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  1. #1
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    Question House under construction - HVAC questions (line set length + proximity)

    New house under construction in San Diego County -- fully permitted, GC, fully licenced subs, etc.

    Good sized house, layout such that there's two sides of the house, one side with more daytime use and second side bedrooms. Two separate HVAC systems, both in unconditioned attic, but attic temps shouldn't be too bad comparatively (cool roof, radiant barrier, top chord R13 insulation). Four ton 14 SEER, 96% AFEU 80K BTU furnace, 1600 CFM for the day use side, three ton 14 SEER, 96% 60K BTU furnace, 1200 CFM for the bedroom side.

    Plans called for both AC condensers on one side of house. GC said that I couldn't do that and said I needed one on each side. I agreed but we didn't explicitly discuss where it would go on "not in the plans" other side. Line set is now been put in outside wall (we are still at studs and outside sheathing stage), and while it's perhaps the best of no good choices on that wall, I hate location, and worse is my wife hates it even more.

    Everything I can find via Google says that the line set length required to get over to the other side is perfectly doable and shouldn't be an issue. It's probably 65' to 75' across the attic then 10' down -- so 75' to 85'. All the stuff I read says I want an 1 1/8" / 3/8" line set -- it looks to be $ to $ online. I don't care about the cost at this apparent moderate cost range.

    Equipment:

    Goodman GSX140481 (4 ton AC), Goodman GMSS960804CN, Aspen CR48A coil w/factory installed TXV (day side use, the line set I wish to relocate)
    Goodman GSX140381 (3 ton AC), Goodman GMSS960603BN, Aspen CR36A coil w/factory installed TXV (bedrooms)

    My questions are:

    - Can the 4 ton setup have the line set moved provided it's treated as a "long line set" with any required long line set treatments?
    - If yes, any ideas why my GC might have said it couldn't be on the other side?
    - Assuming I can move the two to the same side of the house, recommended minimum distance between the two condensers?

    Thanks in advance.
    Last edited by beenthere; 06-17-2019 at 04:54 AM.

  2. #2
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    That’s between the installing contractor and the manufacturer.
    I don’t have a problem with long line sets!

  3. #3
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    Goodman web-site shows the GMSS furnace as " limited inventory ", probably due to having a PSC motor, and as of 3 July 2019 they ( manufacturers ) will not be producing furnaces with those types of motors anymore. Certainly future availablity of PSC motors should be around for many years.

    https://www.goodmanmfg.com/products/gas-furnaces

    90% furnaces, Product overview

    Did not see those combo ( OD unit, ID unit to furnace ) as matched systems, only match found was for the RC48C and not the RC48A the AHRI number did not need a Goodman furnace. I did not check the smaller Goodman bid but that also has the PSC motor in that furnace. That OD unit model number should be GSX14036 or 37 not 38, according to their web-site.

    https://www.ahridirectory.org/Home/D...MrWpZQUDNMNTKr

    I would ask this Contractor for the AHRI number(s) for both systems ( like the one given as an example ) proving a matched system as I did not see their proposal as being one. Could be wrong thou.

    If your comfortable/uncomfortable with the phasing out of your furnace due to the motor that's for you to decide.
    Last edited by Bazooka Joey; 06-15-2019 at 11:18 PM.

  4. #4
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    Quote Originally Posted by Bazooka Joey View Post
    Goodman web-site shows the GMSS furnace as " limited inventory ", probably due to having a PSC motor, and as of 3 July 2019 they ( manufacturers ) will not be producing furnaces with those types of motors anymore. Certainly future availablity of PSC motors should be around for many years.

    <link removed because I can not have a link because I'm still too new>

    90% furnaces, Product overview

    Did not see those combo ( OD unit, ID unit to furnace ) as matched systems, only match found was for the RC48C and not the RC48A the AHRI number did not need a Goodman furnace. I did not check the smaller Goodman bid but that also has the PSC motor in that furnace. That OD unit model number should be GSX14036 or 37 not 38, according to their web-site.

    <link removed because I can not have a link because I'm still too new>

    I would ask this Contractor for the AHRI number(s) for both systems ( like the one given as an example ) proving a matched system as I did not see their proposal as being one. Could be wrong thou.

    If your comfortable/uncomfortable with the phasing out of your furnace due to the motor that's for you to decide.
    Thank you for the info. Not what I wanted to hear / read.

    The proposal was done directly to my GC who totally vouches for the sub. The proposal initially didn't even include the AC and furnace models -- I pressed and was given them, but I wasn't given any coil information. This is a top notch GC, and I overall trust him, but this HVAC experience has been a bit of a bumpy ride.

    As to being comfortable or not, the two units are installed in the attic.

    I am going to talk to both the GC and the HVAC sub Monday -- but before than I'm really struggling to find any data on a 4 ton AC max line set. There's lots of info out there both from Goodman and Puron that show a 60000 BTU / 3 ton can go to 250' with the coil being up to 20' higher than the condenser. But I can't find anything for an 80000 BTU / 4 ton. Nothing. But logically, I'm struggling with that a properly sized line set (1 1/8" / 3/8") on a 4 ton would max out at less than 85'. My wife (and I) really want the both condensers on the one side of the house (architect said it could be done that way and drew plans that way).

    Anywhere I can find documentation to help me for this Monday discussion?

  5. #5
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    https://www.alpinehomeair.com/related/IO-258T.pdf

    Dated 2017-2018 says to contact distributor or use manual page 3 also shows a inverted loop to be installed if Air Handler is higher than OD unit as you seem to indicate that is your situation, probably for better oil return to compressor. The inverted loop does not to be that aggressive basically a wide sweep will suffice, but they want the lines to extend higher than the top of the coil.

    These sizes are recommended for line lengths of 79 feet or less to obtain optimum performance. For alternate line sizing options or runs of more than 79 feet, refer to Remote Cooling Service Manual or TP-107 Long Line Set Application R-410A or contact your distributor for assistance.

    IMO..Probably better following ( have them copy/download the manual to show you they followed it ) the manual as the Contractor can say yep contacted Distributer they told me to do it this way. Who knows if that's a true statement.

    Ask for a commissioning report, which should include the final field refrigerant adjustment charge in subcooling number, static pressures, temperature rise across the HX ( Heat Exchanger ) you throw in amprege draw of the ID and OD motors and compressor etc. etc. are all within manufacturer specifications.

    Furnace motors

    http://www.raleighheatingandairservi...ndards-change/

    Residing in California you do not have to register your system to get the maximum manufacturer warranty, but your labor warranty and the manufacturer warranty should start at closing date.

    Again I would ask for the AHRI numbers to prove matching equipment was installed, keeps them on their toes.
    Last edited by Bazooka Joey; 06-16-2019 at 12:35 AM.

  6. #6
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    Quote Originally Posted by Bazooka Joey View Post
    <Link removed as I'm too new>

    Dated 2017-2018 says to contact distributor or use manual page 3 also shows a inverted loop to be installed if Air Handler is higher than OD unit as you seem to indicate that is your situation, probably for better oil return to compressor. The inverted loop does not to be that aggressive basically a wide sweep will suffice, but they want the lines to extend higher than the top of the coil.

    These sizes are recommended for line lengths of 79 feet or less to obtain optimum performance. For alternate line sizing options or runs of more than 79 feet, refer to Remote Cooling Service Manual or TP-107 Long Line Set Application R-410A or contact your distributor for assistance.

    IMO..Probably better following ( have them copy/download the manual to show you they followed it ) the manual as the Contractor can say yep contacted Distributer they told me to do it this way. Who knows if that's a true statement.

    Ask for a commissioning report, which should include the final field refrigerant adjustment charge in subcooling number, static pressures, temperature rise across the HX ( Heat Exchanger ) you throw in amprege draw of the ID and OD motors and compressor etc. etc. are all within manufacturer specifications.

    Furnace motors

    <Link removed as I'm too new>

    Residing in California you do not have to register your system to get the maximum manufacturer warranty, but your labor warranty and the manufacturer warranty should start at closing date.

    Again I would ask for the AHRI numbers to prove matching equipment was installed, keeps them on their toes.
    Great info, thanks.

    Yep, TP-107 is what I had found, but it stops at 60000 BTU / 3 ton. I'll try to find the Remote Cooling Service Manual. Baring that, I'll press GC/HVAC sub to contact distributor or Goodman, and have them measure actual line length -- maybe it would come in at 79' But, if at all possible, the compressor needs to move as it would be in a terrible place (between a detached garage and house that has only a small area (odd shaped due to different angles) that will be basically impossible to screen and right in view corridor walking from driveway to house entry, not to mention loss of space as this is a space that will be used for a dog go out area.

    As to the motor change, I'm not going to sweat the small annual energy cost of PSC over PCM. I debated the single stage vs dual stage and 14 SEER vs 16 SEER cost / payback / cost when something goes wrong, and with putting in solar that should cover all electric (due to terrible SDGE electric rates, they suck, but they sure yield a short solar payback term of 4 years).

    I'll post back, but I'm feeling a little bit better that I can get the line set moved -- I think the GC and HVAC are just taking the easy route and saying it can't be done. I suspect that the HVAC will (besides cost increase) possibly push back on labor warranty, and I'll have to make sure I get some written instructions from distributor or Goodman to protect equipment warranty.

    And, I'll definitely be asking for the AHRI number(s) for both systems, the commissioning report, and the required HERS test report.

  7. #7
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    Here's what was found, I don't see where you reference 60,000/3 ton to me it's a general guideline. Just says anything over 80' lineset. Dated 2012 I'm sure it's still current.

    Says to install a Crankcase heater ( if it does not already have one ) having a TXV, installing a properly sized OEM hard start kit. Lastly a liquid line solenoid valve ( if OD unit is below the ID coil ) and the inverted trap. Even discusses installing a OEM accumulator by the OD unit in A/C applications page 6. The subcooling changes slightly to 6 degree + - 1 degree taken at ID unit. Page 2 and page 4.

    Page 8 discusses final refrigerant field charge. needing to add a predetermined amount when lineset is over a certain length for starters then do the subcooling charge for final adjustment. Hopefully the Installing Contractor is up to the task. Quite a bit of things to do when dealing with long lineset applications ( if they want to follow the guidelines ) not to mention the added cost of items and the extra labor to do all this. The GC or Contractor probably won't like seeing this.

    https://www.alpinehomeair.com/relate...s%201.2012.pdf
    Last edited by Bazooka Joey; 06-16-2019 at 08:05 AM.

  8. #8
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    https://www.alpinehomeair.com/relate..._Rev_41509.pdf

    Page 1 discusses the reasoning for those parts. I suppose if you want a better chance of a longer life compressor may want to have them follow the guide.

  9. #9
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    After rereading your initial post, if your slightly over the magic 79' I would lean on just the inverted loop by the indoor coil and what the recommended lineset that the install guide suggested. For some reason I thought you where well over that length ( 79' ) reason for all those added parts. But the final decision is yours in regards to what you want to do.

  10. #10
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    I had a brain fart all day yesterday -- my brain was fixated on 20000 BTU per ton AC, not 12000 BTU. That's why I kept thinking the TP-107 document was only going to 3 ton A/C.

    Anyway, I had my meeting with my GC today (no HVAC sub there). It started a little rough as I got the lecture I've gotten several times that he hates it when I get too involved and the "I've built all these houses and how many have you built?" and that going over 80' voids the warranty. After letting him blow off his steam, I then nicely gave him the printout of TP-107 and said it doesn't void the warranty, here's the Goodman document, and you just have to do these additional items.

    I fault the HVAC contractor more than my GC as I think the GC was just taking what the HVAC guy said without any attempt at push back.

    Bottom line, it's going to get moved (I think, he said "still needed to run it by HVAC contractor" but I'm going to blow up if the HVAC guy says no) -- which is good as the other location was truly a horrible place.

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  12. #11
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    The GC and the HVAC Contractors gears in their head are turning after you gave the GC the manual. Keep us posted...

    If they are out there,...would like to see the AHRI numbers for your two systems proving matched systems are being installed...

  13. #12
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    Expect to pay a spiff for this. And if the GC's location is in a dog run, please push for the other side. Dog pee will eat up your outdoor coil in a heartbeat.

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