Adding a Manifold Mixing Station

Discussion in 'HVAC Heating & Cooling' started by Consoleb, Nov 12, 2018.

  1. Consoleb

    Consoleb New Member

    Joined:
    Nov 12, 2018
    Location:
    Western MA
    Hello Everyone,
    First some information, I hope it's clear;
    I have a Burnham ES2 Gas Boiler with a Taco SR502 switch, there are two Taco 007-F5 pumps connected to the boiler. One pump is connected to a thermostat that controls a single loop around the first floor with radiators. The other pump is connected to the Taco SR 502 switch but not too a thermostat, in fact the loop that connects to the second pump was never completed. It goes around the basement but where the pipes meet the corners the elbow are missing on the pipes. The last homeowner probable wanted to put radiators on the 2nd floor, he died before it was completed. When I opened the ballvalve I heard water pouring into the basement and shut it off. I opened the Taco SR 502 switch and the 2nd pump is wired up with power and ready to go.
    Now to my question. I bought a Caleffi 172 Manifold Mixing Station with High Efficiency pump. Rather than adding radiators to the 2nd floor I want to add hydronic radiant heat to two rooms on the first floor.

    1.HOW DO I WIRE UP THE MIXING STATION PUMP ( I KNOW HOW TO WIRE UP THE POWER)?
    2. WHICH PUMP GETS THE THERMOSTAT WIRES?
    I not sure how to set this up so the call for heat goes to the correct pump.
    Any help would be really appreciated.

    Thanks,
    Brian
     
  2. Dana

    Dana In the trades

    Joined:
    Jan 14, 2009
    Location:
    01609
    Neither pump gets the thermostat wires, the SR502 does, and the pumps get powered by the SR502. The low voltage thermostat gets wired to the corresponding zone's thermostat input.

    It sounds like the existing and fully operating zone is running off a single zone relay, with the zone thermostat controlling the relay (?). It would be unusual to control a circulation pump directly with a line-voltage relay, but who knows what hackery lived in the mind of the prior owner/installer ?

    Are you adding radiant floor to rooms already served by the existing zone to be operated as a second stage, or to a couple of other rooms as a micro-zone or ... ???

    Unless they've updated it the Grundfos UPS 15-58 that comes with that Caleffi 172 manifold kit isn't a high efficiency pump, it's an old school 3 speed that burns 60 watts even on "low". (Not that the Taco 007 F5s are anything special, efficiency wise.)

    When micro-zoning it's generally better to use a single ECM drive pump in pressure feedback mode and zone valves. The Taco SR 502 is a 3-zone zone controller designed for separate pumps, but even smaller pumps are usually going to over pump a micro-zone. The PEX loop and flows for just a couple of rooms may not really even need a manifold with flow balancing, etc. a simple thermostatic mixing valve and a single loop would often be enough unless the rooms are really substantial. If you want to do it right, replacing the SR 502 and -007s for a single pump and a multi-zone controller with zone valves may be in order, but design it first, don't hack it.

    If you're going to just forge ahead with the hardware in hand, you have enough to finish the task, even though it's going to chew more electricity than some idealized version. Since you have three pumps and a 3-zone controller on board, wire up the Calleffi/Grundfos power to the remaining zone on the SR502, and the thermostat for that zone to the corresponding thermostat input.

    The ES2 series is tolerant of 110F return water, and if you design the radiant to run off 125-130F water it would still provide some condensing efficiency if you ever swapped it out for a condensing boiler, and the return water to the ES2 would still be warm enough to not destroy the boiler. If you screw up the math and it needs hotter water than that you can crank it up with a twist of the knob on the thermostatic mixing valve. This approach will work whether it's a separate pump or if it's zone valves.

    Is the hot water being served up by the ES2, with an indirect fired tank, possibly using the SR502 (or not)?
     
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  4. Consoleb

    Consoleb New Member

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    Nov 12, 2018
    Location:
    Western MA
    Dear Dana,
    Thanks for your reply. The pump on the manifold is a Grundfos Alpha 2 25-55U. The thermostat on the existing loop is wired to the SR502's first thermostat position. I'm adding radiant heat to two rooms that connect to each other, a 13x12 kitchen, and a 13x16 bedroom/bathroom, they will each have their own loop on the manifold. I thought of having the bedroom have two loops, would that be overkill? I will first remove a small radiator from the kitchen (the kitchen is always freezing in the winter), the future bedroom has no radiator, it had a huge one in the middle of the room??? I took it out.
    I am wondering how the two pumps communicate? Do they need too. From what your saying when I run a new thermostat to the open thermostat slot of the SR502, and connect the manifold pump to the SR502 for power, the set up should work? Will I need to do anything else or will the SR502 control both pumps ( the second unused pump at the boiler and the mixing station pump)? I'm doing this myself due to my budget, I'm out of work and so I have the time. Good news two interviews this week, one tomorrow. Please let me know if I'm asking the right questions. I have to go with the products I have, the new mixing station, pex-al-pex over subfloor, hardwood floor on top. Thanks for your input.

    Brian
     
  5. Consoleb

    Consoleb New Member

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    Nov 12, 2018
    Location:
    Western MA
    The hot water is not being served by the ES2? I have a gas water heater right next to the boiler.
     
  6. Dana

    Dana In the trades

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    Jan 14, 2009
    Location:
    01609
    How do you know the radiant floor will keep up with the load in the kitchen with or without the radiator?

    How do you know the radiant floor will keep up with the load in the bedroom?

    How do you know the radiant zone won't short-cycle with/without the radiator?

    Which version of the ES2? (There's a -3, -4, -5 etc. after the ES2 indicating the number of heat exchanger plates.)

    Have you done any of the design math at all on the radiant floor?

    Almost all versions of the ES2 are oversized for the whole-house heat loads of normal sized insulated house. Breaking it up into micro-zones with low-mass radiation can create some efficiency & longevity issues if there isn't sufficient radiation on each zone to keep the minimum burn times up to 5 minutes or more. If it's giving a dozen burn cycles of 1-2 minutes each per hour it's an efficiency disaster putting a lot of wear & tear on the boiler to boot.

    With the single zone as-is, before yarding out the radiators or adding zones, turn the thermostat way up and time the burn cycles to the nearest 5 seconds, as well as the intervals between cycles.

    The pumps don't communicate with each other at all. They are turned on/off by the SR502. The thermostats tell the SR502 when to turn the pumps on /off. The Alpha2 25-55U seems to be a special Caleffi-only version, can't really tell you how to set it up, so read the Caleffi manual.
     
  7. Consoleb

    Consoleb New Member

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    Nov 12, 2018
    Location:
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  8. Consoleb

    Consoleb New Member

    Joined:
    Nov 12, 2018
    Location:
    Western MA
    Hi and many thanks. The radiator in the kitchen is on the existing loop and I plan to remove it, it is way to small for the room. I used a Heat Loss Calculator and it says the kitchen needs 3614 btuH and the bedroom 5596. I used an online calculator, not sure if it's correct. The boiler is a ES25. The house was built in 1755 and added onto around the 1920's it is 3000sf with 1/3 without any heat. We just close off the back 2nd floor until summer. The two rooms I'm planning on adding radiant heat too are each too cold in the winter. I want to make them a different zone and use the manifold for the pex-al-pex pipe under hardwood flooring.
     
  9. Dana

    Dana In the trades

    Joined:
    Jan 14, 2009
    Location:
    01609
    Online calculators tend to over-state the actual heat loads, often by quite a bit. Correctly evaluating the heat load of an 18th century antique accurately isn't usually possible with online calculators- or even professional tools.

    The ES2-5's 118KBTU/hr DOE output is still probably more than 2x oversized for the heat load of the house, and would be crazy-oversized for a zone that was just a few loops of PEX. The onboard smart controls can probably stretch the burn times a bit, but they're not magic- the laws of physics are self-enforcing. Even barely-insulated house like that with clear glass storm windows over single panes and higher than average air leakage would have a load no more than ~75KBTU/hr @ 0F outdoors. If it's been tightened up and insulated a bit it'll usually be under 50K without going nuts on the retrofit weatherization efforts.

    It's still not clear how you know if the radiant floor would be able to keep up with the design load, even if the room load numbers were correct.
     
  10. Consoleb

    Consoleb New Member

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    Nov 12, 2018
    Location:
    Western MA
    Hi, Yesterday when the temperature really dropped here in Stockbridge MA the house will only heat to 63* no matter where we put the thermostat setting. I went to the boiler and the error code read Err 32 Temperature Sensor Failure. I have not done any of the work we discussed before in earlier posts. I see that I can easily purchase a Temperature Sensor, but is this something a handy person should do. I'm currently out of work so I'd like to do the work myself due to finances.
    Thanks
    Brian
     
  11. WorthFlorida

    WorthFlorida The wife is still training me.

    Joined:
    Oct 28, 2009
    Occupation:
    Retired
    Location:
    Orlando, Florida
    This is from the user manual of your boiler. Your sensor error probably put the furnace in a safe mode though I could not find any documentation. On a sensor failure it may go to a low temperature mode just to keep the home from freezing by not completely shutting down. It may run on a predetermined on/off cycle.

    https://files.gitshare.io/link/xs03UBSJlpw/ES2 I&O Manual.pdf
    https://files.gitshare.io/link/buNddf4Y1Ds/ES2 Users Manual.pdf

    General. This water boiler is equipped with controls
    for proper operation. All controls must be in proper
    working order. Contact a qualified service agency to
    provide annual maintenance as specified in Installation,
    Operating and Service Instructions.
    1. Limit. See Figure 1. A device which automatically
    interrupts boiler operation when the water
    temperature exceeds the set point. Maximum
    allowable temperature is 220°F.
    Original equipment with this boiler is U.S. Boiler
    Intelligent Hydronic Control and Limit Rated
    Temperature Sensor combination. The Intelligent
    Hydronic Control shuts off boiler main burners
    when boiler water temperature exceeds preprogrammed
    Intelligent Hydronic Control water
    temperature set point. Boiler main burners will
    re-light automatically, providing the call for heat is
    present, when boiler water temperature falls below
    pre-programmed control water temperature set point
    less the set point differential.
    2. Flame Rollout Switch. See Figure 1. A device
    which automatically interrupts boiler operation
    when flames or excessive heat are present in the
    combustion area enclosure. The control is a single
    use device. The control is located in the combustion
    area enclosure. If the control was activated to
    interrupt boiler operation, do not attempt to place
    boiler in operation. Contact a qualified service
    agency.
     
  12. Consoleb

    Consoleb New Member

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    Nov 12, 2018
    Location:
    Western MA
    Thanks for your help.
     
  13. Consoleb

    Consoleb New Member

    Joined:
    Nov 12, 2018
    Location:
    Western MA
     
  14. Consoleb

    Consoleb New Member

    Joined:
    Nov 12, 2018
    Location:
    Western MA
    Dear Dana,

    You wrote "If you're going to just forge ahead with the hardware in hand, you have enough to finish the task, even though it's going to chew more electricity than some idealized version. Since you have three pumps and a 3-zone controller on board, wire up the Calleffi/Grundfos power to the remaining zone on the SR502, and the thermostat for that zone to the corresponding thermostat input."
    I finally installed the mixing station and now it is time to wire it up and I have another question that I need your advice with. At the SR502 the thermostat and pump that circulates the house are connected to the first inputs, the second pump is connected to the next circulator input on the SR502 with no thermostat connected to the corresponding input. I understand that you are saying wire the mixing station to the 3rd circulator input and the thermostat to the 3rd thermostat input, is that correct? leaving the 2nd pump that comes off the boiler and will feed the mixing station with no thermostat? Or should the thermostat be connected to the 2nd thermostat input? Any help will be appreciated.

    Thanks again,
    Brian
     
  15. Consoleb

    Consoleb New Member

    Joined:
    Nov 12, 2018
    Location:
    Western MA
    Hi again,
    I still need some help. To clarify I have a Taco SR 502 with only two zones. Inside is show terminals for three but there are only two relays. Someone told me that the circuit boards were made for both 2 and 3 zones.
    The boiler has two Taco 007 pumps and only one is used, the 2nd pump is wired up and plumbed for a loop that was never connected ( in goes around the basement but at the corners the copper elbows were never added, I think the last homeowner was going to add heat to the 2nd floor).
    I added radiant heat loops in two rooms and they are connected to a Caleffi 172 Mixing station, they are not plumed to the boiler or to a thermostat, to to power.
    Should I disconnect the 2nd boiler pump and plum the mixing station to where is was connected and use the zone 2 terminals on the sr502? Or is there a way to leave the current set up as is and still connect the Mixing Station's pump and an additional thermostat.
    I just don't know where to connect the Mixing station to electronically since the sr502 only has two relays. Should I just add it to the 3rd zone terminals?
    Brian
     
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