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 Boiler and Carrier Infinity Heat Pump

I have a Weil-Mclain Ultra boiler, baseboard heat, and I'm also having a Carrier Infinity System (AC and Heat Pump) installed. Is it worth running both the heat pump and boiler at the same time, as a hybrid system, or will the WM Ultra be more efficient running alone for heat?


  • Techman
    Techman Member Posts: 2,144
    Nice set up!.

    If you are operating regular baseboard with a regular baseboard temp of 180* F then compare COP's ,BTU's and comfort. The HeatPump will carry your heat load down to about what temp? The HP can be the 1st stage of heat and the BB can be 2nd stage. The Ultra will not be a "condensing boiler " at regular baseboard temps!
  • lchmb
    lchmb Member Posts: 2,997

    Although it will not condense with 180 degree's,with outdoor reset installed the boiler will not need to run to that temperature except in extreme (design) temps, it will in fact condense at lower temps (spring and fall) .. I cannot talk about a heatpump so I'll pass on a comparison...Next question would be, what is the source for domestic hot water?
  • Reynz_2
    Reynz_2 Member Posts: 98
    Here is the story

    Not only am I installing central air and heat pump, a conventional system, but I also had upgraded insulations (basement and roof deck), and yes, you did ask, so I'll tell ya, a WM indirect HW for the Ultra... My boiler is not set for 180 temp, at the coldest it gets, I have it set at about 157, with a constant circulation BG 100, that supplies a gravity conversion. The supply water temps with the Ultra are as low as I can get them and still be comfortable.. For most of the fall and spring, I don't think it moved beyond 130 degrees. At around 0-10 degrees it may get up to 150-157. So, I suspect that I'll run the boiler and the heat pump together down to about 40 degrees, then just let the ultra do it... However, with the ultra boasting 90% or better while condensing, I'm wondering if I should use the heat pump at all.....
  • lchmb
    lchmb Member Posts: 2,997

    Like I said, I honestly couldnt give you a best way to do this since I am not familiar with heat pumps. I believe that would come down to how much you pay for electricity and fuel. In my area, the more product you use, the cheaper the price, so that may be a factor also (propane). Make sure to get your unit serviced yearly either way by someone familiar with the unit.
  • MrDucks
    MrDucks Member Posts: 27
    edited October 2011
    B&G 100

    Why the B&G Pump?? Just asking & What are your design temps.

                                                     or a 007
This discussion has been closed.