Hi limit 2 fault and a water SW open fault code

[Scarsnhoos]

I have a Rheem model # P-M406A-EN-C gas heater for my pool and spa.
Running the spa the other night and heard a water spraying sound. Checked heater and discovered that the inlet pvc pipe had swelled up to almost 2X it’s normal size just at the intake of the Heater and had popped a small hole in the inlet pipe in this swelled up area causing a high pressure leak.
Ran codes got 1 SW open code and 9 hi limit 2 fault codes as the last 10 stored codes.
Troubleshooting today high pressure switch and both high limit switches are testing closed.
Both filters are cleaned with normal pressure.
Pool system runs fine without heater being turned on.
When I turned on heater for spa operation the leak returned under the high pressure and the inlet/outlet header made a sound as if something was loose inside of it.
Planning on pulling access panels off and cleaning everything I can internally.
I’m thinking one of the switches isn’t opening correctly while heating, however the swelling of the inlet pvc pipe makes me nervous something more drastic is wrong.
Any ideas, as to what I need to look for specifically

 

[ajw22]

Welcome to TFP.

How old is the heater?

Post pics of where the inlet pipe leak and swelling is. Is this a pipe that is part of the heater or the PVC pipe leading up to the union connection to the heater?

Hi Limit is often a lack of water flow causing the water to overheat. If you had a blockage in the inlet pipe that woudl explain the Hi LIMIT fault.

I would work on the cause and fix for the leak and pipe swelling before digging into the heater.

@ps0303 @Pool Clown

 

[Scarsnhoos]

The heater is 8 yrs old. The pipe is pvc that is leading up to the inlet header and connects to it. I will post a picture this evening when I get home.
I have checked “By feel with my hand” both the inlet and outlet pipe of the heater for water flow and both seem to be operating normally. There is flow at the pool pump and filter with normal pressure, and all other piping in the system seems to be operating correctly. I will go through and recheck the system again this evening. Is there something specific to look for in the overall system that will show if there is a blockage?

 

[ajw22]

For schedule 40 PVC to swell up is very unusual. I wonder if your pipe is schedule 40.

I don’t understand how the pipe can sell to 2X, spring a leak, then go back to normal with no leak. Sched 40 PVC is not that flexible.

 

[Scarsnhoos]

It is schedule 40 pipe, all the elbows are as well. I agree pvc isn’t that flexible so it took a lot of heat and/or pressure for it to expand like it did. I will send a picture this evening.

 

[Scarsnhoos]

Sorry I should also add it didn’t go back to its original shape the pipe is still swelled up. The expansion of the pipe is permanent.

 

[ajw22]

Sorry I should also add it didn’t go back to its original shape the pipe is still swelled up. The expansion of the pipe is permanent.

I think that pipe should be replaced.

I suspect something broke in the heater creating a blockage in it. Could be any of the valves discussed on pages 19-20 in http://cdn.globalimageserver.com/FetchDocument.aspx?ID=c404f1c5-ac50-4209-9457-56246d010b20

 

[Scarsnhoos]

Welcome to TFP.

How old is the heater?

Post pics of where the inlet pipe leak and swelling is. Is this a pipe that is part of the heater or the PVC pipe leading up to the union connection to the heater?

Hi Limit is often a lack of water flow causing the water to overheat. If you had a blockage in the inlet pipe that woudl explain the Hi LIMIT fault.

I would work on the cause and fix for the leak and pipe swelling before digging into the heater.

@ps0303 @Pool Clown

My finger is pointing to the hole in the second picture.

 

[ajw22]

This one calls for getting lots of eyes on it.

First time I have seen sched 40 bulge or get a hole.

@JamesW @Jimrahbe @bdavis466 @jimmythegreek @ps0303 @Pool Clown

 

[Scarsnhoos]

This one calls for getting lots of eyes on it.

First time I have seen sched 40 bulge or get a hole.

@JamesW @Jimrahbe @bdavis466 @jimmythegreek @ps0303 @Pool Clown

I think I may have found the culprit. Just went through the whole system inch by inch, and found that there is a flapper valve missing that is connected to a sight glass at a junction in the system plumbing. Pictured below
I replaced this sight glass/flapper valve about 6-9 months ago due to a crack in the sight glass. The valve is completely gone along with part of the metal bracket that connected it to the sight glass. No doubt disintegrated and spread throughout the pipes of the system. I checked the filter no sign of the valve pieces inside it. This makes sense because when I last tested the heater it sounded like something loose was bouncing around inside the heater header where the inlet and outlet pipes are connected.
Picture below of the sight glass/flapper valve, and what’s left of the flapper valve.

 

[Jimrahbe]

S,

I would have to assume the swollen pipe is the result of a heater being allowed to get waaaay too hot... If that is truly the input pipe I would assume the heater is running when the pump is off.

Thanks,

Jim R.

 

[ajw22]

That is a check valve with the spring on the ground and the plastic flap missing.

Can you give wider pictures of where that valve is located? I can’t imagine how pieces from it would get to the heater.

 

[Scarsnhoos]

That is a check valve with the spring on the ground and the plastic flap missing.

Can you give wider pictures of where that valve is located? I can’t imagine how pieces from it would get to the heater.

the junction right above the sight glass that the check valve was attached to is how you can switch between the spa or pool getting flow.
Sorry I can’t provide more detailed info we just bought this house not long ago and previous owner had a pool guy handle maintenance. Owner had no information or plans on how the system is set up. Pool guy unfortunately quite working due to the virus a few months ago. I’m learning on the go here.

 

[ajw22]

So that check valve that broke is on the spa side return. No way any pieces of it can flow into the heater. The pieces went into the return pipe to your spa and may create some blockages there.

Here is what I think happened - You had the spa on with the heater running. The check valve froze shut and blocked any water flow out to the spa. Your pump was running but no water was flowing though the heater. That created a condition similar to what @Jimrahbe said with the heater running with no flow.

I am surprised the Hi Water Temp safety or the Stack Flue safety did not shutdown the heater. But the heater continued running and the water heated out the pipes. Heating PVC causes it to become flexible and thats what you saw with the bulge and the pressure caused by the pump continuing to run.

At some point the pump created enough pressure on the valve blockage that it cracked the flap, things began flowing again, and it looked normal.

You need to replace the check valve and the PVC pipe. I would also inspect the heater for signs of overheating damage. I would also checkout the safety shutoffs in the heater. I would also blow out the spa return line as it may be blocked with pieces of the valve flap.

 

[Scarsnhoos]

So that check valve that broke is on the spa side return. No way any pieces of it can flow into the heater. The pieces went into the return pipe to your spa and may create some blockages there.

Here is what I think happened - You had the spa on with the heater running. The check valve froze shut and blocked any water flow out to the spa. Your pump was running but no water was flowing though the heater. That created a condition similar to what @Jimrahbe said with the heater running with no flow.

I am surprised the Hi Water Temp safety or the Stack Flue safety did not shutdown the heater. But the heater continued running and the water heated out the pipes. Heating PVC causes it to become flexible and thats what you saw with the bulge and the pressure caused by the pump continuing to run.

At some point the pump created enough pressure on the valve blockage that it cracked the flap, things began flowing again, and it looked normal.

You need to replace the check valve and the PVC pipe. I would also inspect the heater for signs of overheating damage. I would also checkout the safety shutoffs in the heater. I would also blow out the spa return line as it may be blocked with pieces of the valve flap.

Okay thanks that makes sense. I wanted to find out what caused the pvc pipe to swell before I simply repaired the pipe. Otherwise the new pipe could do the same thing again. When you mention safety shut offs in the heater, are you talking about the unitherm governer located in the header and also the High pressure switch located on the outside of the header?

 

[ajw22]

When you mention safety shut offs in the heater, are you talking about the unitherm governer located in the header and also the High pressure switch located on the outside of the header?

Link to manual in post #7.

See page 20/21. There are Hi Limit Switches HL1 and HL2 in the Inlet and Outlet headers.

See Figure 39 on page 26.

From page 33...

High Limits
The heater is equipped with two high limits.
On polymer headers both are automatic and are located in
the inlet/outlet header. Both are set at 135°F (57°C).
On ASME brass header both are located on the inlet/outlet
header. HL1 is manual reset and set to open at 160°F
(71°C). HL2 is automatic and set to open at 135°F (57°C).

I don't know what temperature Sched 40 PVC bulges and bursts at but I suspect it is greater then 135F.

 

[Scarsnhoos]

Link to manual in post #7.

See page 20/21. There are Hi Limit Switches HL1 and HL2 in the Inlet and Outlet headers.

See Figure 39 on page 26.

From page 33...

High Limits
The heater is equipped with two high limits.
On polymer headers both are automatic and are located in
the inlet/outlet header. Both are set at 135°F (57°C).
On ASME brass header both are located on the inlet/outlet
header. HL1 is manual reset and set to open at 160°F
(71°C). HL2 is automatic and set to open at 135°F (57°C).

I don;t know what temperature Sched 40 PVC bulges and bursts at but I suspect it is greater then 135F.

Thanks for your advice. I will get the parts ordered and let you know the outcome.