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

Correlating modcon firing rate to gas usage

sandeen Member Posts: 5
I have a triangle tube solo 60, which modulates from 16 to 60 MBTU/hr. The boiler reports a firing rate from 0% to 100% when it's firing. I'd like to correlate this firing rate over time to actual gas usage, just because I'm a geek about data and graphs, and could in theory track therms per heating degree day with just the data available from the boiler (firing rate & outdoor temp).
So - does the firing rate range 0%->100% span the boiler's minimum->maximum input rates of 16 MBTU/hr -> 60MBTU/hr?
Maybe that's a dumb question, but at first I naively thought that the 0% to 100% range covered 0 MBTU/hr -> 60 MBTU/hr, and that wasn't coming out right at all.



  • SWEI
    SWEI Member Posts: 7,356
    The percentage indicated on the TriMax display is the percentage of modulation between the minimum and maximum firing rates. So a PTS60 showing 5% would actually be firing at ~18.2k.
  • sandeen
    sandeen Member Posts: 5
    Great, thanks, that's what I thought, but wanted to confirm. That matches the gas meter fairly well.