Heater safety switches
- Thread starter Veryexpensivepools
- Start date
- Jul 21, 2013
- 66,332
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
It is usually the various over heat safeties.
Short cycling occurs when the heater overheats, the safety opens and shuts it down, the heater cools down, the safety closes, the heater restarts, and around and around it goes.
The majority of the time the overheat is caused by water flow issues not effectively carrying away the heat generated by the combustion.
Short cycling can be from a variety of reasons. Inadequate flow triggering ps, hls, ags, sfs, bad thermal regulator, flame rectification. If this is reference to the Hayward hd400 post we would need more to help. The loop string is checked upon ignition, if everything checks out and is closed ignition sequence will start. It will monitor loopstring during heating. I know time is money and it’s hard to be at a customers house asking questions and waiting for a response. So the best thing you can do is try and follow the manuals troubleshooting guide and ignition sequence. Research on specific symptoms here. If you get hung up we will do our best to help. But specifics are needed.
Last edited:
Are you saying that when short occurs, you go switch by switch isolating them or have you gotten to the point where length of short cycle narrows it down
How do you pinpoint the few when a short cycle happens? I’ve been starting with the igniter / flame sensor but besides isolating each safety switch, I’ve never seen a tech isolate one by one.
- Jul 21, 2013
- 66,332
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
You are going after the sensor and assuming there is a bad sensor.
I assume the sensor is doing its job and look for the flow problem causing the overheat. Either external with dirty filter or misset valves, or internal to the heater with bypass valve or thermal regulator or calcified heat exchanger.
A sensor failure is rarely the root cause of short cycling.
Usually short cycling indicates a sensor is doing its job. For instance some hls will open at 135f and open the switch, it breaks the loopstring and shuts down. It cools and repeats the safety switches are there to protect the heater, doesn’t mean they are bad usually some other problem is causing that area of the heater to overheat.
I don’t understand. That is based on sensors working properly. I’m talking about sensors triggering a shutdown of a heater because it’s/ they’re faulty.
So you’re saying of the hundreds of heaters I’ve seen, the most common problem of short cycling is associated with your conclusions vs faulty switches before trigger and after
Usually if they are are faulty they won’t pass the pre ignition sequence. It just won’t get to the firing stage. Short cycling is caused by a switch opening because it has reached it opening limit. For instance certain high limit switches reach 135f the will open the circuit and the heater will shut down. Doesn’t mean the switch is bad but it’s doing it’s job. If you had an error for loopstring open it means it didn’t pass preignition test and you can test resistance or continuity of each switch. But short cycling you have to figure out the reasoning of the switch opening. But also depending on make and model it could be other issues like flame rectification, gas related, or ignition module. Shut down of short cycling error codes, testing jumpers. These clues all contribute to proper diagnosis.
Similar threads
