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 https://heatinghelp.com/contact-us/.

Lennox Heat Pumps & Philadelphia Winter

We are having two Lennox heat pumps installed in the next few weeks. Upstairs we'll have a ML14XP1 (HSPF maximum of 9) using existing ductwork. Downstairs, we'll have a MPB030S4M (HSPF maximum of 10.3) with three mini-splits. House is ~2500 square feet.

Does anyone have real world experience with how effective these are at heating when the temperature drops below 30 degrees?

We are keeping our gas boiler for the very cold days.

Comments

  • Steamhead
    Steamhead Member Posts: 14,771
    I've never seen a heat pump that worked well below freezing. Every so often some manufacturer comes out with something that is supposed to (remember the Acadia?) but they never live up to the hype. Don't let anyone talk you into trashing your boiler system.
    All Steamed Up, Inc.
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
    SuperTech
  • Hot_water_fan
    Hot_water_fan Member Posts: 143
    Heat pumps work well below freezing, don’t stress. I’m not familiar with Lennox though, worth looking around to find its capacity chart. 
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,199
    I’d probably drop them out at 40 degrees, and use the boiler.
    Nothing is more comfortable than hydronic (radiant) heat.
    steve
    SuperTech
  • Steamhead
    Steamhead Member Posts: 14,771
    Several winters ago, one of our customers' boiler died and we had to replace it in a particularly cold stretch of winter. We were lucky if the daytime high reached 20 degrees. The owners had recently had these super-duper heat pumps installed which were supposed to handle weather this cold.

    Well, they managed to keep the house up to 54 degrees or so. They didn't live up to the hype.

    I used to say heat pumps didn't belong anywhere but the Deep South, but then we had the polar vortex that nailed Texas.
    All Steamed Up, Inc.
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Hot_water_fan
    Hot_water_fan Member Posts: 143
    They work well under freezing, can't stop an installer from putting in something undersized. They're used successfully in locations much colder than Philly.
  • Steamhead
    Steamhead Member Posts: 14,771
    Well, on this job, the owners were told the heat pumps would heat the house satisfactorily down to zero. The fact remains they did not. They did keep the pipes from freezing..............
    All Steamed Up, Inc.
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Ctoilman
    Ctoilman Member Posts: 105
    Heat pump at zero???!!....omg
  • Hot_water_fan
    Hot_water_fan Member Posts: 143
    The right heat pump can easily below zero, but will the installer do the right heat loss and right equipment selection is the challenge.
  • pecmsg
    pecmsg Member Posts: 2,229
    Heat pumps have there place, shoulder seasons 20 - 30°fine after that use your back up source.
  • Hot_water_fan
    Hot_water_fan Member Posts: 143
    edited July 21
    @pecmsg Philly's pretty mild: over the last 36 months 95% of heating degree days were less than 36, so warmer than an average temp of 30. 99.6% were less than 46, so warmer than an average of 20 degrees. It's basically always shoulder season.
  • Jamie Hall
    Jamie Hall Member Posts: 16,654

    The right heat pump can easily below zero, but will the installer do the right heat loss and right equipment selection is the challenge.


    Tell you what, @Hot_water_fan . A hypothetical project for you (that is to say, no way is it going to be done, but it might be interesting for the Wall to see, from your point of view, what would be required -- and you can PM me with a cost estimate).

    Design day: -10F
    Actual measured heating load at -10F: 3,300,000 BTUh
    Existing system: vapour steam
    Proposed system: air to circulating hot water heat pump (probably 4 zones)

    Cost to include demo. and removal of entire steam system, installation and commissioning of heat pump, installation and all piping and auxiliary equipment and controls for hot water heat (true radiant is not an option) (assume four zones). 200 amp 120/240 volt single phase electrical service is available, no upgrade possible at this time.

    I'd add that the property is a registered National Historic Landmark, so National Park Service guidelines for restoration must be followed -- but that is perhaps an unnecessary complication!

    Have fun!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Hot_water_fan
    Hot_water_fan Member Posts: 143
    @Jamie Hall ha! That's good. Luckily (unluckily?) most Americans don't live in houses that big and old. Does the museum have a website? Seems cool
  • Jamie Hall
    Jamie Hall Member Posts: 16,654
    No, we've never created a web site. Nor are we generally open (have you priced liability insurance for a museum?!) -- but anyone from the Wall is welcome to visit almost any time. Send me a PM...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    STEVEusaPAHot_water_fan
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,199
    @Jamie Hall where ya at again? I may take you up on that one day. Would love to see the place.
    Looks awesome.
    steve
  • Jamie Hall
    Jamie Hall Member Posts: 16,654
    northwestern Connecticut, @STEVEusaPA . Two and a half hours from either New York or Boston.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    STEVEusaPA
  • Steamhead
    Steamhead Member Posts: 14,771

    The right heat pump can easily below zero, but will the installer do the right heat loss and right equipment selection is the challenge.


    Tell you what, @Hot_water_fan . A hypothetical project for you (that is to say, no way is it going to be done, but it might be interesting for the Wall to see, from your point of view, what would be required -- and you can PM me with a cost estimate).

    Design day: -10F
    Actual measured heating load at -10F: 3,300,000 BTUh
    Existing system: vapour steam
    Proposed system: air to circulating hot water heat pump (probably 4 zones)

    Cost to include demo. and removal of entire steam system, installation and commissioning of heat pump, installation and all piping and auxiliary equipment and controls for hot water heat (true radiant is not an option) (assume four zones). 200 amp 120/240 volt single phase electrical service is available, no upgrade possible at this time.

    I'd add that the property is a registered National Historic Landmark, so National Park Service guidelines for restoration must be followed -- but that is perhaps an unnecessary complication!

    Have fun!
    Oh, don't forget- system shall heat all rooms to 70° F when the outside temperature is -20°F or the contractor doesn't get paid. That's how they did it in the old days..................
    All Steamed Up, Inc.
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Jamie Hall
    Jamie Hall Member Posts: 16,654
    Which, I might point out, the steam system does very nicely now, thank you!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Steamhead
    Steamhead Member Posts: 14,771
    All Steamed Up, Inc.
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Jamie Hall
    Jamie Hall Member Posts: 16,654
    I do, frequently
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Steamhead
  • pecmsg
    pecmsg Member Posts: 2,229

    northwestern Connecticut, @STEVEusaPA . Two and a half hours from either New York or Boston.

    Next trip on the Cross Sound Ferry I may take you up on that! :)
  • Jamie Hall
    Jamie Hall Member Posts: 16,654
    edited July 22
    A bit over an hour up Rt. 8 from the ferry terminal in Bridgeport, @pecmsg . I'd be delighted! Or an hour and a half or so from New London.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England