Would Replacing My Current Taco 007s with the Variable Speed Delta Ts Do Any Good?

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velvetfoot

Minister of Fire
Dec 5, 2005
10,202
Sand Lake, NY
I have two heating zones with Taco 007s. Would just swapping them out with the new Tacos with the variable speed delta T capability (or equivalent) do any good? What should the delta T be set to?
 
A 007 will draw 80 watts while it runs. A comparable B&G Ecocirc, Grundfos Alpha, Wilo Stratos, or Taco HEC-2 ECM pump would draw no more than 45 watts, more likely 10 watts, because, for a typical zone, normally a low flow/low detaP/high deltaT setting will do the trick.

Calculate hours per day per pump and multiply by watts times dollars per watt-hour times days per year and you'll know dollars per pump per year, then you'll know the economic benefit to weigh against the price of a new pump.

As for HEC-2 deltaT setting, tuning a hydronic circuit so that it 'works' is virtually foolproof. You can only pump about so many gpm down each skinny pipe. Any deltaT setting from 5 up to 40 would likely get the job done. Start with a high setting and if the pump runs forever and the zone never quite gets up to temperature then try a lower setting. A deltaP pump will do the same job as well or better without the need to monkey around with temperature sensors.
 
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I thought about it more. I can see the value of the continuously variable speed pumps with zone valves. Not so sure about a circ for each circuit. Which of course begs the question, circ pumps or zone valves? But they will be more efficient and can be tuned for the desired flow. When I was looking at baseboard specs, they all gave btu/hr/foot numbers for 1 gpm, which seems like a standard, and 4 gpm. The gain usually wasn't too much going from 1 to 4. I'll be working with a buffer tank that won't get much below 140 or so, I recon. Anyway, I think Bob Rohr opined on another thread that flow meters were a good thing, and maybe I could add a couple of those to tune the pumps. (Have no idea what that entails). I am getting some kind of flow noise right after the first elbow into the 1st floor baseboard, so I figure maybe the flow is high and I can use a tunable pump and dial into 1 gpm. Plus, if I ever installed the Heating Edge baseboard, I could dial that circuit into the 1.5 gpm it requires.
I'm sort of resigned that the system will continue to be on/off but still want to maximize efficiency, yet still have a reliable system.
The pump I was originally referring to was the delta T variable speed flavor of the Taco 007: http://www.pexsupply.com/Taco-007-VDTF5-007-Variable-Speed-Delta-T-Cast-Iron-Circulator-Pump-115V
 
How about replacement delta t pumps for the zones and a delta p pump for the boilers to buffer tank? The boiler would feed the zones when a circ zone is on and the tank is depleted; I can see maybe some more variable flows that a delta p pump could react to, plus providing economy.
 
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