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  1. #1
    Join Date
    Jan 2013
    Posts
    12

    Post Questions for Selecting a HVAC Contractor

    In the next few weeks I'll be having several HVAC companies out to my house to discuss the possibilities of adding an AC (currently NG furnace only) unit, heat pump or complete new dual fuel system (I feel that that the current furnace is slightly undersized but would like to see a Manual J to donfirm). I'd like to know all of my options so that my house is comfortable without breaking the bank.

    Through reading the various posts on this site I came up with the following questions, focusing on the installation side:

    • Are you licensed, bonded and insured? What other credentials do you/your company have? How are your guys trained/schooled? (NATE certified technicians, BPI certification)
    • Do you have a book showing what type of work you do?
    • References from past installs?
    • Experience in the industry?

      Equipment Sizing Questions:
    • Have you performed a Manual J heat loss calculation? What are the design temps that you use? What installation values did you use? What are the heating and cooling loads?
    • If heating is much more than cooling loads, is a Heat pump appropriate?
    • What about filter cabinet?
    • What do you do to test the ducts?
    • Can the current ducts handle the airflow of the new proposed system?
    • For a Heat Pump, can you provide me a COP at various temperatures table

      Equipment General Questions:
    • What warranty are you offering? Is that from the contractor, manufacturer or a third party?
    • Are there any rebates or special financing offers?
    • What type of performance do you expect out of the new system?

      Installation process Questions:
    • What responsibilities do I have to prepare for the install?
    • How long will the installation take?
    • After furnace installation, are your install technicians proficient in the use of a combustion analyzer to verify proper firing (not under fired, not enough fuel entering burners) i.e. Do they perform a combustion analysis to make sure burner is set up properly?
    • How do they dial-in the airflow on the new furnace?
    • Do you check static pressure and heat rise?


    Did I forget anything? What would be your thoughts if a customer asked you these questions?

  2. #2
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,696
    Where do you live? What kind of house is it? How old is the home? Where is the furnace, ductwork and registers located?

  3. #3
    Join Date
    Jan 2013
    Posts
    12
    Quote Originally Posted by George2 View Post
    Where do you live? What kind of house is it? How old is the home? Where is the furnace, ductwork and registers located?
    Northeast of Seattle, 2 story with crawl space, 2004 build, downflow garage located, ducts located in the crawl space registered located on the floor in front of windows.

    Previous thread for referance: http://hvac-talk.com/vbb/showthread....all-of-Furnace

    I'm really wanting to know if I am asking all of the right questions to help ensure that I choose a contractor who will do the highest quality job for this application.

  4. #4
    Join Date
    Dec 2010
    Location
    The Quad-Cities area (midwest).
    Posts
    2,696
    Quote Originally Posted by Surprise View Post
    Northeast of Seattle, 2 story with crawl space, 2004 build, downflow garage located, ducts located in the crawl space registered located on the floor in front of windows.

    Previous thread for referance: http://hvac-talk.com/vbb/showthread....all-of-Furnace

    I'm really wanting to know if I am asking all of the right questions to help ensure that I choose a contractor who will do the highest quality job for this application.
    Thank you for the information. A furnace located in the garage presents challenges enough. Throw in a counterflow with ductwork to a crawlspace for a 2 story home really becomes tricky. The advantage you have is where you live. The outdoor temperatures are not too extreme, are they? All the questions listed are good ones to ask. It'll save time (and you won't forget any questions) if you give each contractor a list. Make sure that in the proposal(s) that the things of most importance to you are spelled out completely. A side bar, how does the current system heat? Also, from my experience, the return air side of systems tend to be the weak link. Just a F.Y.I.

  5. #5
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    2,013
    Just a suggestion, but if your qualifying list is to "weed out" the less qualified contractors, you might think about supplying them the list before the visit and ask if they have any issues with supplying you detailed answers to your concerns. Why waste any of your time with someone who might not.... which you won't know until they've been in your home and had the opportunity to try and sell you something? Just a thought.

    I read your other post also. Your complaint about the present system seems to stem from the long recovery time and lack of warm enough air coming from the registers. Another thought: Your furnace is located in the garage and the ductwork in a crawlspace. Is the ductwork in the crawlspace and especially in the garage sealed properly? Is the ductwork in the crawlspace and garage insulated? Long runs of uninsulated ductwork in a cold crawlspace can and will cool the air down some. Air leaks........ well they push and pull heated air from spaces you're not necessarily wishing to spend money heating, not to mention carbon monoxide from the garage. If you add air conditioning you will want all the ductwork insulated anyhow, because if you don't it will possibly condense moisture on it (sweat) and cause other problems.

    Fact: A properly sized furnace is "properly sized" for the coldest day expected throughout the entire year and over-sized for every other day of the heating season. This sizing will lengthen run times when setbacks in temperature are utilized. This lag in bringing a "cool" house back to comfort level is one of the reasons intelligent recovery setback thermostats came about. The mass of the entire home has to be brought back up to temperature also, not just the air...... this amount of extra energy/verses time is not factored into a heat load calculation.

    If your furnace can maintain temperature in your home no matter the temperature outside..... it's at least sized big enough for the home. Doesn't say anything to if it's over sized though. Sizing a furnace for quicker recovery times coming out of setback gives you one side effect ....... now it's even more over sized for all the days during the year when it's not design temperature. Just something to think about.
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  6. #6
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,287
    http://www.climate-zone.com/climate/...a-tac-airport/
    < 5,000 HEATING DEGREE DAYS

    30 DAYS < FREEZING

    SEATTLE
    ASHRAE 99.6% 24.0'F
    ASHRAE 99.0% 28.0'F
    ____________ __

    If one goes more than 40 miles East of Seattle the design conditions are going to be significantly different
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  7. #7
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,287
    Heat Loss might be < 30,000 BTU/Hr for dT = 46'F / 2,000 Sq Ft [ 2 * 1,000 sq feet per floor]

    Might have to add 5,000 BTU/ hr for heat loss from R-6 insulated duct ( 200 feet of 12 inch diameter = 628 square feet)
    Attached Images Attached Images
    Last edited by dan sw fl; 03-29-2013 at 03:58 PM.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  8. #8
    Join Date
    May 2004
    Location
    south louisiana
    Posts
    3,188
    in my location heating only ductwork differs from air conditioning/heating ductwork.

    most existing homes that have/had heating only systems have ducts that
    are all either 6" or 7". whereas for ac/heat the ducts are sized for the room
    to be conditioned. 6" ducts are common in master bathrooms, but for
    larger rooms the ducts should be sized for the room & its heatng/cooling
    requirements.

    I'd ask the companies to evaluate ductwork, see how ducts are sized to
    corresponding rooms (bigger rooms require more air/larger ducts or more than
    one duct)
    checking ductwork for leakage & seal of ductwork.

    yours is hard pipe ducting or flex ducting?

    looks like a pretty comprehensive list of questions.
    ask about how they seal ducts..mastic or mastic tape is
    good, duct tape & foil tapes fail quickly.

    as noted in the other thread, comfort issues/temp differences
    can also be related to air infiltration into the house.
    blower door testing of the house measures & identifies leakage
    as does duct testing measure & identify duct loss.
    both are recommended.
    both BPI & Resnet list auditors/raters nationwide.

    best of luck.
    The cure of the part should not be attempted without the cure of the whole. ~Plato

  9. #9
    Join Date
    May 2007
    Location
    DC Metro Area (MD)
    Posts
    3,371
    You've come up with some very good questions, and you've received good input from others above. I'll second what firecontrol said in that you may catch some people off-guard, so be polite and don't waste their time of course. I think a lot of companies want the chance to please customers who know and appreciate good work as it builds their reputation, and those customers tend to refer them to others. But others shy away from these customers as they know they lack to proper skill set to do the work properly, or they just really do not care to do business with a particular person (and there are situations that warrant this). You don't at all come across as unreasonable to work with; I commend you for understanding the importance of a proper installation and am impressed with your questions. Always remember that the person who is selling the equipment is (almost always) never the person doing the actual install. Again: quality installation practices are key... By now you should have a better idea of which companies to call for an estimate and which to avoid. Maybe not. Good work and good luck -- please keep us posted.
    Last edited by RyanHughes; 04-02-2013 at 11:23 PM.

  10. #10
    Join Date
    Jan 2013
    Posts
    12
    Thanks for all of the insight that you've given me.

    BTW, all of the sales people that have come out tell me that they'll get these type of questions maybe 1 out of 100+ houses. I suppose I'm special... The good salesman are honest and tell me that they don't know some of the answers and will look into them. The great ones will email me later with the answers.

    I contacted one contractor and was told that they always perform a Manual J. A sales guy from that company came out but did not measure anything, I asked him about doing a manual J and was told that they look up the floor plan from the county records and perform their load calc from that. Now, I haven't nor has the previous owner added any additional insulation so I suppose that that might provide acceptable results. What's your take on that method?

  11. #11
    Join Date
    Jul 2006
    Posts
    1,091
    Does your county list the type, sizes and orinantation of your windows?

  12. #12
    Join Date
    Jan 2013
    Posts
    12
    Quote Originally Posted by rickboggs View Post
    Does your county list the type, sizes and orinantation of your windows?
    I'm not sure. Is having that type of information available at the county level common?

  13. #13
    Join Date
    Jul 2006
    Posts
    1,091
    No, but it's needed for the load.

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