Couple questions re: replacing Pentair auto gas shutoff sensor

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otherchuck

Active member
Aug 27, 2012
29
Greetings all,

I have been getting error messages on my Pentair sr400NA heater control panel about an AGS problem, so I got a replacement part. Check out attached photo for a bunch o' stuff. So my two questions are (would have been helpful if they had provided instructions!):

(1) When ordering the part, a couple pictures showed white PTFE tape on the threads and another picture showed instead a red stripe on the threads they describe as Loctite (again, see photo). The part they sent me was the red stripe version. Do I need to add PTFE tape to the threads or is that red stripe a sufficient substitute for PTFE tape?

(2) My current AGS sensor has two prongs attached to two identical-looking wires and there is nothing to indicate that there is some kind of right-vs-wrong (top/bottom, left/right) polarity issue. And yet, the meager description on the site where I ordered this part mentions "color-coded wires" (again, see photo) as though there is some correct prong/wire attachment policy I am supposed to adhere to. Is it in fact the case that either wire can be attached to either prong without running the risk of blowing something up?

Thx!

Otherchuck

auto gas shutoff.jpg
 
Did you test with an ohmmeter that the AGS sensor was open when the heater was off? AGS sensors rarely fail.

AGS errors are usually caused by a bad internal bypass. Too much water is bypassing the heat exchanger internally. What water that is going through is coming out too hot and tripping the AGS switch in the manifold.

Read Pentair MasterTemp Heaters - Further Reading

Your Sta-Rite heater is the same iinside as a MasterTemp heater.
 
otherchuck said:
Greetings all,

I have been getting error messages on my Pentair sr400NA heater control panel about an AGS problem, so I got a replacement part. Check out attached photo for a bunch o' stuff. So my two questions are (would have been helpful if they had provided instructions!):

(1) When ordering the part, a couple pictures showed white PTFE tape on the threads and another picture showed instead a red stripe on the threads they describe as Loctite (again, see photo). The part they sent me was the red stripe version. Do I need to add PTFE tape to the threads or is that red stripe a sufficient substitute for PTFE tape?

(2) My current AGS sensor has two prongs attached to two identical-looking wires and there is nothing to indicate that there is some kind of right-vs-wrong (top/bottom, left/right) polarity issue. And yet, the meager description on the site where I ordered this part mentions "color-coded wires" (again, see photo) as though there is some correct prong/wire attachment policy I am supposed to adhere to. Is it in fact the case that either wire can be attached to either prong without running the risk of blowing something up?

Thx!

Otherchuck

View attachment 478509
Click to expand...
Doesn't matter which wire goes to which terminal as long as they are the two that were originally there, it is just a switch that is either open or closed. To insure no leaks, I always use a bit of Teflon tape. You need to find out why the switch is "tripping." They are simple devices. Unless your old one was corroded it was probably still good and was doing its job.

The AGS trips (opens) when the internal water temperature exiting the heat exchanger is 140 or more. It is a backup to the high-limit switch which is set to open at 135. This is usually caused by too low a flow rate. Possibly a bad internal bypass or thermal regulator.

Is there an external heater bypass partially closed? Is a VSP set to give enough flow to the heater? Its possible to have just enough flow to close the pressure switch but not enough to allow for proper heating. Water that hot can scald as it enters the pool/spa and the heater shuts down to prevent that.
 
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