Buderus indirecr pump?

Dave_22

I asked this question before, but don't really understand the answer!!! I'm looking at two indirects: a S-120 which requires 9.5 GPM @ 6.5 ft hd and a ST-150 which is 15.9 GPM @ 3.9 ft hd. The reason for the lower head on the 150 is because it has a 1" internal coil. Literature says a Taco 007 for the 120 and I'm told a 0011 for the 150 which has lower head pressure?????? Why such a big pump with half the head pressure? I know this will aid in quicker recovery, but unless the boiler is REALLY restrictive, that's a lot of flow! I have seen a lot of GB-142's on here with indirects-is the 0011 the pump to use? I would love to see a graph for the pressure loss of the GB's. Thanks.

hr

Ideally

you want a circ with high GPM flow and low head. Not of lot of pumps fit this spec, although primary loops share the same requirement. Some reverse indirects, like Ergomax also need lots of gpm and have very low pressure drops.

I'd like to see more pump manufactures offer pumps for this spec. Maybe a 3 speed high gpm low head cirs selection

I think B&G has recently beefed up their selection of pumps along this line. Check out their PL series also for some more options.

hot rod

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Dave_22

Thanks HR- I will look into that. It doesn't give me warm and fuzzy feelings when the manuf doesn't have a good answer. I wish evryone would standardize the ratings on indirects instead of twisting them to there benefit.

Ron Schroeder

I have a Buderus LT-160 which has very similar flow and head to the s-150. I found that with 1 1/4" piping and the very minimum of elbows that a 007 would flow enough for full specs. With 1" piping it was too restrictive to take all of the btu's that my boiler was producing and the burner would cycle a couple of times per heat call from the indirect.

Ron

Dave_22

Interesting...... How many BTU boiler do you have?

Ron Schroeder

It's a G115-21 .6gph.

Ron