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trv's and zoning

bovide_4
bovide_4 Member Posts: 161
Thanx. I wonder why they are not more popular. Would they not cut down on these panels with a wall full of circulators?

Comments

  • bovide_4
    bovide_4 Member Posts: 161


    I will be installing an Ultra 155 with a combination of panel rads and radiant. Three questions:
    1) I would like to zone each room. There are 6 rooms with panel rads. Are trv's on the panel rads with constant circ. a better option than t-stats/zone valves(or zone circs)? Do customers mind bending down to the radiator to adjust?
    2) Is it feasible to run the wiring for the circs, relay, zone valves behind the panel? I have to use BX in my area. Queens, NY.
    3) I will apply Hot Rod's suggestion to pipe the boiler circ to the return ahead of the expansion tank to increase pressure to the HX. Also keep the Spirovent at the expansion tank location, or put it on the supply side of the primary loop?
  • TRV
    TRV Member Posts: 1


    > Are trv's on

    > the panel rads with constant circ. a better

    > option than t-stats/zone valves(or zone circs)?


    Yes

    > Do customers mind bending down to the radiator to adjust?


    Depends on the customer, I guess. TRVs are not normally adjusted after the first couple of days. If they need it, install TRVs with remote controls/sensors.
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928


    Yes, they would certainly cut down on walls full of circulators and I have no real idea why they're not MUCH more commonly used here in the US.

    My own house has 12 TRVd "zones" and 4 radiant floors all driven by a single small, variable-speed circulator that's built into the boiler.





  • John Ketterman
    John Ketterman Member Posts: 187


    > Thanx. I wonder why they are not more popular.

    > Would they not cut down on these panels with a

    > wall full of circulators?



    Lets admit it, a lot of HVAC work in this country is done by people who don't know very much about hydronic heat. They know that if the house has one zone, you need one circ. Stands to reason, if you have three zones you need three circs.

    Using TRVs instead requires a bit of experience that the average contractor has not had a chance to gain. If you have different pipe sizes to different zones, or much longer pipes to some zones, a single pump won't send any water to the higher-head zone except when the lower-head zones have turned off. So the system has to be designed carefully. The head seen at the pump and the flow at the pump will vary widely as individual radiators go on and off. Also TRVs can never turn the heat up, only down, and the design has to make sure that all rooms will be warm enough. Not brain surgery, but not trivial either.

    Design effort costs the customer money for something he can't see, so some people resent paying for it. Multiple circs are the brute-force way to go, not as much knowledge or design/planning required. And the customer gets a complicated-looking panel he can show his dinner guests.
  • bovide_4
    bovide_4 Member Posts: 161
    heat loss is:

    panel rad heated rooms = 67,381 btu
    radiant heated rooms= 44,170

    outdoor reset will be used. I will use a manifold for the loops to each room.
    Spring checks on each loop, or just one for the circ?
    And a pressure bypass valve?
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928


    Zero need for check valves either on each branch or for the circuit as a whole but you should definitely use a differential pressure bypass valve after the circulator and before the manifold serving the TRVd circuit.

    The circulator for the TRVd circuit should run continually any time that space heating [might] be required. This is why you have the differential bypass valve--the TRVs can't "tell" the boiler when to fire or the circulator when to run so you err on the "might need heat side". The differential pressure bypass will open in the event that all of the TRVs are satisified with the circulator still running.

    Ideally your TRVd circuit will make a CONTINUOUS call for heat anytime that space heating [might] be required. This philosophy is incompatible with the default behavior of the Ultra as it will continually boost temperature if a call is not satisifed. YOU DO NOT WANT THIS TO HAPPEN!!! Instead you want the TRVd circuit to "ride the reset curve"!!!!!! Disable the "auto boost" if you're using TRVs!

    Here are two different ways to provide that CONTINUOUS call for heat anytime that heating [might] be required in the TRVd circuit.

    1) Use a conventional wall thermostat somewhere convenient in the TRVd area and instruct the homeowner to set somewhat higher than any temperature they want to maintain and use the TRVs to adjust for comfort level. Such thermostat should both run the circulator and make a continuous call for heat. It can also be used for setback for the entire TRVd area.

    2) Use an outdoor temperature sensor to run the circulator and make a continous call for heat anytime it's colder than x° outside. While this may sound low, 55°F is often a VERY good starting place.

    ------------------------------

    What sort of heat transfer mechanism for the radiant rooms?



  • bovide_4
    bovide_4 Member Posts: 161
    I am pondering different choices

    I wussed out and will be sending Wirsbo CAD drawings of the house so they can provide a control strategy and tubing layout.
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