Heater on with pump off

[StacyLT]

Hello,

I heated the pool today and turned it off for the night. It didn’t get as warm as I wanted today so would like to get the pool heating earlier. The pump is set to turn on at 6am. Can I leave the heater “on” overnight and it will fire up in the morning when the pump starts? When the on button is on the heater with the pump off it says “service system”. That’s bc there is no water running through the heater. It’s not doing anything so I can’t imagine it’s hurting anything but want to make sure. I can just get up a little earlier if I have to. Opinions?

Thank you for your time.

 

[UKjames]

As long as the flow switch is working I would say this is fine.

Be careful if the pump has an off time too- you don’t want the heater still heating when the pump stops - that could cause damage.

 

[StacyLT]

Thank you for your reply. I did turn the Pump off last week and left the heater on thinking it would just not run since there was no water flow and the temp went up to 122. I got super scared and turned the pump back on. Its been working fine, so I hope I didn’t damage anything.

 

[ajw22]

As long as the flow switch is working I would say this is fine.

A heater has a pressure switch, not a flow switch. The plumbing can have pressure and the heater can turn on with the pump off depending on the pressure switch setting.

I would not rely on the pressure switch to turn the heater on and off.

 

[UKjames]

A heater has a pressure switch, not a flow switch. The plumbing can have pressure and the heater can turn on with the pump off depending on the pressure switch setting.

I would not rely on the pressure switch to turn the heater on and off.

What’s the purpose of the pressure switch? As noted I incorrectly assumed it was to stop the heater firing when the pump was off.
why noflow Switch?

mrschz when you got to 122 had the heater been running immediately beforehand and you turned the pump off or did the heater kick in when the pump had been off for a while?

I think you should always let the pump run forsomething like at least 20 mins after the heater stops firing before turning the pump off.

 

[ajw22]

The heater pressure switch can be adjusted for the required minimum pressure for the heater to run in ways that a flow switch cannot be.

The pressure swicth is set for a specific pressure and the only time you would need to adjust it is if the heater was located in such a way that the downward pressure of the water from the pool would cause the heater to fire when the pump is not on. The pressure switch should be adjusted by a tech at heater installation if your pool sits higher than the heater and the downward water pressure would cause the heater to fire or continue running when the pump is off.

 

[StacyLT]

What’s the purpose of the pressure switch? As noted I incorrectly assumed it was to stop the heater firing when the pump was off.
why noflow Switch?

mrschz when you got to 122 had the heater been running immediately beforehand and you turned the pump off or did the heater kick in when the pump had been off for a while?

I think you should always let the pump run forsomething like at least 20 mins after the heater stops firing before turning the pump off.

Yes, I turned the pump off and was watching to see what the heater would do bc I was going to leave it on until the pump turned on in the morning. It wasn’t running but the temp was at 98 from the spa and then kept creeping up. After I turned the pump back on after about 5 mins it went back down. I ran it for about 30 mins then turned the pump back off.