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Help Replacing Thrush Pump

Hey guys Im in need of some help... Hopefully the "MAIN WALL" is an ok place to post this.

I have a 2 zone system (piping in basement cement and ceiling plaster) with an old cast iron boiler which I am assuming was put in when the house was built in 1960. I had a b&g 100 on the basement zone that I replaced with a taco007 (Local HVAC guy direction) a couple years ago that has been running great. Last year right when winter was ending the old Thrush HH-1LW pump went out on me. Without doing all the research I should have (didnt look in the right place for the pump curve and impatience on my part) I bought a taco0011 and threw it in. Long story short, I got the system refilled, purged the air and tried the upstairs circuit and it sounded like i still had air in the system or the pump was cavitating. Local HVAC guy came out and said it sounded like there was air in the circuit and that my pump will probably be ok, but he acted like he didnt really know what he was doing as im pretty sure 95% of my area has forced air heating. I was going to try rebleeding the system at a bit higher pressure to make sure I get the air out of the ceiling lines, but Im low on time and money and was hoping I could get some advice. Do I eat the cost for the taco0011 and get a new pump with matching curve? will a taco007 work for the upstairs circuit? a taco0010? I know I will probably need to provide more data to get a good answer but I am a newb at this stuff and would really appreciate any help!

Thank you in advance for your help!!



  • delta T
    delta T Member Posts: 884
    edited September 2016
    We need to know the total length of piping for the longest run (approximately, does not have to be perfect) the total length of the baseboard on the zone, the size of the piping and the baseboard (most likely 3/4" though 1/2" does exist). Also what is the btu/hr input rating for the boiler, and what temperature does it run at?

    This will allow us to get a desired flow rate and then based on the piping a head loss, and then we can size a pump.

    Experience says that 0011 is most likely WAY to big, probably why you are hearing funny noises. A 007 will probably work just fine. With an old cast iron boiler it is not as important to have exactly the correct flow, though there are limits.

    In all reality, it is highly likely that the flow requirements of the entire system could be handled with ONE 007 (though it would take re-doing your piping and controls to add zone valves, not a practical piece of advice, just thoughts on physics)

    You would be surprised how little flow you actually need....

    Edit: too much flow can cause damage to the piping in extreme cases. I have seen 90's with a hole in the back of them caused by over-pumping. It is very hard to under pump a system, but over-pumping is another matter. If it were mine I would ditch the 0011 (assuming the math supports doing so).
  • kcopp
    kcopp Member Posts: 4,395
    No baseboard... its radiant. Buried in plaster.
  • CordBond
    CordBond Member Posts: 3
    Thank you so much for your response! I estimated the longest run to be about 65 feet (pump to house wall and back). I dont have a baseboard as its in the plaster in the ceiling. There are 12 1/2" copper lines leaving the upstairs zone. Im not positive on the BTU/hr but its an American Standard Boiler G-26-DPGC, the nameplate has INPUT:150000 OUTPUT:120000, no units but im guessing it could be btu's. Im not positive on the temp either but I believe it was somewhere around 125-140..?

    My only concern is from the pump to the ceiling, i would estimate its around 13' (rough measure)... and the head on the 007 is only 10'....

    Again thank you for your input! If all it needs is a 007 ill order tonight and throw it in!
  • Steamhead
    Steamhead Member Posts: 16,729
    The Thrush HH pump curve is here:


    The HH-1 looks like it has a similar curve to a B&G 100. If a 007 doesn't work, try a 0010.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • SWEI
    SWEI Member Posts: 7,356
    CordBond said:

    My only concern is from the pump to the ceiling, i would estimate its around 13' (rough measure)... and the head on the 007 is only 10'....

    In a closed system, the height does not factor into pump sizing.
    delta T
  • delta T
    delta T Member Posts: 884
    kcopp said:

    No baseboard... its radiant. Buried in plaster.

    Totally missed that. My bad.

    I would think a 007 will work just fine for you. as SWEI mentioned, the vertical height does not factor into a closed system, only the pressure loss due to friction. This increases exponentially as flow rate increases. The 007 was originally intended to be a replacement for the series 100, I would be surprised if it did not work here.
  • CordBond
    CordBond Member Posts: 3
    Thanks everyone, just ordered a 007 and will throw it in!