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  1. #1
    Join Date
    Jul 2009
    Posts
    18

    Carrier heat pump air temp and other questions

    Hi, all. We will likely be going with a Carrier solution now for our furnace replacement, and we are considering a solution that would pair the Carrier ICS furnace with a Carrier Infinity 16 or 19. I'm having my doubts about this approach and am hoping you regulars can help -- especially those of you who know Carrier equipment well.

    My questions:

    -- Coupled with the Carrier ICS, would the Infinity 16 and 19 deliver heat at roughly the same air temp coming out of the ducts? The 16 uses reciprocating compressors and the 19 uses scroll compressors.

    -- The Carrier dealer says the air temps from Carrier heat pumps are higher than with other heat pumps. Is this true? How much higher? What air temps can we expect? I'm concerned that we'll end up not using the HP to heat if the air temps from the ducts aren't pretty comfortable.

    -- I know heat pumps generally run longer than furnaces and possibly with greater cfm. On a moderate heating day, is there a pretty high cfm going through the ducts a good bit of the day, so that it might feel drafty in some locations, or is the flow pretty low?

    -- If well maintained, which they would be, are the two-stage HPs as reliable as the single-stage models (say, the Performance 15).

    -- I'm considering the two-stage HP instead of a single-stage HP or A/C because the dealer says I'm much more likely to avoid big temp differences between the first and second floor of our home with a two-stage unit when in cooling mood. He estimates I could see a difference of 5 to 12 degrees (F) with a single-stage model but just a few degrees, maybe 3, with a two-stage model. Does this make sense?

    -- The software the dealer uses predicts that I'd save about 50 percent with Carrier ICS and an Infinity HP relative to my current 80 percent gas furnace. Does this sound right to you? It seems a little optimistic compared to some of the online energy-savings calculators I've found. We pay about 10 cents per KWh for electrical and about $1.32 for natural gas.

    Thanks for any help.

  2. #2
    Join Date
    May 2009
    Posts
    196
    Quote Originally Posted by JLSinPDX View Post
    -- Coupled with the Carrier ICS, would the Infinity 16 and 19 deliver heat at roughly the same air temp coming out of the ducts? The 16 uses reciprocating compressors and the 19 uses scroll compressors.
    Compressor type shouldn't make any difference provided the two units have the same output capacity.

    -- I know heat pumps generally run longer than furnaces and possibly with greater cfm. On a moderate heating day, is there a pretty high cfm going through the ducts a good bit of the day, so that it might feel drafty in some locations, or is the flow pretty low?
    Hard to say. The Infinity thermostat will vary system airflow to provide the warmest air possible from the HP. Maximum airflow should be about 350 CFM per nominal ton (e.g. 1050 CFM for a 3 ton unit) but how often the system goes to full air flow is up to the whims of the Infinity algorithms.

    Draftiness, however, will depend on the volume of your house and the quality of your ducting.

    -- I'm considering the two-stage HP instead of a single-stage HP or A/C because the dealer says I'm much more likely to avoid big temp differences between the first and second floor of our home with a two-stage unit when in cooling mood. He estimates I could see a difference of 5 to 12 degrees (F) with a single-stage model but just a few degrees, maybe 3, with a two-stage model. Does this make sense?
    Even temperatures between floors are a matter of ducting and duct balancing.

    Beware that you'll need either zoning or two separate systems (one per floor) if you want/need to keep both floors at the same temperature in all conditions.

    -- The software the dealer uses predicts that I'd save about 50 percent with Carrier ICS and an Infinity HP relative to my current 80 percent gas furnace. Does this sound right to you? It seems a little optimistic compared to some of the online energy-savings calculators I've found. We pay about 10 cents per KWh for electrical and about $1.32 for natural gas.
    Sounds unrealistic at first glance. Work the numbers to see what COP you'd need to cut your heating bills in half and compare it to Carrier's published performance data for their heat pumps.

  3. #3
    Join Date
    Apr 2009
    Location
    WV
    Posts
    75
    My situation sounds similar. I ended up going with the ICS furnace and Performance 15 H model HP on my first floor. This will replace a gas furnace/A/C combo. It's scheduled to be installed so I can't tell you how it is working out. I researched it to death and found that the Infinity 16, 2-stage HP has worse numbers than the Perfromance 15 single stage HP. In my humble opinion, if you decide on a Carrier 2-stage HP, stick with the Infinity 19 solely on the SEER, EER and HSPF numbers alone. From what I can tell, the Infinfity control will vary the fan speed on the ICS furnace to control humidity during cooling even when coupled with a single stage HP.

    My setup is for my first floor. When I replace my upstairs HP, I will probably go with the Infinfity 19 where the cooling load is greater.

  4. #4
    Join Date
    Jun 2007
    Location
    The Twilight Zone
    Posts
    2,964
    Quote Originally Posted by JLSinPDX View Post
    My questions:

    -- Coupled with the Carrier ICS, would the Infinity 16 and 19 deliver heat at roughly the same air temp coming out of the ducts? The 16 uses reciprocating compressors and the 19 uses scroll compressors.

    -- The Carrier dealer says the air temps from Carrier heat pumps are higher than with other heat pumps. Is this true? How much higher? What air temps can we expect? I'm concerned that we'll end up not using the HP to heat if the air temps from the ducts aren't pretty comfortable.
    The Carrier dealer should be able to provide you with technical operating data for each heat pump that lists the air temp after the indoor coil (in both first and second stage) as well as SEER, EER, HSPF, and btu output over a range of ambient temperatures.

    Tell him that you want to see the technical operating data.

    Good luck.

  5. #5
    Join Date
    Nov 2008
    Posts
    1,673
    Quote Originally Posted by JLSinPDX View Post
    -- The software the dealer uses predicts that I'd save about 50 percent with Carrier ICS and an Infinity HP relative to my current 80 percent gas furnace. Does this sound right to you? It seems a little optimistic
    You know a great way to flush out lies? It is so good politicians are afraid of it.
    Ask for the estimates in a sworn statement from a company principal!

    We pay about 10 cents per KWh for electrical and about $1.32 for natural gas.
    1 Therm of energy can be had from approx. 100 cubic feet of natural gas, 29 kwh of elec heat, 8.4 kwh of heat pump heat (COP = 3.5) and 4.2 kwh of heat pump heat (COP = 6.9).
    Look at your past bills for energy usage to calculate payback for your new system.

  6. #6
    Join Date
    Aug 2009
    Location
    Kansas City
    Posts
    258
    No heat pump on the market will match the air temp output of a furnace that I have seen. The carrier thermostat will look at outside temperature and outdoor coil temperature to decide on what cfm the indoor fan should run at. Carrier has the best controls in the industry. So this is probably why your contractor has made the comment about the warmer air. 2 stage units have longer run times which means more consistant temperatures throughout the home. The 50% savings may be optimistic, but it really depends on the insulation value of your home.

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