residential mini splits research dhp-mini split survey... · 2014-07-17 · e3t mini-splits draft...

E3T mini-splits DRAFT report March 31, 2014 of 21

Residential Mini-splits Research E3T Report by WSU Energy Program for BPA

Summary The adoption of efficient ductless heat pump (DHP) technology is moving in the right direction, and is

further promoted as an optimal choice when consumers are able to take advantage of utility incentives

to defer the initial costs. As is the case with most efforts to launch new technologies for widespread

acceptance, strategic implementation of ductless heat pumps will incur similar distribution curves.

Insights gathered from this implementation will help take further advantage of the existing momentum.

Secondary research on the existing programs and installed DHP technologies could allow for additional

extrapolation of data to identify opportunities for more focused exploration or enhance market

transformation. This research survey did not review or evaluate this data.

The WSU research effort focused on reaching out to manufacturers and their distributors to identify

newer or less prominent (market-wise) technologies in order to expand BPA’s current DHP program,

primarily by providing potential research opportunities to validate energy savings and other benefits for

different DHP options.

With the information gathered, opportunities to expand research and identify new categories would

consist of investigating the least adopted indoor units, which include ceiling concealed (ducted), ceiling

cassette (recessed), ceiling suspended, and floor console units.

There is likely an opportunity with multi-split DHPs, but it would require further evaluation of existing

installations and identification of actual energy savings. The commercial-version of ductless heat pumps

for residential applications, referred to as VRFs and which will be discussed later, are not cost-effective

for further exploration as they apply to niche applications (extremely large homes with large enough

comfort/temperature differences and/or needs).

With a very limited response rate in this survey, very few opportunities could be confirmed. However,

with the existing research and pilot programs in the region, the direction needed could certainly be

attained.

Introduction The Bonneville Power Administration (BPA) contracted with Washington State University Energy

Program (WSU) to research residential ducted/non-ducted mini-split systems to determine any potential

to expand BPA’s current Ductless Heat Pump (DHP) category.


This report reviews different types of mini-split systems, indoor units of those systems, and their system

performance, efficiency, cost-effectiveness, challenges and advantages.

The sheer number of combinations of mini-splits systems and their components makes the assessment

of their efficiency, performance, and cost-effectiveness difficult (one manufacturer has over 56,000

possible combinations based on indoor unit type and capacity). Outdoor units or compressors may

connect with a single indoor unit or multiple units. The majority of outdoor units use inverter-driven

compressors that provide variable refrigerant flow (variable capacity flow) yet there are still a few that

are non-inverter driven. Larger capacity outdoor units, commonly used for large residential homes,

multi-family or small commercial applications, have more advanced features that include flexible

controls and heat recovery.

The main types of indoor units, or heads, are: wall units; floor units (consoles) that can be placed as a

radiator might be or against a wall and raised a few inches; ceiling cassettes that appear as a vent in the

ceiling; suspended ceiling units that are similar to wall or floor units and lay flat up against the ceiling,

and; compact ceiling cassettes or concealed cassettes, which are smaller units because they are ducted

to a fan coil unit placed above the ceiling (and can connect to other compact units).

Efficiency varies based on configuration of outdoor units or compressors, their capacity, and the number

or type of indoor units that are used. For example, an outdoor unit with an indoor wall unit may have a

higher efficiency than that same compressor used with a ceiling cassette.

With all these various combinations, it is important to note that units from different manufacturers

cannot be combined. Additionally, most manufactures provide specific criteria for configurations

between outdoor and indoor units, with some having more options and/or flexibility dependent upon

capacity needed.

A full data set from the survey and product matrix is available and complete data, where applicable, has

been extracted within the graphs and tables in this report. Most of this information is most likely known

based on existing or past work that BPA or other regional stakeholders have carried out.

Project Process WSU took the following steps to accomplish the objective:

Held discussions to clarify scope, roles, course of action, etc. Michael Lubliner with WSU

supplied names of contacts with various manufacturers, distributors and DHP experts.

Identified 8 products or categories to survey:

1. Variable refrigerant flow for residential applications

2. Non-VRF multi-head systems

3. Ceiling cassettes

4. Floor consoles

5. Thin-duct/short-run duct systems


6. Combined air/water systems

7. Variable capacity air handler replacement heat pumps

8. Advanced refrigerants

Created a survey that could be taken over the phone or through Survey Monkey. Survey

questions were the same for each of the eight categories. (See Appendix A for survey questions)

Implemented survey to 20 distributors from list provided by BPA, and through WSU contacts.

Received nine replies via the survey, seven of which offered adequate information. Some

responded via Survey Monkey, others verbally over the phone.

Created spreadsheet matrix for the products that included metrics such as SEER, HSPF, capacity,

indoor coil air, etc.

Filled in matrix with data from AHRI and manufacturer’s website.

Entered cost information (both equipment costs only and with installation) from installers along

the I-5 corridor from Oregon and Washington.

Consulted with WSU HVAC engineer and reviewed manufacturers materials and websites, as

well as information from ASHRAE and other websites.

Consulted with WSU residential heating expert.

Terminology and definitions Terminology for mini-splits ductless heat pumps can be contradictory and confusing, partly indicative of

how rapid the technology is evolving and being implemented.

An online ASHRAE exchange discussed the confusion of the terminology of VRF and multi-splits

(https://www.ashraexchange.org/archive/index.php?t-41.html). The heart of the discussion is that

nearly all HVAC DHP systems use variable refrigerant flow, yet using the term “VRF” to identify some of

the variable refrigerant flow systems is misleading.

Commonly, VRF is used to describe commercial systems. DHP for residential applications did not

originally use variable speed compressors. The larger commercial applications started using the

technology, and the term stuck for such applications.

Suggestions mentioned in the ASHRAE exchange to clarify terms include defining split systems

depending on how many indoor units – multi-split or single-split, as well as ducted or ductless.

Below are some definitions and terminology used in this report.

The terms “variable refrigerant flow (VRF)”, “inverter”, “inverter driven”, “inverter compressor”,

and “VRF driven” have the same meaning. The inverter allows the system’s refrigerant flow to

vary according to heating and cooling need, thereby increasing energy efficiency as well as

comfort.

https://www.ashraexchange.org/archive/index.php?t-41.html


A non-VRF or non-inverter driven system can only run in full capacity or not at all, although

there are some “two-step” systems that allow for a middle ground.

The terms “ductless heat pump”, “mini-splits”, “multi-splits”, “multi-heads”, “ductless mini-

splits”, and “mini-splits heat pumps” are interchangeable. They are often referred to as DHP in

this report. DHPs have one outdoor compressor unit, also called a condenser, and one or more

indoor fan coil unit(s). These indoor units, or heads, include wall, floor, and ceiling units that

heat or cool separate zones. Refrigerant is used to transfer heat directly to or from an indoor fan

coil unit(s), mostly displacing the need for ducts. Most utilize variable refrigerant flow

technology (also known as variable capacity or variable refrigerant volume), which adjusts the

amount of refrigerant providing heating or cooling depending on the load need. DHPs have one

set of lines (two lines) from the compressor to each head unit. Thus, a residence with four

indoor units will have eight refrigerant pipes running to and from the compressor. DHP with

multiple heads (multi-splits) can be run in either cooling or heating mode, not both at the same

time. In many models however, the amount of cooling or heating is controlled at the individual

zone unit. Figures 1.1 and 1.2 show simple diagrams of residential ductless heat pumps in the

single-split or multi-split configuration.

Figure 1.1: DHP, Single-Split System Figure 1.2: DHP, Multi-Split System

The term “VRF” is used for ductless heat pumps in commercial applications. VRFs have a single

piping system – two lines of refrigerant connect to the compressor, and the indoor units are

connected to each other in series (Figure 1.3). More heads can be attached to the compressor

than with residential multi-splits, and VRF systems allow for longer refrigerant lines. The indoor

units are generally powered separately while DHP indoor units are powered by the compressor.

In general, VRF systems have more advanced controls than DHP. They allow for more efficient

energy use, moderation and maintenance of temperature, quiet operation, and greater

occupant comfort, as well as not needing to heat or cool all zones at the same time. Sometimes

referred to as ‘heat pump’ VRF systems or VRF heat pumps, they are single-mode systems that

can provide either heating or cooling to the indoor units.

VRF heat pump systems that use heat recovery, sometimes called ‘heat recovery’ VRF systems,

are dual-mode systems that can simultaneously provide heating or cooling to indoor units when


configured properly. Heat can be moved from zones that are in cooling mode to zones that

need heating and vice versa, without the refrigerant traveling through the outdoor compressor

(Figure 1.4). VRF systems have more complex controls and utilize branch boxes to allow for heat

recovery. Heat recovery VRF uses either two pipes or three pipes. The three-pipe system has a

liquid line, a high-pressure vapor line, and a low-pressure vapor line. Controlled by the

expansion valve, heating uses the high-pressure vapor line and the outlet to the liquid line, while

cooling provides the outlet into the low-pressure vapor line.

The opportunity to heat and cool simultaneously creates the potential for a higher coefficient of

performance.

Figure 1.3: VRF, Multi-Split Figure 1.4: VRF w/Heat Recovery

Results As with any survey, responses are dependent on the knowledge of the respondent, as well as the clarity

of the questions. Terms are sometimes used differently. A case in point is that what was classified as

non-VRF by manufacturer representatives were actually VRF products. The terminology used by

standards organizations and that of distributors or installers appears to have created confusion.

With the moderate response rate (9 of 20 responded) from the survey and the quality and quantity of

responses, product data collected included these manufacturers:

o Daikin/York

o Fujitsu

o Gree

o Heat Controller

o Mitsubishi

o Panasonic

o Pridiom


Survey Product Categories Results include responses to the survey, online research, and in-house WSU residential experts.

Of the eight categories reviewed and the survey data provided by respondents we can group these into

two areas. The first being a system-specific category and the second focused on indoor unit types.

The system-specific category includes:

Compressor Type (VRF, non-VRF as compared to DHP)

Specialty Systems (space/water combination and air handler replacement)

Refrigerants

The indoor unit types include:

Wall Mount (data collected, but not a focus area)

Ceiling Cassettes

Floor Consoles

Ceiling Concealed (short-run ducted units)

Ceiling Suspended

Variable refrigerant flow for residential applications

VRF systems are generally used in commercial applications, but are sometimes installed in large homes.

VRFs can connect to more indoor units than DHP, and they are especially applicable in larger

applications. If many zones are needed, they can be more cost effective than putting in multiple single-

split systems or multiple multi-split systems.

VRF systems are more difficult to install than single head DHP because of the greater number of parts,

rules or codes regarding refrigerant piping lengths and control wiring, needing to install manifolds and

the need for the systems to be more precisely designed and balanced.

DHP multi-zone systems only allow cooling or heating. Some VRFs (those with heat recovery) allow

simultaneously cooling and heating. This can solve problems with large homes that need heating and

cooling at the same time in different rooms or spaces.

Most distributors offer VRF for residential applications. Pridiom does not currently, as they are not as

involved with the commercial market, however they will offer the system in 2015.

Mitsubishi and Daikin will only sell VRF systems to installers who have attended one of their training

classes. All the manufacturers provide training opportunities.

Non-VRF multi-head systems

Non-VRF multi-head systems use single-speed non-inverter compressors, so the system is either on at

full speed or off. All the heads (indoor units) are controlled by a single source and each is connected


individually to the outdoor compressor. As far as can be ascertained, there are no non-inverter multi-

head DHPs on the BPA qualified list. Non-VRF systems do not have the capability to vary the heating or

cooling in different zones. There are no individual zone controls. Performance is compromised with each

additional head added to the system, thus reducing the efficiency.

One possible reason to use a non-VRF heat pump is in commercial applications where the

heating/cooling load needs to be constant, such as for data centers or elevator equipment rooms.

However, it is likely that inverter technology would be much more efficient relative to the cost when

upgrading equipment.

Combined air/water systems

Also known as an air-to-water split system heat pump, these systems offer heating, and optional cooling

and domestic water supply. They use the same technology as DHP, but the refrigerant is piped from the

compressor to a hydronic box where water is heated. The water provides heat through radiators and/or

under floor radiant heating coils, and can provide domestic hot water if combined with a specially

designed hot water tank.

These combined systems are currently very popular in parts of Europe and Asia. Those systems often

use radiant heat with an inverter heat pump, cooling to fan coil or head and domestic hot water with

optional solar.

Plumbers or HVAC workers are needed for HPWH installation, depending upon whether water or

refrigerant is used. The units depend on hydronic distribution and are used for both new construction

and retrofit.

Only Mitsubishi and Daikin of the surveyed responses offer combined systems, and Mitsubishi’s system

is commercial. Panasonic will be offering a combined air/water system in the next few years.

Variable capacity air handler replacement heat pumps

Variable capacity air handler replacement heat pump systems replace existing furnaces or non-VRF heat

pumps. Some systems are small ceiling or attic units that have a whole house duct system built around

them. As people upgrade central systems, a variable capacity air handler system can be installed as a

new system. Existing registers and ducts can still be used, so wall mounts or other indoor units are not

necessary, and the amount of piping outside the house is limited. They are sometimes confused with

thin-duct/short-run ducts because the ducts in the replaced system can still be used. When a system is

replaced, the controls must be replaced as well, and only the heat pump manufacturer controls will

work optimally.

The system can be used as both a retrofit and new replacement. Existing ductwork may need to be

modified for retrofit applications, and fans may need to be added to the ductwork as well.


These units are offered by Daikin and Mitsubishi and a few other manufacturers expect to offer them in

the future.

Advanced refrigerants

None of the survey respondents mentioned alternative refrigerants; however, a project is currently

underway researching CO2 as an alternative refrigerant in heat pump water heaters. This may provide a

path to incorporating this advanced refrigerant in space heating-based applications of heat pumps or

combined water/space heating systems in the future.

Wall mount

This is the most common type and easily installed of indoor units available. These units can be placed on

any wall for rooms or spaces that need additional comfort or more efficient space heating, especially

when compared to electric resistance heat.

Wall mount units are the simplest configuration as they have been utilized throughout the world more

prominently. With the introduction of these systems and this type of indoor unit, best practices that

have been established provide a better path for US adoption and quality installations.

Wall mount units utilize independent zone controls via remotes, the unit’s built-in controller and, in

some cases an optional fixed controller may be installed.

The survey data collected indicates comparable heating efficiency but much greater cooling efficiency

than with any other type of indoor unit. See Figures 1.5 and 1.6.

Ceiling cassettes

Ceiling cassettes are indoor fan coil units that mount in the ceiling with only the grill unit showing.

Although they generally do not offer as many features as wall units, they have a diffuser which enables

them to distribute conditioned air over a large area. Ceiling units, as with wall-mounted units, are finely

tuned, with electric motors, directionality, motion sensors, and more. Ceiling cassette’s diffusers rely on

thermal dynamics and air turbulence, and can be located anywhere. Many models have built-in

condensate pumps. A condensate pump allows them to be placed away from outside walls, making

them more versatile. As with all indoor units, an additional refrigerant charge needs to be calculated

when the line set extends past manufacturer specifications.

In retrofit applications, ceiling cassettes are more complicated to install than wall units. They may not be

an option if a floor above constrains the amount of space to install the ceiling unit. Our WSU expert told

of complaints with ceiling cassettes due to cold air blowing from units and poor overall performance.

They also do not perform as well as wall mounts, which is verified by AHRI testing.

Most manufacturers surveyed offer ceiling cassette units. Pridiom only offers these with multi-head

systems, not single-head systems for inventory reasons.


Floor consoles

Also known as floor mounted head units, these can stand upright on a floor, located on a wall a few

inches above the floor, or even half-concealed inside a wall so it does not fully project into the room.

They are appropriate for both new construction and retrofit.

Most manufacturers said they offer floor consoles, with a couple saying they will in the future.

Floor units may be used if the upper wall space is at a premium, such as windows that take up the

majority of the upper wall space and/or where wall units do not fit. If there’s enough furniture, the floor

console units can be hidden, which is not true with wall units. These units can overcome market barriers

of wall units because they can be mounted similar to a radiator. They are not more difficult to install

than wall units and have similar cold weather performance as wall units.

Ceiling concealed (or thin-duct/short-run duct systems

Short-run or thin-duct mini-split systems use small indoor fan coil units installed in the ceiling, attic, or

crawlspace with short duct runs to compact ceiling cassettes in different rooms (e.g., bedrooms on the

same hall). These systems are also called compact-duct, mini-duct or ceiling concealed indoor units.

They can be used in a single-split system and in multi-head systems along with other heads, such as wall

or floor units.

Heating or cooling rooms through one zone in a short-run ducted system is less expensive than

individual DHPs for each room. Yet what is gained in cost savings may be lost in comfort and efficiency.

Ducted or ceiling concealed units are not as efficient due to the lower static pressure of the ducts. As

well, more short ducts added to the same fan coil unit will decrease performance.

As with most conventional, central forced air systems, short-run ducts can be an issue if not installed

properly. Many DHP experts agree that improperly installed ducts is one of the most common causes of

system failures and installation call-backs. Ducts must be properly sized and installed to overcome the

system’s inherent lower static pressure.

These systems are applicable for both retrofit and new construction. However, because of the logistics

of duct installation, new construction is easier and likely more cost-effective. Short-run duct systems can

be less expensive than multiple single-splits in new construction because two or more zones use the

same fan coil unit. For retrofits, they can solve problems in houses with inadequate performance of

existing ducts. They are reportedly not more difficult to install than other types of indoor units, but

there is added complexity and potential quality issues when ducting is involved as it is known with

central forced air systems.

These units tend not to be as efficient compared to the other indoor units.


Fewer manufacturers surveyed offer short-run duct systems than floor consoles or ceiling cassettes,

though some are planning to offer them in the near future. It was noted that Mitsubishi has an

authorized training facility in the Northwest that can provide assistance to installers.

Data

The following overview provides a basic analysis of indoor units from the survey data collected. The

majority of the data collected that included cost information is comprised of one manufacturer as no

other survey respondents provided cost details or no follow-up research with distributors allowed for

the capture of this data. In Figure 1.5, Single-Split Indoor Units are shown with the Heating Season

Performance Factor (HSPF) relative to the retrofit installed cost. The indoor units and their heating

efficiency amongst the types available are comparable, however on the cooling side (Figure 1.6), wall

mount units appear to out-perform the others when smaller capacities are needed and then gradually

become similar in effciency with larger capacity needs.

Fig. 1.5, Single-Split Indoor Units, HSPF v Cost

8

8.5

9

9.5

10

10.5

11

11.5

HSP

F

Retrofit Installed Cost ($ est.)

Single-Split Indoor Units: HSPF over Cost

Wall Mount

Ceiling Cassette

Ceiling Suspended

Ceiling Concealed


Fig. 1.6, Single-Split Indoor Units, SEER v Cost

The following graphs are of rated outdoor units combined with ducted indoor units and non-ducted

indoor units (which are not specified). Provided are both the multi-split or multi-zone products available

to residential installs and the residential/small-commercial VRF systems. There is a lack of consistencies

with survey data and manufacturer specification sheets for the COP at 47/17 degrees F, so there are

fewer data points available. Figure 1.7 shows the outdoor units rated, multi-split DHP and VRF, with

ducted indoor units that compare the HSPF over installed retrofit costs, with Figure 1.8 and 1.9 showing

the same products relative to their Coefficient of Performances (COP) at 47 degrees F and 17 degrees F,

respectively. The following Figures 1.10, 1.11 and 1.12 show the same outdoor units rated with non-

ducted indoor units.

12

14

16

18

20

22

24

26

28

SEER

Retrofit Installed Cost ($ est.)

Single-Split Indoor Units: SEER over Cost

Wall Mount

Ceiling Cassette

Ceiling Suspended

Ceiling Concealed


Figure 1.7, Ducted, Multi-Split and VRF systems, HSPF

Figure 1.8, Ducted, Multi-Split and VRF systems, COP @ 47

8.5 8.5

9.5

9 8.7

9.3

8.9 8.7

10.8

8

8.5

9

9.5

10

10.5

11

Hig

h-H

eat

HSP

F

Retrofit Installation Cost (est.)

Ducted, Multi-Split and VRF: HSPF over Retrofit Cost

Multi-split

VRF

3.62 3.8

3.64

3.26 3.3

2.51

3

2.6

3.7

2

2.2

2.4

2.6

2.8

3

3.2

3.4

3.6

3.8

4

CO

P @

47

de

gre

es

F


Ducted, Multi-Split and VRF: COP over Retrofit Cost

Multi-split

VRF


Figure 1.9, Ducted, Multi-Split and VRF systems, COP @ 17

Figure 1.10, Non-Ducted, Multi-Split and VRF, HSPF

2.56 2.62 2.78

2.54 2.52 2.38 2.2 2.19

3.14

1.5

1.7

1.9

2.1

2.3

2.5

2.7

2.9

3.1

3.3

CO

P @

17

de

gre

es

F


Ducted, Multi-Split and VRF: COP @ 17 over Retrofit Cost

Multi-split

VRF

8.9

9.3

10.5

9.3

9.8

8.75

8.7 8.7

10.6

8

8.5

9

9.5

10

10.5

11

Hig

h-H

eat H

SPF


Non-Ducted, Multi-Split and VRF: HSPF over Retrofit Cost

Multi-split

VRF


Figure 1.11, Non-Ducted, Multi-Split and VRF, COP @ 47

Figure 1.12, Non-Ducted, Multi-Split and VRF, COP @ 17

3.9

4.2

3.9

3.5 3.5

2.59

3.32

2.32 2.45

2

2.5

3

3.5

4

4.5

CO

P @

47

de

gre

es

F


Non-Ducted, Multi-Split and VRF: COP @ 47 over Retrofit Cost

Multi-split

VRF

2.7

2.98

2.78

2.68

2.44

2.39 2.3

2.22 2.17

2

2.2

2.4

2.6

2.8

3

3.2

CO

P @

17

deg

rees

F


Non-Ducted, Multi-Split and VRF: COP @ 17 over Retrofit Cost

Multi-split

VRF


From the survey data collected on multi-split and VRF systems, Tables 1.1 and 1.2 shows the data set by

indoor unit type and capacity with range of efficiencies and cost. Included from the survey responses are

example configurations for both, multi-split DHP and VRF.

Table 1.1: Multi-split DHP Outdoor Units, by Indoor Unit Type and Capacity

Indoor Capacity Possible Heads

EER SEER HSPF COP @ 47

COP @ 17

Retrofit Cost

Ducted Indoor Units 20,000 2 9.1 15.5 8.5 3.62 2.56 $3,740.00

Ducted Indoor Units 24,000 2,3 9.6 15 8.5 3.8 2.62 $4,615.00

Ducted Indoor Units 30,000 2,3 8.2 14.5 9.5 3.64 2.78 $5,050.00

Ducted Indoor Units 36,000 2,4 8.7 15 9 3.26 2.54 $5,430.00

Ducted Indoor Units 42,000 2-5 9.4 14.5 8.7 3.3 2.52 $6,298.00

Mixed Ducted and Non-ducted

20,000 2 10.55 16.75 8.7 3.76 2.63 $3,740.00


24,000 2,3 10.8 16.25 8.9 4 2.8 $4,615.00


30,000 2,3 8.65 16 10 3.76 2.78 $5,050.00


36,000 2,4 9.05 16.5 9.15 3.38 2.6 $5,430.00


42,000 2-5 8.95 16.45 9.25 3.4 2.38 $6,298.00

Non-Ducted Indoor Units 20,000 2 12 18 8.9 3.9 2.7 $3,740.00

Non-Ducted Indoor Units 24,000 2,3 12 17.5 9.3 4.2 2.98 $4,615.00

Non-Ducted Indoor Units 30,000 2,3 9.1 17.5 10.5 3.9 2.78 $5,050.00

Non-Ducted Indoor Units 36,000 2,4 9.4 18 9.3 3.5 2.68 $5,430.00

Non-Ducted Indoor Units 42,000 2-5 8.5 18.4 9.8 3.5 2.44 $6,298.00

Specific (MSZ-GE06NA(2)+MSZ-GE09NA)

24,000 1-3 12.5 17.5 9.3 NA NA $5,815.00

Specific (MSZ-GE06NA(2)+MSZ-GE12NA)

24,000 1-3 12.5 17.5 9.3 NA NA $5,923.00

Specific (MSZ-GE09NA(2)) 20,000 2 12.5 18 8.9 NA NA $4,330.00

Table 1.2, VRF Outdoor Units, by Indoor Type and Capacity

Indoor Capacity Possible Heads

EER SEER HSPF COP @ 47

COP @ 17

Retrofit Cost


Ducted Indoor Units 48,000 2-8 7.4 14.7 8.9 3 2.2 $6,740.00





36,000 1-6 10.95 14.3 8.2 2.71 2.68 $6,623.00


48,000 2-8 7.85 14.85 8.8 3.16 2.24 $6,741.00


48,000 1-8 8.7 15 8.7 2.56 2.13 $7,733.00


60,000 1-12 11.75 16.6 10.7 3.7 3.14 $9,085.00


Non-Ducted Indoor Units 48,000 2-8 8.3 15 8.7 3.32 2.3 $6,740.00

Non-Ducted Indoor Units 48,000 1-8 9 15.5 8.7 2.32 2.22 $7,733.00


Specific (PKFY-P24NKMU-E2.TH(2)+PKFY-P06NBMU-E2(2))

60,000 1-12 12.5 16.7 10.6 NA NA $12,361.00

From the above tables, should there be a need for further research in the large home market or small

commercial market, there could be an opportunity to more thoroughly explore multi-split DHPs and VRF

systems, their related installation costs, efficiencies and cost-effectiveness.

Installation and Weather

According to one of WSU’s residential HVAC experts, all systems with variable speed inverter technology

are capable of providing heat at temperatures well below freezing. However, capacity and efficiency

decreases as the temperature drops, some systems more than others. One suggestion is to size the

system for the average cold temperature in the region, and supplement heating with portable electric

resistance or other means if the weather drops below that temperature.

Most residential single-head DHPs can be self-installed in a day by mechanically inclined homeowners

with common hand tools, power tools and proper guidance. However, the refrigerant and electrical

connections should be done by qualified and licensed professionals. In some cases, warranties only

apply if installed by a professional trained by the manufacturer’s training network. Pridiom does not

have trained installers for DHP, but they require that installers have an HVAC license.

Multi-head systems are less time consuming than installing multiple single-head systems. Installation of

some systems, such as mini-ducted and heads such as ceiling cassettes may be more complicated to

install in retrofit than new construction because of constricted ceiling space.

Challenges and Barriers

Our residential HVAC expert as well as most of the distributors surveyed, describe residential customers

as not keen on the look of wall units. Yet wall units have been proven to be the most efficient of the

indoor units, with the highest SEER and HSPF ratings, and the lowest cost. Education and more

familiarity with the benefits of these units can do much to overcome this perceived barrier, and typical

of many people, they will become used to the unit once it’s in place for a while.


VRF systems are top of the line for performance and comfort, but the cost is prohibitive for most

residential applications. DHP, whether single- or multi-split, usually produces adequate heating or

cooling comfort and is cost-effective.

From an energy perspective, single zone is very efficient. There is a lot of experience from Northwest

installers who have installed multi-zone systems, but some DHP experts believes they’re not as efficient

as single-zone. A general consensus among installers and other DHP experts is that there are many more

service calls on multi-zone systems compared to single-zone, yet about a quarter of all systems installed

are multi-zones. Multi-zones are not as reliable, don’t perform as well in terms of comfort or efficiency,

and installation can be difficult to be put in correctly. Also, consumer education is necessary so that

homeowners know how to use the system adequately. There are not many installations of multi-splits

because they are still quite new and innovative.

Another drawback can be the high upfront costs in large homes relying solely on DHPs for space

conditioning needs.

Advantages

Multi-head DHP has more flexibility to be used in new applications compared to single-head wall-mount

systems. Multi-head in larger homes offers more choice of indoor units for each zone, all with a single

outdoor compressor. Ceiling cassettes, suspended ceiling, compact ceiling, and floor consoles may work

where wall units would not.

Having more types of indoor head units is advantageous in general because different houses have

different heating/cooling needs and are constructed differently. In one house, one or two single-split

wall units may be the most cost-effective, while another house will need multi-splits with ceiling or mini-

ducts.

Conclusions Although sufficient cost data is lacking, it is possible that some of the most promising products, beyond

the already proven application of single-split ductless heat pumps, are Variable Capacity Air Handler

Replacement Heat Pumps to replace non-VRF and furnaces, and combined air/water systems. As well,

under specific conditions, short duct mini-splits can be an effective solution. Mobile home applications

have not been discussed in this paper, but are a very promising application. Heat pumps for mobile

homes often have oversized fans to accommodate poor duct design. DHP retrofits would make HVAC

systems much more efficient.

The following questions could be explored for further research ideas and opportunities:

1. How does the quality of installation and the installation cost of two single-head (single-split)

systems compare to that of a multi-head (multi-split)?

2. Which products are the most difficult to install correctly and why (even with manufacturer-

trained installers)?


3. How can there be better quality assurance with installations, especially of ducts?

4. How does short duct in new constructions compare (cost, efficiency, installation quality) with

VRF piping only?

5. What is the potential for combined air/water systems? Are they cost-effective and energy-

efficient with radiant floor heating and/or potable water heating?

6. What is the energy use breakout of zonal heating (e.g. 50%-main living space, 30% bedrooms,

etc.)? (To help target multi-split applications.)

7. Are there trends related to installations of DHPs from the existing BPA qualified list or NEEA’s

program? This could include single/multi-split systems to help identify better strategies for

deployment and address market adoption barriers.

8. What are the existing marketing/incentives of mini-splits and multi-splits in Single

Family/Manufactured Homes? (this is probably more on the utility/NEEA side)

9. Based on the RBSA data/report, are there possible opportunities in Single Family homes outside

of electric resistance zonal heating, such as with older ASHP and electric boilers?

10. What is the status of other commercial-ready or near commercialized products? This includes:

Alternative refrigerant (CO2)

Integration of DHP in FAF systems


APPENDIX A: Survey Questions

The list of survey questions provided to targeted audience that included distributors of ductless heat

pumps/mini-splits and/or variable refrigerant flow heat pumps in the Pacific Northwest.

Do you currently offer these systems to North American customers? (Y/N/Comments)

If no, do you plan to offer these systems in the next 1-2 years?

Are these systems currently available outside of the North American market?

Please list, or provide links to, the products you offer in this category. You may email a list to

[email protected].

Is this technology more appropriate for new construction, retrofits, or equally applicable? (new

construction/retrofits/both/comments)Are these systems more difficult to install than single-

head mini-splits? Do you have a trained installer network in the Pacific Northwest that can

install these systems correctly?

Does this technology allow for split system heat pumps to be used in new applications which

were previously not practical?

Do some of these technologies overcome specific market barriers that face wall-mounted single

head minisplits?

How do these systems operate under cold weather conditions? Do you have any performance

metrics you can provide for various temperature conditions?

APPENDIX B: Cost, performance and capacity data as supplied by survey respondents

Cassette Concealed Suspended Wall Multi-Head Cost SEER HSPF SEER HSPF SEER HSPF SEER HSPF SEER HSPF Capacity

$2,730 24 13 12,000

$2,890 21.9 12.2 16,000

$3,063 21 10 10,900

$3,237 14.3 10 19,000

$3,238 20.25 10 14,400

$3,320 20.1 11.5 21,600

$3,390 21 10 18,000

$3,437 26 10 10,900

$3,560 15 9.6 10,900

$3,600 17 9.2 22,000

$3,680 23 10.5 13,600

$3,695 15 10 10,900

$3,740 18 8.9 22,000

$3,900 15.4 9.6 13,600

$3,910 16.8 9.3 24,000


$3,950 16 10 13,600

$4,159 14.5 9.2 15.5 8.9 64,000

$4,330 18 8.9 22,000

$4,348 19 10 27,600

$4,449 15.3 9.5 19,000

$4,491 19.2 10 21,600

$4,501 14 9.3 37,000

$4,615 17.5 9.3 25,000

$4,662 20.2 10.3 21,600

$4,840 15.5 10 18,000

$4,880 16 9.6 18,000

$5,000 17.5 10 21,600

$5,011 13.6 8.5 26,000

$5,030 19.5 9.2 22,000

$5,044 14.2 9.8 19,000

$5,050 17.5 10.5 28,600

$5,174 17 10.8 26,000

$5,181 15.3 9.1 36,400

$5,200 14.5 8.2 32,600

$5,430 18 9.3 36,000

$5,566 15.6 9.4 32,000

$5,633 15.85 9.55 54,000

$5,654 16.8 10.9 26,000

$5,815 17.5 9.3 25,000

$5,840 19.5 9.2 22,000

$5,923 17.5 9.3 25,000

$6,039 16 10.2 26,000

$6,250 16.6 9 30,000

$6,292 14.5 8.2 35,200

$6,298 18.4 9.8 45,200

$6,450 19.5 9.2 22,000

$6,623 14.3 9.3 40,000

$6,740 15 8.9 54,000

$6,741 14.85 8.8 54,000

$6,768 14.4 9.3 45,000

$6,861 15.5 9.4 32,000

$6,966 13.6 8.7 32,000

$7,159 14.4 10.2 38,000

$7,523 15 9.8 38,000

$7,634 15.8 10.2 48,000

$7,733 15.5 8.7 54,000


$7,768 16 9.3 38,000

$8,500 16.6 9 30,000

$9,085 16.7 10.8 66,000

$10,491 15.8 10.2 45,000

$11,025 14.4 9.3 45,000

$12,361 16.7 10.6 66,000

residential mini splits research dhp-mini split survey... · 2014-07-17 · e3t mini-splits draft...

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