diaphram expansion tank location on american standard ng boiler

Discussion in 'Boiler Forum' started by driger, Jun 15, 2014.

  1. driger

    driger New Member

    Messages:
    9
    Location:
    Idaho
    i have an old ng american standard 1bj1 105k btu natural gas boiler for baseboard heating(pictured). i notice the diaphram expansion tank is located on the same pipe as the prv that comes out the top of the boiler. i thought these tanks were suppose to be located on the heating loop piping near the boiler.

    is a current location incorrect?

    i am considering replacing the boiler with a slant fin sentinal 105se, so i'm investigating.


    DSCF0465a.jpg
  2. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,137
    Location:
    Maine
    It doesn't matter where the tank is in the system as long as it feels system pressure.
  3. driger

    driger New Member

    Messages:
    9
    Location:
    Idaho
    muchas gracias.
  4. BadgerBoilerMN

    BadgerBoilerMN Master Hot Water Mpls,MN

    Messages:
    303
    Location:
    Minneapolis
    It is not the location of the expansion tank rather, the orientation of the tank visa-vi the pump. The pump should draw water from the location of the expansion tank. The opposite of the set up you have now.

    This boiler was originally installed with an old-school "compression" tank, which also served (poorly) as an air eliminator. We retrofit old American Standard boilers such as this one with a similar arrangement but move the pump to the supply side and add a proper vent.

    Of course all of these boilers are passed their serviceable life, since most have never been serviced, and should be replaced before they hurt someone.
  5. driger

    driger New Member

    Messages:
    9
    Location:
    Idaho
    well i'm installing a new slantfin boiler anyway. it has an air vent on top. can the expansion be located at the pressure relief valve, or should it be on the heating loop?
  6. BadgerBoilerMN

    BadgerBoilerMN Master Hot Water Mpls,MN

    Messages:
    303
    Location:
    Minneapolis
    Pump away from the SlantFin boiler vent and XT.
  7. driger

    driger New Member

    Messages:
    9
    Location:
    Idaho
    the slantfin boiler has a vent on top.

    Heatin4.gif
    Last edited: Jun 18, 2014
  8. BadgerBoilerMN

    BadgerBoilerMN Master Hot Water Mpls,MN

    Messages:
    303
    Location:
    Minneapolis
    Yes. I have been installing them for a few decades. Use the "Alternate".
  9. driger

    driger New Member

    Messages:
    9
    Location:
    Idaho
    so with the air vent on top can xpansion tank simply be mounted under the pressure rv, as it is in with old american standard? or is the alternate setup shown the way to go?

    and it appear the fresh water fills via the air vent pipe, correct?

    thanx.
  10. nhmaster3015

    nhmaster3015 Master Plumber

    Messages:
    836
    Location:
    The granite state
    If YOU are installing the boiler I strongly suggest that you thoroughly read and understand the installation manual that comes with the boiler. The questions you are asking lead me to believe that you have just about no knowledge of hydronics or proper piping and installation procedures. While it may seem a fairly simple task, believe me, it is not and any mistakes made will void the manufacturers warranty and in fact, many manufactures won't stand by their warranty if the equipment was not installed by a licensed and qualified installer.
  11. driger

    driger New Member

    Messages:
    9
    Location:
    Idaho
    nhmaster-

    i'm really not sure why you even bothered posting such a comment, other than to try and make yourself feel important.

    obviously the diagram came from the instructions. and theres obviously more than one way to plumb it.
    Last edited: Jun 20, 2014
  12. Reach4

    Reach4 Active Member

    Messages:
    2,151
    Location:
    IL
    Did you already know about the potential loss of warranty, or did it not matter to you?
  13. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,137
    Location:
    Maine
    I posted it because of this post which pretty much tells me that you are in over your head but by all means, carry on. Full speed ahead captain. LOL

    Btw, for a professional, there is only one way to pipe it.
  14. BadgerBoilerMN

    BadgerBoilerMN Master Hot Water Mpls,MN

    Messages:
    303
    Location:
    Minneapolis
    Hey, the guy is in Idaho, probably still fighting Indians and the nearest licensed technician is two territories away! But, nh has a few good points there. It's Friday. I quit.
  15. Dana

    Dana In the trades

    Messages:
    2,812
    Location:
    01609
    Don't quit now- we're just getting started on the sizing issue!

    The Sentinal 105 SE has 87,000 BTU/hr of output, which is something like 2x the amount of heat needed for most homes, and it could easily be 3x oversized for a smaller better insulated house. You only get a shot at right-sizing the boiler every 20-30 years or so, so while investigating, why not start with analyzing your heat load to avoid oversizing, which has both efficiency & comfort consequences. Unless you're convinced the next ice age is imminent and you'll be seeing -100F temps every winter, you're probably better off with a smaller boiler more appropriately sized for the load. It's very common to find older boilers 2x, 3x, even 5x oversized for the actual heating loads, and relatively rare to find them less than 1.7x oversized (which is the oversizing presumption in an AFUE test.) Just because the last installer put a 105,000 BTU/hr boiler in this place doesn't mean you need to repeat the mistake (and it almost always IS a mistake to install a boiler that big, unless it's an unsually large &/or uninsulated house.)

    If you have fuel-use history on the place it's possible to get a pretty good ball-park on sizing by calculating the fuel-use per heating degree-days, and calculating how much you would need to cover the load at your 99% outside design temp. All the necessary information can be found on a mid-winter gas bill, with the EXACT DATES between meter readings, plus a zip code (so we can look up the weather history for that interval, and estimate the design temp), and both the input & output BTU ratings of the old boiler.

    But if you've already uncrated the thing and started plumbing on it you probably can't take it back for the right-sized version. :-( Within the same model line the SE-70 (smallest in the series) is more than enough boiler for the vast majority of homes in the US.
    Last edited: Jun 20, 2014
  16. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,137
    Location:
    Maine
    I think I rub some folks the wrong way lol but, I have seen more than my share of botched boiler installations over the years. Some done by guys thinking they are professionals. I hate too see all that money, time and effort wasted or at the least misdirected. I'd also bet the boiler is close to 3x oversized and probably will get piped to about 45' of copper fin tube thereby guarantying it won't condense and will suffer an early demise as the poor unit short cycles itself to death. I am currently making a damn good living just doing estimates and consulting work without ever having to pick up a wrench. Most folks listen and believe but there's always a few that think they "have this". Oh well, it's not my money. Like I said. A real professional knows that there is only one way to properly pipe that particular aspect on a boiler.
  17. driger

    driger New Member

    Messages:
    9
    Location:
    Idaho
    well, the estimates from the contractors were @$5500. you might be able to buy 3 boilers for that money. $3500 is a good sum of money to plumb 3 water pipes, a gas line, and connect 4 wires.
    Last edited: Jun 20, 2014
  18. driger

    driger New Member

    Messages:
    9
    Location:
    Idaho
    its being piped to about 90 feet of copper fin tube. and the old boiler barely kept the house warm. the basement where it sits is unfinished and the house is old. winters are also bitterly cold here. according to my calculation it's 20% oversized. if go with one a size smaller it's 20% undersized.
    Last edited: Jun 20, 2014
  19. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,137
    Location:
    Maine
    90' @ about 580btu per lineal foot @ 180 degree water temperature. So your radiated load is about 47,000 but/hr if your old boiler won't keep up with the heat loss neither will the new one regardless of how big a unit you install. and worse yet, it will NEVER run at or even near the efficiencies that it is possible of achieving. Essentially you are throwing your money away.
    Last edited: Jun 21, 2014
  20. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,137
    Location:
    Maine
    No professional would even take on your job without 1st doing a complete manual J heat loss calculation followed most likely by a recommendation that the amount of heat emitters ( radiators, fin tube, convectors) be increased in order to assure that the new boiler can modulate properly and achieve condensing temperatures. Otherwise he would do exactly what you are about to do and then have to put up with your constant phone calls when the system doesn't meet your expectations. From what I've read here already, if you want to do the job right and actually save some money on your energy costs, doing this yourself is going to be disastrous, but I'm betting you aren't going to take the advice anyway.
Similar Threads: diaphram expansion
Forum Title Date
Boiler Forum Adjusting Expansion Tank Pressure Dec 30, 2013
Boiler Forum Sizing a Boiler Expansion Tank Sep 23, 2013
Boiler Forum Expansion Tank Change-Over Jan 2, 2013
Boiler Forum Boiler Expansion Tank Oct 12, 2012
Boiler Forum Sizing boiler allowing for future expansion Sep 10, 2012

Share This Page