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Thread: Replace 1 gas WH with 2 gas WHs ?

  1. #16
    Homeowner Thatguy's Avatar
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    Quote Originally Posted by akm View Post
    1. like the redundancy and capacity of (2) WH, but seems a little over-kill
    2. found (1) 75gal, cost is not that bad considering the simpler piping/venting etc (as previously mentioned in this thread).
    Size (all seem to work for venting height, assuming min 1/4' per ft slope) and cost factors are as follows.

    Cost of (1) Heavy Duty 60gal = $600ish
    Cost of (2) (not Heavy Duty*) 50gal = $550ish
    Cost of (1) Heavy Duty 75gal = $850ish
    60 @ 600 = $10/gal
    50 @ 550 = $11/gal
    75 @ 850 = $11/gal

    So much for Economy of Scale. . .

  2. #17
    DIY Junior Member akm's Avatar
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    Quote Originally Posted by Thatguy View Post
    60 @ 600 = $10/gal
    50 @ 550 = $11/gal
    75 @ 850 = $11/gal
    So much for Economy of Scale. . .
    Seems like good way to compare !
    Actually could look at (2) 50s as 550/100(or maybe a little less if in series) = $5.50/gal (plus a bit more for piping/venting ?
    Still leaning toward (1) 75gal.
    Thanks again for your help.
    akm

  3. #18
    Homeowner Thatguy's Avatar
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    Quote Originally Posted by akm View Post
    Seems like good way to compare !
    Actually could look at (2) 50s as 550/100(or maybe a little less if in series) = $5.50/gal (plus a bit more for piping/venting ?
    Still leaning toward (1) 75gal.
    Once you make your choice, your Utility Function

    "While preferences are the conventional foundation of microeconomics, it is often convenient to represent preferences with a utility function and reason indirectly about preferences with utility functions."

    will be known to all of us, including you! In principle, at least. . .

  4. #19
    DIY Senior Member Runs with bison's Avatar
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    Quote Originally Posted by Thatguy View Post
    60 @ 600 = $10/gal
    50 @ 550 = $11/gal
    75 @ 850 = $11/gal

    So much for Economy of Scale. . .
    Actually, it makes sense since the 75 gallon one has a higher capacity burner: 75,000 Btu/hr. If you based this on 1st hour ratings the result is different.

    Based on the Energy Guide the efficiency factor works out to 0.53, which is pretty low but still will work out to slightly less in the way of losses than two tanks would.

  5. #20
    DIY Junior Member akm's Avatar
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    Think we are ready to take the plung, just need to click the 'purchase' key.

    Drawing of install is attached, does it look ok ?
    Attached Images Attached Images  
    Thanks again for your help.
    akm

  6. #21
    Journeyman & Gas Fitter Doherty Plumbing's Avatar
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    Quote Originally Posted by akm View Post
    Think we are ready to take the plung, just need to click the 'purchase' key.

    Drawing of install is attached, does it look ok ?
    You cannot do the venting like that. At a MIN that second appliance (the most downstream one) must enter the common vent through a wye fitting.

  7. #22
    DIY Junior Member akm's Avatar
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    Quote Originally Posted by Doherty Plumbing View Post
    You cannot do the venting like that. At a MIN that second appliance (the most downstream one) must enter the common vent through a wye fitting.
    Thanks for the comments.
    The dwg is supposed to show the 4in WH vent is entering at the 5x5x4-Y fitting which is 'downwind' from the 5in FAU vent.
    Is that not like what you are saying ?
    BTW, a friend of mine suggest maybe we should first check out the low temp t-stat in case it is not working and not turning on the WH when the water temp reaches the low point.
    Does that have any merit with the existing B-W WH ?
    I think you had mentioned in an earlier thread that the 1994mfr/1996install should merit a new WH.
    Thanks again for your help.
    akm

  8. #23
    Journeyman & Gas Fitter Doherty Plumbing's Avatar
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    Quote Originally Posted by akm View Post
    Thanks for the comments.
    The dwg is supposed to show the 4in WH vent is entering at the 5x5x4-Y fitting which is 'downwind' from the 5in FAU vent.
    Is that not like what you are saying ?
    BTW, a friend of mine suggest maybe we should first check out the low temp t-stat in case it is not working and not turning on the WH when the water temp reaches the low point.
    Does that have any merit with the existing B-W WH ?
    I think you had mentioned in an earlier thread that the 1994mfr/1996install should merit a new WH.
    Quote Originally Posted by akm View Post
    Thanks for the comments.
    The dwg is supposed to show the 4in WH vent is entering at the 5x5x4-Y fitting which is 'downwind' from the 5in FAU vent.
    Is that not like what you are saying ?
    BTW, a friend of mine suggest maybe we should first check out the low temp t-stat in case it is not working and not turning on the WH when the water temp reaches the low point.
    Does that have any merit with the existing B-W WH ?
    I think you had mentioned in an earlier thread that the 1994mfr/1996install should merit a new WH.
    Quote Originally Posted by akm View Post
    Thanks for the comments.
    The dwg is supposed to show the 4in WH vent is entering at the 5x5x4-Y fitting which is 'downwind' from the 5in FAU vent.
    Is that not like what you are saying ?
    BTW, a friend of mine suggest maybe we should first check out the low temp t-stat in case it is not working and not turning on the WH when the water temp reaches the low point.
    Does that have any merit with the existing B-W WH ?
    I think you had mentioned in an earlier thread that the 1994mfr/1996install should merit a new WH.
    Oh ok yes that is ok if you are using a wye fitting!

    However if possible this would be your best bet for venting:



    You always want the lowest input appliance to connect to the venting system last. The blue thing at the bottom of the vent would be an inspection point (usually a plug in the bottom of a T).

  9. #24
    DIY Junior Member akm's Avatar
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    Quote Originally Posted by Doherty Plumbing View Post
    Oh ok yes that is ok if you are using a wye fitting! You always want the lowest input appliance to connect to the venting system last. The blue thing at the bottom of the vent would be an inspection point (usually a plug in the bottom of a T).
    DPH
    Thank you for the followup.
    Sorry about the dwg confusion.
    Y looks more like a T
    Quote Originally Posted by akm View Post
    Thanks for the comments.
    BTW, a friend of mine suggest maybe we should first check out the low temp t-stat in case it is not working and not turning on the WH when the water temp reaches the low point.
    Does that have any merit with the existing B-W WH ?
    I think you had mentioned in an earlier thread that the 1994mfr/1996install should merit a new WH.
    Any thoughts on the other question (above) about 'repair' of existing WH, b4 we make the leap ?
    Thanks again for your help.
    akm

  10. #25
    Journeyman & Gas Fitter Doherty Plumbing's Avatar
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    Quote Originally Posted by akm View Post
    DPH
    Thank you for the followup.
    Sorry about the dwg confusion.
    Y looks more like a T

    Any thoughts on the other question (above) about 'repair' of existing WH, b4 we make the leap ?
    It would be my opinion to replace the tank.

  11. #26
    DIY Junior Member akm's Avatar
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    Quote Originally Posted by Doherty Plumbing View Post
    It would be my opinion to replace the tank.
    Thanks for the confirmation.
    Pretty much agree with your sight-unseen opinion.
    Phoned our local plumbing supply and they suggested could check dip tube, and if that needs replacing, it might be worth it ($12-$13), but if not that, then should probably replace WH.
    Guess will take a look at the dip tube, and if bad, maybe replace and see what happens.
    Make sense ?
    Any suggestions/warnings about checking/replacing dip tube (besides make sure turn off the water, as suggested by the plumbing supply person) ?
    Thanks again for your help.
    akm

  12. #27
    Moderator & Master Plumber hj's Avatar
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    Default heaters

    The "fire up" time for the second heater is immaterial, because it only becomes a factor when the first one is being depleted, and then it fires at EXACTLY the same time/temperature it would have if it were the only heater. In the mean time the first heater has been operating for a substantial time period heating and preheating the water into the second heater, keeping it offline for a longer period of time.

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