Sub Zero Covers
Two tan insulated backflow covers on a concrete pad above a hillside neighborhood — a full-size assembly cover beside a smaller companion cover, with the red gate valves left exposed for access.
Hillside install — full assembly plus companion cover

By assembly and size

1½" double check backflow cover

1½" double check backflow cover sizing starts with the assembly on the tag. At 1½", 6 double check assemblies from the brands we pattern for are common: Watts 007 / LF007, Febco 850 / 850U / LF850, Zurn Wilkins 350XL, Zurn Wilkins 950XLT2, Ames LF2000B / 2000B, and Apollo / Conbraco DC4A / DCLF4A. The price list maps this pipe size to 3 stock covers, and the published dimensions below say which one to pull.

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What "1½" double check" covers on a counter

Double check valve. At 1½" the assemblies your customers bring in are Watts 007 / LF007, Febco 850 / 850U / LF850, Zurn Wilkins 350XL, Zurn Wilkins 950XLT2, Ames LF2000B / 2000B, and Apollo / Conbraco DC4A / DCLF4A. They are not the same size: the Zurn Wilkins 350XL is 15.25" end to end and the Zurn Wilkins 950XLT2 is 20.3125", so "a 1½" double check" is not a single envelope.

The stock covers for 1½"

The April 2026 price list maps 1½" to 30 × 24 (DS3024), 36 × 24 (DS3624), and 42 × 24 (DS4224). The table below orders them closest fit first for each assembly: the cover should clear the end-to-end length across both shutoff handles with room to close at the base.

The base can close

A double check does not discharge, so the cover can close fully to the pad. That holds ground heat in and gives wind nothing to lift.

When to measure instead

Unions, strainers, OS&Y gates, and wall-tight mounts all move an assembly off its spec sheet. If the tag is gone or the install is odd, measure it or send photos for a custom cover. For the type as a whole see double check covers; for another size, start at the fitment hub.

Sub Zero Covers sells through distributors only. Distributor accounts see pricing and availability in the portal; everyone else orders through their supply house, or applies for distributor access.

Assemblies at this size

1½" double check valve assemblies and the cover that fits

Dimensions in inches from each manufacturer's spec sheet with standard shutoffs. Length end to end; heights from the pipe centerline. The cover column is the closest stock fit by published length; confirm against the assembly in front of you.

AssemblyLengthAbove CLBelow CLClosest stock cover
Watts 007 / LF00716.75"3.5"1.375"30 × 24 (DS3024)
Febco 850 / 850U / LF85016.375"4.25"2.25"30 × 24 (DS3024)
Zurn Wilkins 350XL15.25"3.75"2.25"30 × 24 (DS3024)
Zurn Wilkins 950XLT220.3125"5.625"5.625"30 × 24 (DS3024)
Ames LF2000B / 2000B16.75"3.5"1.375"30 × 24 (DS3024)
Apollo / Conbraco DC4A / DCLF4A18"4.5"—30 × 24 (DS3024)

Common questions

Which cover fits a 1½" double check?
One of 30 × 24 (DS3024), 36 × 24 (DS3624), and 42 × 24 (DS4224), chosen by the assembly's end-to-end length. The table above names the closest fit for each double check at this size.
Do all 1½" double check assemblies take the same cover?
Not always. At this size the published lengths run from 15.25" (Zurn Wilkins 350XL) to 20.3125" (Zurn Wilkins 950XLT2). Order by model.
Is this a heated enclosure?
No. Sub Zero Covers are insulated, unheated covers (R-13 standard, R-30 extreme weather). They are not ASSE 1060 listed enclosures. Where a spec calls for a Class I heated enclosure, ask sales before quoting.

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