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Taco X Block application ideas (hr)

hr
hr Member Posts: 6,106
solar as of late. As I type this my shop solar has been banging off and on with a clear, sunny, but cool day. It's pretty common for solar differential controls to bang on and off around the ever moving delta t.

So what about a variable speed circ for this application. It would hunt and find the corect flow (rpm) for the temperature available from the solar panel. PV powered circs operate similar to this.

Alonge thse lines a control option for the Taco X block that would be both the differential control and VS control for the solar side circ.

Now this Taco product could turn any insulated and off the shelf tank into a solar tank. It could be added to electric HW tanks and give you the elemet as a back up. Or on to an indirect tank for a dual HX set up. Solar via the X block and the coil as a secondary HX via a boiler.

tekmar offers a very smart differential control already. Data logs and tracks BTU's harvested. With some clever thinking between Sweet and Knuever :) this should be simple control to design and build.

Why not add an "H" to the Taco X block?? Taco HX-Pump Block. Hard to tell just looking at a picture that it has a heat exchanger glued to the back. HX rings truer to the HVAC shopper.

hot rod

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Comments

  • Joe Mattiello_2
    Joe Mattiello_2 Member Posts: 94
    You are full of new engineer

    You are full of engineering ideas today.

    Joe Mattiello
    Technical Support Technician
    Tel. 401-942-8000 X 484
    Fax. 401-942-2360
    1160 Cranston St
    Cranston, RI 02920
    [email protected]
  • Joe Mattiello_2
    Joe Mattiello_2 Member Posts: 94
    You are full of new engineer

    You are full of engineering ideas today.

    Joe Mattiello
    Technical Support Technician
    Tel. 401-942-8000 X 484
    Fax. 401-942-2360
    1160 Cranston St
    Cranston, RI 02920
    [email protected]
  • Kevin_in_Denver_2
    Kevin_in_Denver_2 Member Posts: 588
    \"Stagnation sensor\" reduces solar short cycling

    There was an article in Solar Today in 1982. It described a collector sensor design that improves btu's collected and practically eliminates short cycling.

    Consider this dilemma:

    Ignore pumping costs for the moment. For a given solar collector, the higher the flowrate, the higher the efficiency. The reason is that the entire collector is cooler and loses less heat to the ambient air. But a high flowrate and small delta T across the collector means the differential controller might shut off the pump, since it's designed only to operate when the Delta T across the collector is 3F-5F minimum.

    PV powered pumps aren't a perfect solution because they might pump when they shouldn't at the end of the day. Hot tank, some sun, some pumping, cool ambient, net heat loss.

    They authors of this article built a separate, tiny glazed collector box for the collector thermistor instead of clamping it to the collector outlet pipe. This "stagnation sensor" is always at the collector stagnation temperature, i.e., the collector temperature at zero flow.

    The theory is that if the stagnation temp. is 3F-5F higher than the storage tank temp., then there is heat to be collected. The stagnation sensor is unaffected by the relatively cold rush of water through the collector when the pump comes on. The sensor remains hotter than the tank water as long as the solar insolation is enough to overcome ambient losses.

    We reduced short cycling and improved heat collection on hundreds of systems by using a version of the stagnation sensor.

    Variable speed pumping is a great way to optimize pumping costs, but it adds complexity and is a difficult problem in drainback systems. In those, you always need the full pumping head until flow is established.
    Superinsulated Passive solar house, Buderus in floor backup heat by Mark Eatherton, 3KW grid-tied PV system, various solar thermal experiments
  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
    How would you use the variable speed

    Would you initiate with a differential controller and then use the variable speed to keep a certain delta tee above the tank temperature? I have been looking at the Taco 00 variable speed circulator for the application of maintaining supply duct temperature in a hydro coil application for a hot water coil downstream of a heat pump. As outdoor temperatures drop and the heat pump capacity drops, supply air temps drop concurrently. The variable speed circ maintains a minimum supply duct temperature and thus keeps the comfort in the system. This new stuff is amazing, and fun to play with.

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