I am having an issue with my Pentair Master Temp 400 pool heater. I am thinking something is wrong with the heat sensor of some sort. The deal is when ever it is at all a little wet outside the heater does not operate normally. The temperature gauge will fluctuate erratically or just think it is a different temperature all together. Today it sprinkled and when I turned on the hot tub it heated for a while but then shut off. I found that when I cycled the heater it kept saying 28 and when I put it the pool back to pool mode it dropped to 24 so I am assuming it thinks the pool water is 24 degrees and will not ignite the heater. Anyways what part should I be looking at? I looked at the schematic but I can't seem to figure out which one I should be thinking about replacing. After it dries out it always seems to operate normally but it aggravates me to no end when it doesn't. Thanks in advance.
Pool heater help - Pentair Master Temp 400
- Thread starter Flippy
- Start date
elwood58
LifeTime Supporter
No loose wires. Everything was snug. Everything appears to start normally as far as the sequence of lights. Same order and then it goes back to 24 on the temperature display. All of the other lights are off except the power light. After studying the schematic some more I am thinking it may be a bad thermistor which is causing it to think the water is too cold. I would imagine they have a safety to keep the heater from starting if the water is below freezing. Otherwise you could have an explosion of hot pressurized water. This isn't documented in the manual, but that is my guess. I plan on seeing what the temperature display later today when it warms up. The water temp should come up a few degrees if we have enough sun and no rain. Anyone else have any ideas?
I think elwood58 may have hit the nail on the head. 24 degrees Celsius is 75.2 degrees Fahrenheit. I bet someone either accidentally switched it or your control board is going bad.
Try this:
To toggle the display between degrees Centigrade (°C)
and degrees Fahrenheit (°F):
1. Turn the Operating Control OFF.
2. Press ?TEMP or ? TEMP for 5 seconds. The display will flash once and change modes (°C to °F or vice versa)
Try this:
To toggle the display between degrees Centigrade (°C)
and degrees Fahrenheit (°F):
1. Turn the Operating Control OFF.
2. Press ?TEMP or ? TEMP for 5 seconds. The display will flash once and change modes (°C to °F or vice versa)
Well now it is back in Fahrenheit but still no heat. How can I tell if the control board is bad? And now when I push the up arrows or down arrow the number will read 65 as where it was before it read 0 when in Celsius mode.
Going back through the manual I found the max set point which was now at 65. So I moved it back up to 102 and the heater is now working. Still wonder what is getting wet when it rains that it is causing the issue. It used to only be when it rained hard that we would have issues. Yesterday was only a light sprinkle. I hope this will keep it working for another few years I really don't want to spend anymore money. Thanks to everyone for your help! It has made owning my pool a lot easier.
ps0303 said:
Yes, I don't see any cracks or any holes either around the control panel. It only happens when it rains.
I heated the spa tonight and we jumped in. No issues. I can't thank you three enough on saving me money.
Make sure you don't have a bad ground somewhere. You could always replace the board and see if that does anything for you. You can test with a lite mist spray from your hose.
I am not sure if this is the issue, but I found the bond wire is not connected. I wonder how the pool inspector did not catch it when we bought the house. It looked like the wire was run into the heater but I looked to the side of it there is a connector on the outside with a lable. Is there a special connector that i need to use?
Thanks again for your help.
Thanks again for your help.
Home inspectors probably miss tons of items all the time. Yes it should be bonded to the pump but in reality it's not a huge deal especially since it's probably been like this since being installed. A bond wire helps prevent electrolysis. If the heater is missing the bonding lug with screw, you will have to find something at a home repair store to make do.
This would not cause your issue though. I see heaters and other equipment all the time that aren't bonded.
This would not cause your issue though. I see heaters and other equipment all the time that aren't bonded.
ps0303 said:
I connected it with a small clamp. I hired a home inspector for the house and a pool inspector for the pool. The pool inspector missed several things in the pool inspection which he should have caught. I wish they would have caught those because it would have saved me several hundred dollars in repairs. The pool inspection was not worth the money I spent on it.
I am having a problem with my MasterTemp 400 heater. I went to turn it on today to heat the pool a little. The "pool on" light came on and the temperature display says 75 but the heater/blower did not start. Now, when I press the "heater off" button, nothing happens (the pool on and temperature display lights stay on). I turned off the power to the entire system for a few minutes and that didn't do anything. Any ideas?
Probably best to start a new thread for your issue.
Sounds like a possible bad keypad since the keys aren't responding to your touch.
Sounds like a possible bad keypad since the keys aren't responding to your touch.