diaphram expansion tank on american standard ng boiler


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Old 06-15-14, 11:59 AM
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diaphram expansion tank on american standard ng boiler

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.

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Old 06-16-14, 04:00 PM
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I can't quite make out the photo. But, from your description, you may be OK. A series of closer photos, in focus, would help. Try to use a real, dedicated digital camera, not a cell phone.

By PRV, you mean pressure relief valve, not pressure reducing valve, right? You can't have a valve in between the relief valve and the system. Being able to valve out the expansion tank, with a drain valve too, is handy for checking the tank's pressure. There is a sticky above this forum that explains all - the water side of the tank must be depressurized to check the air pressure in the tank.

Why are you replacing the boiler? If for fuel cost savings, you can forget it - the payback will be too long.
 
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Old 06-16-14, 05:48 PM
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the expansion tank is screwed into a tee connection that is screwed onto the pipe that comes out of the boiler and is for the pressure relief valve.

and the old boiler has a leak. its got to go.
 
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Old 06-17-14, 03:17 PM
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Oh, OK.

Nowadays, many new hot-water boilers come with a new circulator pump. While you're at it, I would replace the expansion tank and the relief valve, unless they are relatively new. Also a new pressure reducing valve (auto fill valve) and backflow preventer.
 
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Old 06-17-14, 05:14 PM
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Do some homework first.

If you're replacing the boiler, the first thing is to know how big a boiler you need to heat your home.

For that, you need to do a heat loss estimate.

At the top of the message list is a 'sticky' with heat loss estimate programs that you can download and spend a little time inputting data.

OK, so now you know how big a boiler you need.

Next, you need to study piping diagrams of how a modern boiler is installed. For starters here, google the term " PUMPING AWAY " and read the papers on that concept. Once you understand that, you are on your way to home plate.
 
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Old 06-23-14, 09:59 AM
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my heat loss calulation came to @47,000. and i also have 82 feet of finned baseboard.

so i'm going with a Slant/Fin Sentinel SE-70EDP 70,000(input) BTU Natural Gas Boiler. 50,000 btu output.

 
 

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