PROPOSED
Regional Technical Forum
Air Source Heat Pump Commissioning, Controls, and Sizing Specification
Adopted: May 12, 2015
Measure Specification
This document details the measure specification for the RTF Heat Pump Commissioning, Controls, and
Sizing measure for single family and manufactured homes. When installing a new single-speed or twospeed central air source heat pump, heat pump should be installed in accordance with this
specification.
The sunset date for this measure is March 31, 2016.
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Component
Measure Identifiers
Baseline
Specification
Heating zones
Current Practice
Implementation
and Product
Standards
Heat pumps must be new and rated by
Air-Conditioning, Heating and
Refrigeration Institute
The heat pump shall be sized within a
heating balance point of 30°F or lower
Additional Notes
 Check heat pump is new and rated
by AHRI
The recommended method and form for
calculations and selection are available in the ACCA
Manuals J and S.
Component U-values and F-values used in the heat
loss and heat gain coefficients shall reflect the
actual construction of the building and be generally
consistent with those found in ACCA Manual J 8th
Edition, or later.
A natural infiltration rate of 0.5 or 0.8 air changes
per hour shall be used for houses built after 1980 or
before 1980, respectively, in sizing calculations
unless a house (de)pressurization test has been
performed and an estimate is made using the result.
Where available, the results of duct pressurization
testing shall be used to estimate the duct system
efficiency used in sizing calculations. If a duct
pressurization test has not been performed on the
house, a default duct system loss of 25% shall be
used. Exception: If the air handler and all ductwork
are within the thermal envelope of the house, 0%
shall be used as the duct system loss in sizing
calculations.
Sizing for cooling load is outside the scope of this
specification. If the cooling loads justify a larger unit,
than the minimum size required based on the
heating sizing process, the larger unit should be
installed
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Delivery Verification Checklist
 Check for correct heating zone
n/a
 Check contractor used specification
Implementation
and Product
Standards (cont)
3
Auxiliary heat shall be controlled in the
following manner depending on
system type:
 Single stage OR multi stage without
air temperature sensor control:
Auxiliary heat shall be controlled in
such a manner that it does not
engage when the outdoor air
temperature is above 35°F, except
when supplemental heating is
required during a defrost cycle or
when emergency heating is required
during a refrigeration cycle failure
 Multi stage with air temperature
sensor control: Auxiliary heat shall
be controlled in such a manner that
it does not engage when the supply
air temperature is above 85°F
Thermostats for both heating and
cooling shall have a manual
changeover feature or heating/cooling
lockout
Temperature change across indoor coil
after 10 minutes of heating operation
shall be at or above the temperature
split in Table 1 below
If a low ambient temperature
compressor cutout option is installed,
it shall not cutout the compressor at
temperatures above 5°F
Air flow across the indoor coil shall be
either:
 As specified in the heat pump
manufacturer’s literature
 If not specified in the literature, ≥
325 CFM per 12,000 Btu/hr output
at AHRI rating conditions (at 47°F)
Approved measurement methods include using a
TrueFlow plate or using the duct pressurization fan
matching method per plate or fan manufacturer’s
instructions.
Implementation
and Product
Standards (cont)
The total external static pressure
acting on the system air handler shall
not exceed 0.8 in of water (200 Pa)
after the new heat pump is installed
Table 1:
Minimum Temperature Split (°F)
CFM per Ton
Outdoor
Temperature (°F)
300
350
400
450
5
13
11
10
9
10
15
13
11
10
15
17
15
13
11
20
19
17
15
13
25
20
18
16
14
30
21
19
17
15
35
23
21
18
16
40
25
23
20
18
45
28
25
22
20
50
31
27
24
22
55
34
29
26
23
60
36
31
28
25
65
38
33
29
26
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Recommendations for Commissioning Controls and Sizing Programs
The following sections provide additional guidance to support commissioning, controls, and sizing
programs. These additional recommendations are not included in the RTF measure specification.
However, the RTF recognizes these as best practices for commissioning, controls and sizing.
1. Auxiliary Heat Sizing. Installed auxiliary heat capacity shall not exceed 125% of the heating design
load.
a. The recommended ASHRAE winter design temperature and cooling design temperature for
the nearest weather station representative of the installation shall be used. Exception: If
State or Local code specifies a design temperature, the State or Local code design
temperature value shall be used.
a. .
2. Penetrations. Refrigerant piping passing through openings in the unit cabinet or the building
structure shall be properly sealed.
3. Compliance with Applicable Codes and Manufacturer Requirements. Installation must comply
with all applicable codes and be installed according to the manufacturer’s specifications, including,
but not limited to, those for sizing, airflow, protective devices, equipment placement, refrigerant
piping, refrigerant charge, condensate management, and fossil fuel back-up systems.
4.
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