air source heat pump specifications proposed revisions

Air Source Heat Pump SpecificationsProposed Revisions

Regional Technical ForumSubcommittee

July 2, 2013

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Overview

• Why We’re Doing This– Research Into Action 2011 Recommendations for

PTCS Heat Pumps• Simplify process/paperwork• Simply specifications by focusing on key EE drivers

– Goal Today: Get consensus from the subcommittee on revisions to the heat pump specifications. (Next step would be to present to the RTF for approval)

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Current Savings CalculationsMeasure Savings Based On

Upgrades - Box efficiency upgrade (9.0 HSPF) from “current practice” (8.5 HSPF).

Conversions- Conversion to “current practice” heat

pump (8.5 HSPF) from pre-conditions of electric FAF.

Commissioning, Controls, and Sizing

- Houses require a larger unit than experienced in “current practice”

- Increased use of the compressor (and less of the auxiliary heat) than experienced in the “current practice”.

Notes: - “Current Practice” assumes an “undersized” heat pump.- Improvements in duct system efficiency is not included in any of these

measures’ savings calculations.

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Current ASHP Measure Specifications

Measure Requirements

UpgradesHeat pump system must be installed in substantial compliance with PTCS specifications. Exception: PTCS Commissioning, Controls, and Sizing are not a requirement of this measure.

Conversions

Heat pump system must meet or exceed minimum federal efficiency standards, be new, and be installed in substantial compliance with PTCS specifications. Exception: PTCS Commissioning, Controls, and Sizing are not a requirement of this measure.

Commissioning, Controls, and Sizing (CC&S)

Heat Pump must be installed in substantial compliance with the PTCS specifications (including the commissioning, controls and sizing portions).

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Major Components of the Current PTCS ASHP Specification

• Minimum HSPF & SEER Rating• Protective devices

– (crankcase heater, liquid-line filter drier, delay timer, motor start-assist kits, low ambient cutout, etc.)

• Installer Training• PTCS Commissioned Heat Pump Certification

– auxiliary heat controls, airflow, and refrigerant charge• Sizing• Auxiliary Heat Controls• Refrigerant Charge• Ductwork

– Design, sizing, and installation– Air Tightness (calls for PTCS certification)

• Airflow• “Workmanlike” installation

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Proposed ASHP Measure Specifications

Measure Requirements

UpgradesHeat Pump shall be new and have an HSPF rating of not less than 9.0, as certified by AHRI. Installation must comply with all applicable codes and manufacturer’s requirements.

ConversionsHeat Pump shall be new and be rated by AHRI. Installation must comply with all applicable codes and manufacturer’s requirements.

Commissioning, Controls, and Sizing (CC&S)

Installation must comply with the Air Source Heat Pump Commissioning, Controls, and Sizing Specification.

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Major Components of the Proposed ASHP CC&S Specification

1. Compressor Control (low ambient cutout)2. Sizing3. Auxiliary Heat Controls

• Other “Less Major” Components– New system, rated by AHRI– Seal Refrigerant Line Penetrations– Indoor T-stat to prevent heating/cooling cross-cycling– Meets Codes and Manufacturer Requirements

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Discussion

• What about…– PTCS Duct Certification?– PTCS Heat Pump Certification?• Installer Training?• QC/QA Inspections?

– Proper Refrigerant Charge?– Proper Airflow?

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Discussion – PTCS Ducts

• Why the proposal removes the requirement– The RTF lists this as a separate measure.– Savings for the heat pump measures do not

include duct sealing.

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Discussion – PTCS HP Certification • Why the proposal removes the requirement

– Simplicity. • Under the RTF guidelines, there are a number of options on how to define

the measure and its associated inspection requirements. – The proposal moves the bulk of the inspections from the “front

end” of the program (PTCS) to the “back end” of the program (Evaluation).• PTCS certification is designed to do inspections along the way; an

evaluation of the program would verify certification was achieved at each site (or within the drawn sample).– Evaluated Savings = Sum [ (UES savings) x (# sites with verified certification) ]

• This proposal increases the level of inspection performed by the evaluator. Without a certification to rely on, the evaluator would verify the specification was met at each site (or within the drawn sample).– Evaluated Savings = Sum [ (UES savings) x (Number of sites that meet the

specification) ]

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Discussion – Refrigerant Charge• Why the proposal removes the requirement: (Source: 2005 HP Study)

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Discussion – Refrigerant Charge• And…

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Discussion – Airflow

• Why the proposal removes the requirement– Because the savings currently do not assume an improvement

in airflow.– ECM blowers can meet airflow requirements, but can cause

increase in energy use.

• But– The next two graphs (from the 2005 HP study) show low

airflow effects both efficiency and capacity– The third graph shows that low airflow showed up in about

30% of the sites inspected.

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Discussion – Airflow (efficiency)

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Discussion – Airflow (capacity)

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Discussion – Airflow (field audits)

Note: “Low airflow” is defined as < 300 CFM per ton.

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Discussion - Airflow

• Should the savings assume about 30% of the “current practice” cases have poor airflow?

• Should the CC&S specification add back in some of the airflow requirements (roughly section 6.3 of the current specifications)?– Proposed Language:

• Air flow across the indoor coil shall be as specified in the heat pump manufacturer’s literature, or greater than 300 cubic feet per minute (CFM) per 12,000 Btu/hr output at AHRI rating conditions if the manufacturer’s literature is not specific.

• The total external static pressure acting on the system air handler shall not exceed 0.8 inches of water (200 Pa).

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Subcommittee Recommendations to RTF

• Adjust “current practice” assumptions to reflect inadequate airflow in some cases?

• Adopt Revised Specifications?– Add airflow requirements?