Greetings - eti 400 not firing

[Mackboron]

Hey all, I am a local swim coach in Portland, Or and we have been partnering with an Elks club to run practices at their pool. I have been taking care of the pool for the last 5 or 6 years and for the most part things have gone pretty well. In the summer we've heated the pool with 60 solar heating panels on the roof of the building. However, in May 2021 we ended up getting 4x Pentair eti 400 heaters to heat the pool year-round for swim practice so we were loosing time at the local community pool. They've worked well unless the flow drops and then they spit out all these error codes. I backwash and clean all filters and make sure flow is good to go and then they fire up again after a hard restart. This fall the solar and natural gas heaters were working in tandem, which I'm not going to let happen in the future because the flow drops significantly and the gas doesn't really work. During that time something happened to a couple of the heaters and after getting a tech out we're still baffled. When we turn the heaters on the 'heater' led lights up for one second and then it immediately switches to the red 'service' light. Codes are 'tf, hls, tf, --'. We've switch out the thermal fuse, high limit switch, and even the parent board (the pentair tech on the phone said that was likely the issue since the heater isn't even trying to fire). Has anyone seen or heard about this happening before? I'm wondering if the heater trying to fire while the solar was kicking on too may have messed something up and the codes aren't really telling us what is actually the problem. I have two heaters working and was thinking about hot swapping parts to figure out what part is actually not working but I'm scared to even go down to one heater. We're hanging on by a thread with just the two right now. Any wisdom would be helpful!!

 

[JoyfulNoise]

*BUMP*

Maybe @ajw22 or @JamesW or @1poolman1 or @swamprat69 might be able to advise …

And just as a side note - the Introduce Yourself sub-forum isn’t a great place to put a problem request in to as it may get overlooked. It’s a sub-forum intended mainly for welcoming new users. The Mods may choose to move this thread to a different sub-forum. Just an FYI in case you make any future posts.

Welcome to TFP

 

[JamesW]

However, in May 2021 we ended up getting 4x Pentair eti 400 heaters to heat the pool year-round for swim practice so we were loosing time at the local community pool.

What is the flow rate?

Does each heater have a flow switch that ensures that each heater is getting the minimum flow?

It's difficult to get the balance of flow right to each heater.

Are you sure that the plumbing is correct?

What pump do you have?

 

[JamesW]

Each heater should have a flow meter and a flow switch where the flow switch is activated by at least 40 gpm.

Assuming 40 gpm per heater, you need a minimum of 160 gpm and at 50 gpm per heater is 200 gpm.

Check the water temperature differential (Delta T) and the stack flue temperature.

There are two tridicator gauges, which monitor the water temperature in degree Fahrenheit and pressure in psi.

Are the heaters indoors or outdoors?

Have you filed a warranty claim?









(14) 475603 Tridicator.

https://www.pentair.com/content/dam/extranet/nam/pentair-pool/residential/heaters/eti-400-eti-250/eti-400-user-manuals/eti400-heater-manual-english.pdf

 

[Mackboron]

Thanks Joyful noise, I wasn't quite sure and appreciate you looping some folks in. Yes, I'm a little disappointed that flow gages weren't installed when the heaters were installed. I don't remember seeing a flow switch. The heaters are indoors and I did not have any issues for the last year and a half. I'll work on adding some pictures of the heater set-up. It is similar to the picture provided however the feed to the four heaters hooked up in parallel comes in between heaters #1 & #2. Last I checked the pressure gage on all of them had a similar reading. Heater #4 generally shuts off first due to low flow. Right now it is heaters #1 & #3 that are not working. Heaters #2 & #4 are working fine which were actually kind of down this fall when they would flip between solar and gas. #2 had a short we fixed after all of these issues and #4 will often shut off first due to low flow so it was likely already off-line.

At this point we're fairly confident that this isn't a flow issue. When it is a flow issue the heater will turn on run for about a minute and then shut off when the Stack Flue Sensory temp goes over 150* or 170* I think. At this point the heaters are not even attempting to turn on. It blinks orange for less than a second then immediately goes to the red service light. I am not able to get the stack flue temp on heaters #1 & #3 because they won't start up. Or I guess I can pull those up and see what they look like even though they won't run. Anyways, the fact they don't even try and start up is what led the Pentair Tech to suggest to the service technician that maybe it was the heater control board. We've replaced the control board, thermal fuse and the HLS and the issue persists. Pentair tech and service technician are stumped at this point. They are trying to get a Pentair Rep out to look at the heaters but in the meantime we're barely hanging on to keep swim practice rolling.

I will work on finding answers out about the pool pump, and get some pictures of the set-up. If need be I'll start working on a warranty claim. The pool service company is still working with me but they are pretty stumped and I'll see if need be they'll help me with the claim. Thanks for the help.

 

[JamesW]

I suspect that flow issues are probably a major factor in the overall problems.

In my opinion, it’s foolish to install heaters like this without a flow meter and a flow switch.

The heaters are over $8,000.00 each, so including flow switches and flow meters is good insurance for a nominal extra cost.

In my opinion, Pentair should include a real flow switch with their heaters.

They can include a flow switch with a SWG, so I’m not sure why it would be so difficult to include one with an $8,000.00 heater.

I suspect that a chronic lack of flow has likely damaged the heaters and they might have multiple failed components.

Since the heaters are indoors, you need to supply the correct amount of supply air and the venting needs to be sufficient.

Based on the fact that all of the heaters are malfunctioning, the problems are almost definitely related to poor installation, which might be water flow, air supply, venting etc

 

[ajw22]

At this point the heaters are not even attempting to turn on. It blinks orange for less than a second then immediately goes to the red service light.

Do the blowers start running in the heater before before it throws the red service light?

Someone needs to follow the start sequence of the heater to understand where it is failing. The blower turning on is one of the first things in the start sequence.

 

[JoyfulNoise]

I’d also call into question why THIS particular model of heater was installed. Not that you can do anything about it, but the eTI heaters are one of Pentair’s highest cost models. They are dual heat-exchanger systems that utilize titanium heat exchangers and an intake pre-heater designed to extract the most heat energy out of the combustion gas. That all sounds good from a “green efficiency” standpoint but it makes the heaters horribly complex to diagnose and repairs are more expensive. The flue gases also condense due the large amount of heat extraction and require that the condensate liquid be carefully neutralized and discharged so as to not damage any metallic components or cement surfaces.

I’m sure you had nothing to do with the purchase and installation of these heaters but they are definitely going to be very finicky. This is definitely NOT something you should be troubleshooting or fixing on your own. Whoever owns this community pool needs to pay for the proper service technicians to come in and get it working. Your standard pool technician isn’t going to have much experience at all with this type of heater and so Pentair will likely have to send out one of their field engineers to look at it. There may be HVAC technicians that could get into it but they rarely want to do any work on pool equipment because it’s all downside for them to take on jobs like that.

 

[JamesW]

The installation has to be gone over in detail to see where the problems are.

There might be problems with air supply, electrical supply, gas supply, water flow, venting etc.

Until you get the installation right, the problems will continue.

I would install a flow meter and a flow switch for each heater.

Was the installer a licensed gas contractor?

 

[Mackboron]

Do the blowers start running in the heater before before it throws the red service light?

Someone needs to follow the start sequence of the heater to understand where it is failing. The blower turning on is one of the first things in the start sequence

Pretty sure I haven't heard the blower turning on when the heater starts up. I'll double check tomorrow morning but I'm not kidding when I say that the orange heater light turns on for less than a second and then the service light turns on.

Found this in the manual:
The air flow switches (AFS) sense the pressure differential between both of the air metering orifices. As soon as there is
sufficient air flow, the AFS closes, completing the circuit to the Fan Conrol board. The gas ignition control then opens
the gas valve and the fuel mixture is ignited by the Direct Spark Ignition (DSI). On a call for heat, the blowers are
energized for 15 seconds, the gas valve opens simultaneously as the direct spark igniters are energized, then ignition
occurs. The heater is equipped with a digital operating control that enables the user to pre-set the desired pool and spa
water temperatures. The control enables the user to select between pool and spa heating, and features a digital display.

So perhaps it is one of these steps. I will keep digging and talking with the pool service tech. Thanks for your help!

 

[Mackboron]

I’d also call into question why THIS particular model of heater was installed. Not that you can do anything about it, but the eTI heaters are one of Pentair’s highest cost models. They are dual heat-exchanger systems that utilize titanium heat exchangers and an intake pre-heater designed to extract the most heat energy out of the combustion gas. That all sounds good from a “green efficiency” standpoint but it makes the heaters horribly complex to diagnose and repairs are more expensive. The flue gases also condense due the large amount of heat extraction and require that the condensate liquid be carefully neutralized and discharged so as to not damage any metallic components or cement surfaces.

I’m sure you had nothing to do with the purchase and installation of these heaters but they are definitely going to be very finicky. This is definitely NOT something you should be troubleshooting or fixing on your own. Whoever owns this community pool needs to pay for the proper service technicians to come in and get it working. Your standard pool technician isn’t going to have much experience at all with this type of heater and so Pentair will likely have to send out one of their field engineers to look at it. There may be HVAC technicians that could get into it but they rarely want to do any work on pool equipment because it’s all downside for them to take on jobs like that.

Yeah, hind-sight is 20/20. The swim team bought them in order to heat the pool so we could practice. We're grass roots with a pretty tight budget. I was totally in on the process and reviewed multiple options presented to us by different pool companies. In order to install four standard pool heaters there was going to need to be a lot of prep and piping to create a proper site to place the heaters. With the eti 400's ability to vent with PVC it made it possible for us to already use a site we had indoors that lined up well with the current piping. Will keep the pressure on the contractor that installed to get things squared away.

 

[Mackboron]

I suspect that flow issues are probably a major factor in the overall problems.

In my opinion, it’s foolish to install heaters like this without a flow meter and a flow switch.

The heaters are over $8,000.00 each, so including flow switches and flow meters is good insurance for a nominal extra cost.

In my opinion, Pentair should include a real flow switch with their heaters.

They can include a flow switch with a SWG, so I’m not sure why it would be so difficult to include one with an $8,000.00 heater.

I suspect that a chronic lack of flow has likely damaged the heaters and they might have multiple failed components.

Since the heaters are indoors, you need to supply the correct amount of supply air and the venting needs to be sufficient.

Based on the fact that all of the heaters are malfunctioning, the problems are almost definitely related to poor installation, which might be water flow, air supply, venting etc

I totally agree that they should have included a flow meter on the installation. At that point I was pretty ignorant of the set-up and it is interesting that techs from the same company come in and ask why there isn't a flow meter. 100% Pentair should have a flow switch on these as well.

I think you're definitely onto something with the flow issue. However, the low flow only becomes an issue when we try and run the solar and gas heaters at the same time. In the future I'm planning on only having one system go at a time. Most of the time it isn't much of an issue but this fall when they were both running the flow was dropping to the heaters consistently.

Only two are having issues right now and the other two are really fine.

Thanks for your insight. As my father likes to say, "Education is expensive."

 

[JamesW]

However, the low flow only becomes an issue when we try and run the solar and gas heaters at the same time.

The problem is that you have no idea how much flow each heater is getting.

You need to know the total system flow and the flow to each individual heater.

You can't say that flow is not a problem unless you measure the flow.

The heaters do not have any ability to detect flow; all they can detect is pressure.

People think that as long as the heater does not throw a "Flow" error, the flow must be good.

However, this is an incorrect assumption and it is based on a fundamental design flaw, which is the lack of a dedicated flow switch.

 

[JamesW]

You also have to check the gas supply and pressure.

(4) 400,000 btu/hr heaters require 1.6 million Btu/Hr, which is 1,600 cubic feet of gas per hour.

Is the supply able to provide that much gas at the required pressure?

Have you verified the gas pressure?

(4) 400,000 btu/hr heaters also require a lot of combustion air supply.

Is there adequate air supply?

How is the air supply being provided?

Any defect in the design, engineering, architecture, installation, maintenance or operation will cause premature failure of the heaters.

 

[Mackboron]

Picture of the heaters. Venting and air intake is adequate based on what I'm reading in the book. Gas was installed by a certified plumber who understood what is needed. We even had to upgrade the gas meter for the building to get the capacity we needed.

Total system flow is 375 gallons per min.

 

[JamesW]

Check the water temperature differential (Delta T) and the stack flue temperature.

 

[Mackboron]

Temperature differential looks to be about 25 degrees. In at 80 and out at 115 in both heaters. Stack flue temp in #2 is 125 and #4 150. After a backwash and making sure flow is optimal stack flue is 120 & 145 respectively.

 

[JamesW]

Temperature differential looks to be about 25 degrees. In at 80 and out at 115 in both heaters.

115 - 80 = 35 degrees.

 

[Mackboron]

115 - 80 = 35 degrees.

Very true! Any thoughts on that?

 

[JamesW]

It’s at the maximum, but not out of the acceptable range.

These heaters are very complex and expensive.

You really need a qualified professional to check everything.