Pentair mastertemp 400 cycling due to low gas flow?

[bobca1]

Unless of course *gulp* the line is half full of water. Perfect example of where you would get a normal static w/c reading and then a ridiculously low reading under load. But in your case, it has been like this since day one?

Tell me again why you have not called warranty???

I was relying on my pool service, who did the install of the automation and the heater. He investigated, called Pentair, told me the problem was "low gas flow" and most likely was a bad line. I trust him, but I also wanted to get a second opinion from a plumber before I spend $3000+ and rip up concrete, but the 2 plumbers that come out gave me completely different answers. I am going to get a 3rd plumber out next week. At this point I have tested the pressure at the heater inlet valve and confirmed the dynamic pressure is too low which rules out the problem being the heater. Its definitely gas supply problem.

I was also thinking water in the line but other than a leak are there other common ways that water can get in there? Moisture in the gas that can condense over time? Or I would not rule out something bizarre happening in past either I bought the house from bank foreclosure so who knows... the last owners did destroy some stuff including HVAC when they were kicked out.
But, if it is a leak then I am back to same outcome have to replace the line.

 

[bobca1]

I know you said you have had the gas company install a larger meter but did you have them pressure test the line to the heater? I would hate to see you install a bigger line and still have a similar issue. Did you by chance do the readings as explained in the manual? As Pool Clown suggests as well, exhaust all possibilities before installing a larger pipe. Pipes usually rot from the outside in and will get a hole in them before any obstruction occurs.

No, they did not test, but I tested it myself this week:
reading at meter with ALL gas appliances in house running: static 7.3, dynamic (+pool heater running) 7
reading at inlet side of heater valve (house gas appliances off): static 8.29, dynamic -1.17

The manual says the dynamic needs to be above 4, and not drop more than 2 from the static reading. I am well below that range!

- - - Updated - - -

Unless of course *gulp* the line is half full of water. Perfect example of where you would get a normal static w/c reading and then a ridiculously low reading under load. But in your case, it has been like this since day one?

Tell me again why you have not called warranty???

If there is water in the line, can it be removed? disconnect both ends and try to attach a shop vac?

 

[bobca1]

There's a screen in the inlet to the gas valve to keep debris out of the valve. That would be worth checking. Also, taking apart some of the pipe near the heater would allow for inspection of the inside of the pipe. Check the sediment trap just outside of the heater to see what that's catching. Check the shut off valve just outside of the heater.

Check the regulator feeding the supply line to the heater.

Note: Make sure that anyone doing work on the gas supply is properly qualified to do so.

How many btu/hr was the old heater and did it work properly?

The old heater only worked for about 3 months after I bought the house, that failure and the high electric bill due to single speed pump is what led me to replace the whole system.

There is no sediment trap by the heater, yes I would suspect the screen too but it's been cycling since day 1. I'll still check it and the valve too.

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[Pool Clown]

Well, if you had a previous owner that was getting creative at sabotage, i suppose that would be a good way to get the next owner to pull out his hair. It would be easy enough to check if you had access to, say a 20# bottle of CO2 and try blowing the line out. Ive never tried shop vac-ing out a line, but i would have to think it would be extremely slow going that way.

Note:I didn't mean to tell you to "go out and get a bottle" and do this. You need to get someone who deals with these. Reason being that you want to have a regulator on the bottle so you don't hurt your self in the event that you hit a blockage and the line instantly equalizes with the service pressure in the bottle (~1500 psi). You could try an air compressor, but i dont think it could deliver the volume of air that you need to "push" any water that may be in there out. Although, you would probably be able to at least determine if there is water in there or not.

 

[setsailsoon]

I was relying on my pool service, who did the install of the automation and the heater. He investigated, called Pentair, told me the problem was "low gas flow" and most likely was a bad line. I trust him, but I also wanted to get a second opinion from a plumber before I spend $3000+ and rip up concrete, but the 2 plumbers that come out gave me completely different answers. I am going to get a 3rd plumber out next week. At this point I have tested the pressure at the heater inlet valve and confirmed the dynamic pressure is too low which rules out the problem being the heater. Its definitely gas supply problem.

I was also thinking water in the line but other than a leak are there other common ways that water can get in there? Moisture in the gas that can condense over time? Or I would not rule out something bizarre happening in past either I bought the house from bank foreclosure so who knows... the last owners did destroy some stuff including HVAC when they were kicked out.
But, if it is a leak then I am back to same outcome have to replace the line.

Bob,

Gas produced from oil and gas wells is treated prior to putting it into gas trunk lines and distribution systems. In this process the gas is dehydrated to eliminate the potential problem with internal corrosion in distribution pipelines. They also extract contaminants such as sulfur to reduce corrosion and heavier components (such as ethane, propane, butane) so the gas will fall within it's heat value specification (usually 970-1100 Btu/cu. ft.). Pipeline companies have very large incentive to ensure gas is dry since they're protecting their huge investment in the pipelines and the failure of a line can cause catastrophic results. Excursions do occur but very infrequently and the normal dry gas would quickly absorb any small amount of water in the line caused by an excursion. Gas lines don't fail very often and when they do it is almost always due to external corrosion or damage from construction or farm equipment hitting the line. I'm more familiar with pressure control valves and meters in the much larger trunk lines and in those lines we install a particulate filter upstream of the valves and meters to prevent erosion damage. I would expect your meter to be protected with a screen upstream and your regulator to have an internal screen or filter as well. Lines do plug from internal corrosion but it's extremely rare and a plugged screen or filter is more common. After 30 years either could happen but based on my experience I'd check the filter or screen first. May be worth explaining your problem to the gas company and asking them to check or replace your regulator to be sure it's not plugged to avoid an unnecessary $3000 expenditure on your part. It's unlikely they will balk but if they do you should send a letter to their supervisor explaining if the problem turns out to be a plugged screen or filter you'll expect them to refund your cost of unnecessary line replacement. A plugged screen or filter would cause excessive pressure drop when flow rate increases.

Working on this problem must be very frustrating and I hope this helps.

Chris

 

[bobca1]

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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[JamesW]

Good job. Thanks for the update.

 

[setsailsoon]

Bob,

A+ for persistence and effort! It's a good example of why I am so glad to be a member of this community.

Congrats and best regards,

Chris

 

[bobca1]

Well I'm making progress but heater is now having a new problem. Gets the spa to 90 degrees then burner is cycling again. New problem, now the red service heater light comes on. I looked on back of the control board and the HLS led is on. Going to check the other posts on here now I'm sure I'll find good info and the solution. Tonight's soak will have to wait

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[bobca1]

Yep its the thermostat. Temporarily removed it from the housing, ran the heater without it and it kept going right on up to 100. Going to order replacement on amazon.

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[JamesW]

If you're getting a HLS error, the thermal regulator or internal bypass might be bad.

See this post. The Sta-Rite is basically the same heater except for the outer shell.

Sta rite pool heater problems

 

[bobca1]

If you're getting a HLS error, the thermal regulator or internal bypass might be bad.

See this post. The Sta-Rite is basically the same heater except for the outer shell.

Sta rite pool heater problems

Yep that seems to be the culprit. Took it out and it does look a bit gunked up. I put the cover back on without the thermostat and the heater runs fine up to the set point so I'll get a new one. What does this thermostat do anyway is it a safety feature? I figured it might work without just like a car does when the thermostat sticks (closed) causes engine to overheat.

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[JamesW]

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.

 

[ps0303]

Did you use thread sealant on the parts? I use thread tape and then sealant. If you didn't, I would suggest that you redo it all correctly at least with the thread sealant.

Glad you found the issue although I would caution folks to doing this unless you are VERY confident in knowing your skills.

 

[bobca1]

Did you use thread sealant on the parts? I use thread tape and then sealant. If you didn't, I would suggest that you redo it all correctly at least with the thread sealant.

Glad you found the issue although I would caution folks to doing this unless you are VERY confident in knowing your skills.

Important point. Yes I use Pro Dope on all gas threads. This is not a typical DIY project and should only be done by someone with proper plumbing experience.

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[Pool Clown]

That gas valve should have never been installed in that location. It looks like a high pressure valve. Note that it has a more restricted area in the middle of the valve.

 

[Pool Clown]

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...

Make sure that you have latest version (v5.2.733) for BOTH the brick and your home computer software. I usually don't check the version, i just go ahead and update. Alot of times, simply updating the version fixes the communication problem.

Remember to uninstall the old desktop software BEFORE you update with the new.

Just so your terminology is good, in the Pentair world, they call the protocol adapter a "brick". In the rest of the world Brick=junk.

Seems fitting at times...

 

[bobca1]

Make sure that you have latest version (v5.2.733) for BOTH the brick and your home computer software. I usually don't check the version, i just go ahead and update. Alot of times, simply updating the version fixes the communication problem.

Remember to uninstall the old desktop software BEFORE you update with the new.

Just so your terminology is good, in the Pentair world, they call the protocol adapter a "brick". In the rest of the world Brick=junk.

Seems fitting at times...

Seems my brick is bricked. I called pentair today they said it has not connected to their system since the fall. I had a problem with last year too tech support did some updates while remotely connected to my PC that fixed the problem for a few months before it failed again. This time I think tech support will send me a replacement they are looking into "authorizing replacement under warranty".

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[bobca1]

That gas valve should have never been installed in that location. It looks like a high pressure valve. Note that it has a more restricted area in the middle of the valve.

Yeah that's what I immediately realized when I saw it too, looks like it's been this way since the beginning. And check out the position of the bolt compared to the open valve position it has to be at an angle I have never seen that before on a valve like this usually the bolt shroud be square with direction of the valve. Between that and the goo no wonder no gas was getting through!


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[Pool Clown]

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.