Pentair Minimax 250 NT - wont fire

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tb40

tb40

0
Nov 9, 2017
34
Yorba Linda
Just moved into a home with an in-ground pool with a Pentair Minimax 250 NT heater that has not been used in at least five years. This unit has four LED indicator lights - Power, Pressure, Heat, and Service. With the pump turned on, the heater's power light comes on, but the unit does not fire up.

Bypassed / jumped the pressure switch with a paperclip as a first troubleshooting step. The pressure light now comes on, but no heat light / ignition / nothing else happens.

Fair to assume that I need to replace the pressure switch? I would like to be logical in the troubleshooting steps I take going forward.

Should I first focus on cleaning out the gas lines and burners? Or something else?

Any help would be greatly appreciated!
 
Do a inspection of the entire unit. Make sure you didn't have mice inside chewing on wires etc. Then make sure you have gas flow. Not sure if this is a natural or propane gas unit. If propane, make sure the tank is full, valve is open etc. Also if propane, many times the propane company puts a "lock out" on the tank when the owner sells the home so that the new owner sets up an account. If you own the tank then that you don't have to do anything.

How does the unit look? Any rusted holes in the bottom etc. If so, you will be wasting you money to repair.
 
ps0303 said:
Do a inspection of the entire unit. Make sure you didn't have mice inside chewing on wires etc. Then make sure you have gas flow. Not sure if this is a natural or propane gas unit. If propane, make sure the tank is full, valve is open etc. Also if propane, many times the propane company puts a "lock out" on the tank when the owner sells the home so that the new owner sets up an account. If you own the tank then that you don't have to do anything.

How does the unit look? Any rusted holes in the bottom etc. If so, you will be wasting you money to repair.
Click to expand...

Thanks very much 303 for your response...

The unit is natural gas, and I'm not quite sure how to check and make sure there is flow. The previous owner had the gas line turned off, but at our request the gas company came out and lit pilot lights etc in our house, and showed us how to turn on the pool heater gas line. The line has two cut off valves, one at a junction near the meter, and another right before the pool heater in the pool equipment enclosure. I turned both valves to the on position, and just assumed that it had flow.

The unit is in reasonably good condition, but is old for sure and has some rust. I live in Southern California, so we don't have the degree of rust issues that other parts of the country experience. I will likely know more after I take out the burners and inspect, but I do wonder if it's worth it to start replacing parts that range from $30 - $500 in hopes that it fixed the problem.

I was interested in understand the replacement cost, and noticed that new heaters can go for as little as $800. In our case, we are heating a pretty small in ground jacuzzi, and will NEVER heat our pool. Does it make more sense to just purchase something new?

Pentair MasterTemp Low NOx Pool Heater | 461058

Pentair MasterTemp Low NOx Pool Heater | 461061
 
There could possibly be air int he line for any reason since it was shut off. Bleeding the line of the air might need to be done. Hopefully here is a union close to the heater you can use to bleed the line. Now I'm not saying that is all that needs to be done but it would be a start. Yes you have to start wondering at the age of the unit and possible repair costs if it is worth the repair. If you are handy with a volt meter you could try troubleshooting it yourself.

Not aware of any new units for that price, $800. Most pool heaters new should be over $1500 if you buy and install yourself. Keep in mind that if you do this, you could have issues with any warranty related issues down the road. Manufacturers are a bit picky with the DIY folks.

Raypak is the choice of heaters to go with. They have the best track record of any unit on the market today. I trust them 100% over any other brand. I wouldn't put anything less than a 250K BTU unit on there.
 
ps0303 said:
There could possibly be air int he line for any reason since it was shut off. Bleeding the line of the air might need to be done. Hopefully here is a union close to the heater you can use to bleed the line. Now I'm not saying that is all that needs to be done but it would be a start. Yes you have to start wondering at the age of the unit and possible repair costs if it is worth the repair. If you are handy with a volt meter you could try troubleshooting it yourself.

Not aware of any new units for that price, $800. Most pool heaters new should be over $1500 if you buy and install yourself. Keep in mind that if you do this, you could have issues with any warranty related issues down the road. Manufacturers are a bit picky with the DIY folks.

Raypak is the choice of heaters to go with. They have the best track record of any unit on the market today. I trust them 100% over any other brand. I wouldn't put anything less than a 250K BTU unit on there.
Click to expand...

Got distracted with other issues, but now have lots of pressure from the wife to get this fixed or replaced.

Thanks for the advice, I'll try bleeding the line.

If I have to go the replacement route... You said you wouldn't recommend putting anything smaller than 250k BTU, but what if we are literally NEVER going to heat the pool? We would be using it 100% to heat the jacuzzi, which is fairly small to average in size.
 
ps0303 said:
The difference in price in a 200K vs a 250K unit is maybe $150. So why not get the 250K unit for the extra amount of money.
Click to expand...

I was looking at a 150k btu pentair unit that costs exactly 1,000k including shipping and tax. The 250k units I'm seeing are 50% higher in cost. I may be missing something though...

Pentair MasterTemp Low NOx Pool Heater | 461058

Pentair MasterTemp Low NOx Pool Heater | 461061

I hear you on spending a little extra, but here in Socal we really never need to heat the pool, and wouldn't for cost reasons anyway.
 
How long would your old unit take to heat your spa when you wanted to use it? I only suggest the 250K as most folks want a faster heat up. You have a 250K unit now so why go down in size? A 150K unit is really small.
 
ps0303 said:
There could possibly be air int he line for any reason since it was shut off. Bleeding the line of the air might need to be done. Hopefully here is a union close to the heater you can use to bleed the line. Now I'm not saying that is all that needs to be done but it would be a start. Yes you have to start wondering at the age of the unit and possible repair costs if it is worth the repair. If you are handy with a volt meter you could try troubleshooting it yourself.
Click to expand...

Circling back to this issue... I finally got a chance to do some meaningful troubleshooting with my brother who is a lot more knowledgeable that I am with regard to electrical, etc.

Did the following:

* "Bled" the gas line, ensure that unit has adequate gas flow
* Pulled, inspected and cleaned the burner - pretty minimal rust, and in surprisingly good shape
* Bypassed the various sensors (pressure, high temp, etc). Pressure indicator light comes on when we bypass that sensor, but unit still doesn't fire.
* Attempted to meter test the output of the small transformer mounted to the right (if you are looking into the unit with the main panel off). Reading were all over the place, seeming to indicate it was faulty. However, when we unplugged it, all indicator lights went out... which seems to suggest it was working correctly???


Unit seems new enough, burners are clean / no rust, so I'm leaning towards repairing instead of replacing.

Next Steps:

* Should I go ahead and replace the small transformer, as the price is negligible?
* Any additional troubleshooting steps I should take at this juncture?
* What about the gas valve? How do I test?

Again, the unit is powering on, we are able to get the pressure light on, but unit does not fire.

Thanks for any assistance!
 

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I got it working!!!

I feel stupid, but the unit is "managed" by a compool system, and as soon as I changed the heat source on the indoor control panel and cranked the temp setting, it fired right up. LOL. I'm glad I didn't rush out and replace it.

How exactly does this work? I'm assuming there is a remote wire that triggers the unit on and off? Would I just disconnect that if I wanted to manually turn on and off and regulate temperature?

Still need to troubleshoot a variety of minor tweaks (pressure sensor is bad, doesn't get BLAZING hot, etc) but it's working and ready for summer.

Thank you for your help!!!
 
Glad you have it working. Yeah didn't mention nor did I ask if you had an automation system.

There is a two wire connection between the controller and the heater. The heater also has a REMOTE button on the panel. When it is pressed, the Remote LED lights up. If you press the Remote button and turn the LED Off it is now out of Remote mode and you can control the heater manually from its control panel.
 
Thanks for your help, rooking move not mentioning the automation system.

This heater is one of the older, basic models that does not have any kind of display... just the off/pool/spa button, the two heat dials, and four indicator LED lights (power, pressure, heat, service).

My instincts tell me that I could just disconnect the remote wiring, but I don't want to screw anything up at this point.
 
The remote system only allows me to set the temperature to 105 degrees (seems to be a hard coded limit)... The max temperature the system is achieving is adequate for children and general use, but I'd like to be able to occasionally turn it higher when I want it blazing hot.

At this point, I'm not sure if its the actual heaters high temp sensor limit, or if its a remote system temperature that is limiting the heat. I'd also like to understand better how it all works, so that if at some point the automation system goes haywire, I know how to manage everything manually.
 
The heaters shouldn't get your water "blazing hot." There are health reasons for why. Heaters are not supposed to go above 104 and making any changes to make that temp higher is asking for trouble. So if you set the remote to some crazy temp, the heater will shutdown at the 104 degree. It is like that for safety concerns.
 
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