Heater cycling too often?

[dw886]

Hi-

We just started our heat on Friday, so I'm watching things pretty closely at this point. What I've noticed is that the heater seems to cycle quite a bit. It's almost like it just barely hits the set point, turns off, temp creeps down just a little in the next few minutes, and it fires right back up.

I have my IntelliFlow has different speeds for heat / no heat:

• Normal 24x7 speed: 1550 (~25GPM so my SWG can run)
• Heat Active: 2300 (~60GPM because I read that my MasterTemp heater is most efficient here)

Pump is drawing water from both the deep end drain and 2 skimmers - all are open 100%. I'm thinking that the different pump speeds may be playing a role here, as the water is slowing down, and then maybe cooling some as it returns.

Here's an example, between 6am and 7am this morning while the ambient air temp was around 60 and the pool was set to 86. Autocover is closed the entire time. The heater turned on 20 times:


On a normal home heating thermostat, there's a temperature differential that you can set before the heater kicks in, so you could say that it has to drop 2 degrees before the heat is active instead of just 1. I can't find a setting for this in my EasyTouch panel or in the ScreenLogic configuration.

Looking for advice on if this is normal, and if not, what I should be doing to address it?

 

[ps0303]

You need to go outside and physically monitor the heater. Unless you do this, you won't know if the unit is showing an error code. There is a possibility that the thermal regulator or other part is causing the unit to shut down and then once it cools off it starts back up again heating. Also, since I'm guessing you are heating all the time, are you sure the pump is running at the correct RPM while the heater is trying to heat?

 

[The dog]

Sounds to me the heater is shutting down due to low flow rate. Like the guys say above go outside and watch the heaters operation and check the panel for status.

 

[dw886]

Pump is definitely spinning up to 2300 RPM as the system calls for heat and the heater kicks in. Once the heater turns off, it drops back down to 1550. I've physically watched this part multiple times yesterday while working outside near the pad. Maybe I'm being too aggressive with the cycling up / down of the pump? I know that I need at least 1490 for my SWG to not show "Low Flow", which is why I'm at 1550. My FlowVis shows almost 30 GPM at that speed.

I'm dealing with about a 25+ degree temperature differential between the air and the pool. I believe that it's really shutting off because it's hitting the set point, but a few minutes later after shutting off and the pump slowing down the temp sensor gets cooler water, which I'm thinking could be happening as the water slows down it's cooling off more as it travels from the pool back to the equipment pad.

Here's why I think that - this is from Friday / Saturday as the pool was initially heating. The only time it turned off was when it hit 84 yesterday morning, and then when I saw it was at 84, I thought "what the heck", and clicked up twice more setting it to 86.


If I watch screenlogic, it's constantly bouncing between 85 and 86, and the heater is set to a set point of 86. It's currently 64 degrees outside, and at 6am this morning it was closer to 55.

 

[The dog]

Try running it at 2500 for a couple hours and see if what you said is true. Maybe it will be more consistent.

 

[dw886]

Good plan - pump is now running at heater rpm all of the time to see if it makes things more consistent.

 

[dw886]

Not sure how conclusive this is yet, because the ambient air temperature started increasing at the same time that I set the pump to stay consistent, but I made the change right around 10am.



Are most people ramping up their VS pumps when the heater runs? If the two things are correlated, I would think that may other people would see this too.

My pad is about 20' from the pool. Ground temp as reported by the state ag extension office yesterday was 58 degrees for bare soil, and 54 degrees for turf soil. We have lots of landscaping left, so we're probably closer to "bare soil" at this point. That being said, one skimmer is on the close side, and one is on the far side of the pool from the equipment pad. I'd guess that they're both probably about 50' - 60' runs bringing the water back. I'm wondering if the water is cooling on it's way back from the skimmers to the pump, and the slower pump speed is enough to knock another degree of temp off of the water. There's a ~30 degree temp differential between the ground temp and the water...

 

[The dog]

I get what you are saying. 30 degree change and the long runs could be the culprit. It heats up to temp. Then runs and that's what cools it down so quick. The ground is a big heat exchanger.

 

[ps0303]

Ever since these multi speed pumps have come into play there have been issues with heaters. If you're going to heat the pool then run the pump at the correct speed all the time. I also can't see that changing speeds on the pump so many times a day is going to be good for the pump.

Oh the days of a single speed pump were so wonderful. Everything worked without having to tweak this or that.

 

[dw886]

It seems crazy that I can't allow it to move more than 1 degree before the heater kicks in. I'm thinking that 2 degrees would make the cycles far less frequent, but would mean it had to recover 2 degrees of heat, so it may run longer...

After I changed the pump speed yesterday, the sun came out and the weather warmed up. The heater didn't run at all from 10:30am until 5am this morning. The auto-cover seems to really help with heat. The heat setpoint was 86, but the pool yesterday evening hit 90 after getting a full day of sun (and an ambient air high temp of 86).

 

[dw886]

The other thing that I've noticed is that the water temp sensor varies wildly. I've been watching the ScreenLogic front page for the last 30 seconds. Pool was at 86.....then 85......then 87........then 86......then 85.... It's changed at least 5 times in under a minute.

Is this normal? My temp sensor is installed the stock way (a drilled 3/8" hole with a hose clamp holding it in place after the filter but before the heater). It's changed about a dozen times in the time that it's taken me to compose this message...