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  1. #1
    Join Date
    Jun 2008
    Location
    SF Bay Area
    Posts
    10

    Feedback on suggested system components?

    Hi Folks-

    I'm a homeowner looking to have AC added to a ~4 yr old, single story, 2195 sq ft house w/ central heating (it is a carrier--5 ton, i believe--gas furnace that resides in the attic).

    i have had a couple of HVAC professionals come in and give me quotes for adding AC and media-type air cleaner to the existing furnace and ducting.

    Both have recommended a Bryant 534ANR048 13-SEER 4-ton streamline condenser unit (the site i selected for installation has some constraints) along with an Allstyle plenum coil added to the existing ducting.

    One specified the coil as an "All Style ductboard coil, M# ALSB048" and the other listed the ASFM4821.

    I have two questions:

    - Neither company performed Manual J calculations to arrive at the size of the unit; instead, they both "estimated".. indicated that the full calculations required 2 hrs to perform and were unnecessary. Is this is common practice for HVAC installations and are such rules of thumb are likely to be accurate? Certainly both these companies appear experienced in their trades but this is the first time i've ever had to add AC to an existing home and I'd hate to have them get the system sizing or overall design wrong.

    - What's the professional consensus around the specific condenser recommended by these companies? Are there other alternatives (besides the equivalent Carrier unit) that have the same (small) footprint? Are there any noteworthy differences between this and the Carrier?

    - Re: the coils, I've read on this site that the Allstyle coils are considered builder grade and not high quality. Are there any alternative types of coils that may be better matched to the rest of the system?

    - I haven't been able to find any information about these two specific coils on the Allstyle site. Are there any noteworthy differences between the two types of coils that have been recommended (ALSB048 vs ASFM4821)?

    thanks for any help or feedback you can provide,
    -js

  2. #2
    Join Date
    Feb 2004
    Location
    Kingsport, Tennessee
    Posts
    649

    Manual J

    I suggest that you get more estimates from reputable dealers that do load calculations on all their jobs. I prefer all components to be from one manufacturer if possible. Good luck.
    Every job is a self-portrait of the person who did it.

  3. #3
    Join Date
    Jun 2008
    Location
    SF Bay Area
    Posts
    10
    Thanks for the reply mr big.

    It sounds like running Manual J load calculations is considered a standard part of the trade, then?

    If it really does take 2 hours to calculate, then I can see why this is something installers would want to avoid.

    These two companies were recommended to me by my real estate agent and have high satisfaction rankings on angieslist.. but, of course, I suspect that says more about how they treat their customers than how well they design HVAC systems (don't get me wrong, customer service is important too.. but I'm more concerned about getting a skilled installer who will do excellent work and build the best system possible).

    Does anyone have recommendations on how to find reputable and skilled HVAC installers in my area? are NATE certification, ACCA membership, NCI certification, etc useful discriminators?

    Alternatively, if there are folks on this board who are available to do an installation in the SF Bay Area (South Bay actually--Mountain View), please feel free to post or PM me.

  4. #4
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Quote Originally Posted by js19707 View Post
    Thanks for the reply mr big.

    It sounds like running Manual J load calculations is considered a standard part of the trade, then?

    If it really does take 2 hours to calculate, then I can see why this is something installers would want to avoid.

    These two companies were recommended to me by my real estate agent and have high satisfaction rankings on angieslist.. but, of course, I suspect that says more about how they treat their customers than how well they design HVAC systems (don't get me wrong, customer service is important too.. but I'm more concerned about getting a skilled installer who will do excellent work and build the best system possible).

    Does anyone have recommendations on how to find reputable and skilled HVAC installers in my area? are NATE certification, ACCA membership, NCI certification, etc useful discriminators?

    Alternatively, if there are folks on this board who are available to do an installation in the SF Bay Area (South Bay actually--Mountain View), please feel free to post or PM me.
    It could take two hours,but with a computer ,it's minutes,however there's the time to measure wundows,walls,etc.,and make a sketch of the home.

    Most seem to avoid doing the calculation,likely they estimate the size needed on the larger side,so as not to have inability to cool.

    With a house that never had A/C ,load calc is a must.

    The sources you list above are a good place to start looking.

    Call from the ones that are on more then one list.Ask"Will do be able to do a Man. J,S and D ,to size,select equipment and double check the existing duct system"

    Keep dialing until you get a yes!

  5. #5
    Join Date
    Jun 2008
    Location
    DFW area
    Posts
    13
    I just had our entire HVAC system replaced in our house just a week or so ago. I too went through getting bids from 4 different contractors. Prices varried widely too I might add .. even matching apples to apples!!

    Only one of the 4 actually did a Manual J load calculation, and did it all on his laptop encouraging me to look on at all the information he entered. It did not take anywhere near 2 hours!

    I had a 2.5 ton originally (plenty old) and never kept the house cool during peak summer loading! Surprisingly the Load calc called for a 3.5 ton! Believe it or not, NONE of the other 3 contractors did any measurements whatsoever, and each of them "guessed" a 3 Ton unit would be more than adequate. I was uneasy about that and only adding another 1/2 ton wasn't the info I was really looking for.

    So, the long and short.... I learned that the 1/2 ton units don't come with some of the nicer features...dual speed scroll compressors, variable speed motors and the like, so I went to 4 ton system.

    I am absolutely thrilled with the new unit. The house has never felt so good and is quick to cool down 3 or 4 degrees in just a few minutes, then goes into slow speed mode. Some may say I went overboard.. I dont' think so.

    Long and short - get the Manual J load done from someone! It gives you a benchmark rating to work from. Even if that is off 20%, better than shooting off the mouth with speculation or 'his advice'. Leave the guessing to someone else. I have had a very rapid learning curve on HVAC stuff in the last month or so while researching stuff.

    Good Luck ------->

  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,935
    How constriant is the area for the condenser.

    Guessing at size, could get you high humidity, or not cool enough.
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  7. #7
    Join Date
    Jun 2008
    Location
    SF Bay Area
    Posts
    10
    Quote Originally Posted by beenthere View Post
    How constriant is the area for the condenser.
    Well the location I was hoping to put the condenser unit is to one side of the garage. That side of the house also has "boat parking" (the previous owner had a boat, and while I don't plan on going nautical i'd hate to lose it if it's a feature that might help sell the place if/when i ever move). AIUI the recommended Bryant unit measures (approx) 44"x17"x37" and only requires 6" of clearance from the wall. This size fits in the chosen location and seems to leave enough room for some one to park (assuming they don't back into the condenser unit).

    There is another alternate site which will accommodate a larger unit but would be visible from the backyard and would require removing some plants and possibly a small tree (and, thus, has a low WAF--wife acceptance factor). If it saves me a significant amt of money to relocate to the alternate site I may be able to sell it (i might have to buy her something with part of that money, though!)

  8. #8
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Quote Originally Posted by avflyguy View Post
    I just had our entire HVAC system replaced in our house just a week or so ago. I too went through getting bids from 4 different contractors. Prices varried widely too I might add .. even matching apples to apples!!

    Only one of the 4 actually did a Manual J load calculation, and did it all on his laptop encouraging me to look on at all the information he entered. It did not take anywhere near 2 hours!

    I had a 2.5 ton originally (plenty old) and never kept the house cool during peak summer loading! Surprisingly the Load calc called for a 3.5 ton! Believe it or not, NONE of the other 3 contractors did any measurements whatsoever, and each of them "guessed" a 3 Ton unit would be more than adequate. I was uneasy about that and only adding another 1/2 ton wasn't the info I was really looking for.

    So, the long and short.... I learned that the 1/2 ton units don't come with some of the nicer features...dual speed scroll compressors, variable speed motors and the like, so I went to 4 ton system.

    I am absolutely thrilled with the new unit. The house has never felt so good and is quick to cool down 3 or 4 degrees in just a few minutes, then goes into slow speed mode. Some may say I went overboard.. I dont' think so.

    Long and short - get the Manual J load done from someone! It gives you a benchmark rating to work from. Even if that is off 20%, better than shooting off the mouth with speculation or 'his advice'. Leave the guessing to someone else. I have had a very rapid learning curve on HVAC stuff in the last month or so while researching stuff.

    Good Luck ------->
    Heat Pump or furnace?

    Did they rework the 2.5 ton duct system ,when installing the 4 ton?

    Any idea what the static pressure of the duct system is now/You only would if they tested it,or you have an Infinity Control that gives you the static.

    Assuming you have a VS indoor fan,high satic can cause issues,hoping the re-did the ducts so you have no issues.

  9. #9
    Join Date
    Jun 2008
    Location
    DFW area
    Posts
    13
    Quote Originally Posted by dash View Post
    Heat Pump or furnace?

    Did they rework the 2.5 ton duct system ,when installing the 4 ton?

    Any idea what the static pressure of the duct system is now/You only would if they tested it,or you have an Infinity Control that gives you the static.

    Assuming you have a VS indoor fan,high satic can cause issues,hoping the re-did the ducts so you have no issues.
    No, I have not had a static pressure conducted on it. They are coming back early next week for follow up and 'fine-tune' the dampers and ducts and perhaps reconfigure some dip switches on fan A/H unit. I will ask for the static test at that time. The controller is Honeywell FocusPro 6000series ( I think), not the VisonPRo IAQ themo. The system is using a gas fired furnace. The system is a Amana ASX16 seer and matched 80% gas furnace / AH.

    Yes, they added an additional 8x10 supply vent with flex duct and added a 16 x 16 return using 10 inch flex duct. The rest of the house has rigid ducting put in in 1984 when the house was built - all still well insulated. The downstairs is virtually impossible for adding in more ducts as second story sits on top... (although they did find a place to add one and there actually is one more place that they could (and probably should) add another. There are 9 supply vents (various sizes -) and 3 large return air sources. All go into VERY large insulated supply and return plenums in the attic.

    The vast majority of the 'main rooms' we spend time in are large with doors and a lot of windows getting blasted all day by the summers sun. I do have a 'desktop' non-precision set of gages temp, humidity, and a barometric pressure gage. Humidity is around 45% down about 15% from previous system - none of the ducts are dripping water or even moist.

    What sort of 'problems' would you allude to me having with a 4 ton unit? What should I insist on these guys doing when coming back next week to finalize and fine tune the system - not that I can really tell that anything needs to be done. All rooms are well balanced temp wise as they are.

  10. #10
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    High static,increases operating cost,and can cause early indoor motor failure.

    Not saying that's is your situation.Thr ducts they added sound like the coul be all the extra you need,If you origial ducts were well sized in the begining.


    Where did the add a supply ,that didn't cause the room to get to much air?

  11. #11
    Join Date
    Jun 2008
    Location
    Florida
    Posts
    26
    As far as the Manual J--You can play with the numbers to get anything you want.

  12. #12
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,935
    And that means what?

    The only time someone makes it say what ever. Is when they installed a size that doesn't work.

    If a company takes teh time to do one berore the sale, they don't fudge them to say what ever.
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  13. #13
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
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    18,836
    Quote Originally Posted by Shark207 View Post
    As far as the Manual J--You can play with the numbers to get anything you want.
    What would be the point if you did all the measurements,etc.??

    Of course you can do it,but if someone does it correctly ,you'll be proven wrong.

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