Heater turning on by itself?

Vapor

Member
Jun 7, 2014
13
Nj
I have a pentair mastertemp 400 for about a year now without any problems. However twice in the past week I come home from work to find the heater on in spa mode. I do not have automation. In order to turn on the heater I have to manually push either pool or spa mode on the unit. I do have a pentair variable speed pump that turns on in the morning and cycles through different speeds for approx 8 hours. I have security cameras and verified that no one touched the heater controls. Thoughts?
 

Vapor

Member
Jun 7, 2014
13
Nj
We had some nasty thunderstorms roll through prior to this. Never lost power though. All other electronics in the house seem fine.
 

Vapor

Member
Jun 7, 2014
13
Nj
Ok it happened again this morning. Turned itself on to spa mode about 2 hours after pump started. Customer service not available until Monday. In the mean time should I just shut the gasline off so it doesn't ignite? Unfortunately the breaker switch also powers the pump so that is not an option.
 

txnole

LifeTime Supporter
Aug 18, 2014
544
Amelia Island, FL
When you say gasoline, are you referring to natural gas or propane... or some type of generator?

This doesn't seem like a heater problem - after all, it is heating in spa mode, correct? I would immediately look at your programming. Perhaps someone made a change or there is an overlapping schedule? It would be best if you could power down the heater rather than just cutting the gas. Pentair support can help if you have a Pentair controller, but I don't believe you have a heater problem.
 

Vapor

Member
Jun 7, 2014
13
Nj
Natural gas line to the pentair mastertemp. i do not have an external controller or timer to power on the unit, I have to manually turn it on via the keypad on the unit. However, now it is somehow turning itself on. So turning off gasline is not recommended? I suppose I could configure the spa mode to have a max temp lower than the current water temp to avoid it heating the pool unwantedly.
 

ps0303

TFP Expert
In The Industry
Jul 6, 2011
4,049
FL
The better thing would be to open the unit up and pull the internal power plug to keep it off. I wouldn't even want it to try and fire.

Inside is a metal box with a screw on the right hand side, unscrew it a bit to get the front door flap to open. Then in the left hand corner is either a red or black plug of looped wires. Pull that and it will keep the unit from getting any power.

It sounds like a bad board.

Yes Pentair can help you some on the heater.
 

Vapor

Member
Jun 7, 2014
13
Nj
Great idea, I'll try it. In the meantime I am still waiting on the service company to call me for an appointment slot. If they take any longer I'll just replace the keypad myself if it looks like that is the problem. Waiting on them is just not worth my time for such an easy fix.
 

Vapor

Member
Jun 7, 2014
13
Nj
They ended up showing up today with little advanced notice. They only replaced the control board as they didn't have the key pad with them in there truck. Hopefully, it does the trick.
 

Vapor

Member
Jun 7, 2014
13
Nj
Problem still existed with new control board. They got the keypad and returned to install it. Seems that you were right pool clown. Thanks everyone.
 

DdotSamoht

New member
Aug 24, 2016
1
Cypress, Texas
I have a Hayward and exactly the same problem twice this week for the first time ever.

Twice I saw steam rising off the pool. Checking the heater, it was on Spa Mode instead of Standby.

It had heated my pool up to 102 degrees!!! I didn't even know it could go that high.

Anyway, did you figure out what is going on?

Is it a bad board? My heater is several years old now.

My power did go out yesterday for several hours. You think that could be the problem?

Very disturbing since like you I have to physically turn it to Standby or I am paying a much higher electricity cost for no pleasure.
 

Shrader

New member
Sep 19, 2017
1
Humble
I have a PentAir and after Hurricane Harvey came through we have had this same problem. The Heater comes on by itself after about 5 minutes of turning the pool pump on. We had power issues for about a week straight.
 

hosanders

New member
Nov 14, 2018
1
Southlake, Texas
Dear Pool Clown - you saved me so much money with this advice. My heater was coming on when the time turned on the pump. I unplugged the ribbon cable as you suggested and tested it and the pool heater did not come on. I ordered a replacement touch pad, took all of 10 minutes to replace it and it works perfectly. I ordered the generic brand from Amazon - 1/3 of the cost, and works fine. Thanks tons!
 

OrangeAndBlue

Silver Supporter
Aug 19, 2017
87
Houston, TX area
I had this same issue last year on my mastertemp 400. Ultimately the control membrane on mine was bad as well and the Pentair tech replaced it. The membrane was a different problem altogether though, and that was not what was causing the heater to turn on by itself. I can verify this myself as I've seen the heater turn itself on even when the membrane was working.
The Pentair tech explained that the mastertemp will try to fire again if it wasn't properly shut down during the previous run. After you turn off the heater with the 'off' button on the membrane, the heater will still be in cool-down mode for a while. If the pump / water circulation is shut off before this cool-down has completed, the heater will not have fully shut off. The next time the pump is turned on, the heater will fire again after a few minutes. To prevent this, you need to keep the pump running for at least 5 minutes after shutting off the heater.
If possible, it's also a good idea to have a hard power switch for the heater installed so you can completely cut the power after turning it off. My PB had not installed such a thing, so the Pentair tech kindly put one in for me on my panel.
 

Pool Clown

In The Industry
Sep 5, 2008
2,185
Silicon Valley, CA
The MasterTemp, and the Max-E-Therm, actually all heaters now have some sort of cover that shades the touch pad. This cover is extremely important to the health of the touch-pad/membrane! UV light really accelerates the aging of these touch-pads.

Although it helps keep the rain out, its primary function is to shade the panel from UV.

If you lose it, or it breaks, replace it!
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
21,283
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
I had this same issue last year on my mastertemp 400. Ultimately the control membrane on mine was bad as well and the Pentair tech replaced it. The membrane was a different problem altogether though, and that was not what was causing the heater to turn on by itself. I can verify this myself as I've seen the heater turn itself on even when the membrane was working.
The Pentair tech explained that the mastertemp will try to fire again if it wasn't properly shut down during the previous run. After you turn off the heater with the 'off' button on the membrane, the heater will still be in cool-down mode for a while. If the pump / water circulation is shut off before this cool-down has completed, the heater will not have fully shut off. The next time the pump is turned on, the heater will fire again after a few minutes. To prevent this, you need to keep the pump running for at least 5 minutes after shutting off the heater.
If possible, it's also a good idea to have a hard power switch for the heater installed so you can completely cut the power after turning it off. My PB had not installed such a thing, so the Pentair tech kindly put one in for me on my panel.
I see you are using Intermatic mech timers. Intermatic has the 156T4042A ( 156T4042A - Intermatic
) which can be added to a timer to turn off the heater 20 minutes before the pump will be shut off. It is included if you get the Intermatic T104P201 timer ( T104P201 - Intermatic
).
 

OrangeAndBlue

Silver Supporter
Aug 19, 2017
87
Houston, TX area
I see you are using Intermatic mech timers. Intermatic has the 156T4042A ( 156T4042A - Intermatic
) which can be added to a timer to turn off the heater 20 minutes before the pump will be shut off. It is included if you get the Intermatic T104P201 timer ( T104P201 - Intermatic
).
Thanks ajw22, this is good to know. I have the Intermatic T32404R and it doesn't look like that includes the fireman switch.
Unfortunately I'm not sure it would help our specific situation that much. I never use the heater during the normal daily pool pump cycle that the timers are set for. We only use the heater for the spa, and we predominately use the spa late in the evening after the normal pump cycle has already completed. So on the nights we want to use the spa, I manually turn on the pump and the heater (outside of the set timer cycles). Then I manually shut them both off when we're done. Initially my problem was that I was turning off the pump too soon after turning the heater off. Now I wait at least 10-20 minutes after turning the heater off to shut off the pump, and then I kill power to the heater completely with the switch the technician added just to be sure.
It doesn't seem like automatically shutting the heater off 20 minutes before my normal pump cycle will help much in this situation. I will still consider getting it added anyway, however. Thanks for the tip.