likes
    Quote Originally Posted by hvacker View Post
    I was talking about a PM bid. The contractor might have commissioned the equipment or gone over it. Point being the contractor should be confident things are ok. Keep the faith.
    "Keep the faith?" I thought you were an atheist? ...But anyways, you're lucky enough to have techs bid contracts? We get salemen that only care about the model, serial and if it's operational.

  16. #104
    Join Date
    Feb 2004
    Location
    New Mexico
    Posts
    8,583
    Post Likes
    Quote Originally Posted by GorillaTight View Post
    "Keep the faith?" I thought you were an atheist? ...But anyways, you're lucky enough to have techs bid contracts? We get salemen that only care about the model, serial and if it's operational.
    Even atheists have faith in something if only that the sun will rise tomorrow.
    About salespeople. I know some hold their own BUT I remember one that didn't. So
    I started looking at how a tech could be the primary sales person w/o really having to sell as many tech will tell you if asked "I'm not a GD sales person."
    I asked myself, how much information would be needed to accurately price a PM.
    Not much it turns out. 5 things actually.
    The idea was to turn a form with this info and have the office send a bid. I wanted to reduce the time to bid a PM to 15 minutes. The info would be entered into a spread sheet and automatically calculated. That was 1991. The system was beta tested up to 20 tons and I used it for many years.
    That why I know those that shotgun PM's or treat all units as the same are not bidding accurately and might also why they say there in no money in PM's.
    I once thought of marketing the program if there was any commercial interest.

    The PM labor time was roughly based on a national poll of what contractors charged for the example 5 ton R/T combo unit, both the time for a complete inspection and for an operational check. Other size/types were figured from there.
    I know shops will be different which is why a PM has to be outlined as to what's included. Just can't have techs taking off on their own determining what's important or the PM might not be profitable.
    Give me a relay with enough contacts, and I'll run the world!

    You can be anything you want......As long as you don't suck at it.

    USAF 98 Bomb Wing 1960-66 SMW Lu49

Page 8 of 8 FirstFirst 12345678

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Related Forums

Plumbing Talks | Contractor MagazineThe place where Electrical professionals meet.