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.

How to control DHW temps with a Munchkin T50 boiler?

Hi - I've got the manual for the Munchkin and have read it many times cover-to-cover. I'm clear on how to set the upper and lower temps that control when the boiler fires if a t-stat is calling for it. However I don't see anything that describes how the domestic hot water gets controlled. I do NOT have the Vision system if that matters.

I know the DHW circuit gets "priority" but at least in the user manual there is no mention of how that works or how to control that. Would welcome any pointers or perhaps i need to track down a service manual?


  • pedmec
    pedmec Member Posts: 713
    From my understanding the vision one is programmed into the 925 controller. the 925 is the standard controller for all lines of munchkin. if you use a 10k dhw sensor it will automatically pick up the sensor when connected and start functioning.

    if you use a aquastat its just on off. both connect to the x8-7, x4-2.

    I have a munchkin 199m. Installed in 2005. I have not used the vision one programming as put my indirect hot water tank on the heating manifold. Can't get hot water in warm weather shutdown. I hate the 925 controller as it seemed like a dinosaur even when i put the boiler in 2005. I can never remember the proper procedure to access the parameters. i really love the small footprint.

    I did the schooling for the vision 1 and 2. I have the cds and i even had the cables set up so i could access all the controls on the 925. At the time that was pretty cool. set up my laptop and away i went.

  • HomerJSmith
    HomerJSmith Member Posts: 1,927
    edited November 2022
    Vision 1 sys is an outdoor reset sensor and a indirect tank sensor. Programing the tank sensor is done with the control board by going into the 925 board in the boiler and setting the parameters.

    Since you don't have an indirect sensor, the high limit is controlled by a tank aquastat, therefore, the hi-temp of the tank is controlled by the aquastat and not by the 925 board. The aquastat controls the temp differential, hi-limit, and when to turn on the boiler indirect circuit.

    The aquastat turns the indirect pump on or opens a zone valve and turns the boiler on. The programing of the 925 board determines a lot of the parameters that affect the indirect.

    To control the temps and other settings, you need Vision 1.