Issue with consistent heating of spa

[tminasian]

It has been taking about 3.5-4 hours to bring my spa (I don't have a pool) up to temperature (102 deg.) on a couple of occasions. Of the last four times I have used it, it heated up fine (1.5 hours), the next time took 3.5 hours, the next time 1.5 hours, and most recently 3.5 hours.

I checked out the heater and the "Heating" and "Spa" LED lights up when I turn it on.

Any ideas on what could be the issue or what should be some of the things I evaluate on the heater?

 

[Bama Rambler]

It's very difficult to help with this type issue without knowing your general vicinity because your weather could have a lot to do with it.

How is the flow through the system?
What's the filter pressure?
What is the starting water temp for each of the runs?

 

[Casey]

Welcome to TFP. Please add your location to your profile so we can help you.

 

[tminasian]

Sorry for the delay in responding...I had someone come out and look at my spa while I was on vacation. I just got back. His feedback is that my Sta-rite SR400NA heater needs a new thermal regulator and thermistor. I am not so sure this makes sense. I changed the thermal regulator myself about 2 years ago. Could it go bad again that quickly? Could the actual issue just be the thermistor?

Some more background on this. We are in So. Calif. The water temp. is usually in the mid 70's when we fire up the heater.

Again, sometimes I fire up the heater and it does not consistently heat up the water and takes too long to complete the process. Additionally, the service light on the heater comes on. If I turn off the heater, wait, and turn it on again, the service light does not come on and it works fine.

I looked into replacing the thermistor, looks straight forward. I could change the thermal regulator again. What would you recommend to further diagnosis the issue? THX

 

[tminasian]

Spa Issues

It has been taking about 3.5 hours to bring my spa (I do not have a pool) up to a temperature of 102 deg. on a couple of occasions. Of the last four times I have used it, it heated up fine in 1.5 hours, the next time took 3.5 hours, the next time 1.5 hours, and most recently 3.5 hours.

I checked out the heater and the Heating and Spa LED lights up when I turn it on.

I had someone come out and look at my spa. His feedback is that my heater needs a new thermal regulator and thermistor. I am not so sure this makes sense. I changed the thermal regulator myself about 2 years ago. Could it go bad again that quickly? Could the actual issue just be the thermistor?

We are in So. Calif. The water temp. is usually in the mid 70's when we start the heater.

To summarize, sometimes I start the heater and it does not consistently heat the water and takes too long to complete the process. Additionally, the service light on the heater does come on when the heater does not work properly, but I do not see any error codes. If I turn off the heater, wait, and turn it on again, the service light does not come on and it works fine.