Mastertemp 400 Shutdown Issue & E05 error

freebsdrules

Well-known member
Sep 3, 2019
46
delaware
Hi all-

So last week we had an issue with our heater that I thought we resolved but it happened again today when I went out to turn on the heater. Below is what happened, how we thought we resolved it and what happened since. Any advice is appreciated!

Regards,
Peter

Last Week Issue - last week, when I turned the heater on, it would ignite and then hiss after a few seconds, start vibrating, and then shutoff. It would do this over and over again, never staying light more than 30 seconds. I had an HVAC guy who, with the help of a pentair tech, assisted me in troubleshooting the issue. We believe that the thermo regulator had gone bad (confirmed by removing per tech's instructions and heater ran OK). We replaced (from amazon) and everything worked perfectly for a few days. I did get an E05 error sometime later last week but shut everything down and turned back on and no further issues. We were away over the long weekend and I went out to turn on the heater this morning and got the same issue from before. I took the outside case off and the SFS looks OK but I ordered one on Amazon to replace in case. I turned everything (including pool equipment) off again and back on and it's now running (for 30 minutes so far). The exhaust temperature is sitting at about 350 or so.

Should I replace the SFS at this point if there are no other issues? Any other thoughts? Will report back if I continue to have the reoccurring issue later today. Thanks in advance!
 

freebsdrules

Well-known member
Sep 3, 2019
46
delaware
Ok, to add a bit to what is happening now. It looks like it ignites and is heating while the exhaust temperatures rises to about 355. Then it shuts off and the system flashes the "service heater" light. It then cools down and fires back up and repeats. Do you think it's a bad SFS?

Thanks,
Peter
 

JamesW

TFP Expert
Mar 2, 2011
16,080
What lights are coming on on the back of the board?

Is it still saying E05?

The following are the LEDs:

1.....PS (Pressure Switch)
2.....HLS (High Limit Switch)
3.....SFS (Stack Flue Sensor)
4.....AFS (Air Flow Switch)
5.....AGS (Automatic Gas Shutoff).
6.....Service System
7.....Thermistor
8.....Heating
9.....Pool On
10...Spa On
11...Service Heater.

 

freebsdrules

Well-known member
Sep 3, 2019
46
delaware
Ok, I'm getting 2.....HLS (High Limit Switch). No E05 error (or any other one for that matter) shows on the front of board. And no more vibrating, it just shuts down. Thoughts? And, many thanks in advance, really appreciate the help and advice!
 

JamesW

TFP Expert
Mar 2, 2011
16,080
All signs point to lack of sufficient water flow through the heat exchanger.

This can be due to several things:
1) Thermal regulator not opening.
2) External bypass open.
3) Internal bypass broken.
4) Pump too small or on too low rpm.
5) Scale in heat exchanger.

I would start by checking the thermal regulator.

 

freebsdrules

Well-known member
Sep 3, 2019
46
delaware
Ok, so I took out the thermal regulator, confirmed it is working, reseated it and restarted. All is OK for the moment (5-10 minutes in). Will check in 30 min or so.

The temperature is hovering around 360. Is that too high? Even if it stays on, should I be checking anything else? That video was extremely helpful to figure out that the regulator is in fact working. Thanks again!
 

JamesW

TFP Expert
Mar 2, 2011
16,080
The stack flue sensor (SFS) shuts down the heater if the flue gas temperature reaches 480° F (249° C). That will give an E05 error.

The stack temperature should be under 400 degrees for your heater.

If the thermal regulator is good, check the internal bypass. You can see the spring part by looking in the water inlet or the disc part by looking in the thermal regulator hole with the thermal regulator removed.

What is the flow rate going to the heater?

Is there an external bypass?
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
8,926
Northern NJ
All signs point to lack of sufficient water flow through the heat exchanger.

This can be due to several things:
1) Thermal regulator not opening.
2) External bypass open.
3) Internal bypass broken.
4) Pump too small or on too low rpm.
5) Scale in heat exchanger.

I would start by checking the thermal regulator.

A clogged filter can also reduce water flow into the heater.

Having details of your pool in your signature would help us help you.

What type of filter do you have?

What is current filter pressure?

What is clean filter pressure?

You have a SS, 2 Speed or VS pump?
 
  • Like
Reactions: JamesW

freebsdrules

Well-known member
Sep 3, 2019
46
delaware
Thanks again! Will try to take a look at the internal bypass.

I'm very new to all of this. Flow rate looks like it was around 20 PSI. I went ahead and backwashed the filter and PSI went down to about 14. I don't believe we have an external bypass.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
8,926
Northern NJ
I'm very new to all of this. Flow rate looks like it was around 20 PSI. I went ahead and backwashed the filter and PSI went down to about 14.


TFP guideline is backwash your filter when the PSI increases by 25% from the clean pressure. Your filter was due for a backwash.

Post pics of your equipment pad.
 

freebsdrules

Well-known member
Sep 3, 2019
46
delaware
Ya, I figured it needed a backwash and perhaps that's part of the issue.

Equipment includes: Hayward Pro Grid D.E. Filter (not sure exact model, will have to take another look), Pentair WF-26 Motor, Pentair MasterTemp 400, and a Pentair IntelliChlor IC40.
 

freebsdrules

Well-known member
Sep 3, 2019
46
delaware
Ok, so problem has returned. Worked last week the couple of times we had it on including all day Friday/well into the night. Backwashed again this morning and turned heater on and it's now heating for a few minutes and then shutting off with a service heater light. It ignites again in another minute or two and the cycle continues.

When trying to look at the internal bypass, what exactly am I looking for?

Thanks!
Peter
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
8,926
Northern NJ
You still getting the HLS LED lit?

See...


 

JamesW

TFP Expert
Mar 2, 2011
16,080
What error codes are you seeing?

What LEDs are lighting up?



If you look in the hole where the thermal regulator goes, you should be able to see the black disk.

If you look in the water inlet, you should be able to see the spring.

Do you have a picture of the system?
 

freebsdrules

Well-known member
Sep 3, 2019
46
delaware
Thank you both. Yes, I am still getting the HLS LED lit. When I take out the thermal regulator, I just see a hole. Not sure if this is what it's suppose to look like or not? Attached is a pic of the system and the hole where the thermal regulator goes. Thoughts?
 

Attachments

Last edited:

JamesW

TFP Expert
Mar 2, 2011
16,080
Can you undo the unions and look in the inlet to see if you can see the spring?

 
Last edited:

freebsdrules

Well-known member
Sep 3, 2019
46
delaware
I'll give that a try. The more I read and think about it, the more I think the internal bypass broke and the rattling I was getting at first was plastic working it's way through the pipes. It looks like a job I can do although more of a hassle than I would prefer. If I can remove the union and take a look at the spring, what I am looking for to indicate whether or not it has failed/broken?
 

JamesW

TFP Expert
Mar 2, 2011
16,080
When you look in the hole where the thermal regulator goes, do you see the disk in the picture or just a hole?

Not the hole straight back. The disc should be on the top wall.