Sta-Rite Heater - Failed Transformer?

[jackheney]

Hi all,

My pool company came out to open my pool this week and told me the heater (a Sta-Rite max-e-therm 400hd) was broken. It wouldn't power on b/c of some "hard short" (their words) that they couldn't diagnose and it couldn't be repaired, I'd need a new heater. After they left I took a quick look, and I found that a mouse and its babies had made their home inside the box that houses the ignition and blower control. After shutting of the breaker, cleaning out all the shavings they dragged in, and taping up some of the exposed wires, I turned the power back on but am still getting nothing on the LEDs. I traced the power through the system and it seems like I've got voltage all the way through to the 120/240 pins on the transformer. My voltage detector isn't sensitive enough to validate voltage on the 24 VAC side, so I took a multimeter to the jumper that comes off that side of the transformer and don't see any voltage registering. I'm guessing it's possible that I'll end up having to replace the entire control board, but was thinking about just replacing the transformer first (it's far cheaper). I guess I'm just looking for some guidance on my thought process here...do these transformers tend to fail, especially if the mouse somehow shorted the 120/240 and 24 circuits together?

Thanks!
Jack

 

[jackheney]

I subsequently realized I could test the transformer with my multimeter. Resistance on the 24 VAC side (between blue & yellow) is 1 ohm. On the 120/240 side, White / Black resistance is 19 ohms, White/Brown resistance is 75 ohms. This *seems to* suggest maybe the transformer isn't bad?

 

[JamesW]

Maybe some pictures would help.

Is your supply power 120 or 240 volts?

 

[jackheney]

Thanks James...It's 240v. Pictures (including the mouse!) attached.

 

[JamesW]

When you apply power, does the display show anything at all?

 

[jackheney]

No...none of the LEDs come on

 

[JamesW]

Are you getting 240 going into the transformer?

Note that you won't get a LED on the Fenwal Ignition Control Module unless there is a fault.

 

[setsailsoon]

No power to the display is often a good indicator you have a fried secondary on the transformer but check the fuse first. But I have seen the transformer secondary go before the fuse even though it shouldn't. If you don't want to wait for a replacement you can get a temporary pretty cheap at big box stores in the irrigation section. You'll have to use the existing connectors spliced from the old transformer. These rat problems can be simple or a real pain but way better than replacing the whole unit. I'd make sure you do a diagnosis for each component before you replace it. We see a LOT of unnecessary costs with random replacement before doing the simple tests. We have experts like @JamesW @ajw22 and @swamprat69 that can help you test before you replace.

Chris

 

[jackheney]

I guess the voltage levels on the primary side are the next thing I should check. I stuck a current detector on all the input wires and they're hot, but I didn't measure the voltage there.

And sorry, I should have been more clear. The membrane control panel on the top of the unit is where I'm not seeing any of the LEDs come on.

 

[jackheney]

Thanks Chris...the pool company clearly didn't dig in too deep, and then called me later in the day and said my only option was "replace the whole heater for $5K". Setting aside that it's only a $2700 unit, I was kind of annoyed that there was zero effort to actually diagnose the problem, let alone help me solve the problem cost effectively. The help here has been awesome already, many thanks!

 

[jackheney]

Ok, I measured voltage on the Primary side. I get ~110V when I test red/white, but only 1V when I test black/white. I think that suggests I do have a problem on the Primary side, right?

 

[JamesW]

Check the power where it comes in to the heater.

What switch is supplying power to the heater?

Is the power leaving that switch at 240 volts?

 

[jackheney]

Measuring across the black and red terminals where the initial connection to the heater comes in yield 60V. I'm beginning to doubt both my multimeter and my electrical skills

There's an electrical panel right by the pool equipment, let me give that a go.

 

[JamesW]

Show a picture of the multimeter so we can see if it's set up correctly.

 

[jackheney]

Ugh. I've been chasing ghosts. Looks like the pool company (I suppose reasonably) pulled the electrical line in the breaker box. I need to go shut off the sub-panel and reconnect...and then I suppose start this exercise all over again. Apologies, I should have validated the continuity before I wandered down this road. Back in a few

 

[JamesW]

Ok. Be safe. Don't do anything that you're not sure about.

 

[jackheney]

Ok...same problem (no lights on membrane panel on top of heater, no activity in the heater), but new data - Getting 27v on the secondary side of the transformer per the multimeter, and the fuse is still intact. So now I'm hypothesizing - fried control panel?

 

[JamesW]

Cycle power and watch the control panel to see if the boot sequence displays.

 

[JamesW]

You have an external controller connected to the fireman's switch. What external controller do you have?

Is the fuse on the fireman's switch good?

 

[jackheney]

I'm back...and James is a genius. I jumpered the fireman's switch and lo and behold I had heat! My shoddy work to deal with the mouse destruction needed a bit more cleaning up, but with some new connections to the fireman's switch the whole thing is put back together and up & running. I can't thank you enough, and I'll certainly be taking some of the $5000 that the pool company wanted to charge me and redirecting it to support this forum. I solved the problem with some wire cutters and two new wire nuts . Thanks for all your help and patience.