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Advice on potentially updating HVAC systems for big old house?

spencerr96 Member Posts: 1
Here's background in case it needs to be considered. I moved into a big old house. It was built around 1900. It has an unfinished basement; the first floor has baseboard heat and central air; the second floor has baseboard heat and I use 2 portable AC units for cooling; the attic is unfinished but I eventually want to finish it because its quite roomy and has beautiful windows--we plan on making it an art studio/recreation area. The first and second stories together (not including the basement and attic) the house is approximately 3000sqft. I'm updating exterior walls to add fiberglass insulation as most the walls lack modern insulation and have plaster and lath. I'm gonna insulate the second floor ceiling and also insulate the attic roof since we want to make it a living space. The baseboard heat is ran by a small electric boiler with backup fuel oil when it gets to really low temperatures. I live in the upper Midwest US where winters can be brutal and summers get to be pretty hot.

I was given advice by a family member to get a gas boiler. And the house in its current state is costly to heat in the winter. This is my first house and am a complete noob to HVAC systems. What would be a cost-effective HVAC system for my needs? Is it even worth to update HVAC now since it's still working (although it's pretty old)? I've heard ductless heat pumps are good but are expensive to run and may not work in subzero temperatures. Idk.

I also don't understand on-peak and off-peakheat? Like, do I need 2 heat sources? Can't I just use one heat component?


  • Steamhead
    Steamhead Member Posts: 17,000
    First of all, you're doing the right thing by tightening up the house. This means that when you replace the boiler and A/C units, you can get smaller ones. When that time comes you'll need to do a heat-loss calculation for the boiler and a heat-gain for the A/C.

    Second, does the house have natural gas service? If not, and you want to go gas, you're limited to propane which in many cases is more expensive per BTU than oil.

    Where exactly are you located?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Mad Dog_2
  • Mad Dog_2
    Mad Dog_2 Member Posts: 7,241
    edited August 2023
    Upper peninsula of Michigan? Minnesota?  Heaven up that way...Mad Dog 🐕 
    HVACNUT Member Posts: 5,887
    If there's plenty of attic space, you could do a central AC system for the second floor. Put the air handler in the attic in an easily accessible location for service. Run all ductwork then box it in. Then one or two ductless heads for the finished attic. 
  • Jamie Hall
    Jamie Hall Member Posts: 23,635
    As @Steamhead said, where in the upper Midwest? Makes a difference...

    Simplest approach would be a gas (if you have natural gas, or if you are in or near a farming community where LP is reasonable in price) or oil boiler to power your existing baseboard for heating, and then a heat pump for the second floor AC and heating in the shoulder seasons, and heating and AC for the repurposed attic. It may or may not be able to give you adequate heat for that space in the winter -- that's where the "where" comes in.

    I have to say this -- I hope you are not removing the plaster and lathe and putting up drywall... a serious, but very common, error in working with older houses. And I hope you are having the old windows refurbished and storms added, rather than putting in modern windows -- which won't last.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England