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Circulator Replacement

I have a customer with a 1940's ranch, slab on grade with an overhead monoflow-T system, with cast iron rads. and a lot of concealed piping. The B&G 100 series 1/6HP circulator has seized up from lack of maintenance by the service company. The boiler is a gas Smith GB100W 146,000 BTU. Steel expansion tank with airtrol fittings. The thermostat controls the circulator only. Single zone system with fixed water temperature and no boiler protection piping or controls The boiler is adjacent to the breakfast nook and the old circ was loud. High electric rates. The house was built by the founder of the construction firm that i work for. who was exceptionally good at thinking things through. The piping arrangement seems very well thought out and there is a master coin air vent in the utility area near the boiler to purge the system, which has little air issues. ! 1/2" iron pipe supply and return in boiler room.

Question 1. I need a recommendation on a replacement circulator. The Owner probably needs one that does not require oil.

Question 2. Would a ECM motor like a TACO Viridian be worth it. For electrical cost and boiler protection?

Question 3. Should i have it switched to pumping away while i'm changing out the circ.

Thanks,

Chris

Comments

  • JohnNY
    JohnNY Member Posts: 3,230
    The Taco 0010, generally speaking, is a good replacement for the B&G 100.
    My opinion, and I hate giving opinions, is that an ECM motor would not be well-paired to a system with the developed head across piping full of monoflo tees.
    Yeah.
    I'm thinking that's trouble.

    Someone might, however, be glad to prove me wrong.

    So let's see.
    Contact John "JohnNY" Cataneo, NYC Master Plumber, Lic 1784
    Consulting & Troubleshooting
    Heating in NYC or NJ.
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    Bob Bona_4Gordy
  • hot_rod
    hot_rod Member Posts: 22,122
    I think an ECM in a fixed speed mode would be fine if you find one with a similar curve.

    The B&G Vario is a nice ECM with a selector switch for fixed speed operation.

    With that boiler you probably only need 10- 12 gpm?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Gordy
    Gordy Member Posts: 9,546
    edited October 2015
    The OP stated series 100 "1/6 hp". I believe that is the 100 HV series. If so a direct B&G wet rotor replacement with same curve, and using 60 watts less power is a PL30. All though the flange to flange measurements are a bit smaller than the 100
  • unclejohn
    unclejohn Member Posts: 1,833
    edited October 2015
    The Taco 007 is the replacement for the BG series 100. I would use a pump with a speed selector though. The Wilo has speeds and flanges that rotate.
  • Gordy
    Gordy Member Posts: 9,546
    edited October 2015
    So to the op the question is the system worked well since 1940's with that size circulator. the HV uses 228 watts 1.9 amps. The PL 30 uses 168 watts 1.4 amps assuming 120 volts. As for other things if it's not broke don't fix it. Pumping way is a beautiful thing, but not always absolutely necessary.

    The power consumption difference is about 2 bucks a month if the heating system runs 8 hours a day which is a lot, and KW charge is 12 cents a KW.
    JohnNY
  • hot_rod
    hot_rod Member Posts: 22,122
    But why so much pump on a 146K input boiler?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    SWEI
  • Gordy
    Gordy Member Posts: 9,546
    edited October 2015
    How do you know.
    I guess if one wants to toy around with circ choices without being able to know all the piping to calculate head by all means play with it. You could install pressure gauges on inlet outlet at the present circ, and calculate head by differential pressure.

    I guess the point is what's there works. If it's the 100 HV then the pl30 gets the circ to a wet rotor and cuts down power consumption by 60 watts with same curve performance.

    Either way with the high electric bills I would not blame the circ which is not set up as constant circulation maybe 6 bucks a month during heating season..... If everyday was a design day.
  • ChristopherJ
    ChristopherJ Member Posts: 6
    OP here.
    The main follows the L shape of the attic. There is 150 feet of 1 1/2" iron main piping with approximately 9-90 degree elbows. The take offs to the radiators are 3/4" most are approximately 10 feet each. There is addition with two radiators that probably share one pair of mono flow fittings. The furthest radiator in the addition probably 30 feet from the main. There are a total of 10 slenderized radiators and 24 feet of uninsulated main that serves as the radiator on the second floor.

    A little history, last year I was sitting at the kitchen table near the boiler and heard the T& P valve open. I asked how often that happened, homeowner replied for the whole heating season and that service company had replaced T & P twice now 50psi Found expansion tank full and PRV stuck open.

    Chris
  • Gordy
    Gordy Member Posts: 9,546
    edited October 2015
    Is there velocity noise when the system is running?

    Also need to know number of diverter T's in the system their pressure drop is cumulative. Would 24 be correct?

    Actually a piping layout sketch is even better.

    And is the present circ a 100 HV, or just a 100. Series 100 is 1/12th hp. The series 100 HV is 1/6th hp. The two have very different pump curves the 100 is flat while the HV is steep.
  • Gordy
    Gordy Member Posts: 9,546
    I'll stab with present info and call it 9.5 feet of head. Which puts you just under 10 gpm with the VT 2218 lower portion of the middle 1/3 of the curve speed 4 @58'watts. I would caution though that the present set up has not had much air issues which could be from the higher velocities of the present circ.
  • ChristopherJ
    ChristopherJ Member Posts: 6
  • Gordy
    Gordy Member Posts: 9,546
    Circs an HV
  • ChristopherJ
    ChristopherJ Member Posts: 6
    Thanks, I ordered the PL-30. I'm in construction but this is outside of what I normally do. Finding anyone to work on boilers in this part of the world--far western Kentucky--is difficult. There is a lot of just rip it out and put in forces air here. TheWall helped rebuild my personal steam system in Vermont, and it ran like a clock on 6oz of pressure.

    Thanks to all that helped.

    Chris