Pump sizing

Jim E

My customer has a locked up pump no tags or lettering of
any kind it is a steam system changed to water two story
house how do I size the proper pump for this system


THANKS Jim

Brad White_2

To start, Jim

I would need the boiler nameplate rating (fuel input, BTU output both gross and net "I=B=R" ratings and burner rating (gph)if oil or BTU's per Hour if gas.

From there it can be determined the maximum amount of heat to be delivered in BTU's per hour.

And from that we can establish a flow rate which normally but not always is based on a 20-degree temperature drop (BTU's per hour divided by 10,000) or a larger temperature drop which would dictate less flow.

The amount of pressure required is another matter, but if the pipe sizes are large (older steam pipes) the pressure requirements tend to be quite low in my experience. Each job is different!

Without knowing radiator and pipe sizes, the above is probably the best place to start.

Jim E

BTU,s

213,000 input
170,000 output

Jim E

BTU,s

213,000 input
170,000 output

Jim E

BTU,s

213,000 input
170,000 output

Jim E

BTU,s

213,000 input
170,000 output


Sorry about the repeats the wife is trying to
learn me computers

Brad White_2

BTU's

No worries on the repeats, Jim
No worries on the repeats, Jim

:^)>

From what you say here, the 170,000 BTUH would require 17 gpm if a 20-degree drop and 8.5 if a 40 degree drop. 40 degrees may be too much for an older cast iron boiler without special controls (water coming back too cool) so we could stick with 17 GPM, maybe 13 if we split the difference.

What are the main pipe sizes and would you describe the longest run for me? Not just length but pipe sizes and fitting in each size. Longest run would be from the pump outlet to the farthest radiator and back. By "farthest" means that if the one most distant has a straight shot of piping but one closer has oodles of fittings (oodles is a qualified engineering term meaning "gobs") then the fitting-intensive run wins.

Get back to me and let's see where we can take this.

Jim E

Piping

is mostly concealed is three inch that I can see in the
basment. I would say the longest run would be 120 ft.
Guessing by the lay out of the house there are not alot
of turns. Maybe 8 turns.

Brad White_2

Three Inch Pipe???

With what you describe it would be hard to detect a meaningful head loss. Would you consider thermostatic radiator valves at the radiators? I am thinking of some way to balance the system based on temperature. Macon makes a nice valve and Tunstall here in MA makes a kit to convert your angle valve to a TRV by replacing the guts.

My guess would be that the total head loss would be less than 4 feet, maybe another foot for a TRV, call it 5 feet.

A Grundfos 15-58 FC seems suitable on speed 3. (The "FC"=flow check- a good idea where gravity flow probably happens severely).

At 5 feet the pump will deliver 15 GPM, not quite the 17 you call for, but pretty good. If water leaves your boiler at 180 F it would return at about 157 F. (22.7 F delta-T).

An alternate selection (just to try one) would be a Grundfos UP 26-120 U. This will deliver the 17 gpm at 5 feet of head but has a steep pump curve. It will handle up to 35 feet of head at no flow, and in the middle, 10 gpm at over 20 feet of head. A little difference in flow means a bid difference in head. Stick to the 15-58 FC in my opinion.

Jim E

Black iron pipe yes

How would a Taco 0011 compare to the Gundfos 15-58 Taco is
what is more common in this part of the county.

Brad White_2

A Taco 007 or 0010 would be a better choice

The curve matches the 15 GPM at 5 feet point nicely but drops off rapidly. The 0011 has a very steep curve (high head).

My choice would be a Taco 0010 which will deliver 17 GPM at about 8 feet of head, so you have some room in both directions.

What I like about Grundfos and others are variable speeds. You can get Grundfos on line, but Taco is a good pump. I think you are all set!

Jim E

THANKS

Have a good evening


JIM E