Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

WM Ultra new installation question

BC_2 Member Posts: 14
I am installing a WM ultra 105 boiler with 5 zones using a circulator for each zone and a TACO SR-506 controller.

What is the best method to wire the indirect domestic water heater?

Should I connect the aquastat and pump for it to the boiler or to the SR506? The boiler operates at a 120 degree F max temp for my radiant floor zones. In order to take advantage of the boiler temp running at 190 degrees I suppose that I would need to hook up the hot water heater to the boiler leads. The drawback to this method is that I would lose the priority function on the SR506. Could I hook up the aquastat leads to both the SR506 and the boiler and pick up the power lead from either one. I would guess that this would signal the boiler to high fire and also shut off the other circulators until the hot water heater demand was satisfied. Please let me know your recommendations. Thanks


  • Glenn Sossin_2
    Glenn Sossin_2 Member Posts: 592
    MCBA Board used in Ultra

    has a built in Priority for DHW. Connect your DHW circulator to terminals 3&4 of the line voltage block. The DHW aquastat wires to terminals 3&4 of the low voltage block. When the DHW aquastat calls for heat, the module shuts down the boiler circulator, activates the DHW circulator and immediately sets target outlet water temperature to 190°F. This provides automatic priority heat allocation to the indirect water heater for maximum response and recovery. On a DHW call, the logic board will disconnect power to the CH (central heating) circulator.

    Use the xx contacts of the SR-506 to create the heat demand across terminals 5&6 on the low voltage block. This will fire the boiler based on the parameters you set for the reset curve.

    As with any technical product, you should read the manual to be sure you've installed and wired the boiler correctly. The instructions for wiring are found in the control supplement manual. If you lost or misplaced this, you can download off the internet.

    Hope that helps you.

  • BC_2
    BC_2 Member Posts: 14

    Thanks Glenn
This discussion has been closed.