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garrygoeson
garrygoeson, Home Appliance Technician
Category: Pool and Spa
Satisfied Customers: 469
Experience:  Over 27 years Repairing Pool & Spa Equipment,Gas Heaters,& Whirlpool Bath Tubs. Certified by many Pool & Spa Manufacturers.
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We have a pentagram minimax nt pool heater. Recently

Customer Question

We have a pentagram minimax nt pool heater. Recently replaced the air flow switch . Ran fine for a few days but now it only heats to 81 when its set to 85 and then we get ee02 error code. Just replaced the thermistor probe but it still won't heat past 81. I hear and smell the gas kick on. Fan blows air just fine. Not sure what else to replace now.
JA: Sometimes pool issues that that you think will be really complicated end up being easy to fix. The Pool Technician I'm going to connect you with knows all the tricks and shortcuts. Is there anything else the Pool Technician should be aware of?
Customer: We replaced the fan last year. It's about 9'years old
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Pool Technician about your situation and then connect you two.
Submitted: 5 months ago.
Category: Pool and Spa
Expert:  garrygoeson replied 5 months ago.

Hi;

My name is Garry. I'll be glad to assist you with your heater.

Expert:  garrygoeson replied 5 months ago.

You most likely have a PENTAIR Minimax NT heater. If you are getting the "E02" error code on the display, this stands for High Temperature Limit Failure.

Expert:  garrygoeson replied 5 months ago.

You want to first check the flow of water into the heater to make sure it is not restricted by the filter, excess leaves or other debris in the filter pump basket, or some other cause. Let me know what you find and we can continue from there. Thank you.

Customer: replied 5 months ago.
how do we fix the high temp limit? Is that another sensor we should replace???
Expert:  garrygoeson replied 5 months ago.

There are 2 Hi Limit thermostats located on the in/out Top-Sub Header Assembly. One is set shut the heater down when the INTERNAL water temp, (inside the Header), reaches 115 and the other will shut down at 150 degrees F.

If there is some external cause, such as a flow issue, as I mentioned earlier, then replacing the 2 Hi-Limits will not solve the problem. If you just want to replace them anyway, if you feel they are faulty, here are the part #'s: 471587 & 471694.

Customer: replied 5 months ago.
Are here any other ways to verify the flow??
Expert:  garrygoeson replied 5 months ago.

Since you are getting the heater to go to 81, before you get the error code, the flow MAY be ok? However, if you want to verify that it is not dropping at the time you get the error code when the heater shuts down, you could install a Flow Meter on the return line to the pool. If you are at the heater at the exact time it shuts down, you can touch the in/out Header to feel if it is very hot, indicating a lack of water.

Customer: replied 5 months ago.
If I want to replace the hi limit sensors are the 2 parts you mentioned earlier how do I tell which one on the heater matches the part number?? When I look online those parts come up as the 115 hi limit switch and 150 hi limit thermostat.
Expert:  garrygoeson replied 5 months ago.

Remove each Hi Limit, and look on the side, (the metal part) and the temp numbers should be stamped on them.

Customer: replied 5 months ago.
Ok thanks. I don't think it's a flow problem as we have a chlorinator as well and when the there are flow problems that will show a red light for flow and that doesn't happen when we get the error code. There a 3rd part that I see by the temp switches. I looked up the part and its a pressure switch. Part not 473605. Could that be an issue? These switches heat up when the heater is working. Could they be hearing up so hot themselves that the hi temp switches is triggered??? Something is reading the temp wrong so that it trips that limit but I just ain't know what that is.
Expert:  garrygoeson replied 5 months ago.

It is very unlikely that it is the pressure switch! The hi limits are called "Safeties", and are there to protect the heater from severe damage. They will only heat up if the temperature of the in/out header gets too hot. This condition is usually from the water entering the heater not moving at a steady rate, or not enough water entering the heater due to lack of flow. To find the exact cause involves troubleshooting the heater. It could also be possible the H- Limits are just faulty, and will need to be replaced.

Customer: replied 5 months ago.
Just so I'm clear the h limits you are referring to are the 2 parts you mentioned earlier??
Expert:  garrygoeson replied 5 months ago.

Yes. They are circular shaped, located near the pressure switch on top of the Header.

Expert:  garrygoeson replied 5 months ago.

If you feel the information I supplied was helpful, please submit a Positive Rating, as this is the only way I get credited for assisting you with this. If you have additional questions on this topic, just post them here, and I can continue helping you as often as you need.

Thank you very much!

Customer: replied 5 months ago.
One more question, we currently have a Hayward .5 horse power pump but we know that the pipes can take up to a 1.5 horse power pump . At least that is what our pool guy said when we had work done last year. Could it be a pump issue???
Expert:  garrygoeson replied 5 months ago.

Are you telling me your pump is 0.5 H. P., or is it 5 H.P.? See if your pool guy can tell you how many GPM (Gallons Per Minute) your pump sends to the heater. The heater is designed to run between 20 to 120 GPM, depending on what model heater you have.

If your pump is 0.5 HP, it is possible to be too low on GPM, and if it's 5HP, it's possible it could be too high on GPM.

Let me know what you can find out on this. Thanks.

Expert:  garrygoeson replied 5 months ago.

If you want to know the exact number of Gallons Per Minute for your heater , tell me the model #.

Customer: replied 5 months ago.
We have a Hayward super pump. Model number s48h2n122b1. 1/2 hp
Expert:  garrygoeson replied 5 months ago.

I'm sorry for not making it really clear. I need the model and serial number of the heater. The minimum GPM dependes on the heater size that is determined by the heater model.

Customer: replied 5 months ago.
Pentair heater minimax 250 dv. Heater identification nbr is htr 250 nt std nh. Also says 125 psi working pressure
Expert:  garrygoeson replied 5 months ago.

The minimum GPM for a 250 heater is 30. Depending on the amount of distance the pump is from the heater, and other engineering factors, there may be a possibility the pump could be under 30 GPM. I would have no way of knowing what it is pumping since I can't see the set up of your system. Maybe your pool tech can determine what the GPM is?

Customer: replied 5 months ago.
I really don't think it's the pump as we have had the same one for several years and the heater never had issues until this year. We are at our wits end and really don't know what else the problem could be
Expert:  garrygoeson replied 5 months ago.

If you can verify you are consistently getting good water flow to the heater, you can replace the 2 hi- limits. Since you're getting that fault code, and the hi-limits are not opening because they are getting too hot, it is possible they can be defective.

Expert:  garrygoeson replied 5 months ago.

​I sent you the info with the part numbers on June 10.

Expert:  garrygoeson replied 5 months ago.

Are you interested in replacing the Hi-Limit Switches? I have given you the best alternative based on what you are telling me about water flow.

Customer: replied 5 months ago.
We replaced one of them. The outtake switch. It didn't fix the issue. I need to order the other one.
Expert:  garrygoeson replied 5 months ago.

OK. I'm hoping the other one will resolve it for you

Customer: replied 5 months ago.
There is another part that has a model of 472125 which the Internet says it's a pressure switch. What does this part do and could it cause an issue as well??
Expert:  garrygoeson replied 5 months ago.

I am basing my suggestions on the fault code you state you are seeing, "E02". If the light on the left of the display, "PRESSURE SW" is staying lit when the problem occurs, I would not consider it to be the pressure switch.

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