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Boiler with mini split for heating

sunlight33
sunlight33 Member Posts: 378
in THE MAIN WALL
A mini split system (2 ton, 3 indoor units) was install in my house, but this summer has only been mild so far. I have a mod-con boiler and I know the mini split is more energy efficient in heating as well. What's the best for me to do to save the most on heating this coming winter? I live in upstate NY and the house is 25+ years old so I most likely still need to reply on the boiler during the coldest months.

Comments

  • JStar
    JStar Member Posts: 2,752
    Heat

    Is the boiler installed correctly? Was an outdoor reset sensor installed and programmed correctly?
  • sunlight33
    sunlight33 Member Posts: 378
    Yes

    Everything's good.
  • Zman
    Zman Member Posts: 7,609
    Comparison

    Check out the attached spreadsheet. After you plug in the local energy costs you need to figure out what the COP  of your mini split is at different outdoor temps.

    There be a point when the outdoor temp makes the COP of the mini split low enough so that the Mod/Con becomes more efficient
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Jack
    Jack Member Posts: 1,047
    Confirm the "balance point"

    That Z speaks of. The manuf has the outputs, and associated electrical inputs, at various temps. Most of the multis that I am aware of are not as efficient as the individual units. For instance, my dual 12 unit is 16.5 seer and 9.5 HSPF, while my single 12 is 25/12. Those a 5 yr old systems and the numbers may have improved on the multis. It makes a difference. You can run the numbers, but net/net every system and building has a personality. You have the excellent options. On a cold day you will quickly decide what makes you comfortable, and when it is cold, that is all that matters
  • TonyS
    TonyS Member Posts: 849
    The mini split was

    probably sized for the cooling load at 24000. Have a heat loss done and plot the curve. See at what outside temp 24000 will still satisfy the load and do your COP comparisons at that temp. Below that temp it doesn't matter if the mini split is cheaper to run...it wont be big enough.

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