Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Heating and Cooling Coils
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## Coated fins, all-copper construction, or stainless-steel tubes shall be specified where the coil serves a coastal, marine, or chemically corrosive airstream.
−## Galvanized-steel drain pans shall not be used below cooling coils; condensate at a typical pH of 5 to 7 attacks the zinc coating within a few years of service. {note}
+## Galvanized-steel drain pans shall not be used below cooling coils; condensate at a typical pH of 5 to 7 attacks the zinc coating within a few years of service.
## Drain pans below cooling coils shall be Type 304 stainless steel as a minimum, and Type 316 stainless steel in coastal or chemically aggressive environments.
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# Coil Type and Performance Selection {toc}
−## The coil type shall be selected to match the system fluid and service: chilled water, hot water, standard or distributing steam, direct expansion, or glycol runaround. {note}
+## The coil type shall be selected to match the system fluid and service: chilled water, hot water, standard or distributing steam, direct expansion, or glycol runaround.
```datasheet
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### The coil casing and frame shall be galvanized steel conforming to ASTM A653/A653M, stainless steel, or aluminum as scheduled.
−### Casing materials, coatings, and drain pans located in the airstream shall meet the flame-spread and smoke-developed limits of NFPA 90A. {note}
+### Casing materials, coatings, and drain pans located in the airstream shall meet the flame-spread and smoke-developed limits of NFPA 90A.
```datasheet
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## Distributing (non-freeze) steam coils shall be specified for every mixed-air, outdoor-air, or preheat application where air below 32 °F can reach the coil face.
−## Each distributing-coil circuit shall discharge through a float-and-thermostatic steam trap sized for the supply pressure plus a safety factor. {note}
+## Each distributing-coil circuit shall discharge through a float-and-thermostatic steam trap sized for the supply pressure plus a safety factor.
## Steam supply pressure for distributing heating coils shall be as scheduled, typically in the range of 2 to 15 psig.
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## DX coil distributor type, number of refrigerant circuits, and expansion device shall be matched to the specific condensing unit refrigerant, capacity, and expansion control.
−## A DX coil whose circuiting does not match the condensing unit causes oil logging, flash gas in the distributor, and capacity loss; the coil and condensing unit are a matched pair, not independently selected components. {note}
−
−## Refrigerant piping between the DX coil and the condensing unit, including line sizing, leak testing, evacuation, and brazing qualifications, is specified under [[sync/refrigerant-piping]]. {note}
−
```datasheet
label: DX Expansion Device
…5 unchanged lines
```
+## A DX coil whose circuiting does not match the condensing unit causes oil logging, flash gas in the distributor, and capacity loss; the coil and condensing unit are a matched pair, not independently selected components. {note}
+
+## Refrigerant piping between the DX coil and the condensing unit, including line sizing, leak testing, evacuation, and brazing qualifications, is specified under [[sync/refrigerant-piping]]. {note}
+
# Glycol Runaround Coils {toc}
## A glycol runaround loop pairs a coil in the supply airstream with a coil in the exhaust airstream, connected by a pumped glycol circuit, to recover energy between physically separated supply and exhaust air handlers. {note}
−## Glycol runaround coils shall be constructed as hot water coils but selected and rated for the design glycol concentration and the resulting fluid properties. {note}
+## Glycol runaround coils shall be constructed as hot water coils but selected and rated for the design glycol concentration and the resulting fluid properties.
−## The pumped glycol piping loop connecting the paired coils is specified under [[sync/hydronic-piping]], while this standard governs the runaround coil construction and rating. {note}
−
```datasheet
label: Glycol Concentration (by volume)
…6 unchanged lines
```
+## The pumped glycol piping loop connecting the paired coils is specified under [[sync/hydronic-piping]], while this standard governs the runaround coil construction and rating. {note}
+
# Drain Pans {toc}
−## A drain pan under a cooling coil must capture all condensate that drips from the fin surface and all condensate that is blown off the leaving face and entrained downstream; an undersized pan lets condensate reach the fan section and downstream duct, where it promotes biological growth and corrosion. {note}
+## A drain pan under a cooling coil must capture all condensate that drips from the fin surface and all condensate that is blown off the leaving face and entrained downstream; an undersized pan lets condensate reach the fan section and downstream duct, where it promotes biological growth and corrosion.
## Drain pans shall be provided below all cooling coils and below any coil where condensation can occur.
## The drain pan shall slope toward the drain connection at not less than 1/8 in. per ft, with 1/4 in. per ft preferred.
+```datasheet
+label: Drain Pan Slope
+type: range
+unit: in/ft
+min: 0.125
+max: 0.25
+step: 0.0625
+default: 0.25
+```
+
## The drain pan shall extend downstream of the coil leaving face by not less than 2 in. per foot of coil height, and in no case less than 6 in.
## Omitting the downstream drain pan extension dimension from the drawings allows blown-off condensate to bypass the pan; the extension is a dimensioned requirement, not a default. {note}
+## The drain pan material shall be specified for each cooling coil, using Type 316 stainless steel in coastal or chemical-exposure environments and Type 304 elsewhere.
+
```datasheet
label: Drain Pan Material (cooling coils)
…5 unchanged lines
```
−```datasheet
−label: Drain Pan Slope
−type: range
−unit: in/ft
−min: 0.125
−max: 0.25
−step: 0.0625
−default: 0.25
−```
−
## Condensate Trap {toc}
### The condensate drain shall be trapped, and the trap seal depth shall equal the negative static pressure at the drain pan in inches w.g. plus a 2 in. minimum.
−### A trap sized for less than the actual negative static pressure at the drain section air-locks on a draw-through unit or blows through on a blow-through unit, causing pan overflow and sewer-gas ingestion; the seal depth is governed by the actual pan static pressure, not a fixed dimension. {note}
−
```datasheet
label: Drain Configuration
…5 unchanged lines
```
+### A trap sized for less than the actual negative static pressure at the drain section air-locks on a draw-through unit or blows through on a blow-through unit, causing pan overflow and sewer-gas ingestion; the seal depth is governed by the actual pan static pressure, not a fixed dimension. {note}
+
# Testing {toc}
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## Coils shall be installed level and square in the casing or duct, with the fin face perpendicular to airflow and the tube headers oriented as scheduled.
−## A replacement coil must be removable from its casing without cutting the coil frame or disassembling adjacent ductwork; pull-out clearance that is not confirmed at design produces RFIs and change orders at the retrofit. {note}
+## A replacement coil must be removable from its casing without cutting the coil frame or disassembling adjacent ductwork; pull-out clearance that is not confirmed at design produces RFIs and change orders at the retrofit.
## Pull-out clearance equal to the full coil width plus access shall be provided so the coil can be removed without cutting tube or disassembling adjacent sections.
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## Steam coil condensate connections shall be piped to the trap with the pitch and drip-leg arrangement required for the coil construction type, with connection to the condensate system per [[sync/steam-and-condensate-piping]].
−## Coil headers and connection stubs shall be insulated under [[sync/mechanical-insulation]] after pressure testing and acceptance. {note}
+## Coil headers and connection stubs shall be insulated under [[sync/mechanical-insulation]] after pressure testing and acceptance.
## Coil installation shall comply with the drain pan, trap, and clearance provisions of the International Mechanical Code and the airstream material provisions of NFPA 90A.
## General mechanical coordination, access, identification, and equipment support requirements common to this work are addressed under [[sync/common-work-results-mechanical]]. {note}
−## Coils serving dedicated outdoor air units shall be coordinated with the deep-cooling and dehumidification provisions of [[sync/dedicated-outdoor-air-systems]]. {note}
+## Coils serving dedicated outdoor air units shall be coordinated with the deep-cooling and dehumidification provisions of [[sync/dedicated-outdoor-air-systems]].
# Delivery, Storage, and Handling {toc}
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- Spare condensate trap assembly (one per coil type)
```