Baseboard knocking with Steam on is it the pump?

acl10

My baseboard is connected to my steam boiler. The baseboard runs fine when the steam is off and the boiler runs fine when the baseboard is off. When they are both on together there is constant water hammer. I used to have a Armstrong Astro 230ci pump that had 3 speeds when it broke I changed it for a Taco 007-sf5. When the Armstrong was in I didnt have this problem. I dont rmemeber having this problem right after I chaged the pump last year. This year I started having the water hammer as above. Does anyone think it has to do with the type of pump. I dont want to change it unless thats the problem. Is the taco stronger or weaker and thats the problem? or its faster or slower? I cant figure out what to do.
Can someone look at the specs and tell me if they are all that different does one have to many GPMs or any other ideas. Thank you

https://www.taco-hvac.com/uploads/FileLibrary/100-1.8.pdf

https://armstrongfluidtechnology.com/~/media/documents/specifications/submittal-data/astro-2-circulators/10_584_astro2_3speed_submittal.pdf?la=en

https://www.amazon.com/ARMSTRONG-PUMPS-110223-305-Armstrong-Circulator/dp/B00QW29XDU/ref=sr_1_1?ie=UTF8&qid=1517922572&sr=8-1&keywords=armstrong+astro+230ci

https://www.amazon.com/Taco-007-SF5-Cartridge-Circulator-Stainless/dp/B01LX6VBGO/ref=sr_1_6?ie=UTF8&qid=1517921745&sr=8-6&keywords=taco+007-sf5

acl10

Picture of current pump on Supply line from left side of boiler to baseboard



Return line into right side of boiler

Big Ed_4

You need an boiler by pass to temper down the condensation loop ... From its return just before the circulator with an valve to regulate ...

acl10

I called Taco and they told me that the Taco model I had was half the power of the Armstrong I will now try to change it

JUGHNE

I believe we kicked this around before. Did you try to turn the pump around and change the direction of flow into/out of the boiler/piping. IIRC the only thing that was changed before the problem began was the pump change out.

acl10

I think I finally solved it. When the Armstrong 230ci pump went I tried a Taco but didn't realize that it was much weaker then the one I had, that model was half the power of the Armstrong. Today I put an Armstrong 230ci in again and it seems to run smooth no more hammer because the water goes faster with more pressure back into the boiler

acl10

You need an boiler by pass to temper down the condensation loop ... From its return just before the circulator with an valve to regulate ...
Can you please explain this

Big Ed_4

acl10

I put back in an Armstrong 230ci and set it on the 3rd speed and no more water hammer. I had put the wrong size pump in last time and it wasnt powerfull enough

Danny Scully

You put the wrong pump in again (in my opinion). It should be a 3-piece bronze b&g 100, but best of luck anyway and glad it’s solved for now.

acl10

Why is that pump better. I would like to know for next time. Or I might even change it if its that much better. These Armstrongs only last me a year or two before they go.

acl10

Also is this one compatible https://www.amazon.com/gp/product/B003QS8CLM/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

Dave0176

acl10 said:

Why is that pump better. I would like to know for next time. Or I might even change it if its that much better. These Armstrongs only last me a year or two before they go.

The biggest problem with the small high speed pumps is the bearings are lubricated by the boiler water, which happens to be acidic because it’s a steam system. It wrecks havoc the cast iron volute and bearings. The Bell &Gossett all bronze 100AB is a three piece pump that has oil lubricated bearings and a bronze volute, so the boiler water don’t affect it.