30 lb

hr

to your particular application. System capacity, temperature, building elevation, operating pressure, are all part of the equasion.

They may have meant a #30 expansion tank, not 30 gallon.

Plenty of sizing info out there for exp tanks, contact the tank dealers or reps.

I like the expansion tank sizer on the Hydronic Design Studio. Try a free demo at www.hydronicpros.com..

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M Ransley

30 lb

I had a Weil McLain PFG 5 boiler instaled in the basement of a 3 story house , 4 levels if you include basement. of an apx 6000 sq ft house a year and a half ago. The 12lb auto feeder has the HWH boiler at 12 lb at 80 degrees, but at 160 reaches 30 lb blowing the saftey valve. Weil Mc Lain said I need a 30 gallon tank , and that the makeup could have scaled the boiler reducing it efficency 10 % , or worse ruin it in a few years making it crack from scale. I hear no popping , and dont think it leaked out more than a few galloms but i dont know, its Chicago water and not to hard. But my installers solution is to move the auto feed to the expansion tank from the return line . The old hwh boiler had no auto feed.
This guy has been pretty honest to me, But in the last month an AO smith 100g 225000 btu water needs replacement at a bldg, He said All commercial water heaters are 80%, well AO Smiths Cyclone 250A is 94% and the 300000 btu is 99%. And he said all commercial steam boilers are 80%, but now im learning there are condensing units, Point is Do I trust him now. NO. I found the HWH problem, he is avoiding it and he first blamed me.....Is Weil right that i may have reduced efficency, or worse, I realy dont know how much blew off. I do have the 3rd floor an 2 second floor radiators closed off but he said it wouldnt make a diference.

hr

Best to use a

sizing table or formula. Building height, fill pressure, system capacity, operation temperature, are part of the info you need.

They may have meant a #30 bladder type tank ??

Contact a dealer or rep for sizing help. www.hydronicpros has a demo software with a expansion tank sizing program. This may help.

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Ray Landry

There's no such thing as a condensing steam boiler. He's right, steam boilers can't get out of the 80% range because of the high temps they need to run at to make steam.

I think the A.O. smith 90 plus water heaters are new technology. Don't blame the guy for not knowing about them. Not everyone knows everything.

He may be on the right track with the expansion tank, if you can hear it add water during operation. If you don't hear it adding water, his solution would probably be to switch to something like an extrol 60. Especially with it being a three story house. Another factor when sizing the tanks is if you have glycol in your system, it expands more than water.