Raypak Heater Hi Limit 1 Fault - Help Requested

[Awali]

New poster..please be kind

I'm having frequent issues with my Raypak spa heater (new in 2020) showing a high limit 1 fault but I can't find a pattern about what triggers it or when. It happens multiple times a week when we are home and using the spa. However, I noticed that when we left town for a week, it did not experience the fault.

I have a new Pentair spa pump installed last year, have checked the skimmer, cleaned the filter, and the water level is fine so I believe the water flow is fine unless there's a blockage somewhere that I can't see. The fault does not clear on its own, even when the water temp is far below the 135 degrees that my research says triggers the fault.

One complicating factor: the pool equipment is quite far from the spa, and a lot of heat is lost as the water travels so far underground. I have adjusted the temperature sensor calibration in Pentair SL Config to be about 10 degrees lower than the water temperature actually is, so that it will heat beyond 104 and we have an actually hot spa vs warm spa. I don't believe it's getting anywhere close to 135 degrees, but could this be a factor?

My thoughts so far on why it may be happening. Would love feedback on if these are reasonable or not:
1. Using the spa pump and heater outside of its schedule...could it be something with the egg timer or manually turning on the spa that trips it?
2. Not having enough natural gas flow? We have gas fireplaces in the house that we use frequently...though I would think that low gas would mean the water is colder, not hotter, but throwing everything out there

Very open to other ideas on what to test or change and thanks for your expertise.

 

[1poolman1]

New poster..please be kind

I'm having frequent issues with my Raypak spa heater (new in 2020) showing a high limit 1 fault but I can't find a pattern about what triggers it or when. It happens multiple times a week when we are home and using the spa. However, I noticed that when we left town for a week, it did not experience the fault.

I have a new Pentair spa pump installed last year, have checked the skimmer, cleaned the filter, and the water level is fine so I believe the water flow is fine unless there's a blockage somewhere that I can't see. The fault does not clear on its own, even when the water temp is far below the 135 degrees that my research says triggers the fault.

One complicating factor: the pool equipment is quite far from the spa, and a lot of heat is lost as the water travels so far underground. I have adjusted the temperature sensor calibration in Pentair SL Config to be about 10 degrees lower than the water temperature actually is, so that it will heat beyond 104 and we have an actually hot spa vs warm spa. I don't believe it's getting anywhere close to 135 degrees, but could this be a factor?

My thoughts so far on why it may be happening. Would love feedback on if these are reasonable or not:
1. Using the spa pump and heater outside of its schedule...could it be something with the egg timer or manually turning on the spa that trips it?
2. Not having enough natural gas flow? We have gas fireplaces in the house that we use frequently...though I would think that low gas would mean the water is colder, not hotter, but throwing everything out there

Very open to other ideas on what to test or change and thanks for your expertise.

Gas flow won't cause that, nor will using the pump outside a schedule. For some reason the water coming from the heat exchanger is too hot in the manifold. Yes, it is possible that the limit switch is bad, but that seldom happens. Is the heater also making a lot of noise like a "banging?"
The first thing to check is if there is enough water flow. If you have a bypass valve, be sure it allows all the water to go to the heater. If a VSP, be sure the speed is high enough to supply the heater. After that, there may be a problem with the internal manifold bypass (check this first) or the Unitherm governor.

 

[Awali]

Gas flow won't cause that, nor will using the pump outside a schedule. For some reason the water coming from the heat exchanger is too hot in the manifold. Yes, it is possible that the limit switch is bad, but that seldom happens. Is the heater also making a lot of noise like a "banging?"
The first thing to check is if there is enough water flow. If you have a bypass valve, be sure it allows all the water to go to the heater. If a VSP, be sure the speed is high enough to supply the heater. After that, there may be a problem with the internal manifold bypass (check this first) or the Unitherm governor.

Thanks for your reply. This problem has been happening for months and there was never a noise in the heater until this week, when there is now what I would call a "rattling" rather than a "banging." I do have an Intelliflo VSP, currently set to 37 gpm for its regular setting and 50 gpm for its high setting. I moved it to gpm as opposed to rpm thinking that if there was some slight blockage, keeping it on rpm might not be allowing enough water to flow through, but changing to gpm has not resolved the issue - I made that change about 2 months ago. It's an in-ground spa (not sure if that matters).

I'll confirm the bypass valve is fully open and research the internal manifold bypass and the Unitherm governor.

Thanks again.

 

[ajw22]

The rattling you hear is the water boiling in the heater.

RayPak Heaters - Further Reading

www.troublefreepool.com

Things you can try...

• replace both high limit sensors and add thermal paste
• replace unitherm governor
• replace internal bypass
• add a heat shield

Some folks have added a heat shield above the HLS sensors. This thread describes how the high limit fault was fixed by insulating the header around the sensors.

New Raypak LP heater issue. high limit fault

Just installed my new heater. It keeps tripping the high limit 2 switch. I think it’s a 135 degree trip. I put a thermocouple on that switch and noticed that if the side cover is off, it runs 120 - 128 degrees. If I put the cover back on it runs 127 - 137 degrees and trips. Why would it run...

www.troublefreepool.com

 

[crashnaz75]

New poster..please be kind

I'm having frequent issues with my Raypak spa heater (new in 2020) showing a high limit 1 fault but I can't find a pattern about what triggers it or when. It happens multiple times a week when we are home and using the spa. However, I noticed that when we left town for a week, it did not experience the fault.

I have a new Pentair spa pump installed last year, have checked the skimmer, cleaned the filter, and the water level is fine so I believe the water flow is fine unless there's a blockage somewhere that I can't see. The fault does not clear on its own, even when the water temp is far below the 135 degrees that my research says triggers the fault.

One complicating factor: the pool equipment is quite far from the spa, and a lot of heat is lost as the water travels so far underground. I have adjusted the temperature sensor calibration in Pentair SL Config to be about 10 degrees lower than the water temperature actually is, so that it will heat beyond 104 and we have an actually hot spa vs warm spa. I don't believe it's getting anywhere close to 135 degrees, but could this be a factor?

My thoughts so far on why it may be happening. Would love feedback on if these are reasonable or not:
1. Using the spa pump and heater outside of its schedule...could it be something with the egg timer or manually turning on the spa that trips it?
2. Not having enough natural gas flow? We have gas fireplaces in the house that we use frequently...though I would think that low gas would mean the water is colder, not hotter, but throwing everything out there

Very open to other ideas on what to test or change and thanks for your expertise.

Adjusting the temp for the automation won't cause the heater to heat above 104, safety features inside the heater prevent that from happening, the pentair water temp sensor should be mounted to the plumbing just past the discharge of the pump to read water coming from the spa, of course this may also pickup a small degree of motor heat that may offset the temp reading by a degree or two. Just be extremely careful adjusting temps trying to compensate for what you would call a long plumbing run as soaking in temps above 104° for extended periods can KILL you. I suggest having a local pool professional come and inspect the equipment and not leave it up to guess work from online forums. Be safe and be smart, your life may depend on it.