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.

i installed new honeywell aquastat L 8148 J Can I install a millivolt gas value

I replaced old aquastat in December. It has a switch to use in case of electric outage. i want to buy a new gas valve but i don't know which one . I don't have many power outages here but thought it might be nice to have some heat when the power is out. My HB Smith boiler is 38 years old and good shape. I have old pilot light set. will a millivolt valve work? Would I be better off replacing gas valve with the same one the has lasted 38 years. thanks Greg


  • Tim McElwain
    Tim McElwain Member Posts: 4,608
    You can install a Honeywell VS820A-1054 3/4" by 3/4". You will need to replace the pilot with a Q314 pilot than can hold a 750 millivolt generator (Q313A-1139). Make sure you also follow the powerpile valve wiring instructions with the L8148J. This will allow you to control the burner in a power failure by switching the manual switch on the L8148J to MAN position. The burner will cycle on limit and if you have circulators open the flow check valves if zone valves place them on manual.