Skip to accessibility statement
Free shipping on orders over $99
●
Your Zip:
43230
ORDER STATUS
Your Zip:
43230
HELP
MENU
CONTACT & SUPPORT
Live Chat Offline:
Email Us
SIGN IN
0
CART
×
SIGN IN
Shop by Category
Plumbing
Heating
HVAC
Electrical
PEX
Fittings
Valves
Tools
Resources
Our Team
Account
Order History
Returns
Customer Support
Give Us Feedback
Tools
Reorder
Quick Order
Saved Carts
Lists
Resources
PEX Plumbing
PEX Tools
Radiant Heat
Boiler Room
Plumbing Supplies
Air Conditioning
Video Library
Project Calculators
Find Parts For Your Unit
Filter menu expanded
Filters
Hide Filters
56 items
Reset
SORT
Top Sellers
Default
Price ▲
Price ▼
Product Availability
–
Show In Stock Only</strong> Filter (21)
Show
In Stock Only
(21)
Category
–
Replacement Parts (27)
Connection Size
–
1/2" Filter (1)
1/2" (1)
1" Filter (5)
1" (5)
1-1/4" Filter (1)
1-1/4" (1)
Application
–
Liquid Flow Filter (28)
Liquid Flow (28)
Replacement Part Filter (26)
Replacement Part (26)
Size
–
3/4" Filter (3)
3/4" (3)
1/2" Filter (2)
1/2" (2)
1" Filter (15)
1" (15)
1-1/4" Filter (8)
1-1/4" (8)
Review Score
–
5 Filter (10)
(10)
4 Filter (2)
(2)
Price Range
–
$10 to $15 Filter (2)
$10 to $15 (2)
$20 to $25 Filter (3)
$20 to $25 (3)
$25 to $30 Filter (2)
$25 to $30 (2)
$30 to $35 Filter (1)
$30 to $35 (1)
$35 to $40 Filter (3)
$35 to $40 (3)
$45 to $50 Filter (1)
$45 to $50 (1)
$50 to $60 Filter (1)
$50 to $60 (1)
$60 to $70 Filter (1)
$60 to $70 (1)
$70 to $80 Filter (2)
$70 to $80 (2)
$80 to $90 Filter (1)
$80 to $90 (1)
See More
Home
Heating Supplies & Parts
Flow Switches
Mcdonnell & Miller Flow Switches
Mcdonnell & Miller Flow Switches
56 items
FILTER
Grid
List
Sort: Top Sellers
120611 Compare Checkbox
Compare
FS251, General purpose flow switch w/ NEMA 1 enclosure
SKU:
120611
McDonnell & Miller
SKU:
120611
Brand:
McDonnell & Miller
(18)
–
+
$202.30
each
ADD TO CART
Add to List
In Stock
Get 55 by
Tue, Jun 9
Total Available: 298
In Stock
Get 55 by
Tue, Jun 9
Total Available: 298
Add to List
114400 Compare Checkbox
Compare
FS4-3, 1" General Purpose Flow Switch - Paddle Style
SKU:
114400
McDonnell & Miller
SKU:
114400
Brand:
McDonnell & Miller
(10)
–
+
$309.00
each
ADD TO CART
Add to List
In Stock
Get 67 by
Tue, Jun 9
Total Available: 464
In Stock
Get 67 by
Tue, Jun 9
Total Available: 464
Add to List
120610 Compare Checkbox
Compare
FS254, General purpose flow switch w/ NEMA 4 enclosure (Replaces FS8-W)
SKU:
120610
McDonnell & Miller
SKU:
120610
Brand:
McDonnell & Miller
(10)
–
+
$270.90
each
ADD TO CART
Add to List
In Stock
Get 28 by
Tue, Jun 9
Total Available: 179
In Stock
Get 28 by
Tue, Jun 9
Total Available: 179
Add to List
310451 Compare Checkbox
Compare
FS4-15SS, Stainless Steel Paddle Kit includes a 1", 2", 3", & 6" Paddle
SKU:
310451
McDonnell & Miller
SKU:
310451
Brand:
McDonnell & Miller
(3)
–
+
$27.57
each
ADD TO CART
Add to List
In Stock
Get 21 by
Tue, Jun 9
Total Available: 89
In Stock
Get 21 by
Tue, Jun 9
Total Available: 89
Add to List
114760 Compare Checkbox
Compare
FS5-3/4, 3/4" Flow Switch
SKU:
114760
McDonnell & Miller
SKU:
114760
Brand:
McDonnell & Miller
(3)
–
+
$310.42
each
ADD TO CART
Add to List
In Stock
Get 14 by
Tue, Jun 9
Total Available: 69
In Stock
Get 14 by
Tue, Jun 9
Total Available: 69
Add to List
114780 Compare Checkbox
Compare
FS5-1, 1" Flow Switch
SKU:
114780
McDonnell & Miller
SKU:
114780
Brand:
McDonnell & Miller
(7)
–
+
$386.07
each
ADD TO CART
Add to List
In Stock
Get 5 by
Wed, Jun 10
Total Available: 10
In Stock
Get 5 by
Wed, Jun 10
Total Available: 10
Add to List
113200 Compare Checkbox
Compare
FS1, 1/2" Flow Switch
SKU:
113200
McDonnell & Miller
SKU:
113200
Brand:
McDonnell & Miller
(4)
–
+
$290.50
each
ADD TO CART
Add to List
In Stock
Get 8 by
Tue, Jun 9
Total Available: 34
In Stock
Get 8 by
Tue, Jun 9
Total Available: 34
Add to List
309100 Compare Checkbox
Compare
11, No.11 Switch Replacement
SKU:
309100
McDonnell & Miller
SKU:
309100
Brand:
McDonnell & Miller
(1)
–
+
$230.73
each
ADD TO CART
Add to List
In Stock
Get 3 by
Tue, Jun 9
Total Available: 50
In Stock
Get 3 by
Tue, Jun 9
Total Available: 50
Add to List
119700 Compare Checkbox
Compare
FS7-4, 1-1/4" Flow Switch-Paddle Style
SKU:
119700
McDonnell & Miller
SKU:
119700
Brand:
McDonnell & Miller
–
+
$502.05
each
ADD TO CART
Add to List
In Stock
Get 5 by
Tue, Jun 9
Total Available: 23
In Stock
Get 5 by
Tue, Jun 9
Total Available: 23
Add to List
114550 Compare Checkbox
Compare
FS4-3D, 1" Flow Switch 4-3 W/2 SPDT Switches
SKU:
114550
McDonnell & Miller
SKU:
114550
Brand:
McDonnell & Miller
–
+
$331.27
each
ADD TO CART
Add to List
In Stock
Get 16 by
Wed, Jun 10
Total Available: 17
In Stock
Get 16 by
Wed, Jun 10
Total Available: 17
Add to List
115400 Compare Checkbox
Compare
FS6-3/4, 3/4" Flow Switch-High Sensitivity
SKU:
115400
McDonnell & Miller
SKU:
115400
Brand:
McDonnell & Miller
(9)
–
+
$486.25
each
ADD TO CART
Add to List
In Stock
Get 5 by
Tue, Jun 9
Total Available: 8
In Stock
Get 5 by
Tue, Jun 9
Total Available: 8
Add to List
120201 Compare Checkbox
Compare
FS7-4W, 1-1/4" Flow Switch w/ NEMA 4X enclosure
SKU:
120201
McDonnell & Miller
SKU:
120201
Brand:
McDonnell & Miller
(1)
–
+
$678.73
each
ADD TO CART
Add to List
In Stock
Get 2 by
Tue, Jun 9
Total Available: 8
In Stock
Get 2 by
Tue, Jun 9
Total Available: 8
Add to List
114641 Compare Checkbox
Compare
FS4-3S, 1" Flow Switch w/Stainless Steel Body, monel bellows
SKU:
114641
McDonnell & Miller
SKU:
114641
Brand:
McDonnell & Miller
–
+
$546.00
each
ADD TO CART
Add to List
In Stock
Get 3 by
Tue, Jun 9
Total Available: 9
In Stock
Get 3 by
Tue, Jun 9
Total Available: 9
Add to List
115600 Compare Checkbox
Compare
FS6-1, 1" Flow Switch-High Sensitivity
SKU:
115600
McDonnell & Miller
SKU:
115600
Brand:
McDonnell & Miller
(2)
–
+
$460.94
each
ADD TO CART
Add to List
Backorder
Get it by
Tue, Jun 30 - Wed, Jul 8
Backorder
Get it by
Tue, Jun 30 - Wed, Jul 8
Add to List
309000 Compare Checkbox
Compare
7B-1R, Resistor for 7B switch w/ SA7-3 Wire Kit
SKU:
309000
McDonnell & Miller
SKU:
309000
Brand:
McDonnell & Miller
–
+
$320.00
each
ADD TO CART
Add to List
In Stock
Get 2 by
Tue, Jun 9
Total Available: 17
In Stock
Get 2 by
Tue, Jun 9
Total Available: 17
Add to List
310802 Compare Checkbox
Compare
SW-FS250, Replacement Switch for FS250
SKU:
310802
McDonnell & Miller
SKU:
310802
Brand:
McDonnell & Miller
–
+
$121.98
each
ADD TO CART
Add to List
In Stock
Get 1 by
Tue, Jun 9
Total Available: 3
In Stock
Get 1 by
Tue, Jun 9
Total Available: 3
Add to List
120100 Compare Checkbox
Compare
FS7-4E, 1-1/4" Flow Switch w/ NEMA 7 & 9 enclosure
SKU:
120100
McDonnell & Miller
SKU:
120100
Brand:
McDonnell & Miller
–
+
$882.44
each
ADD TO CART
Add to List
In Stock
Get 2 by
Wed, Jun 10
In Stock
Get 2 by
Wed, Jun 10
Add to List
113550 Compare Checkbox
Compare
FS1-J, High Sensitivity Flow Switch, 1/2" NPT (w/ BSPT Threads)
SKU:
113550
McDonnell & Miller
SKU:
113550
Brand:
McDonnell & Miller
–
+
$366.42
each
ADD TO CART
Add to List
In Stock
Get 2 by
Wed, Jun 10
In Stock
Get 2 by
Wed, Jun 10
Add to List
306700 Compare Checkbox
Compare
FS7-28, Bronze Paddle Kit for FS7
SKU:
306700
McDonnell & Miller
SKU:
306700
Brand:
McDonnell & Miller
–
+
$30.95
each
ADD TO CART
Add to List
In Stock
Get 2 by
Wed, Jun 10
In Stock
Get 2 by
Wed, Jun 10
Add to List
336900 Compare Checkbox
Compare
FS4-3T-25, Paddle Kit for FS4-3T
SKU:
336900
McDonnell & Miller
SKU:
336900
Brand:
McDonnell & Miller
–
+
$61.86
each
ADD TO CART
Add to List
In Stock
Get 1 by
Tue, Jun 9
In Stock
Get 1 by
Tue, Jun 9
Add to List
304300 Compare Checkbox
Compare
FS1-17, Replacement Switch for Flow Switches
SKU:
304300
McDonnell & Miller
SKU:
304300
Brand:
McDonnell & Miller
–
+
$144.94
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
120191 Compare Checkbox
Compare
FS7-4SW, 1-1/4" Flow Switch w/ Stainless Steel Body, w/ NEMA 4X Enclosure
SKU:
120191
McDonnell & Miller
SKU:
120191
Brand:
McDonnell & Miller
–
+
$1,354.11
each
ADD TO CART
Add to List
In Stock
Get 2 by
Wed, Jun 10
In Stock
Get 2 by
Wed, Jun 10
Add to List
336101 Compare Checkbox
Compare
FS4-15RP, Reinforced Stainless Steel Paddle Kit w/ 1" & 6" Paddles
SKU:
336101
McDonnell & Miller
SKU:
336101
Brand:
McDonnell & Miller
–
+
$26.22
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
114795 Compare Checkbox
Compare
FS5-S-1, 1" Flow Switch w/ Stainless Steel body
SKU:
114795
McDonnell & Miller
SKU:
114795
Brand:
McDonnell & Miller
–
+
$1,522.83
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
120605 Compare Checkbox
Compare
FS8-WZ, 1" Flow Switch w/ ANSI terminal connections
SKU:
120605
McDonnell & Miller
SKU:
120605
Brand:
McDonnell & Miller
–
+
$256.85
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
120150 Compare Checkbox
Compare
FS7-4EL, 1-1/4" Flow Switch w/ NEMA 7 & 9 enclosure, w/extended paddle & paddle arm
SKU:
120150
McDonnell & Miller
SKU:
120150
Brand:
McDonnell & Miller
–
+
$751.93
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
336000 Compare Checkbox
Compare
AF1-122, Paddle Kit for AF1 & AF1-J
SKU:
336000
McDonnell & Miller
SKU:
336000
Brand:
McDonnell & Miller
–
+
$55.26
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
301200 Compare Checkbox
Compare
AF1-21, Replacement Gasket for Air Flow Switch
SKU:
301200
McDonnell & Miller
SKU:
301200
Brand:
McDonnell & Miller
–
+
$10.54
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
305512 Compare Checkbox
Compare
FS4-3D-17, Replacement SPDT Switch for Flow Switches
SKU:
305512
McDonnell & Miller
SKU:
305512
Brand:
McDonnell & Miller
–
+
$36.47
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
306800 Compare Checkbox
Compare
FS7-28S, Replacement Paddle for FS7-F4
SKU:
306800
McDonnell & Miller
SKU:
306800
Brand:
McDonnell & Miller
–
+
$46.33
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
308000 Compare Checkbox
Compare
S-2, Switch Cover Replacement
SKU:
308000
McDonnell & Miller
SKU:
308000
Brand:
McDonnell & Miller
–
+
$23.62
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
310478 Compare Checkbox
Compare
FS8-33, Replacement Switch
SKU:
310478
McDonnell & Miller
SKU:
310478
Brand:
McDonnell & Miller
–
+
$133.00
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
114642 Compare Checkbox
Compare
FS4-3DS, 1" Flow Switch w/Stainless Steel Body and 2 SPDT switches
SKU:
114642
McDonnell & Miller
SKU:
114642
Brand:
McDonnell & Miller
–
+
$684.08
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
114793 Compare Checkbox
Compare
FS5-DS-1, 1" Flow Switch w/Stainless Steel body, 2 SPDT switches
SKU:
114793
McDonnell & Miller
SKU:
114793
Brand:
McDonnell & Miller
–
+
$1,310.60
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
119750 Compare Checkbox
Compare
FS7-4D, 1-1/4" Flow Switch w/2 SPDT
SKU:
119750
McDonnell & Miller
SKU:
119750
Brand:
McDonnell & Miller
–
+
$658.54
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
120175 Compare Checkbox
Compare
FS7-4SE, 1-1/4" Flow Switch w/ Stainless Steel Body, w/ NEMA 7 & 9 enclosure
SKU:
120175
McDonnell & Miller
SKU:
120175
Brand:
McDonnell & Miller
–
+
$1,081.06
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
304400 Compare Checkbox
Compare
FS4-3COV, Replacement Cover for Flow Switch
SKU:
304400
McDonnell & Miller
SKU:
304400
Brand:
McDonnell & Miller
–
+
$23.87
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
310801 Compare Checkbox
Compare
GSKT-FS254, Gasket for FS254
SKU:
310801
McDonnell & Miller
SKU:
310801
Brand:
McDonnell & Miller
–
+
$12.52
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
300311 Compare Checkbox
Compare
FS1/6W-GSKT, Gasket for FS1-FS6W Flow Switch
SKU:
300311
McDonnell & Miller
SKU:
300311
Brand:
McDonnell & Miller
–
+
$87.00
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
337900 Compare Checkbox
Compare
FS7-28L, Replacement Paddle for FS7-F4
SKU:
337900
McDonnell & Miller
SKU:
337900
Brand:
McDonnell & Miller
–
+
$172.15
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
120160 Compare Checkbox
Compare
FS7-4S, 1-1/4" Flow Switch w/ Stainless Steel Body
SKU:
120160
McDonnell & Miller
SKU:
120160
Brand:
McDonnell & Miller
(1)
–
+
$1,079.16
each
ADD TO CART
Add to List
In Stock
Get 1 by
Wed, Jun 10
In Stock
Get 1 by
Wed, Jun 10
Add to List
120171 Compare Checkbox
Compare
FS7-4SJ, 1-1/4" BPST General Purpose Flow Switch - Paddle Style
SKU:
120171
McDonnell & Miller
SKU:
120171
Brand:
McDonnell & Miller
–
+
$1,631.68
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
301450 Compare Checkbox
Compare
AF3-122, Paddle Kit for AF3
SKU:
301450
McDonnell & Miller
SKU:
301450
Brand:
McDonnell & Miller
–
+
$38.50
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
304290 Compare Checkbox
Compare
FS1-14, Replacement Gasket for FS1
SKU:
304290
McDonnell & Miller
SKU:
304290
Brand:
McDonnell & Miller
–
+
$20.42
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
337550 Compare Checkbox
Compare
FS7S-4R-4, Paddle Arm Kit
SKU:
337550
McDonnell & Miller
SKU:
337550
Brand:
McDonnell & Miller
–
+
$220.00
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
337650 Compare Checkbox
Compare
FS7-VL-4R-4, Long Paddle Arm Kit
SKU:
337650
McDonnell & Miller
SKU:
337650
Brand:
McDonnell & Miller
–
+
$265.09
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
115652 Compare Checkbox
Compare
FS6-W-1, 1" Flow Switch w/ NEMA 4X enclosure
SKU:
115652
McDonnell & Miller
SKU:
115652
Brand:
McDonnell & Miller
–
+
$545.76
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
120301 Compare Checkbox
Compare
FS7-4WL, 1-1/4" Flow Switch w/ NEMA 4X enclosure, w/extended paddle & paddle arm
SKU:
120301
McDonnell & Miller
SKU:
120301
Brand:
McDonnell & Miller
–
+
$653.55
each
ADD TO CART
Add to List
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Backorder
Get it by
Wed, Jul 8 - Wed, Aug 5
Add to List
1
2
Refresh
×
Video