Page 1 of 2 12 LastLast
Results 1 to 13 of 26
  1. #1
    Join Date
    Sep 2013
    Posts
    13
    Post Likes

    Converting an RTU from R22

    So I've got a customer that has a Trane YSC model rooftop with two circuits. Circuit 1 has a bad compressor due to the bearings in it failing. Circuit 2 has a compressor that has shorted. Due to the increase in price of 22 the customer was wanting to convert it from 22 to one of the 22 replacements. Has any one had any experience converting an entire RTU to either 407c or 422d or whatever random "drop-in" is being pushed now. Thanks.

  2. #2
    Join Date
    Jan 2012
    Location
    Arrowhead Stadium
    Posts
    1,180
    Post Likes
    With a new compressor I would recommend r407c, has a slight gain in capacity.

  3. #3
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    30,480
    Post Likes
    407C with POE in a new compressor. New ones come with POE.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist
    Member, IAEI

    AOP Forum Rules:







  4. #4
    Join Date
    Aug 2002
    Location
    Southold, NY
    Posts
    21,443
    Post Likes
    2 bad compressors
    R-22
    20+ years old

    Replace the RTU

  5. Likes DerkPerk, thatguy liked this post
  6. #5
    Join Date
    Feb 2006
    Location
    Phoenix,AZ
    Posts
    3,603
    Post Likes
    Quote Originally Posted by pecmsg View Post
    2 bad compressors
    R-22
    20+ years old

    Replace the RTU
    What if the customer doesn't even own the building, let alone the unit? But, are responsible for repairs? Are you going to fix it or let them call someone else?

  7. #6
    Join Date
    Oct 2018
    Posts
    19
    Post Likes
    Quote Originally Posted by KB Cool View Post
    What if the customer doesn't even own the building, let alone the unit? But, are responsible for repairs? Are you going to fix it or let them call someone else?
    You work the your customer and the property manager/building owner to replace the unit. The tenant covers the repair cost towards the new unit and the PM the rest.

    It’s a win, win, win, win. Your customer gets a new unit that doesn’t need repairs, the PM gets a new unit for 30-50% off, you don’t have to fix a piece of shit AND you’ve just started a new relationship with a new customer, the building PM!!!


    Sent from my iPhone using Tapatalk

  8. #7
    Join Date
    Feb 2006
    Location
    Phoenix,AZ
    Posts
    3,603
    Post Likes
    Quote Originally Posted by clutze View Post
    So I've got a customer that has a Trane YSC model rooftop with two circuits. Circuit 1 has a bad compressor due to the bearings in it failing. Circuit 2 has a compressor that has shorted. Due to the increase in price of 22 the customer was wanting to convert it from 22 to one of the 22 replacements. Has any one had any experience converting an entire RTU to either 407c or 422d or whatever random "drop-in" is being pushed now. Thanks.
    yes, definitely 407c. I've done a bunch of them with no problems. Just make sure the unit's running great before you leave. Also, you can go with Scroll's instead of those way too big R2D2 Trane climatuff's. Just at least get one mounting bolt in it. Oh yeah, be sure to check the blower section for filter dryer's that like to clog. You need to change them out. I've seen them left behind by other techs.

  9. #8
    Join Date
    Feb 2006
    Location
    Phoenix,AZ
    Posts
    3,603
    Post Likes
    Quote Originally Posted by DerkPerk View Post
    You work the your customer and the property manager/building owner to replace the unit. The tenant covers the repair cost towards the new unit and the PM the rest.

    It’s a win, win, win, win. Your customer gets a new unit that doesn’t need repairs, the PM gets a new unit for 30-50% off, you don’t have to fix a piece of shit AND you’ve just started a new relationship with a new customer, the building PM!!!


    Sent from my iPhone using Tapatalk


    Hmm, I never thought of it that way. Especially when the customer is going to help foot the bill of the new unit. I'll have to give it a go next time.
    Thanks

  10. Likes DerkPerk liked this post
  11. #9
    Join Date
    Sep 2013
    Posts
    13
    Post Likes
    Thread Starter
    Well the unit itself isn't 20 plus years old. And everything else on it is in great shape. Maintenance has been performed regularly, and the customer is really good about getting repairs made that are needed. They have 40 RTUs and this one is kind of a trial/experimental unit for them. It serves a maintenance shop and they have another unit that also serves the same shop. While I would agree that a new unit would be great, I have been talking with the customer and the brain trust of big wigs is wanting them to go away from r22 units in the near future. You know going greener and saving energy and all that. So he is wanting to replace all of the RTUs right around the same time. So the main idea is to get it up and running reliably until money arrives for the big swap.

    Another question I've got, and I don't know if anyone will have an answer, but who decided 410 was the way to go? Why do they we use 407c? Liebert has been using it since

  12. #10
    Join Date
    Feb 2006
    Location
    Phoenix,AZ
    Posts
    3,603
    Post Likes
    If I had to guess it would be Carrier (united technologies) as our local distributor doesn't even sell a jug of r22 anymore even though it's still legal. Also, Carriers were the first 410 units I ran across. Trane was still selling 22 units at the time. I also heard they got pissed off over the Dry 22 units being sold by other manufacturers.

  13. #11
    Join Date
    Jul 2010
    Location
    napping on the couch
    Posts
    11,764
    Post Likes
    Quote Originally Posted by KB Cool View Post
    What if the customer doesn't even own the building, let alone the unit? But, are responsible for repairs? Are you going to fix it or let them call someone else?
    Often the person renting or leasing is responsible for repairs but the building owner is responsible for equipment replacement.

    I would say a 20 year old unit with 2 bad compressors needs to be replaced.

    Any way to get the building owner to pay for the needed replacement? You are opening up a bag of worms replacing compressors.

    But if you have to repair, go the 407c route.

  14. #12
    Join Date
    Jul 2010
    Location
    napping on the couch
    Posts
    11,764
    Post Likes
    Quote Originally Posted by clutze View Post
    Another question I've got, and I don't know if anyone will have an answer, but who decided 410 was the way to go? Why do they we use 407c? Liebert has been using it since
    That is an amazingly good question and one I've been asking for years. I have yet to get a good answer.

  15. #13
    Join Date
    Nov 2001
    Posts
    90
    Post Likes
    Quote Originally Posted by clutze View Post
    Another question I've got, and I don't know if anyone will have an answer, but who decided 410 was the way to go? Why do they we use 407c? Liebert has been using it since
    The change happened fairly early in my career with a big AC manufacturer, and I was not in compressorized products at the time, so I am not 100% sure about this, but pretty sure:

    Back then, the change was driven by Ozone Depletion Potential (ODP) and the requirements to get away from ozone-depleting refrigerants agreed upon by most countries in the Montreal Protocol. Dupont (now Dow) was pushing R-410A, which is a 50-50 blend of R-32 and R-134a. The big advantage over other candidates was that it ran at high pressure, which allows compressors and coils to get smaller than they could otherwise using R-22, R-407C or R-134a, which are medium-pressure refrigerants. R-410A also has the advantage of having a large Refrigerant Concentration Limit, which allows larger systems than other refrigerants without the need for leak detectors. Carrier was among the first to announce they would use R-410A, though I don't know that things would have been different if they had not.

    R-407C was a short-term substitute because it could be dropped into R-22 systems. The downside is that is does not perform quite as well and has a large glide. That is, the blended refrigerants evaporate at different temperatures for a given pressure, so the evap temperature is not consistent as it moves through the coil.

    I'm looking at ASHREA 34 - Designation and Safety Classification of Refrigerants as I type this, and I just noticed that R-407C is 23% R-32, 25% R-125 and 52% R-134a, so it's pretty close to a 48-52 mix of R-410A and R-134a. Kind of interesting - I did not know that before.

    One thing I learned during a recent ASHRAE seminar on low-GWP refrigerants is that replacements will no longer be able to be condenser only. With the new refrigerants, leak detectors will be required in the indoor air handler, and apparently this will require that the air handler be replaced. The speakers implied that you can't just add a leak detector to the existing unit.

  16. Likes Brian8383 liked this post
Page 1 of 2 12 LastLast

Posting Permissions

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