Page 2 of 3 FirstFirst 123 LastLast
Results 14 to 26 of 28

Thread: furnace too big

  1. #14
    Join Date
    Oct 2002
    Location
    Mahopac NY
    Posts
    448
    Lets go back to plan A... Do a heat calc, rip it out, and install a correctly sized unit.
    Dogs truly are man's best friend!!

  2. #15
    UPDATE, first I have to say this, some people can not trot out and buy a new furnace, car or whatever everytime a serviceman or mechanic tells the to, sometimes spending a couple hundred trying to fix something suits their wallet better than spending a couple grand plus buying new.
    Here's what i done and they should get a good many safe years out of their unit.
    I took out the 1.00-80 and replaced it with an .85-80 and had the option of going down to .70. I took out a cold air return duct that they had in the basement 10 feet from the unit, patched the hole and ran a hot air duct to an unheated entrance room away from the furnace.
    I told them to keep the door that leads down to the basement closed, they left it open to relieve some of the heat from their big unit, now the basement is a nice 60 degrees.
    CO2 11%-unchanged
    draft .025 from .050
    stack 420 from over 600
    have the fan limit on at 160 and off at 100
    heat rise is a little high --about 90 should be 85 or under.
    efficiency about 83%
    cost to heat for the next yr--unknown.

  3. #16
    Join Date
    Sep 2004
    Posts
    654
    When you changed the nozzle to a smaller size, you did adjust the amount of air, right?

    The other thing found strange, to me at least, was the draft decreasing when the smaller nozzle was used. Are you checking the draft when the burner is running at the breach?


  4. #17
    yes, draft is .025 at the box and at the flue.
    air was 0, now is open about 3/16"
    there is enough draft to suck your hat off, it's an 8' flue going into an 8X12 chimney, should be a six inch flue for the smaller nozzel

    [Edited by oilie hands on 03-26-2005 at 01:23 AM]

  5. #18
    Join Date
    Sep 2004
    Posts
    654
    Originally posted by oilie hands
    air was 0, now is open about 3/16"
    That makes it sound like you opened the air, from zero to 3/16".....probably the other way around if you installed a smaller nozzle. You should be using the side disk to adjust air on the Beckett burner as well, not the larger band. Small firing rates should use the disk for adjustment, it promotes better burning (says Beckett anyways).


    Originally posted by oilie hands
    ....there is enough draft to suck your hat off, it's an 8' flue going into an 8X12 chimney, should be a six inch flue for the smaller nozzel
    Chimney size doesn't have to be sized to the firing rate, that's what the draft regulator is there for. Open that while the burner is running steady-state to obtain -0.02" WC over the flame. More draft never hurts, but cuts efficiency.....too little draft and the fire suffers and can even burn the end cone Becketts are known for.



    [Edited by oilie hands on 03-26-2005 at 01:23 AM] [/B][/QUOTE]

  6. #19
    Join Date
    Jul 2001
    Location
    Delaware
    Posts
    1,232
    Originally posted by casturbo

    The other thing found strange, to me at least, was the draft decreasing when the smaller nozzle was used. Are you checking the draft when the burner is running at the breach?
    I noticed that too but then when I saw the drop in stack temperature, I realized less heat up the chimney = less draft. I don't remember seeing any smoke or CO numbers. Often when you reduce nozzle size, CO goes way up. Not trying to be picky, just cautious.
    Work is for people who don't know how to fish.

  7. #20
    it pays to be questioned and picky when playing with fire.. thanks
    heat rise is about 80
    CO2-11 CO-6
    my old eyes and glasses saw between 0 and 1 smoke
    younger eyes said 0, i didn't argue.

    [Edited by oilie hands on 03-26-2005 at 11:53 AM]

  8. #21
    Join Date
    Jul 2001
    Location
    Delaware
    Posts
    1,232

    Old eyes

    Roger that on the old eyes. I do question the CO reading. I've never seen a CO as low as 6 PPM. I would consider 60 to be very good.
    Work is for people who don't know how to fish.

  9. #22
    Join Date
    Nov 2004
    Location
    Skokie , IL near chicago
    Posts
    1,139

    Angry

    so sorry oillie , but when i bought my house the home inspector passed the furnace as mechanically sound in the summer . During the first winter it was apparent that the btuh capacity was oversized . The unit would ramp up quickly & shut off causing long cycles & poor heat . Turning up the stat didn't help , just did the same thing ata higher temp . I think you'll find that the only solution will be to s**t can that unit and do a proper heat loss , etc . Your'e wasting yourtime with trying to correct this system , in my always humble opinion ,Jack

  10. #23
    Join Date
    Sep 2004
    Posts
    654
    Originally posted by rojacman
    ..... I think you'll find that the only solution will be to s**t can that unit and do a proper heat loss , etc . Your'e wasting yourtime with trying to correct this system , in my always humble opinion ,Jack
    Jack, I don't disagree having the correct size unit is better, but the unit in question is not all that oversized and downfiring an OIL furnace to match the heat load is very practical, economical, and provides desired comfort. I see it everyday and it flat out works on an oil furnace. Now maybe a gas unit wouldn't do so well, but it really applies with an oil furnace.


  11. #24
    Join Date
    Nov 2004
    Location
    Skokie , IL near chicago
    Posts
    1,139

    Thumbs up

    CScotti Your.e right , my situation was a gas furnace only de-tuneable 12 to 15% , plus i was looking very forward to changing to a properly sized unit w/2stage , variable speed, etc. For my customers i like to fix problems 'till it's not cost effective . great job Jack

  12. #25
    I guess if you live in a big city you can tell people that you can't help them or won't even give it a shot and walk away, but when you live in a small town of under 3000 people and the 4 towns around you are all under 3000, it dosen't take long before you get a reputation of just being a person that wants to sell new furnaces, we have a couple "servicemen" like that around here and they are spending most of their time setting home or taking weekend and night calls just to eat, I even know one person that was called in by his boss and told to stop pushing new units and start using his tools and get his hands dirty. I think it's just a matter of being honest, if it's just plain unsafe, show them and most people understand, but if it is just a matter of doing a little work, no problem.
    I would love to have customers standing in their driveway with their wallet and tell me to put in a new unit on every call, but them days are over in the northeast. 4 yrs ago i could get a 90000 BTU unit for under a thou, now it's over 1500. prices sky rocketed and so did the unemployment lines. Anytime i can make a few hundred and save the customer a couple thou plus leave them with a safe unit, it makes my day.

  13. #26
    Join Date
    Jul 2001
    Location
    Delaware
    Posts
    1,232

    Oilie hands

    Thank God I'm not the only one left out there who knows there are solutions other than selling new equipment. I get so tired of hearing things like "Your furnace is 10years old you should replace it.". Any half decent furnace should last at least 20 years if installed close to properly.
    Work is for people who don't know how to fish.

Page 2 of 3 FirstFirst 123 LastLast

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