Hello. I have a problem with a fairly new Pentair Mastertemp 400 heater. I haven't found anyone with the exact problem so I'm posting the details here. The heater is about 1.5 years old. It's been working fine since it was installed. But the last 3 times I've tried to use it, it stops heating at about 95 degrees and displays an AGS error. If I power it off and back on, it will start heating again but stop at the same temperature, which is within a couple of minutes once the spa is hot.
At first startup, it works for a good 30 minutes (depending on the starting temperature of the water). After reading some other posts here, it seems it must be flow causing "too hot" conditions or the AGS sensor is reading that it's too hot even though it isn't.
Regarding the temperature, I've stood at the heater and the display says the spa is 95 degrees when it cuts off. I have an intelli touch control and the indoor display shows about 95 or 96 degrees on the spa when it cuts off. I assume that uses separate thermometer and it looks like that is on the PVC that goes into the heater. I don't know of any way to get the true water temperature coming out of the heater that is being returned to the spa. But the water jets in the spa do not feel unusually hot.
Regarding the flow, I don't know how to measure that. I do not have an external bypass. I have a one speed pump. I did recently replace the filter but in an effort to solve this, I back washed it and cleaned the pump basket. There was no change in the heater behavior. I have learned that there is this somewhat fragile internal bypass but I wouldn't expect it to get as hot as it does if it were broken or stuck wide open. Maybe it's a little bit open?
I'm wondering if anyone here has a theory as to what's going on here.
Thanks.
At first startup, it works for a good 30 minutes (depending on the starting temperature of the water). After reading some other posts here, it seems it must be flow causing "too hot" conditions or the AGS sensor is reading that it's too hot even though it isn't.
Regarding the temperature, I've stood at the heater and the display says the spa is 95 degrees when it cuts off. I have an intelli touch control and the indoor display shows about 95 or 96 degrees on the spa when it cuts off. I assume that uses separate thermometer and it looks like that is on the PVC that goes into the heater. I don't know of any way to get the true water temperature coming out of the heater that is being returned to the spa. But the water jets in the spa do not feel unusually hot.
Regarding the flow, I don't know how to measure that. I do not have an external bypass. I have a one speed pump. I did recently replace the filter but in an effort to solve this, I back washed it and cleaned the pump basket. There was no change in the heater behavior. I have learned that there is this somewhat fragile internal bypass but I wouldn't expect it to get as hot as it does if it were broken or stuck wide open. Maybe it's a little bit open?
I'm wondering if anyone here has a theory as to what's going on here.
Thanks.
