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.

Weil Mclain Ultra indirect domestic hot water fault

Hort Member Posts: 5
edited June 2020 in THE MAIN WALL
Recently I have noticed that during most calls for domestic indirect hot water heating that the return temperature is a few degrees hotter than the supply temperature and I get a lockout that automatically resets itself in time.
I have a post pump time set for 20 sec. but there does not seem to be a pre-pump time to set that may keep this from happening. This is DHW priority 1.
This is a recently new situation but has occurred during the heating season and now during warm weather shut down for house heat. Weil Mclain Ultra 105 series 3
Any thoughts?


  • Hort
    Hort Member Posts: 5
    edited June 2020
    Max supply 160.
    mod on diff 2
    mod off diff 10
    Max rate 94%
    Min rate 20%
    Lockout usually occurs during first call for hot water in early morning