Diaphragm expansion tank location on American Standard ng boiler

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driger

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i have an old ng American Standard 1bj1 105k btu natural gas boiler for baseboard heating(pictured). i notice the diaphragm 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
 
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Tom Sawyer

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It doesn't matter where the tank is in the system as long as it feels system pressure.
 

BadgerBoilerMN

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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.
 

driger

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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.

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?
 

driger

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the slantfin boiler has a vent on top.

Heatin4.gif
 
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driger

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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.
 

NHmaster3015

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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.
 

driger

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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.
 
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Reach4

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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.

Did you already know about the potential loss of warranty, or did it not matter to you?
 

Tom Sawyer

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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.

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.
 

Dana

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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.
 
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Tom Sawyer

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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.
 

driger

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Did you already know about the potential loss of warranty, or did it not matter to you?

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.
 
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driger

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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.

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.
 
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Tom Sawyer

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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.
 
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Tom Sawyer

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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.

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.
 
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