New installation thinking

bovide_4

I am about to install a new replacement steam boiler and water heater for a building with 8 apartments and 2 stores. The old boiler was 474 MBH. My heat loss with a 1.5 pick up factor is 292,300 btu's. I have three questions I am pondering:

1) Each apartment has only two or three radiators, and two 2" exposed steam risers. Does the 1.5 pickup factor include the 2" risers? They will never be insulated as they are the radiators.

2) The boiler is in a pit. The old boiler had an oil burner. The new boiler is atmospheric.(Burnham Independence) (I wanted an HB Smith, but there are businesses above, and noise is a problem) I should center the boiler in the pit to avoid problems with combustion air, right?

3) There is only a 6' ceiling around the perimeter of the boiler pit. There is not enough height for a gas fired atmospheric water heater. I am thinking about an indirect water heater, but am not thrilled about firing >300 mbh for hot water in the summer. Is it a waste to run this boiler with an indirect, or is it worth the trouble of opening the pit to fit a standard water heater?

Jamie Hall

On that pit...

be very careful with the new boiler that the water line is at the same elevation, give or take an inch, as the old one.  Otherwise you will have trouble.  You may have to set the new boiler up on blocks or on a concrete pad to achieve this...

STEAM DOCTOR

boiler sizing

When sizing steam boilers we measure the edr of the radiators (heat output) and not the heat loss of the building. Also 33% IS industry standard for pickup factor on steam boilers but that could vary depending on insulation, length and size of steam mains etc.

bovide_4

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BN: Yes, I should clarify, that the square feet is the EDR sum of the rads.

I used a pickup factor of 1.5 instead of 1.33 to account for the 2" bare pipe riser radiators.



Jamie Hall: just thinkng out loud. Would a lower water line in a pit boiler increase the "A" dimension, and is that a good thing? Gonna do a drop header, too.

Gonna read the section in my TLAOSH.

STEAM DOCTOR

A dimension

Anytime you raise or lower the water level of the boiler there is potential for A dimension issues. The only way to know for sure is to measure the height of the lowest horizontal pipe above the boiler water level and the height of the boiler water level. There needs to be 28" between the two.

bovide_4

thanks

Thanks, but I know what an "A" dimension is.

I am curious though, as to what people here think about using an indirect on a larger boiler.