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Adding indirect water heater, wiring relay

DLDL
DLDL Member Posts: 10
I currently have 3 heating zones each with its own circulator with a taco sr503 relay (not utilizing the priority option) And a domestic hot water coil in my peerless 108k btu boiler. I want to add an indirect water heater. Do I need to get an SR 504 or is there a way to keep and wire up the Sr 503 and use the priority for the water heater? Thanks in advance

Comments

  • Leon82
    Leon82 Member Posts: 684
    Is your 503 expandable relay? If so I think you can ad a 501 and use the 503 priority for the indirect.

    Does the boiler have its own dhw control?
  • DLDL
    DLDL Member Posts: 10
    Thanks for replying! Not sure, here are pics if this will help.
  • DLDL
    DLDL Member Posts: 10
    FYI a plumber friend of mine is doing the install next week, but he's on vacation right now. I want to have all of the material ready for him.
  • DLDL
    DLDL Member Posts: 10
    If it helps everything was installed new in 2011
  • R Mannino
    R Mannino Member Posts: 434
    I would replace the dual aquastat with an Aquasmart or Hydrolevel and use that to drive the indirect circulator. It will save you some oil too.
  • DLDL
    DLDL Member Posts: 10
    Would that mean switching the boiler to a cold start? If so does anything else need to be done as far as settings/wiring with the existing sr503 relay? Also would that allow me to have the indirect set up as a priority? Thanks
  • Eric_32
    Eric_32 Member Posts: 267
    You can disable the lo-limit on that relay without buying a new aquastat.

    If you don't, the boiler will still think it is making hot water through the tankless coil and want to maintain temp. Usually the lo is set at 160 and high on 180.

    To disable your existing aquastat relay, and make it a cold start boiler, You will need a skinny flat screw driver and a small orange wire nut. Turn off the power to the boiler.

    Looking at the control, you will see a white wire near the diff screw. Use the screw driver to depress the slot along side the wire while pulling on the white wire, to remove it out of it's spot.

    Do the same thing for the Red wire closest to the LO dial, now connect these two wires together using the wire nut. Turn the power back on. The control will now only respond to a call from a thermostat or the indirect, and no longer maintain temp.

    I think the easiest thing would be to replace the Taco mulit box with a 504 or 506-EXP one. Now you can run the indirect off the priority zone and you can add outdoor reset to it with a Taco PC-700.
    j a_2
  • R Mannino
    R Mannino Member Posts: 434
    You can set the new control to have the boiler "warm" start so it never goes completely cold. Terminals X-X in the SR503 would wire to T-T on the new control. To keep priority would require some rewiring between the SR 503 and the new control but it is possible.
  • DLDL
    DLDL Member Posts: 10
    Thanks for the good ideas! So your saying to leave the tankless coil to preheat the water feeding into the cold inlet to the storage tank?
  • gennady
    gennady Member Posts: 837
    In my opinion you do not need indirect water heater, you need storage tank connected to the coil. Install aquastat on the storage tank to control pump. see attached.
    LionA29j a_2
  • R Mannino
    R Mannino Member Posts: 434
    gennady said:

    In my opinion you do not need indirect water heater, you need storage tank connected to the coil. Install aquastat on the storage tank to control pump. see attached.

    That does make the wiring easier!
  • DLDL
    DLDL Member Posts: 10
    Only problem with that is I don't know if that will meet our HW demands. 5 people, 3 baths, 2 washing machines, 2 dishwashers. Was planning on getting a 45 or 60 gallon htp super stor. If 2 showers are going at the same time, that's 5 gpm so after 12 minutes the HW in the storage tank will run out and then basically we would be running directly from the tankless coil in the boiler, which can't keep up as it is. Any thoughts?
  • SWEI
    SWEI Member Posts: 7,356
    edited February 2016
    If you take the path Gennady suggested above, you can use a conventional electric water heater as the storage tank. They're cheap enough -- go ahead and get an 80 gallon (or larger) if that's what you need. They also come with a thermostat that can easily be repurposed to run the circulator (a la @icesailor .)
  • DLDL
    DLDL Member Posts: 10
    null
    gennady:
    In your illustration your using an indirect WH, no? Don't see how using an electric WH would work in this situation. You have the existing boilers tankless coil working as a replacement for the indirect WH zone. And then the cold and hot domestic lines connected as normal. An electric WH will only have 2 connections- cold in, hot out. Am I missing something here?
  • gennady
    gennady Member Posts: 837
    edited March 2016
    I actually showed storage tank, not an indirect fired water heater, storage tank has 4 connections on the bottom.
    Just my 2 cents.
  • gennady
    gennady Member Posts: 837
    edited March 2016
    Electric heater piping
  • hot_rod
    hot_rod Member Posts: 16,547
    Also include a thermal expansion tank
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    j a_2
  • DLDL
    DLDL Member Posts: 10
    edited March 2016
    Spoke to my plumber friend today who's helping with the install. He recommends getting the expandable sr504 relay w/priority, eliminating the tankless coil, and going with the indirect set up the normal way. He's repaying a favor and not charging me labor, but obviously going this route will cost more for materials. If money wasn't an issue, (within reason) which option would you all choose? Also what size/brand tank would you go with considering my HW needs mentioned above?
  • Leon82
    Leon82 Member Posts: 684
    edited March 2016
    If you go that route you could use the 504 exp since you would only need 4 zones.
  • DLDL
    DLDL Member Posts: 10
    Leon82Leon82
    If you go that route you could use the 504 exp since you would only need 4 zones.

    Oops I meant to say the 504
  • BillAllen
    BillAllen Member Posts: 103
    Wow all these comments! Okay I just finished the job and YES I did need an indirect the tankless was corroded and gone!
    Anyway, Its up and running but why does the boiler circ continue to run when the SS circ runs and they both shuts together too.
    The boiler circ is doing nothing it is not circulating anything just going along for the ride. Must be a way to wire the SR 504 so when a call to reheat the DHW only the circ for that is activated.

  • Paul48
    Paul48 Member Posts: 4,469
    We have no information, to form an opinion, and provide an answer. Is the boiler piped primary/secondary? What make and model boiler?
    j a_2