Pentair Mastertemp 250 HLS recurring issues

[thecabana]

Last November, at the beginning of "hot tub season," we went to go fire up our heater and the service light came on. Pool repair company found that the high limit switch had failed/went bad, so they replaced it. Heater was working great all season, no additional issues.

A couple months later, we started having issues with the spa slowly draining back into the pool when the pump was low or off. Pool repair company came to replace check valve. Didn't resolve issue. Came back and replaced internals on check valve protecting the heater from chlorine. Didn't resolve issue. They then gave us the runaround for 3 months and ghosted multiple appointments. We ended up leaving it alone because it did not drain much, and refilled quickly when the pump was on it's higher speed during the day w/ spa overspill.

A couple days ago, we went to fire up our heater for the first time in a while, and it struggled to fire up, then the service heater light came back on, and the keypad totally froze. The screen was still working (was showing current water temp and changed a degree here or there during the daytime vs. nighttime) but there was no way to turn off the unit because the buttons weren't working. It wasn't heating, and we turned off the gas also going to the unit. We then started having issues getting the pump to prime & not have air in it after using the automation (very old, 1996 AquaLink 2) to switch from spa to pool mode.

Today, a pool repair company came (different one from 2022) to check it out and they said they will need to replace the keypad/display, and that the high limit switch is bad again, and also needs to be replaced. They said that it's possible the internals on our actuator valves that switch from pool mode to spa mode could use some repair/replacement because of age, and they suspect that is what is causing the spa to drain back into the pool slowly. Without using the automation controller (on a wall inside our house), when they messed with the valves, they had no issue getting prime and there hasn't been any air in the system.

So a couple questions I'm curious about:
1. Is is common for the HLS to fail or need to be replaced annually? Is there something that maybe I'm doing/not doing that is causing that or making it worse? Would love to not have to replace it every year unless that's "normal."
2. Is it possible that the automation operating the actuator valves causes them issues when operating them "manually" (or using the buttons on the actuators themselves) doesn't?
3. Maybe a silly question...but does the pump need to be off or on when switching from pool to spa mode? Or does it not matter?

THANK YOU for all your knowledge and support!

 

[mas985]

So a couple questions I'm curious about:
1. Is is common for the HLS to fail or need to be replaced annually? Is there something that maybe I'm doing/not doing that is causing that or making it worse? Would love to not have to replace it every year unless that's "normal."

Not common but are you operating the heater on low flow rates or always on higher flow rates? Operating a heater on flow rates that are below the rating can cause complications.

2. Is it possible that the automation operating the actuator valves causes them issues when operating them "manually" (or using the buttons on the actuators themselves) doesn't?

No. If you use the manual switches and you make the valve turn to each stop location, then the actuator is fine. Also, with the control, toggle through the Spa, Pool and Spillover modes and make sure the valves are in the proper positions for each mode.

3. Maybe a silly question...but does the pump need to be off or on when switching from pool to spa mode? Or does it not matter?

It does not matter.

 

[1poolman1]

Last November, at the beginning of "hot tub season," we went to go fire up our heater and the service light came on. Pool repair company found that the high limit switch had failed/went bad, so they replaced it. Heater was working great all season, no additional issues.

A couple months later, we started having issues with the spa slowly draining back into the pool when the pump was low or off. Pool repair company came to replace check valve. Didn't resolve issue. Came back and replaced internals on check valve protecting the heater from chlorine. Didn't resolve issue. They then gave us the runaround for 3 months and ghosted multiple appointments. We ended up leaving it alone because it did not drain much, and refilled quickly when the pump was on it's higher speed during the day w/ spa overspill.

A couple days ago, we went to fire up our heater for the first time in a while, and it struggled to fire up, then the service heater light came back on, and the keypad totally froze. The screen was still working (was showing current water temp and changed a degree here or there during the daytime vs. nighttime) but there was no way to turn off the unit because the buttons weren't working. It wasn't heating, and we turned off the gas also going to the unit. We then started having issues getting the pump to prime & not have air in it after using the automation (very old, 1996 AquaLink 2) to switch from spa to pool mode.

Today, a pool repair company came (different one from 2022) to check it out and they said they will need to replace the keypad/display, and that the high limit switch is bad again, and also needs to be replaced. They said that it's possible the internals on our actuator valves that switch from pool mode to spa mode could use some repair/replacement because of age, and they suspect that is what is causing the spa to drain back into the pool slowly. Without using the automation controller (on a wall inside our house), when they messed with the valves, they had no issue getting prime and there hasn't been any air in the system.

So a couple questions I'm curious about:
1. Is is common for the HLS to fail or need to be replaced annually? Is there something that maybe I'm doing/not doing that is causing that or making it worse? Would love to not have to replace it every year unless that's "normal."
2. Is it possible that the automation operating the actuator valves causes them issues when operating them "manually" (or using the buttons on the actuators themselves) doesn't?
3. Maybe a silly question...but does the pump need to be off or on when switching from pool to spa mode? Or does it not matter?

THANK YOU for all your knowledge and support!

1. It is very uncommon for a HLS to fail at all unless water chemistry is bad and it gets corroded. They are simple switches that open at a specific temperature. One shouldn't blame the safety item for doing its job, but find out why it is doing it. Most likely a water flow problem (dirty filter, slow VSP speed, etc.), bad thermal regulator, or bad internal bypass.
2. No.
3. Most automation will turn the pump off when rotating valves. It doesn't hurt if it stays on, though. It was a problem with older valves where the internal seal could be replaced (water flowing could move the seal from its mounting), but not with newer ones, newer being in the last 25+ years.

 

[thecabana]

1. It is very uncommon for a HLS to fail at all unless water chemistry is bad and it gets corroded. They are simple switches that open at a specific temperature. One shouldn't blame the safety item for doing its job, but find out why it is doing it. Most likely a water flow problem (dirty filter, slow VSP speed, etc.), bad thermal regulator, or bad internal bypass.
2. No.
3. Most automation will turn the pump off when rotating valves. It doesn't hurt if it stays on, though. It was a problem with older valves where the internal seal could be replaced (water flowing could move the seal from its mounting), but not with newer ones, newer being in the last 25+ years.

1. Okay interesting. I'll have to investigate this. Definitely could have been flow this time because we were having some issues with it. If it's low VSP speed, it would only matter to have the speed up when actually running the heater, correct?
3. Our automation really only moves the two actuator valves right now, it is unable to control the pump or the heater or anything else. It's very old, almost 30 years old (1996). I'm not sure if the valves themselves are that old or not. But I'd have to turn the pump off manually before changing the mode on automation if I wanted it off during the switch.

 

[thecabana]

Not common but are you operating the heater on low flow rates or always on higher flow rates? Operating a heater on flow rates that are below the rating can cause complications.


No. If you use the manual switches and you make the valve turn to each stop location, then the actuator is fine. Also, with the control, toggle through the Spa, Pool and Spillover modes and make sure the valves are in the proper positions for each mode.


It does not matter.

I think almost always on higher flow rates because we almost exclusively use it for the spa, never the pool. Probably at least 2550rpm. How can I find the flow rating? Would it be on the heater somewhere?

The only things controlled by our automation are the two actuator valves that change it from pool to spa mode. The spillover is a manual valve only. We just keep that open all the time - is there an issue keeping the spillover on during spa mode? (It doesn't "work" during that mode of course, so we never thought to turn it off).

Thanks for all your help! We bought this home about a year and a half ago and are doing what we can to learn about the pool, but it's a journey!

 

[1poolman1]

I think almost always on higher flow rates because we almost exclusively use it for the spa, never the pool. Probably at least 2550rpm. How can I find the flow rating? Would it be on the heater somewhere?

The only things controlled by our automation are the two actuator valves that change it from pool to spa mode. The spillover is a manual valve only. We just keep that open all the time - is there an issue keeping the spillover on during spa mode? (It doesn't "work" during that mode of course, so we never thought to turn it off).

Thanks for all your help! We bought this home about a year and a half ago and are doing what we can to learn about the pool, but it's a journey!

Don't worry about the actual flow rate, just find the speed that works. The flow will always go down when the spa is in operation as all the flow is restricted by the jet orifices, which are no more than 1/4" in diameter.
If you want to know, the minimum for that heater is 25gpm, but just pick a speed that allows the heater to fire, then add a couple of hundred rpm to allow for the filter getting dirty and you should be good.
Do you have actual Jandy-brand valves? If so, does the handle say "Never Lube?" Are the bodies black instead of grey? You don't have to worry about the pump running while the valve turns with those (which you most likely have). If they are Pentair brand, they are also of that type. Those are the most common brands of valves used in that time period.

 

[thecabana]

Don't worry about the actual flow rate, just find the speed that works. The flow will always go down when the spa is in operation as all the flow is restricted by the jet orifices, which are no more than 1/4" in diameter.
If you want to know, the minimum for that heater is 25gpm, but just pick a speed that allows the heater to fire, then add a couple of hundred rpm to allow for the filter getting dirty and you should be good.
Do you have actual Jandy-brand valves? If so, does the handle say "Never Lube?" Are the bodies black instead of grey? You don't have to worry about the pump running while the valve turns with those (which you most likely have). If they are Pentair brand, they are also of that type. Those are the most common brands of valves used in that time period.

Okay great, thank you!

Yes, they are the black, Jandy brand "never lube" valves. The pool repair company is recommending replacing the valve diverter internals on them to see if that will help with water slowly draining from the spa (since we already replaced the check valve).

 

[1poolman1]

Okay great, thank you!

Yes, they are the black, Jandy brand "never lube" valves. The pool repair company is recommending replacing the valve diverter internals on them to see if that will help with water slowly draining from the spa (since we already replaced the check valve).

If it isn't the check valve, the most common issue is a valve that only looks like it is completely closed to a port. It just takes a degree or two of not completely covering the port for a spa to leak down.

 

[thecabana]

If it isn't the check valve, the most common issue is a valve that only looks like it is completely closed to a port. It just takes a degree or two of not completely covering the port for a spa to leak down.

Oh interesting.

It's definitely not the actuators because they were replaced and it's still happening. Is there a particular valve I should be looking at or checking? (Sorry - newbie!)

 

[1poolman1]

Oh interesting.

It's definitely not the actuators because they were replaced and it's still happening. Is there a particular valve I should be looking at or checking? (Sorry - newbie!)

While most of the time the actuators are set to turn a true 180 degrees (if that is how your system is designed), sometimes they can be slightly out of adjustment. A picture of your plumbing, showing the return and suction valves in "pool" position would help.
Does your spa overflow when in normal pool mode?

 

[thecabana]

While most of the time the actuators are set to turn a true 180 degrees (if that is how your system is designed), sometimes they can be slightly out of adjustment. A picture of your plumbing, showing the return and suction valves in "pool" position would help.
Does your spa overflow when in normal pool mode?

Here's a photo of our plumbing, in pool mode.
Yellow = valves that turn to change pool to spa mode
Red = pool fountain feature (currently off)
Blue = spa spillover feature (currently on)

As a note, the check valve that is below the spa spillover valve is the new one, the old one was the kind you couldn't change out the internals, and it was on the other side (above) the valve originally.

 

[1poolman1]

View attachment 544354
Here's a photo of our plumbing, in pool mode.
Yellow = valves that turn to change pool to spa mode
Red = pool fountain feature (currently off)
Blue = spa spillover feature (currently on)

As a note, the check valve that is below the spa spillover valve is the new one, the old one was the kind you couldn't change out the internals, and it was on the other side (above) the valve originally.

Do you have the problem if you completely close the valve circled in blue? If not, it is still the check valve, they can get a bit of debris, or even a drip of glue, on the inside that doesn't allow them to seal completely.
You can also, without disturbing the valve position, carefully remove the actuator circled in yellow (4 screws), take the handle off of it, put it carefully on the valve itself and see if it will close the spa port just a bit more. If so, that actuator needs to be re-adjusted to completely shut that port off when it changes to pool mode, as it set in the picture.
Hopefully you are not using that tablet feeder. If you are, it is probably causing damage to the return valve diverter, the booster pump, the spillover valve, the fountain valve, the new check valve, and the heater when the system is off. If you run the pool 24/7 it is less of an issue.

 

[thecabana]

Do you have the problem if you completely close the valve circled in blue? If not, it is still the check valve, they can get a bit of debris, or even a drip of glue, on the inside that doesn't allow them to seal completely.
You can also, without disturbing the valve position, carefully remove the actuator circled in yellow (4 screws), take the handle off of it, put it carefully on the valve itself and see if it will close the spa port just a bit more. If so, that actuator needs to be re-adjusted to completely shut that port off when it changes to pool mode, as it set in the picture.
Hopefully you are not using that tablet feeder. If you are, it is probably causing damage to the return valve diverter, the booster pump, the spillover valve, the fountain valve, the new check valve, and the heater when the system is off. If you run the pool 24/7 it is less of an issue.

The issue persists if the spa spillover valve (blue circle) is closed. It actually makes it worse, because the spa doesn't refill at higher pump speeds without the spillover on.

I'll look into the port on the actuator, thank you!

I am not using the tablet feeder! Though I know it was in heavy rotation before we bought the house 1.5 years ago. I use liquid chlorine primarily, tabs in a floater if we are away for a long time. The pump also does run 24/7, just on lower speeds overnight.

 

[1poolman1]

The issue persists if the spa spillover valve (blue circle) is closed. It actually makes it worse, because the spa doesn't refill at higher pump speeds without the spillover on.

I'll look into the port on the actuator, thank you!

I am not using the tablet feeder! Though I know it was in heavy rotation before we bought the house 1.5 years ago. I use liquid chlorine primarily, tabs in a floater if we are away for a long time. The pump also does run 24/7, just on lower speeds overnight.

If the spa continues to drain with that valve closed, the only obvious choices are both the suction and return valves. One, or both, may not be completely closing the "spa" port, allowing the spa to drain.
Good job on not using the tab feeder.