Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Furnaces
…309 unchanged lines
## Each furnace shall meet or exceed the minimum heating efficiency required by ASHRAE 90.1 Table 6.8 for its capacity category, and shall not be less efficient than the federal minimum AFUE of 80% for non-weatherized gas furnaces.
−## For new commercial construction in Climate Zones 4 through 8, condensing furnaces of at least 95% AFUE should be specified.
−
−### The DOE northern-climate condensing rule has been subject to legal challenge; ASHRAE 90.1 Table 6.8 and the ENERGY STAR 95% AFUE level are the stable specification levers for driving condensing equipment without relying on the contested federal regional standard. {note}
−
−## Where ENERGY STAR certification is required by the project, each gas furnace shall be ENERGY STAR certified at no less than 95% AFUE.
−
−## The AFUE or thermal efficiency stated on the submittal shall be the certified rating at the furnace's rated firing condition.
−
−### Annual fuel utilization efficiency (AFUE) is established by the ASHRAE 103 test method and applies to furnaces below 225,000 Btu/hr input; thermal efficiency applies to commercial warm-air furnaces at or above that threshold, which are outside this standard. {note}
−
```datasheet
label: Minimum AFUE
…6 unchanged lines
```
+## For new commercial construction in Climate Zones 4 through 8, condensing furnaces of at least 95% AFUE should be specified.
+
+### The DOE northern-climate condensing rule has been subject to legal challenge; ASHRAE 90.1 Table 6.8 and the ENERGY STAR 95% AFUE level are the stable specification levers for driving condensing equipment without relying on the contested federal regional standard. {note}
+
+## Where ENERGY STAR certification is required by the project, each gas furnace shall be ENERGY STAR certified at no less than 95% AFUE.
+
```datasheet
label: ENERGY STAR Certification Required
…5 unchanged lines
```
+## The AFUE or thermal efficiency stated on the submittal shall be the certified rating at the furnace's rated firing condition.
+
+### Annual fuel utilization efficiency (AFUE) is established by the ASHRAE 103 test method and applies to furnaces below 225,000 Btu/hr input; thermal efficiency applies to commercial warm-air furnaces at or above that threshold, which are outside this standard. {note}
+
# Cabinet and Heat Exchanger {toc}
…12 unchanged lines
## The blower shall be the type indicated (PSC or ECM); ECM blowers shall be furnished where modulating or variable-capacity operation is specified.
−### An ECM (electronically commutated) blower maintains airflow against varying static pressure and consumes less energy at part load, which is why it is paired with two-stage and modulating furnaces. {note}
−
−## The blower speed shall be set at startup so that the supply-air temperature rise falls within the range listed on the furnace rating plate.
−
−### Each furnace lists a minimum and maximum temperature rise (for example 35°F to 65°F, or 45°F to 75°F); operating below the minimum risks condensation in a non-condensing heat exchanger, and operating above the maximum trips the high-limit and shortens heat-exchanger life. {note}
−
```datasheet
label: Blower Motor Type
…5 unchanged lines
```
+### An ECM (electronically commutated) blower maintains airflow against varying static pressure and consumes less energy at part load, which is why it is paired with two-stage and modulating furnaces. {note}
+
+## The blower speed shall be set at startup so that the supply-air temperature rise falls within the range listed on the furnace rating plate.
+
```datasheet
label: Listed Temperature Rise Range
…7 unchanged lines
```
+### Each furnace lists a minimum and maximum temperature rise (for example 35°F to 65°F, or 45°F to 75°F); operating below the minimum risks condensation in a non-condensing heat exchanger, and operating above the maximum trips the high-limit and shortens heat-exchanger life. {note}
+
# Venting and Condensate {toc}
…70 unchanged lines
## Where the furnace integrates with the building automation system, the interface method (24 VAC hardwired contacts, 0-10 VDC analog, or communicating protocol) shall be specified before the furnace is ordered and coordinated with [[sync/hvac-controls-instrumentation]] and [[sync/building-automation-system]].
−### Factory-installed communicating control boards are not standard on all models; specifying the interface late forces field workarounds or re-ordering. {note}
−
```datasheet
label: Control Interface
…7 unchanged lines
```
+### Factory-installed communicating control boards are not standard on all models; specifying the interface late forces field workarounds or re-ordering. {note}
+
# Filters and Cooling-Coil Cabinet {toc}
…156 unchanged lines
default: "One set of replacement filters per furnace"
```