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  1. #1
    Join Date
    Apr 2014
    Posts
    1

    Default selecting a replacement furnace for 2-story condo

    I live in a two story condo in Denver, built 1972. Stupid furnace is in a closet upstairs, thus during extreme cold weather the downstairs can be as cold as 55 degrees and we must use electric portable heaters. We replaced the HVAC 15 years ago. Feel like I got sold an inadequate system. Starving for intake air according to one service tech who serviced it in recent years. Ducts other than those in the closet are all behind drywall. Hot air duct to downstairs goes off the back side of the furnace, hot air for upstairs comes off the front of the furnace and includes a baffle to supposedly help regulate the amount of air allowed up/down. No clue how to effectively set the baffle. Looking for the terminology related to getting gas furnace which has two stages / thermostats to provide better heat downstairs. Cooling is less of a problem. Have new windows and decent but not great insulation.

  2. #2
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    6,694

    Default Re: selecting a replacement furnace for 2-story condo

    Your furnace is not "stupid", but your previous installer may have been.

    You need to relocate the furnace. Get estimates from new contractors who come with valid references that you can actually verify. At 15 yrs old the furnace has seen better days, consider replacing it. I've had furnaces last as few as 10 years, and some that are still going at 35 years old - so age is not the only factor.

    Also, since you are in a condo, you may be limited to what you can do (check with the HOA - some of them are vicious and quick to sue).

  3. #3
    Join Date
    Aug 2008
    Posts
    85

    Default Re: selecting a replacement furnace for 2-story condo

    Quote Originally Posted by denver49 View Post
    Looking for the terminology related to getting gas furnace which has two stages / thermostats to provide better heat downstairs. Cooling is less of a problem. Have new windows and decent but not great insulation.
    What you are referring to is called a "zoned forced hot air heating system", and there have been quite a number of innovative components introduced in recent years to address exactly the problems you identify in your post.

    dj makes some important points---who is responsible for the condo's heating equipment, the HOA or yourself????

    From your post, it sounds like you have already spent lots of $$$ on past heating equipment.

    A zoned system requires that the dampers be modified to individually motor-driven (or suction air-driven) dampers & that separate T-stats be installed in the upper & lower parts of your condo that will individually turn on & off the furnace & AC when each of the separate zones call for heat/cooling----this has become a very hot topic in forced air heating systems remodeling in recent years because previously, most forced hot air heating was confined to one zone that created exactly the problem you are experiencing in many homes heated with forced hot air; the concept of zoning in heating registers has existed for decades in forced hot water heating systems, & now has become popular in FHA heating as well.

    The concept of 2 separate, individually controlled T-stats is based on the idea that each T-stat is a separate zone in the same condo, each capable of "calling for heat" on its own---when the lower room (with its own T-stat) gets cold enough, the contacts of the lower room T-stat CLOSE, ("calling for heat"); this sends an electrical signal to the furnace to TURN ON---and the furnace STAYS turned on until the temperature in that lower room gets high enough to OPEN the T-stat contacts, shutting down the furnace (an overide feature will keep the furnace blower motor running for several additional minutes to purge residual duct heat so it is not wasted/lost)---it should be easy to see that such a system should be much more effective in heating separate areas of a condo than the one you have now.

    You've done the right thing in contacting a HVAC technician in the past----contact MORE HVAC people until you find one who can give you the expertise & answers you are looking for---this problem can be solved, perhaps with your existing heating equipment.

    The TOH video shows an example of what's widely known as a RETROFIT JOB for installing individually-controlled dampers & separate T-stats into an existing FHA system, the one in the video based on a small-diameter vacuum-tubes system; there are many others---most of them operate on electrically-driven 24v motors on each of the room dampers (see the zone-first site for photos of electrically-driven dampers) that are individually opened & closed in conjunction with the individual zone T-stat call for heat; the other aspect of the TOH video is that there's over a dozen individually-controlled dampers----ordinarily half a dozen or less electrically-controlled dampers are all that's needed for a small condo.


    http://www.thisoldhouse.com/toh/vide...292832,00.html
    http://zonefirst.com/wp-content/uplo...signManual.pdf
    http://howstuffworks.com/home-improv...on-system3.htm
    Last edited by dodsworth; 04-15-2014 at 06:58 PM.

  4. #4
    Join Date
    Aug 2007
    Location
    Portland, Oregon, formerly of Chicago
    Posts
    1,804

    Default Re: selecting a replacement furnace for 2-story condo

    You don't state where the downstairs vents are located. Are they down at floor level or in the ceiling? If they are up high, you may never be comfortable on the lower level. I have seen this arrangement in homes in California where they are more concerned with air-conditioning than heating. Unfortunately, I once visited friends in LA who had such an arrangement with the furnace upstairs and the downstairs vents up high. It was a cold period for LA with temps in the 30's. It was uncomfortably cold downstairs and I kept running upstairs to warm up!

  5. #5
    Join Date
    Aug 2007
    Location
    Portland, Oregon, formerly of Chicago
    Posts
    1,804

    Default Re: selecting a replacement furnace for 2-story condo

    You don't state where the downstairs vents are located. Are they down at floor level or in the ceiling? If they are up high, you may never be comfortable on the lower level. I have seen this arrangement in homes in California where they are more concerned with air-conditioning than heating. Unfortunately, I once visited friends in LA who had such an arrangement with the furnace upstairs and the downstairs vents up high. It was a cold period for LA with temps in the 30's. It was uncomfortably cold downstairs and I kept running upstairs to warm up!

    Since this is a two story condo, I assume there is no heated apartment under you to keep you warmer?

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