Results 1 to 5 of 5
  1. #1
    Hello, My names Norm, I Live in Kalamzoo, Mich. and am new here.
    I have recently purchased a house built in 1958 that is in need of a new system. It is a 3500 sq/ft two story with a partial basement modern style home with close to 100 single pane windows. It is a flat roof with good insulation. The walls that are not glass also have good insulation. The upper level is open on two side to the lower level. Forced air system with one large return in the basement under the open stairwell. It has two large outside air ducts (approx. 2 ft.dia.) one that goes directly to the furnace through a weighted damper and the other directly to the furnace room (this one has been closed off). 3 zones: all of main floor on one zone, upper level has one for master bedroom and one for the remainder. Originally it had an oil burner that was changed by the previous owner to gas. There is also a 5 ton connected.

    I have had a couple of contractors out to evaluate and recommend. One wants to put two, 2 stage 80% variable speed amanas for the first floor, splitting the main level into two zones and then one furnace for the upstairs.
    Others want to use one furnace with modulating dampers for zoning.

    Opinions on multiple furnaces to single furnace? Aside from the maintenance costs being higher.

    Have not done load calcs but the original system was designed by some guy out of NYC in '57 and here are his notes on the print:
    Net heat loss 293,538 btu
    pickup and duct loss 58,708 btu
    total heat loss 352,246 btu

    zone one 590cfm
    zone two 1395cfm
    zone three 3505cfm

    design data outdoor -10
    indoor 70

    he spec'd a campbell model 200d 1/2hp blower originally.

    There is now a 150k btu furnace being used. The house heats and cools fine but there are great temp swings between rooms, I would guess at least 10 degrees or more at times. Heating bills were 600usd at peak winter. (70degrees).

    Suggestions?


  2. #2
    Join Date
    Sep 2002
    Posts
    3,708
    Yes,replace your windows..try to upgrade the building envelope,and then go for the smaller havc equipment.

    I can only assume the high heatloss is due to pulling in outside air and not so much the loss of the envelope.

    And to that I could only ask why would this home even need to pull in outside air?


  3. #3
    According to the engineer in a letter to the architect:

    "We have included infiltration losses on this building because of the large crack areas around the numerous windows. When a strong wind blows, infiltration is inevitable."

    "Our duct sizes are based on 120 degrees inlet temperatures. many manufacturers base inlet temps on 140 to 160 f thus reducing the duct size."

    "I would advise keeping the fresh air inlet in the boiler room. This can be open to bring in fresh air during intermediate heating seasons and can be closed during winter months."

    "The reason we seperated the master bedroom from the other bedrooms is that the heat from the living room (which flows through the large opening) might satisfy the thermostat in the master bedroom. if the small bedrooms were place on the same zone, they would remain cold until the master bedroom thermostat called for heat."

    I am not sure what all this means ie: "inlet temps" and "intermediate heating seasons"

    Maybe it was designed to allow outside air to come in and circulate during the summer months. It was not designed with air-conditioning, that has been added at a later date.

    I am not sure if we could ever recoup the cost of replacing the windows. Even at only, say, 100 bucks each that would take 10,000usd. That's a lot of heating seasons.

  4. #4
    Anyone? Beuller?

  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,712
    Originally posted by classicform
    According to the engineer in a letter to the architect:

    "We have included infiltration losses on this building because of the large crack areas around the numerous windows. When a strong wind blows, infiltration is inevitable."

    This is a large part of your 600 dollar heating bill, new windows could cut the cost by 50% or more.

    "Our duct sizes are based on 120 degrees inlet temperatures. many manufacturers base inlet temps on 140 to 160 f thus reducing the duct size."

    With the smaller furnace you have now, this may be the cause of uneven heat, dampers installed in each supply branch should help even out the rooms.

    "I would advise keeping the fresh air inlet in the boiler room. This can be open to bring in fresh air during intermediate heating seasons and can be closed during winter months."

    Outside combustion air intake, required for furnace/boiler rooms with less then 50CF air per 100k btu.

    "The reason we seperated the master bedroom from the other bedrooms is that the heat from the living room (which flows through the large opening) might satisfy the thermostat in the master bedroom. if the small bedrooms were place on the same zone, they would remain cold until the master bedroom thermostat called for heat."

    Not sure what you mean here, but zoning the mbr, is quite often a good idea.

    I am not sure what all this means ie: "inlet temps" and "intermediate heating seasons"

    By inlet temps he was reffering to the supplies, he designed for a temp 20 to 40 lower then normal at that time period.

    Intermediate heating season, is the 40 and above days of winter.

    Maybe it was designed to allow outside air to come in and circulate during the summer months. It was not designed with air-conditioning, that has been added at a later date.

    I am not sure if we could ever recoup the cost of replacing the windows. Even at only, say, 100 bucks each that would take 10,000usd. That's a lot of heating seasons.


    If your heating bill for the year is over 2 grand, the windows would pay for themselves in about 6 years. Since you could use a smaller furnace\furnaces.

    Haing 2 new furnaces installed instead of one big one, has some advantages.

    If one breaks in the middle of the night, you always hae the other one till morning.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event