littleboss
New Member
Posts:46
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| 31 Dec 2018 06:39 PM |
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Looking at the Fujitsu units they offer wall mount, floor mount, slim duct and compact cassette styles.
How does the efficiency of these types vary? For example is a slim duct or compact cassette less efficient?
I have read somewhere Dana posted about where to locate the units. I would prefer a floor mount vs a high up on the wall location so it should be more efficient?
Finally are the XLTH units as efficient as the standard units?
Thanks
Thanks |
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Dana1
Senior Member
Posts:6991
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| 03 Jan 2019 04:29 PM |
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The XLTH units are at least as efficient at low temp as their comparable non-XLTH units. Better still, they self protect from defrost ice damage that can sometimes happen at low temp. Floor mount units are typically more efficient than high wall types in heating mode due to the fact that they're taking in lower-temp air near the floor, but that doesn't show up in AHRI testing, which assumes the same entering air temperature independent of whether it's a floor unit or even a ceiling cassette.
What you really care about is the efficiency at part load at your average wintertime temperatures, and the capacity at your 99% outside design temperatures, and the minimum modulation level reltive to your shoulder season loads. Undersizing can cut into efficiency, but oversizing can too, if it's minimum modulation level is a lot higher than your load at +47F (one of the AHRI test temperatures.)
To compare COPs and capacities at different levels & temperatures of different models, download the NEEP spreadsheet. The link should be up and running later this week(?)
https://neep.org/node/3725/download/b8d1bfe31bf9ce47b653aca123c6feeb
If they don't post the update soon PM me your email and I'll send you December's version next week.
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Dana1
Senior Member
Posts:6991
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| 03 Jan 2019 04:30 PM |
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The XLTH units are at least as efficient at low temp as their comparable non-XLTH units. Better still, they self protect from defrost ice damage that can sometimes happen at low temp. Floor mount units are typically more efficient than high wall types in heating mode due to the fact that they're taking in lower-temp air near the floor, but that doesn't show up in AHRI testing, which assumes the same entering air temperature independent of whether it's a floor unit or even a ceiling cassette.
What you really care about is the efficiency at part load at your average wintertime temperatures, and the capacity at your 99% outside design temperatures, and the minimum modulation level reltive to your shoulder season loads. Undersizing can cut into efficiency, but oversizing can too, if it's minimum modulation level is a lot higher than your load at +47F (one of the AHRI test temperatures.)
To compare COPs and capacities at different levels & temperatures of different models, download the NEEP spreadsheet. The link should be up and running later this week(?)
https://neep.org/node/3725/download/b8d1bfe31bf9ce47b653aca123c6feeb
If they don't post the update soon PM me your email and I'll send you December's version next week.
See this post:
https://www.greenbuildingadvisor.com/question/right-priorities-on-neep-hp-data |
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littleboss
New Member
Posts:46
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| 03 Jan 2019 05:29 PM |
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Thanks, I will see if I can get it downloaded and figured out. |
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SciGuy
New Member
Posts:33
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| 08 Jan 2019 10:15 PM |
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Posted By Dana1 on 03 Jan 2019 04:30 PM
The XLTH units are at least as efficient at low temp as their comparable non-XLTH units. Better still, they self protect from defrost ice damage that can sometimes happen at low temp. Floor mount units are typically more efficient than high wall types in heating mode due to the fact that they're taking in lower-temp air near the floor, but that doesn't show up in AHRI testing, which assumes the same entering air temperature independent of whether it's a floor unit or even a ceiling cassette.
What you really care about is the efficiency at part load at your average wintertime temperatures, and the capacity at your 99% outside design temperatures, and the minimum modulation level reltive to your shoulder season loads. Undersizing can cut into efficiency, but oversizing can too, if it's minimum modulation level is a lot higher than your load at +47F (one of the AHRI test temperatures.)
To compare COPs and capacities at different levels & temperatures of different models, download the NEEP spreadsheet. The link should be up and running later this week(?)
https://neep.org/node/3725/download/b8d1bfe31bf9ce47b653aca123c6feeb
If they don't post the update soon PM me your email and I'll send you December's version next week.
See this post:
https://www.greenbuildingadvisor.com/question/right-priorities-on-neep-hp-data
Hi Dana,
I'd love to see the December NEEP spreadsheet too. It appears that the new update is still not out.
Thanks,
Hugh
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Dana1
Senior Member
Posts:6991
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| 08 Jan 2019 11:19 PM |
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Looks like NEEP won't be posting downloadable spreadsheets this year, but will have some other format for dealing with it:
https://neep.org/initiatives/high-efficiency-products/emerging-technologies/ashp/cold-climate-air-source-heat-pump
"In early 2019, NEEP will launch a new database to house the ccASHP product list. The database will provide a more consumer friendly format to more easily access the available product information." |
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Dana1
Senior Member
Posts:6991
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| 09 Jan 2019 09:56 PM |
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Looks like the NEEP list has been updated, but they made it hard to surf-to from the main website (I got to it via the MassSave website):
https://neep.org/system/files/ColdClimateAir-SourceHeatPumpSpecificationProductListing-Updated1.2.19.xlsx
https://neep.org/node/3725/download/d4470144b29894e18ece9f2ff2eb3140
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littleboss
New Member
Posts:46
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| 14 Jan 2019 05:43 PM |
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Another question: I see that multiple heads decrease the efficiency. Is this only true if all of the heads are running? If I only run one head at a time does the SEER increase?
Thanks |
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Dana1
Senior Member
Posts:6991
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| 14 Jan 2019 06:13 PM |
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Posted By littleboss on 14 Jan 2019 05:43 PM
Another question: I see that multiple heads decrease the efficiency. Is this only true if all of the heads are running? If I only run one head at a time does the SEER increase?
Thanks
Not necessarily, but sometimes. A single half-ton head running on a bigger multi-split can be well below the compressor's optimal most-efficient operating point. Under the right outdoor temperature conditions and right head size it might be able to beat the average COP when
letting multiple heads cycle on/off, but there isn't enough information in the engineering manuals or third party testing to be able to say what that operating point is.
For most fully modulating mini-splits the optimum point is usually somewhere between 1/4-1/3 of the full capacity at a given temperature, but even that varies quite a bit by compressor type and coil design. |
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littleboss
New Member
Posts:46
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| 14 Jan 2019 06:17 PM |
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Posted By Dana1 on 14 Jan 2019 06:13 PM
Posted By littleboss on 14 Jan 2019 05:43 PM
Another question: I see that multiple heads decrease the efficiency. Is this only true if all of the heads are running? If I only run one head at a time does the SEER increase?
Thanks
Not necessarily, but sometimes. A single half-ton head running on a bigger multi-split can be well below the compressor's optimal most-efficient operating point. Under the right outdoor temperature conditions and right head size it might be able to beat the average COP when
letting multiple heads cycle on/off, but there isn't enough information in the engineering manuals or third party testing to be able to say what that operating point is.
For most fully modulating mini-splits the optimum point is usually somewhere between 1/4-1/3 of the full capacity at a given temperature, but even that varies quite a bit by compressor type and coil design.
Thanks again! |
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