Pentair mastertemp 400 cycling due to low gas flow?

[bobca1]

The thermal regulator prevents water from going through the exchanger until the heater fires and warms to at least 120 degrees. This helps prevent condensation on the exchanger from cold water. If it's stuck closed, water will be trapped in the exchanger and overheat.

I found this diagram online it actually acts as a temperature controlled mixing valve when the outlet temp reaches 120 or higher the thermostat opens and allows "cool" inlet water to bypass the heater coils thus lowering outlet temp into safe range.

How a Gas Pool Heater Works

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[Pool Clown]

Oh, and update that brick (and the desktop) anyway, it could very well begin to work again. And if you start screen logic and just get a black screen, run the updater again. Black screen usually means all the update files didn't take the first time.

 

[bobca1]

Yep, when the valve is open completely it should look like a diamond not a square. I usually see a groove cut into the box from corner to corner to show the position of the gate in the valve. Not only did you have decreased flow through the valve, it was also only half open. Sorry, didn't even pick up on it when i saw it the first time it was posted.

Ok thx that's good to know for future reference. No groove on this one. The plumbers that came out to look, and the gas company when they replaced the meter did not catch it either.

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[bobca1]

Oh, and update that brick (and the desktop) anyway, it could very well begin to work again. And if you start screen logic and just get a black screen, run the updater again. Black screen usually means all the update files didn't take the first time.

I'll give it a try. But when I ran the updater last time it could not find the brick to update it. I'll check support site make sure I have latest versiond and try again.

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[bobca1]

I'll give it a try. But when I ran the updater last time it could not find the brick to update it. I'll check support site make sure I have latest versiond and try again.

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Yep it was the brick. Got a replacement today, plugged it in and now I can connect local and from mobile app again. So now just need to install the new thermostat this weekend and then will be 100% operational again, and just in time usually April is when it gets warm enough here to start enjoying the pool.

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[JamesW]

The thermal regulator blocks water from exiting the heat exchanger until the water is at least 120 f. When not heating, all of the water goes through the internal bypass. When the heater fires, and the water in the exchanger reaches 120 f, the thermal regulator opens to allow water flow through the exchanger. The thermal regulator only allows a portion of the water to go through the exchanger. A lot of water still goes through the internal bypass. The water from the exchanger and the water from the bypass mixes together to limit the water returning to the pool.

The reason for the thermal regulator is so that cold water won't continuously run through the exchanger. Cold water going through the exchanger can create condensation in the unit.

Also note that units with a thermal regulator need to be winterized if the outside temperature gets to freezing since there is no flow through the exchanger, even with the pump on.

 

[aldenniconner]

Problem solved! The issue was indeed low flow, but not due to the line it was just a faulty valve. The stopper on back of the valve was loose so it was not closing or opening at the right position. In addition there was what looked like rubber sealant that had accumulated in the valve opening further restricting it. Huge thank you to everyone that gave the helpful suggestions on this forum! What was most unfortunate was that I can't find a reliable plumber here in my area 3 plumbers came to check the line, none of them wanted to invest the time to troubleshoot and verify the line was really bad. Took me a good part of the day to open the line up and fix it myself, but it's done right and cost me $100 for the meter and the pipe fittings vs the $3000+. Since there was no union by the meter I had to cut through the fitting to get it apart. Then I could see into the valve and see it was obstructed. Removed the valve, hooked up my shop vac and got good flow through the disconnected line. Then for good measure pressure tested up to 100psi and it held pressure just fine. Reassembled eliminated the valve put in a union this time. The local hone depot didn't have all the galvanized pipe parts I needed discovered there is a Orchard supply in thousand oaks this is now my new favorite hardware store!! Tested with manometer I get 8in static and 6 in now dynamic. Spa is heating now in about hour I'll be in there for a well deserved soak ??
Will start on the next problem later this week, my mobile app stopped working can't connect to pentair automation I think the network adapter is bricked but that's a topic for another thread...

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Hi bobca1, I have a similar problem as you had with the Pentair MasterTemp which is really frustrating. You said that there was a valve blocked or restricted. I didn't see a valve in the picture. Are you referring to the main shut off valve from the gas company? The heater is new and under warranty. They came out and say that the static is 7 inches and dynamic drops down to 6.8 and then to -3.4 for a few seconds and then back to 6.8. This is according to the service persons digital meter. Thanks, aldenniconner

 

[ps0303]

So if it is under warranty and they came out and looked at it, what did they say was wrong?