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You Guys Run Circ Pump all the time?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by Tennman, Jul 18, 2012.

  1. Tennman

    Tennman Minister of Fire

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    Had a discussion with Taxi about whether I should shut down my boiler barn to house circ pump when the HX blower is not on. Here's my question; it takes energy to get nearly 400' of water moving at whatever fpm the Taco 0013 gets it moving. So what do you guys do? I know there has to be a big spike in amps (energy) to get the water moving again from dead stop, and I know in my case, when it's pretty cold my fan cycle time goes way up. There has to be some point where it's more efficient to start/stop a truck vs keeping it slowly rolling (energy analogy). I don't remember this being discussed so I've just assumed ya'll keep the water moving all the time like I do. Still hoping to add storage this year, but competing business and home projects are putting it at risk. Been kinda quiet lately.

    AND for heavens sake EW.... Stick around!! We love ya!

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  2. webbie

    webbie Seasoned Moderator Staff Member

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    In most such cases, the idea that keeping things going saves energy is not true!

    Most pumps and motors use a capacitor start up which does use a bit more to start, but nowhere near what would be used over a period of time.
  3. woodsmaster

    woodsmaster Minister of Fire

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    I would have the circulator shut off to keep mixing in storage down.
  4. BoilerMan

    BoilerMan Minister of Fire

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    I agree. To start up a 240watt (0013) circ is about the same as running it for 2 minutes. There are some variables, but trust me is is much less expensive to control it with an aquastat and turn off with the blower in WAHX. Not to mention the added wear of 24/7 running. A 0013 is not a cheap pump to replace.

    TS
  5. Tennman

    Tennman Minister of Fire

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    Huh.... I was kinda expecting a vacillating.... "well maybe" answer. Nice to get a clear heck no! Makes sense about reducing the mixing from the big pump. Even my inefficient house has longer than 2 minutes between when the fan comes on. Thanks for the data there Taylor and webbie.

    JT, as I recall your boiler is in an outbuilding like mine correct? So are you controlling your circ pump thru a relay triggered by the thermostat? If yes then I guess you have one of those CAT something wires in the ground to control the pump based on demand. I suppose I could move my 0013 to the house but it's pretty noisy. I hear it humming as I approach the boiler barn.
  6. woodsmaster

    woodsmaster Minister of Fire

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    I actually leave mine run about 20 hrs / day. I have a good delta t in the winter with my panel rads and a slow flow.
    I have to leave mine run most of the time for my sidearm to heat my dhw. Idealy I would go on demand dhw with a flat plate and one of those delta t pumps for the rads.
  7. BoilerMan

    BoilerMan Minister of Fire

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    All you need to do is run some 12gauge out to your boiler shed. Either pull through some already buried conduit or you could bury some #12-2 UF directly but I would only do that as a last resort. You should already have a pipe (conduit) out there just pull the wire to the shed and connect it to the pump. How is your blower controlled now? It should be connected through a relay to a room thermostat in the living room etc. It so, get another and wire the thermostat inputs in parallel and use one to power the "new" wire out to the pump, and the other existing one still powering the blower. I'd not use the same relay to power both the blower AND the pump.

    However, I'd use a strap-on aquastat to power the blower and the thermostat would run the relay which would run the pump (still in the shed). If that makes sense.

    Either way make shore you still have the dump aquastat power the pump so the heat makes it to the house and nothing overheats.

    TS
  8. Tennman

    Tennman Minister of Fire

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    Good input Taylor. My boiler and pump are about 200' from the blower/furnace. I was thinking of putting the pump relay near the pump and only run a wire from the house to control the relay instead of running pump power from the furnace. I don't know if that low voltage from the Tstat can go that distance and power the relay on. I've got electrical folks around me to solve that problem. Yes, at the moment I have two thermostats on my wall. One controls the propane furnace and the other controls the furnace fan when the boiler is up. So I presume my "boiler" tstat is only talking to the blower relay in the furnace. I'll have to bury a new control line to get to the relay in the boiler barn, but that's not a big deal. My internet and TV dishes are out near the barn so I already have some small underground stuff.

    I think I get the aquastat.... the Tstat gets the hot water moving but the blower doesn't come on until water reaches the set point..... Very cool. Whereas I wanted to combine the two tstats into one more modern one, by keeping two tstats as is I have really two totally independent systems, propane and wood.
  9. goosegunner

    goosegunner Minister of Fire

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    I have similar distance between my forced air coil in the house and the boiler/storage in the shed.

    My furnace calls for heat it sends a singnal to a Taco zone controller above my primary/secondary manifold. The controller is wired so whenever a zone calls for heat it also starts on demand the primary pump.

    I changed it to on demand when I added storage. It minimizees mixing of the tank. If you circulate all the time you will not have a stratified tank.

    Example;

    Tank is 180 on the top and 130 on the bottom. When you are heating the return water could be 150. It will mix the tank some but only during heat cycles.

    When you have no load with continuously circulating water the return could be 175, that will mix the tank down fast because it never stops. 24/7 you are taking hot water off the top and putting it into the bottom of the tank. With forced air heat you want to do everything you can to keep hot water at the top as long as possible.

    My next upgrade is going to be a buffer tank in the house near furnace and water heater. That way I can deplete the buffer tank and send the water back to the bottom of storage.

    It will also keep hot water near the water heater so I can set up a plate exchanger for on demand DHW.

    gg
  10. Tennman

    Tennman Minister of Fire

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    Yeah GG, this is all starting to sink in. My plan is to use a Laddo 21-100 to control the circulation between boiler and storage. Obviously it is a much smaller gpm so hopefully it won't mess with my stratification like the 0013 will. I like the idea of a buffer since it should trigger the aquastat for the fan sooner having energy stored near the HX. It's a challenge just to replace the water heater down in our root cellar. You planning on something like 100 gal for the buffer? I'm learning a lot with this thread.
  11. goosegunner

    goosegunner Minister of Fire

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    I think I will use at least 100 gallon tank. Might go bigger. I have a walk out basement so maybe what ever I can get in the door and fit next to my water heater.

    gg

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