how to get hot water heat up to attic?

Discussion in 'HVAC' started by Chuckles, Oct 1, 2003.

  1. Chuckles

    Chuckles Guest

    My last hot water question for a while, I promise...

    In the new house we just bought, there is a partially finished attic
    with a radiator. The attic is essentially at 3rd floor level, so the
    radiator may be 25-30 ft above the basement boiler and circ pumps. I
    bled the radiator, and air came out of it very slowly---it probably
    took 30 min for it to fill up. Not surprisingly, in normal operation,
    no heat gets up there at all.

    Is putting in a more powerful main circulator pump a possible
    solution? If I look at the curves on the Bell & Gossett's web page,
    some pumps move lots of water at zero head, but others can move more
    water at a given large head. The pump we have now is rated to go to
    zero gpm at 24 ft head, which fits with what I described above.

    So if I get another pump that fits in the same space, and has some
    finite gpm at say 30ft head, will this work better? Or am I being
    naive and the water will merely take the path of least resistance
    through the lower radiators, and after a while the pipes will burst
    due to the higher pressure?

    Is there another method to divert water up to the attic?

    Many thanks,
    Chuckles, Oct 1, 2003
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  2. Chuckles

    Bubba Guest

    Chuck. You're getting no water, right? Ever think that maybe water
    PRESSURE is your problem? Put all the pumps on you want. It wont solve
    the problem. Ever think water PRESSURE might be your problem?
    Hint: Too much water pressure and you will have a funny little water
    leak coming out of a "thing-a-ma-bob" on your boiler.
    Bubba, Oct 1, 2003
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  3. Chuckles

    Chuckles Guest

    (Chuckles) wrote in
    Actually, my mistake, I read the wrong chart. The pump in this zone now is
    a B&G Series 100, which goes to zero gpm at only 8 ft head. It does go up
    to the 2nd floor, which is more than 8 ft., and maybe that is because of
    the water main pressure in addition to the pump-created pressure?
    Chuckles, Oct 1, 2003
  4. Chuckles

    Chuckles Guest

    Huh? Pumps increase the pressure, to push water higher than it would go
    Chuckles, Oct 1, 2003
  5. Chuckles

    Steve Scott Guest

    I'm only posting to alt.hvac. Are you checking here?
    Steve Scott, Oct 1, 2003
  6. Chuckles

    Steve Scott Guest

    You miss the point here. A circ works by pressure differential. It's
    not a displacement pump.
    Steve Scott, Oct 1, 2003
  7. Did you actually bleed the radiator until water came out? Did you add
    sufficient water to the system so that you actually could bleed the highest
    radiator in the system?

    The other thing to check is to make sure that your expansion tank is not
    saturated with water. My experience is that in a multi-story house, unless
    you have a diaphram type expansion tank, over a long period of time, the air
    tends to migrate from the expansion tank to the highest radiator in the

    The pump head capacity is not an issue. The pump does not actually need
    enough strength to push the water to the 3rd floor, as the system should
    already be full. It only needs to circulate the water.

    If you are not getting heat, your radiator valve may be closed, or there
    might be air trapped in a line between the boiler and the 3rd floor. It is
    also possible that the 3rd floor radiator is so far from the boiler, that by
    the time the heat gets that far, the thermostat has already shut down the

    Another possibility, is that in older systems that have been added on and/or
    converted from gravity systems, where the radiators are connected in
    parrallel, rather than in series, the hot water will create its own
    convection, and some of the more remote radiators will not get any heat. In
    these situations, you may need to add additional circulating pumps,
    restrictor valves, or otherwise replumb the system so that you get proper

    The key 1st question is whether the 3rd floor radiator ever worked properly.
    Then you need to figure out exactly where all the pipes go and try to
    understand what is happening.

    Mike Schumann
    Mike Schumann, Oct 1, 2003
  8. Chuckles

    gerry Guest

    [original post is likely clipped to save bandwidth]
    Don't confuse pumps with circulators. Once the system is bled of all air,
    the down pressure on the return just about equals the pressure needed to
    pump water up. There is no concept of head that applies.

    That's why they are called circulators, not pumps.

    A few possibilities:

    - the system isn't totally bled

    - ther is a path of lower resistance, fluids always (almost) pick the path
    of lowest resistance.

    gerry, Oct 1, 2003
  9. Chuckles

    Steve Scott Guest

    And let's not forget to adjust the pressure in the tank if it's a
    diaphragm tank.
    Steve Scott, Oct 1, 2003
  10. Why? What will happen if the pressure is lower?
    Heathcliff Bambino, Oct 1, 2003
  11. It will implode on cold mornings.

, Oct 1, 2003
  12. Chuckles

    Steve Scott Guest

    For one thing you can start to draw air into the system as the
    pressure in lines at upper points of the system drops below ambient.
    Steve Scott, Oct 1, 2003
  13. Chuckles

    Bubba Guest

    Exactly as I thought. You dont have a clue. Let me give you another
    Have you ever thought that your WATER PRESSURE might be your problem?
    One last clue:
    Have you ever thought that if you didnt even have a pump at all would still work? Not very well, but for all intents
    and would.
    Now..........Do you have that "pressure thing" figured out?
    One final clue:
    Dont think like a pump. Think like water with its ass being spanked
    all the way up the pipe.
    Bubba, Oct 2, 2003
  14. Chuckles

    Noon-Air Guest

    <sigh> Its not about pressure...its about volume
    Noon-Air, Oct 2, 2003
  15. Chuckles

    Bubba Guest

    Are you argueing with me? :)
    You mean like I'll turn on my 100 series B&G pump with about 24 psi
    (or so) of PRESSURE on it and see if it circulates and heats to the
    3rd floor.
    Now you can turn on your 100 series B&G pump with about 4 psi of
    PRESSURE and ANY or ALL of the VOLUME you want and we will see who's
    system heats the third floor.
    That the kind of volume you are talking about or did I miss a joke or
    smiley face or am I just all out of sorts from all the fucking moron
    idiots calling me yesterday and today wanting bids and price shopping
    when I am so god damn busy I aint about to entertain them with
    numerous papers and slick brocheures cause I'll never get caught up as
    it is?!!
    Whewwwwww! There! Now I feel much better.
    Bubba :)
    Bubba, Oct 2, 2003
  16. Chuckles

    Noon-Air Guest

    at 1 cc/hr
    at 50gpm
    yup..that too :) pay attention young grasshopper...
    There are 2 rules in life.....
    First....don't sweat the small shit.......
    Second.......everything is small shit. :)
    Noon-Air, Oct 2, 2003
  17. Chuckles

    Steve Scott Guest

    Until they invented hydronic circulating pumps gravity systems worked
    quite well. Just expensive as the dickens with 2-3" runs in

    In fact, I had a pump on a new 2 story house fail last year. The
    house heated just fine with a 3/4" baseboard series loop. The only
    clue was that the indirect WH was taking it's own sweet time coming up
    to temp which can be a problem if it's prioritized. :) BTW, we
    generally use a single pump with zone valves.
    Steve Scott, Oct 2, 2003
  18. Chuckles

    Steve Scott Guest

    Geez, I better tell you I was agreeing with you in my last post. :)

    BFWIW, all this really depends on the piping method used, was it
    installed properly in the first place (it's surprising how many never
    functioned properly) and the connected load.

    It's possible the OP may have some sort of restriction in the system
    if it takes a long time for the air to get out of the top floor
    radiators while the system is calling for heat. Could also be a
    possibility the pressure is set so low he's sucking air into the
    system. That would be worse on the top floor. There are several
    guesses that could be made.
    Steve Scott, Oct 2, 2003
  19. Chuckles

    Steve Scott Guest

    No, this is incorrect. You need sufficient fill pressure to keep from
    introducing air into the system as the pressure drops at upper levels.
    Most all fill valves come set at 12psi because that's about how much
    cold pressure you need to keep from dropping below ambient pressure
    with a two story house.

    You need .434 psi per foot of elevation difference between the boiler
    and the highest output device plus 5 psi for a cushion. So with a 3
    story house assuming about 5' from the top of the boiler to the bottom
    of the first floor and about 9' from the bottom of the floor joist to
    the ceiling of the next floor you'd have about 26' to the top of a
    radiator on the third floor. The cold fill pressure should be about
    26x0.434+5=16.3. Call it 17 psi. A diaphragm tank should be
    precharged to the same level.

    This isn't to maintain water flow. It's just to make sure that the
    pressure inside the piping is greater at it's lowest point than the
    ambient pressure when the system is running.

    For the OP the pump head you've been referring to is the amount of
    piping resistance (commonly called head) the pump will deliver a given
    quantity of water. When looking at the pump curve you consider what
    the needed gpm is and what is the required head for that gpm. You
    then select a pump that will deliver that or slightly more. The
    distance to the highest radiator isn't a factor because the water
    returning balances out the force required to get the water up there.
    BTW, the needed flow rate is roughly 1 gal per 10,000 btu.

    Whew, so you'll get the same flow at 24 psi as you will at 4 psi but
    you may introduce mucho air into the system at 4psi.
    Steve Scott, Oct 2, 2003
  20. Ummm.... this is a sealed sytem. This is hot water, not
    steam. You could hook your vacumn pump up to it and pull a vac on it
    if you wanted ( don't know why, but you could ).

    So, where exactly does this air get in ?

, Oct 2, 2003
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