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Hydro-Air Water Temps

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Ted_9
Ted_9 Member Posts: 1,718
in THE MAIN WALL
Sounds like a nice set up. The customer must be happy.

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  • Jeremy_8
    Jeremy_8 Member Posts: 8
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    Water Supply Temp?

    What should be the supply temp from the boiler to a hydro-air unit? Can this be reset based on OA or do you need a constant temp? What about a low limit aquastat on the coil? What should that be set to before allowing the blower to turn on?
  • Joe Grosso
    Joe Grosso Member Posts: 307
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    You can't use reset on a hydo-air system,the reverse aquastat on the coil will prevent blower operation on a drop in water temp
  • Ken_8
    Ken_8 Member Posts: 1,640
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    Say

    What?

    Think of constant circulation. Think of constant fan.

    Now think of variable speed circulation. Then think of variable speed fans...

    Bada,

    Bing?



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  • Boilerpro_3
    Boilerpro_3 Member Posts: 1,231
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    Yeah, what Ken said

    I replaced the boiler ( and the air handler got replaced too) on a system that used a proportional thermostat controling a Barber Coleman 3 way valve that fully reset the water temp to the hot water coil in the air handler. The system was nearing 50 years and provided excellent comfort. BTW, the system had all its supply vents at the ceiling on interior walls and returns at the floor and used a very large blower.

    An early air turnover system that is now all the rage in warehouses.

    A tekmar injection control is now running the system with PID logic.

    Boilerpro
  • Mitch_4
    Mitch_4 Member Posts: 955
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    I had a

    customer with a hydro air that has different outputs listed for different water temps. from 120°-180°. He IS using an outdoor reset , and there has been no problems with the unit. The blower is NOT variable speed. He does have protection for when the temps get to condensing point.

    Mitch
  • Dave Yates (PAH)
    Dave Yates (PAH) Member Posts: 2,162
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    hydro-air & reset

    We faced this issue, but with a twist - hydro-air coupled up to a condensing/modulating boiler. I spent hours on the phone with various hydro-coil manufacturers trying to explain my need to have a wide delta-T in order to remain well within condensing temps while delivering sufficiently warm air over a wide range of delivery temps. Not one could get past the normal 20 degree delta-T thinking, so we simply used the fattest coil we could buy - a six-pass hydro-coil. The system worked beautifully and we had no problems keeping return water well bekow 140 no matter how hot we set the supply. The boiler's control utilizes partial outdoor reset to flat-line once it drops to 120 F.

    Switching from oil-fired hot air to a high eff gas-fired condensing boiler saved them fuel costs and the hydronics allowed us to relocate the boiler to the opposite side of their home - away from the media room where the oil burner's noise had been objectionable. We also added an indirect to eliminate the second oil burner and wrapped an addition with Runtal rads.

    The air side received new A/C, UV-steralization, steam humidification & HEPA side-mounted filtration.

    Now - if only I could get the hydro-coil guys to think outside the box!

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  • Dave Yates (PAH)
    Dave Yates (PAH) Member Posts: 2,162
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    they're

    de---lighted! Comfort levels went way up. IAQ went way up. Energy bills went way down.

    It's interesting to listen to folks whose comfort levels go up in spite of their still having an air-based system. Hydro-air definately improves comfort over forced hot air & kicks the snot out of heat pumps!

    We replaced a heat pump in a neighboring town and their electric water heater with a hi-e combo boiler/domestic tank within a tank gas-fired unit. Added radiant for the first floor and hydro-air for the second floor. Comfort up, bills down - so much so, the electric co stopped by to investigate. No more chilly nights in thick sweaters hoping spring will soon arrive!

    It's a niche market, but one that looks like it will have a bigger stake as chilled water units become more popular for the A/C side. I don't see dead people, I see micro-zoning with small point-of-use chilled/hot water air handlers (wall or floor mounted). Add Inverter technology to the system and you'll have efficiencies that beat ground source heat pumps!

    Tis an exciting time to be alive in the trades.

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  • joel_19
    joel_19 Member Posts: 931
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    DY

    Daves got it !! We've been doing that for several years . run whatever temp you want ! Reset no problem ! just loose that stupid temp switch . ECM motor would make it even better i haven't done it with ECM yet but probably will soon. of course your coil and ductwork needs to be properly sized and most importantly needs to be very well sealed and insulated b. Leaky ductwork is the primary culprit when it comes to air based houses being uncomfortable . Leaky ducts will un-ballance the place and can dramatically increase the heat loss .

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  • TJ_3
    TJ_3 Member Posts: 24
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    Hydro reset with ECM

    Easy to do, I use a pair of air handlers with ECM motors, the hot water comes from a Weil McLain Ultra (with built in reset) the overall system is controled by a Tekmar indoor outdoor panel (it sets up the temps for the in floor injection system)I use two stage themostats to control the air handler. When you need a little heat, the 1st stage brings the blower on at a low speed (at those times the Tekmar is keeping temps low) when the need for heat is greater, the 2nd stage of the themostat brings the blower on at a higher speed (and the Tekmar responds to that quite nicely)
  • Jeremy_8
    Jeremy_8 Member Posts: 8
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    What about...

    A Unico air handler with a Buderus boiler and logamatic controller? The aquastats on the Unico airhandlers are currently set for 140°. There is one unit for the 1st floor and one for the 2nd.
  • Trevor Baptista
    Trevor Baptista Member Posts: 27
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    I am using an ultra boiler with a trane variable speed air handler. I added a hydro coil to the airhandler and everything is working great. The water temp is regulated by an outdoor temp sensor and the fan speed is regulated by the T-stat and how much heat the call needs.
  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
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    Why not?

    I'm with Dave about the hot water coil people. Like trying to squeeze lemonade from a chicken to get useful information. I recently set up a 2 zone hydro coil with a Tri Tube Prestige boiler and set the Outddor reset to 165 at 10 degrees and 120 at 65. My method? SWAG. A Scientific Wild **** Guess. The customer is warm and the boiler is condensing in mild weather, so I must have guessed right or a little high. If I lived nearby I'd stop in and shave it down now and then to see where comfort and efficiency intersect. I have plans for my house system, when I get time and money. (when will that happen?) I plan to use a 14 SEER Trane heat Pump with hydro air for backup instead of electricty. I'll put the hot water coil on the discharge of the air handler and bring it on with a supply sensor in the ductwork that will bring the back up heat on when the discharge air drops below 120. This way the heat pump can run all Winter but cycle off because the discharge air never goes below 120. Comfort remains intact and savings from the heat pump continue. I saw charts that showed the Heat Pumps are more efficient than fossel fuels even down to -10. WW

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  • jwade55_3
    jwade55_3 Member Posts: 166
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    We are doing quite a bit of this.

    Bottom line is what is the heat output required of the AHU? Most Mfg's that I've dealt with list their units at 140deg EWT. Typically derate charts are available, lowest I've seen is 130deg. Just had one project come on line, 10 FCU's, designed for 140 ewt at design day, Taco Variable speed setpoint circulator, the circ varies to maintain discharge air temp, as the load changes in the space, so does flow. Yesterday water temp at 128, space temp holding at 74 (elderly folks), return water around 94. Munchkins cranking out the condensate.

    My dealings with ECM motors are that they are "Variable speed" only in the respect that they ramp up and down to settings. I think Carrier modulates the speed of their ECM motor in zoned systems base on static pressure.

    J
  • jwade55_3
    jwade55_3 Member Posts: 166
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    Dave Yates

    Have a project in the design phase with 27 of these, heat and cool. Geothermal WtoW units will supply CW & HW. I love this stuff!

    J
  • NYplumber
    NYplumber Member Posts: 503
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    wide

    How wide can I size the Dt for on a 75mbh coil? Is there a standard like we have for radiant, baseboard and for pannel radiators?



    Thanks in advance.
    :NYplumber:
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