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New Heating and air-conditioning system needed

Noviceatthis
Noviceatthis Member Posts: 11
edited August 2020 in Oil Heating
Apologies, I posted in a previous discussion. I did read the first replies thank you. Here is my updated thread.

I need to replace both my boiler and air conditioning units. My heating system is oil-fired and I have baseboard heating and hot water from it. I have two-zone air conditioning in the basement and roof and two fans outside.

I have received three quotes from different HVAC suppliers with different specs. My current supplier quote is over the new bidders.

The quotes have many variables including three different aircon and two different boiler manufacturers. The SEER ratings are different, the ton capacities quoted are different and the allocation of the different specs are different upstairs and downstairs.

Is there a simple way to understand what the best overall value is?

Thank you in advance for your advice.

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 15,391
    and here is my post from the other thread, to get the ball rolling

    If you're thinking of replacing the boiler and the AC, you really need to go back to square one -- or find a competent professional who will do it for you (they exist; there three in Massachusetts whom I would recommend very highly, if I knew where in the state you were located).

    I'm going to make an assumption here: that your system is hot water heat, not steam. If that is the case -- and in any case for the AC, the first thing that needs to happen before anyone can recommend a boiler or other work is to get an estimate on the total heat loss of your house. It's called a Manual J, and it will be the first thing a pro. will do (there is an on-line calculator, too, put out by Slant-fin, which you could use for fun, to check).

    Then the boiler is sized to that heat loss. There is no other way to select a boiler size other than the proverbial wild a__ guess. Then you can set about selecting the proper boiler for the job -- again, with the help of a real pro. who knows the boiler, how to install it -- and will maintain it down the road, since they all need at least some maintenance.

    Another look at the heat loss calculation will also give you the heat gain for air conditioning -- and thus help the pro. select the best units for that. Again, there is no substitute.

    There are many options. Some installations may be able to use heat pumps for a large part of both the heating and cooling load in "shoulder" seasons. Unless your house is very tight and has lot of solar gain and storage, though, you will still need some back up heat in the colder months, and that can be oil (or gas, but that may not be available). Or you can go with straight air conditioning, and a properly sized oil boiler. Or... but a good pro., who is not married to one way of thinking or one partiular brand, can evalute the options and advise you on the merits of various approaches.

    One option they won't give you is straight electric resistance heat -- it will be more expensive, and isn't anywhere near as environmentally friendly as the options I've mentioned above.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Noviceatthis
  • Noviceatthis
    Noviceatthis Member Posts: 11
    Thanks, Jamie. I am in Pennsylvania -Lehigh Valley. The three quotes offer different systems, but to your point, I am not sure whether they have done a heat loss calculation.
  • Noviceatthis
    Noviceatthis Member Posts: 11
    Still agonizing over the decision.
    Which boiler type for hot water and baseboard water heating? Which SEER rating for upstairs and downstairs? What tonnage? Comparison of warranties? Do I need a purifier or dehumidifier? Carrier v Lennox aircon system?.
    The two suppliers quoting are long-established and reputable. The costs are similar. Heat loss tests have been carried out. What is the one most important decision in all of this that would tip the scale in this buying process?
  • ratio
    ratio Member Posts: 2,729
    The installer.
    HVACNUTCanucker
  • HVACNUT
    HVACNUT Member Posts: 3,802
    Ask for references. Do they have a website with before and after install pics? Will they be a reputable service company for years to come?
  • Noviceatthis
    Noviceatthis Member Posts: 11
    Thanks, ratio, and HVAC. I know them both. They have both been well established for decades. I trust either of them and the overall cost difference is wafer-thin. This has been an eye-opening experience. You try and learn all this stuff, and unlike you guys who are the experts, I become modestly knowledgeable for a short period of time and then hope I never need to be an expert ever again.

    Thanks for your help.
  • pecmsg
    pecmsg Member Posts: 1,904
    edited September 2020
    The names of the installers are more important then the names on the boxs.
    As you see 3 different sizes so there all guessing. You have only 1 chance of getting the correctly sized equipment and thats by doing a Manual "J" Load Loss Calculation.
    http://efficientcomfort.net/assets/documents/Sizing_Selecting_for_Proper_Humidity_Control.pdf
    http://efficientcomfort.net/assets/documents/Another_View_on_Equivalent_Sizing.pdf
    http://efficientcomfort.net/assets/documents/Bigger_is_Not_Better-Sizing_Air_Conditioners_Properly.pdf
    http://efficientcomfort.net/assets/documents/Understanding_HVAC_System_Design_Issues.pdf

    Not a fan of or an endorsement of Angies List but a must read:
    https://www.angieslist.com/articles/difference-between-best-hvac-brands.htm
  • pecmsg
    pecmsg Member Posts: 1,904
    You can do your own Manual "J" Here

    https://www.loadcalc.net/
  • Noviceatthis
    Noviceatthis Member Posts: 11
    Apparently the load calculation for the second floor came to 2.6 tons of cooling. One supplier is saying that over 2 tons will lead to humidity issues upstairs. The other is saying that 2 tons is undersized for the requirement and is only prepared to quote for 3 tons. Could be a deciding factor. Any thoughts?
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