Pentair ETI 400 gets to 96* and service heater light comes on

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lakechampionmike

lakechampionmike

In The Industry
Feb 17, 2021
8
Glen Spey, NY
Pool Size
113000
Surface
Plaster
Chlorine
Liquid Chlorine
Hey there. New to TFP- but glad I found it- tons of useful information so far. I have a pentair heater for a 8,700 gal spa. when I have it heat up, the water temp will get to 96* and then service heater light comes on, and it stops heating. If I shut it off, and turn it back on, the service light is off and it will climb back up to 96* and same thing happens. the only error code I can get it to show is a Stack Flue Sensor, which I think is an old code but i'm not sure. Has any one else experienced this? if so, what was the remedy? I've tried calling Pentair and they "send out a technician" and then I get a call a week later from the nearest "technician center" and they say they don't service my area.
 
Just to be clear, you have the Pentair UltraTemp ETI HYbrid HP & Gas heater? And your error occurs when heating with gas?

That type of SFS error often occurs due to low flow where the flow of water is not absorbing all the heat generated and too much heat is going up the flue stack which overheats and trips the SFS.

We don't know as much about the details of the ETI heater as we do about the MasterTemp but I think many of the diagnostics are similar. Read about dealing with SFS errors in Pentair MasterTemp Heaters - Further Reading

It would be helpful to know details of your pools and equipment. Please create your signature with details of your pool and equipment.

Do you have a VS pump? What speed is it running? When did you last clean your filter?
 
ajw22 said:
Just to be clear, you have the Pentair UltraTemp ETI HYbrid HP & Gas heater? And your error occurs when heating with gas?

That type of SFS error often occurs due to low flow where the flow of water is not absorbing all the heat generated and too much heat is going up the flue stack which overheats and trips the SFS.

We don't know as much about the details of the ETI heater as we do about the MasterTemp but I think many of the diagnostics are similar. Read about dealing with SFS errors in Pentair MasterTemp Heaters - Further Reading

It would be helpful to know details of your pools and equipment. Please create your signature with details of your pool and equipment.

Do you have a VS pump? What speed is it running? When did you last clean your filter?
Click to expand...

Thanks for the response. sorry for the lack of info!
it is not the hybrid heater, it only uses propane to heat.
I do have a VS pump, it's running just fine at 312GPM (it's an 8k gal spa) the whole setup is 2.5 years old, I backwashed the sand filter about a week ago when it reached a 10psi differential between influent and affluent pressure.
Good thought on the SFS. i'm going to see if I can locate the sensor and check its condition.
 
Your manual is at https://www.pentair.com/content/dam...ters/eti-400/eti400-heater-manual-english.pdf

From page 11...

VIEW STACK FLUE GAS TEMPERATURE: Press and hold the POOL ON (or SPA ON) button for more than 5 seconds to view the current Stack Flue Gas temperature. Each heat exchange has one temperature sensor (SF1 and (SF2), the SF1 temperature is displayed on the heater’s LCD with a dot on the upper left corner of the LCD. Scroll up or down to display the SF2 current temperature and the dot will not be displayed on the LCD.

Follow the Troubleshooting on page 44.
 
ajw22 said:
Your manual is at https://www.pentair.com/content/dam...ters/eti-400/eti400-heater-manual-english.pdf

From page 11...

VIEW STACK FLUE GAS TEMPERATURE: Press and hold the POOL ON (or SPA ON) button for more than 5 seconds to view the current Stack Flue Gas temperature. Each heat exchange has one temperature sensor (SF1 and (SF2), the SF1 temperature is displayed on the heater’s LCD with a dot on the upper left corner of the LCD. Scroll up or down to display the SF2 current temperature and the dot will not be displayed on the LCD.

Follow the Troubleshooting on page 44.
Click to expand...


Thanks for the advice. I pulled the sensors and they were heavily corroded. I cleaned them up and i'm still having the issue. I checked the temperature about 15 minutes after the heater fires up, one sensor is reading 140's (around 145) and the other reads 165-166. I suppose I need to figure out if it's a bad sensor, or if something is actually causing the exhaust to heat up too high?
 
lakechampionmike said:
Thanks for the advice. I pulled the sensors and they were heavily corroded. I cleaned them up and i'm still having the issue. I checked the temperature about 15 minutes after the heater fires up, one sensor is reading 140's (around 145) and the other reads 165-166. I suppose I need to figure out if it's a bad sensor, or if something is actually causing the exhaust to heat up too high?
Click to expand...

At 2.5 years old it should be within the Pentair 3 year warranty you should have got for buying 3 Pentair units.

Insist on warranty service.
 
ajw22 said:
At 2.5 years old it should be within the Pentair 3 year warranty you should have got for buying 3 Pentair units.

Insist on warranty service.
Click to expand...

Long story, but yes. been down that road. they put in a service order at the nearest pentair service provider and i finally get in touch with them, they say "we don't service your area". so I contact the 2nd closesest, same thing. so on and so fourth. so I think i'm on my own for this one!
 
good thought. ours exhausts on the roof, since it's located inside of a pump room. maybe i'll take the exhaust apart and try to temp it. thanks for all the help! I'll report back if I have any news. I likely won't get to it until after the weekend.
 
I was going to ask you for some pics of your equipment.

Being in the pump room are you sure you have sufficient fresh air intake for the heater? Insufficient air intake can give bad air/fuel ratio causing sooting and high exhaust temperatures.

From Pentair MasterTemp Heaters - Further Reading

Normal exhaust temps should be in the range of 290-350. 350-500 is considered high and you should look for:
  • Sooted exchanger(external) due to improper gas pressure or lack of proper venting. either supply of fresh air or exhaust, or both. Heater is being starved of air and the resulting air/fuel mix is too rich (fat).
  • Calcified exchanger (internal) due to improper water chemistry. Note: Not necessarily right now, but at some point in the past, and for a while. This does not happen overnight.
  • Flow or velocity issue. Water is moving too slowly through the exchanger, gathering or absorbing too much heat, and is not carrying it away quickly enough to keep the heater at a workable temp. In this case, you may have a valve closed down, but not fully closed, or may be wanting to save a little more money on your electricity bill, so you turned down your VS pump as low as you can get away with. You will need to turn it back up to correct this !
Check the interior for obstructed venting (intake and exhaust). Animal nests, spiders, mud dauber nests against the air blower vent, can all block the air flow and lead to an overheat and SFS error.
 

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SOLUTION::UPDATE::
Okay, so I figured out the solution for this. Basically, all I needed to do was open the windows in the pump/heater room. Apparently there is a sensor, but i'm not sure which one, that detects pressure in the room. I think most of these heater are outdoors so it isn't an issue, however in my situation it is located in a small pump room. As the temperature of the room increased so did the pressure so the heater would basically shut off. It never gave an error code except for SFS. The room temperature never go above 70 degrees, which was weird but since opening the windows, I haven't had the issue. Hopefully this helps someone who stumbles on this same issue.
 
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