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Thread: New Forced air heat/ a/c concerns due to water heater.

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  1. #1
    DIY Member m3rdpwr's Avatar
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    Default New Forced air heat/ a/c concerns due to water heater.

    Hello all.

    Currently I have an original with home 42 year old Janitrol forced hot air system.

    I am looking to get central air, so it makes sense to replace all.
    Looking at A/S Trane, and Lennox at the moment and trying to decide which to go with.
    So any insite on that would be helpful.

    The problem comes with this.
    The water heater is fairly new and vents through the chimney along with the furnace.
    With the new furnace being direct vent, I'm told I would have to line the chimney for the water heater.
    Okay, no big deal, maybe $400-$500 or so it was thought.

    Back in 1985 the owner decider to add an additional brick wall and platform for a wood burning stove.
    When they put up that wall, they cemented and bricked in over the vent going out and through the chimney.
    This being the case, I've been told to put in a liner I would have to bust out part of the chimney from the inside of house to feed over the liner. Oh god, now we are talking 1400-1800 after re-bricking part of the fireplace.

    So, the other choice is for the installer to install a Bradford White 40 Gallon Direct vent system.
    Since I would have it done at the same time as the HVAC system, he would do it for $1700.

    (Since code states water heater does not create enough vent heat for draft type.)

    Im stuck because regular vent water heaters are cheap, and will they work without power, etc.
    I kind of worry about the direct vent just because of extra things to go wrong.

    Most people I talk to say break the chimney out and line it, better in the long run.
    That a simple water heater is the way to go and cheaper to replace parts wise and labor wise.

    What is your thoughts?

    Also any thoughts on the Trane/Lennox debate?

    If I missed something to mention, please ask.

    Thank for your time.

    -Mario

  2. #2
    General Engineering Contractor ballvalve's Avatar
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    What does lining a chimney have to do with installing a new furnace? If its direct vent condensing,
    run the furnace vent out the sidewall.

  3. #3
    Retired Defense Industry Engineer jadnashua's Avatar
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    A power vent on the WH would let you go out the sidewall, or possibly up to the roof (there are limitations on how far, varies with models). The fans can go before the tank leaks, but it isn't that much more, and would solve that problem. But, what would happen if you plug that now unused section of the chimney? You really don't want an open channel sitting there unused. Not sure what the proper procedure would be, and that might add to the equation on deciding which is better.

    As to the brand, both are good. From a comfort level and maximum potential energy, a two-stage burner and a variable speed fan will improve comfort and overall efficiency. Any heating/cooling system works best when it is running constantly. A variable speed fan helps to avoid that cold surge in the winter until the ducts warm up, runs longer and has less wind chill effect unless it really needs the full speed (which it ramps up to and may never use). The variable speed during the cooling season lets the thing extract significantly more moisture out of the house during the startup and shutdown periods when it runs the fan slower. This lets the air linger a little longer through the cooling coil and therefore extract MUCH more moisture per pass. Now, if you live in the dry desert, this isn't an issue, and maybe a detriment, but for most of us, it will make it feel much more comfortable at a higher temp since the air is dryer. There is some truth to the 'but it's dry' issue you hear from those in the hot dry desert...you can tolerate higher temps if it is dryer more easily. Proper sizing is also crucial, as oversizing will be more expensive to buy, run, and have lousy comfort.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIY Member m3rdpwr's Avatar
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    Right now, my chimney has 3 flu's (sp?).
    One for the water/heating, one for the wood stove and one for the fireplace.

    The chimney has a screened cap on it, so I don't think I am too woried.
    We were going to cap it off in the furnace room if I replaced both the heat and water.

    As far as the Lennox model goes, it was the Signature Collection for heat SL98V which I think is top of the line residential. Variable Speed motor and Variable-capacity operation for heat stages.
    For the A/C still Signature Collection, but thinking mid range, because to go one step up from XC17 to XC21 it was $1600 extra. Many argue it would take forever to make the money back in savings and since the house is only about 1600sq ft living space it may not make a differance. 3Ton heat and 2.5ton A/C if I remember for the forced air systems.

    In total, I was quoted $9800 for the Heat and A/C soup to nuts.
    The power humidifier to replace the old drump one was an extra $460.
    Finally the Water Heater was another $1700.

    All prices included permits, electric, pump and lines to drain into washer drain half way across house, top of the line iComfort Stat just introduced.

    If I were to go best A/C it would pump it up another $1600.
    If I didn't have to replace the water heater, I would have concidered it.

    The Trane stuff was about the same spec's and a little less money, so that was a wash.

    There are some good rebates, but still a lot of money.

    Thanks for your input.

    -Mario
    Last edited by m3rdpwr; 02-02-2011 at 11:36 AM.

  5. #5
    DIY Member m3rdpwr's Avatar
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    I shoudl have added on the Lennox A/C XC17 and XC21 the only difference I see was up to SEER 17 and SEER 21 respectively.

    Also the XC21 was two stage where the XC17 was not.
    62db versus 69db so XC 17 a little less.

    Warranty on all is still 10 years.

    Thanks.
    Last edited by m3rdpwr; 02-04-2011 at 04:48 PM.

  6. #6
    DIY Member m3rdpwr's Avatar
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    To answer your question, according to code, I can not just have my current water heater venting through a clay liner.
    Not enough heat from the exhaust of the water heater causing condensation and other problems.
    It would have to have a aluminum or stainless liner installed.

    Quote Originally Posted by ballvalve View Post
    What does lining a chimney have to do with installing a new furnace? If its direct vent condensing,
    run the furnace vent out the sidewall.
    Last edited by m3rdpwr; 02-04-2011 at 04:49 PM.

  7. #7
    Retired Defense Industry Engineer jadnashua's Avatar
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    SEER is an acronym - and the higher the number represents higher efficiency. Depending on your utility costs, it may never pay back to get the bigger unit.

    But, 1600 sq ft may be too small for a 3T unit. The worst thing you want is an oversized a/c unit. Do not buy anything until they run an analysis on YOUR house, using the widow size, placement, type, insulation amounts, building orientation, and factor in how well sealed it is, then equate all that to the normal temperature and humidity levels and determine your 'design day' worst case. It is not uncommon to avoid this and end up with a unit that is way oversized. This compromises comfort and economy. If in-between sizes, you might opt for the smaller one unless you reach that design day temp often. For example, you might have a once in 10-years where it gets to -10 degrees, but the 'normal' low is 5 in any given year. You might not want to design it for -10, because it rarely not only reaches that temp, but it doesn't stay there forever. If the house was at your desired temp during the day, and it only got to that super cold temp early in the morning, it wouldn't have been steeping in the super cold very long, and you may never notice. Same with the a/c size. If the a/c is running constantly, drying the air, and you go 5-degrees over the design temp for a couple of hours, you may never notice. It's when it stays there for a long time, or you shut down, then want to cool a very hot house where that extra capacity comes into play. But, once it does reach the set point, it only needs to run a very short time...that creates cold, clammy conditions, not very comfortable.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  8. #8
    DIY Member m3rdpwr's Avatar
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    The old heater is original at 42 years old.
    100,000 BTU in and 80,000 BTU out.
    80% efficient I guess.

    All contractors who have come in have estimated 61k-66k BTU at ~98% efficient.
    They all also said 2.5 ton a/c.

    I said 3 ton heat, because that's what I translated from the part number ending in 30 for size.

    The house was built in 1968 and is very loose.
    I've seen what was in the wall, tin foil with papser backing. About R7 from what I've heard.

    Some joker put up basement walls with studs facing flat with no insulation and paneling.
    So, I am working as I said with a loose house.

  9. #9
    Retired Defense Industry Engineer jadnashua's Avatar
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    Make them show you how they calculated that! Using square feet alone is NOT going to work. Your old furnace could have been 3x oversized or more. Unless on a really cold day in the winter it never shut off and the house got cold, it's probably oversized...how much is the important factor.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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