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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: 15,342
    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.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
    SuperTech
  • Hot_water_fan
    Hot_water_fan Member Posts: 537
    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: 5,689
    I’d probably drop them out at 40 degrees, and use the boiler.
    Nothing is more comfortable than hydronic (radiant) heat.
    steve
    SuperTechPC7060
  • Steamhead
    Steamhead Member Posts: 15,342
    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.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Hot_water_fan
    Hot_water_fan Member Posts: 537
    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: 15,342
    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.
    Towson, MD, USA
    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: 537
    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: 2,898
    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: 537
    edited July 2021
    @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: 18,953

    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: 537
    @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: 18,953
    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: 5,689
    @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: 18,953
    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: 15,342

    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.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Jamie Hall
    Jamie Hall Member Posts: 18,953
    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: 15,342
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Jamie Hall
    Jamie Hall Member Posts: 18,953
    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: 2,898

    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: 18,953
    edited July 2021
    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
  • josh28
    josh28 Member Posts: 4
    Finally got the heat pumps installed. Now using them to keep home warm.  I'm wondering if their performance so far is typical. 

    Weather here (Philly suburbs) this November: lows around freezing and highs around 55F (13C).  Heat pumps are doing an adequate job keeping the house comfortable.  I have always expected we may need to use the boiler when it drops well below freezing but it's not 'winter' cold yet.

    Our electricity usage increased by more than I expected.  Daily usage before using heat pumps was about 18kWh/day.  Usage since using the heat pumps is 45kWh/day (so w/ heat pumps we're +27kWh/day).

    We have a Lennox MPB030S4M downstairs with 3 wall units and a Lennox ML14XP1-030-230 upstairs (using existing ductwork)

    I would have a little more confidence that they're working correctly if the wall units didn't have multiple error codes when they were first installed (since resolved) but has affected my confidence a bit.

    Is there best practice recommendations for adjusting the temperature with the wall units?  Leave on desired temp?  Adjust up and down during sleep/daytime?

    Thanks.
  • pecmsg
    pecmsg Member Posts: 2,898
    Heat pumps you set and forget.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,010
    @josh28

    keep the updates coming i would like to see how this turns out
  • jumper
    jumper Member Posts: 1,843
    >>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..................<<

    Was that when furnace coal was a buck a sack delivered? For most places 70° @ -20° is oversized unless house is Canada2000 or better.
  • Hot_water_fan
    Hot_water_fan Member Posts: 537


    Pretty similar climate to yours: this is all of my electricity usage, not just heating. I have a ducted unit and a ductless unit, both Mitsubishi’s. 32kBtu total. 21 kwh/day for everything including 24/7 blower fan. .4 therms for water heating. 

     The below gas usage is from 11/2/2020, same average temperature. Used 2.7 therms (18kwh of electricity, including the ductless that day). 

    COP somewhere between 2.6 (all 21 kwh for heating) and 4.5+ (Say 21-9 for other uses). About 35- 60% cheaper than gas.


    lkstdl
  • josh28
    josh28 Member Posts: 4
    I'm wondering if we have a faulty system or a bad install or something else. Our mini-split is unable warm our living room beyond 68 degrees. Even today when it was 52 degrees outside, we peaked at 68 in the living room. The wall unit is set at 76.

    It's mid-December and we haven't had to use our boiler yet which is nice. But it's been a very mild fall so far. And we're often using a space heater to make ourselves comfortable.

    Our installer was last here about a month ago. He recommended not using the 'auto' setting on the fan and turning it up all of the way. This has had a negligible effect.

    System size is 28,000 BTU. We have three wall units.

    Any comments, suggestions, recommendations?
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,010
    None, except call the installer and tell him your not thrilled
  • Steamhead
    Steamhead Member Posts: 15,342
    edited December 2021
    We'd need to know what the heating and cooling loads are for your house. If I had to guess based on what you've posted so far, I'd say the heat pumps are sized for the cooling load, which is significantly smaller than the heating load.

    Long story short- time to turn on the boiler.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
    SuperTech