sta rite max e therm 400 gas heater blows fireman's fuse when turning on power

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J

jlgoode

0
Jul 21, 2018
18
huntington/ny
Hi all,

This has been a hair-puller for me. Heater was working fine then just stopped. Initial call to tech support and found transformer dead. Replaced- still blowing fuse.

Tech call #2- told control board was bad, replaced it- still blowing fuse.

Tech call #3- again, after about an hour, was told to replace membrane switch. Replaced it, fuse still blows right when I throw the circuit breaker.

I also changed the ignition control module, still blowing fuse.

I went through the wiring harness and cannot find anything causing a short. Only thing I can think of is trying a blower motor. But at that point, I may just replace the unit.

Tech support was not help for me, and costly to follow their guidance.

Any help is greatly appreciated.

Thanks,

Jeff
 
Nothing has changed in 8 years, all the incoming connections in the box on the side of the unit are intact and I cannot find anything that would cause a short. It was working just fine, then went completely dead. I can't see what would change the voltage coming from the circuit breaker, but I will definitely check it.

Thanks
 
Pool Clown said:
The fuse protects the safety circuit (28~32V) from shorts, or i should say everything that could be damaged by a low voltage short. This includes the firemans switch circuit, or in the case of automation, the control wire (on/off command). Check the wire, if applicable, that runs from the heater to the main automation panel OR time clocks' firemans switch for a short due to a chewed or pinched(to ground) wire.

Actually, open the heater up and check all the wiring for this too! If you find one wire chewed, there are bound to be more.
Click to expand...

I took the wire harness out to inspect it, nothing chewed. I should have mentioned the heater is not on a timer or automation, I have to manually turn it on and off.
 
Please disregard my post, i need to dig up the schematic on this heater and look at it. I have had this issue a couple of times in the past and cant remember what the fix is...

Stay tuned.

What is happening is, one leg of the low voltage is shorting to ground. How and where that is happening is what i cant remember.
 
So, Pool Clown, you are saying I should check the 3 wires that go from the heater to the electrical panel? They are in a Weather proof casing, I would have to pull them through. Also, if I had a short at the breaker panel, wouldn't the breaker trip when I turn on the power?

Is there any chance one of the many sensors is causing this issue?

Thanks again
 
jlgoode said:
So, Pool Clown, you are saying I should check the 3 wires that go from the heater to the electrical panel? They are in a Weather proof casing, I would have to pull them through. Also, if I had a short at the breaker panel, wouldn't the breaker trip when I turn on the power?

Is there any chance one of the many sensors is causing this issue?

Thanks again
Click to expand...

No, stop. Your issue is with the LOW voltage side. The three wires in the conduit is the high voltage side.

Think of it this way. High voltage, BREAKER in the panel protects. Low voltage FUSE in the heater protects.

Sheesh, that sounded like Yoda... You get what i mean though, right?

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Although the sensors carry the low voltage, no, i don't think so. I have never had a switch sensor (pressure, AGS, AFS, Hi Limit) fail shorting to ground. They fail open. There is no connection to ground with these switches. The Hi Limit, and the air flow switch are either encased in epoxy, or have a plastic case, with no path way to ground. Pressure switch is in a plastic case, threaded into a plastic housing.

Chewed wires is #1 cause of opens and shorts in these heaters.*


*in my area.
 

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jlgoode said:
PC,

I had to replace the wire harness 2 years ago due to rodents. It looks good as far as I can tell.
Click to expand...


PC,

Update, I put wiring harness back and tried turning on with 24vac wire pulled out of ignitor. No fuse blown, then I tried it with the wire plugged in and the fuse did not blow; but I everything was dead- no sounds, nothing on control board or membrane pad.

I took a volt meter to the power supply wires and got a reading of zero on both. Starting to wonder if the actual breaker in the pool control box is bad?????

Also, does it make a difference which fuse wire is plugged into the actual fuse versus the metal bar next to it in the terminal board?

I'm really confused about this now. All wires look just fine.

Any thoughts?

Jeff
 
If you are now not getting any power TO the heater, and the pump is running, something has changed, and you may need to get a tech out there if you are not comfortable chasing high voltage electrical problems. Otherwise, you need to find out where you are loosing the power to the heater.

Like i said before, The heater SHOULD be sharing power (same breaker) with the pump, but that is just the recommended way to wire it, and not always guaranteed. That's why you, or someone, needs to chase the wiring from the heater to the breaker. The majority of motors, heaters, and SWCG's run on 220V *. That means 2 110V breakers that are, or should be tied together. Again, not always, but that is the standard. Look at all the breakers and see if they are labeled. You may be able to tell if the heater and the pump are on the same breaker or not. If you find a breaker labeled heater, go ahead and flip it to the off position. And i mean physically push the switch to the off position. This will reset the breaker, if tripped, and then push it back to the on position. Hopefully, things will come back to life.



* In may area.
 
My pump is on a 2 switch breaker, but the heater is on a single breaker. Its how I have been turning off power to the heater when I work on it.

I don't even know if I can find a tech here on Long Island, NY. Everyone I speak to says they work on these heaters by process of elimination, which is what I have been doing.
 
Starting at the breaker, Make sure you have voltage there. Then go to the junction box on the heater its self, and check for voltage there. If you have voltage to that point, then check for voltage at L1 and L2 Those two points are on either side of the fuse block and should be labeled as such.

BTW, was the control board you replaced BRAND NEW in a factory sealed package? You didn't get it two party (used) from ebay or anything like that, right?
 
If you get power at the L1 and L2, disconnect the TH, IND, VAL as well as the 24V from the ICM before you re-apply power to the heater (leave GND connected).

Apply power.

If the fuse holds, plug the 24V back in. If it blows ICM is bad (i know you just replaced). If holds, begin to plug in other wires one at a time checking the fuse with each wire. Problem will lie with the circuit/wire that causes fuse to blow

TH is the air flow switch circuit
IND is the pressure and the hi limit citcuit.
VAL is the AGS and gas valve circuit.

Remember, fuse blowing is indicating a short, not a bad switch. So we are looking harder at the wiring than the switches!!

If you dont get power at L1 & L2, but you do have it at the junction box in the heater, You have something going on with the 120/240 voltage plug. I have run into a couple where the wire connectors didn't get completely pushed into the plug (at factory). You would need to remove the plug and look at all the pins and compare them to see that they are all evenly sticking out the same (within the plug).

I asked about where you got the board because a bad or "blown" board will often not look any different than a good one. That goes for the ICM as well.
 

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