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Help diagnosing hydro air problems....



  • Tim Potter
    Tim Potter Member Posts: 272
    edited May 2014


    I agree on adding a zone control, wiring is simpler & cuts down on the technician check out time on a service call, its either black or white as to which zone is calling.


    Taco ZVC404-EXP gives priority to hot water & has ability to add boiler reset if desired.

    Taco ZVC 404 if basic unit wanted.

    Clammys point of a more knowledgeable contractor is worth noting too....
    Winter Park, CO & Lenexa, KS
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,239
    Maybe you don't have a problem?

    I just read through this whole thread and the one thing that jumped out at me more than anything, there was no mention about whether the 2nd story is able to maintain a stable temp when it is cold outside. I read about hot pipes and warm pipes, and room temperature air instead of hot air. It also sounds like you have some thermo siphoning going on which is easily addressed with a couple flow checks, as was previously mentioned.

    If the circuit to the unit has been purged multiple times, you most likely don't have a blockage.

    If the pipe in the attic gets hot when the zone is off due to thermo siphoning, that means "A. there is water in the pipe" "B. there is no air in the pipe". At least not enough to cause a problem.

    If the rest of the house heats, that means the circulator is not broken.

    I also read that it takes an hour to heat up the second story when it's cold out. Nothing unreasonable about that considering that if you are setting back the thermostat the MRT (mean radiant temp) will be low.

    Make sure both your supply and return ducts are sealed properly. Make sure the air handler is not damaged allowing excessive leakage.

    If you want the air blowing out to feel warmer and the return water pipe to be hotter, you have to slow down the air flow during heating. If your unit does not have wiring preparations in place to do that, you will have to have someone build you a little control with a couple relays to accomplish the goal.

    Your heat loss may increase slightly if you raise the supply air temp due to duct losses, duct tightness, infiltration, exfiltration, etc...

  • Techman
    Techman Member Posts: 2,144
    edited May 2014
    hydro coil

    What size copper pipe is the supply line coming out of the boiler? When the 2nd fl zone was purged, the Water Pressure Reducing Valve would have to have the fast fill lever opened. Was it? At the AHU in the attic, the hot supply line should have been the bottom pipe,was it? If I'm seeing right, when the zone was purged, the purging water went up the return pipe and into  the top pipe of the AHU , making it awful hard to get the air out of the hydro coil. That air vent in the attic, is the vent connected directly onto the heel tee? It should have a pipe nipple raising the vent up a little. With no call for heat ,at the AHU are  both pipes were hot? Are both pipe for this zone hot in the basement ? Deffinetly check the fan speed for the heat side, the fan speed has to be lower for the heat as compared to hi speed for the AC. The vertical rise , from the boiler to the attic is only how many feet? A separate AHU for the new addition is a good idea,being a separate area. The heat and cooling loads/demand is different than the main house.