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Pressure Drop/Failure Heater


Premium Member
Jan 3, 2016
Model Number
Modine PA105 A
Less than 1 year
Modine PA 105 A

Resideo valve w/standing pilot

Old/New Shop Heater. New Install

Modine PA105 A. All new parts. New Resideo valve w/standing pilot.

Input rating 105K BTU

Tank supply press 70 psi at 40 degrees F

Supply Lines:

Tank to 1st stage reg = 3/4”

1st stage reg to 2nd stage reg = 3/4”

2nd stage reg to wall = 3/4”

Wall to valve = 1/2” (less than 15 ft - HomeFlex SS line)

Line and valve Pressures:

1st stage input = 70 psi

1st stage out 10 psi static and with burner on

2nd stage in = 10 psi static and with burner on

2nd stage out = 14” wc static and with burner on

Valve input = 14” wc static

= 8” wc with burner on. This is the problem.

Valve output = 6.5” wc with burner on

Unit fires normally, runs for about 2 minutes, then valve closes, and unit shuts down, including pilot. Pulled all lines apart to check. All clean and free of debris. Valve screen clean. Blew 130 psi through line. No debris. Passed 1/4” plastic weedwacker cable through 1/2” HomeFlex line in wall easily. Put all back together. Same thing. Only a few hairs left. Please help. No ideas at this point other that replace line in.
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