Am I safe to turn on this old Minimax NT gas heater?

[caleyjag]

I inherited this heater with our house, which we bought last year. I have no idea how old it is or when it was last operational. First time pool owner. I've done quite well replacing some pumps and lighting on my own, but this seemed the most dangerous task so I have left it until last. While we can continue to live without it, it would be good to get it running, at least for the hot tub.

The one part that was clearly busted was the ignitor, which I have a new part for.

Rats had set up home inside the casing and there was a fair bit of debris. I have cleared as much as I can get to easily, but it's definitely possible there's a fair bit of accumulated dry material in harder to get to interior spaces.

Electricals seem to be working fine. The control panel is lighting up and looks healthy. Wiring seems to be okay for the most part.

The blower motor/capacitor looks pretty corroded to me. Hopefully that's just the exterior but I suspect that is wishful thinking.

I'd imagine the thermistor is probably gone but no way to know without running it.


I'm kind of nervous to turn on the gas and fire this thing up. Am I at risk of a fire or other problem, or can I trust the device to error out if something is wrong?

 

[ajw22]

I think this is the manual for your heater - https://images.inyopools.com/cloud/documents/pentair-heater-minimax-nt-ln.pdf

The safety controls are described on Page 22. If no one has bypassed any of them the risks are small in trying to turn on the heater.

The blower is the first thing that needs to turn on. The air flow switch will sense the blower is operating and the water pressure switch will sense there is water flow. These signals will be sent to the Fenal box that controls the gas valve to heat the igniter and open the gas valve. If you don’t have proper air flow and water flow the Fenwal will not start the ignition process.

Given the age of the heater and the way the it looks I would not spend a lot of money throwing parts into it to make it work.

 

[JamesW]

I would recommend a service call to do an on site inspection before you try to operate the heater.

The heater looks old and in poor condition. I would not put any significant money into it if it isn't working.

 

[JoyfulNoise]

I’m with Alan ... it’s worth tossing a match at it to see if it lights up but I wouldn’t waste too much time or money on it. If the blower motor is bad, it won’t start up and you’ll definitely hear it (or not hear it). Everything inside that box is “$200 here” or “$300 there” to replace so you’ve got to decide how much money you’re willing to thrown down the rabbit hole chasing after ghosts ...

 

[caleyjag]

Thanks everyone.

I will try to fire it up this week and see what happens.

I'd already seen some of the prices for the spare parts, so yeah, don't think it's a rabbit hole I want to go too far down.

I've already spent more than I would have liked on this pool this year and we aren't desperate for heat so if a new heater is needed that's a can that can be kicked down the road for a while.

 

[SEO_9C1]

So, did you light it up?

 

[caleyjag]

Following up on this thread.

I got the igniter part in today (the old one was busted) and, after a deep breath, fired it up. I haven't run it in the 18 months I've owned the property, and I suspect the previous owners didn't run it for a (very) long time either prior to the sale.

Surprisingly, it kind of whirred into life and after a bit of initial screaming settled into a steady hum.

Video of heater in current state

The panel however was not responsive. Just said OFF and the buttons didn't really seem to do anything. Holding the up temp arrow flashed up this (the only feedback I can get from the panel so far):



Not quite sure how to diagnose the unit further at this point so any tips welcome!

 

[caleyjag]

Reviewing the manual linked above, an LED is blinking (Fig 24 in the manual) which suggests an 'air flow fault'. This seems reasonable due to the condition of the motor (you can see it in the video).


Was hoping to salvage this myself but looks like it might be time to get the pros in to quote on a replacement unit?