Starite heater blower starts intermittently

[Tony4444]

Good day! After a few months of trouble-free heating, yesterday my heater shut off before the preset temperature. (STARITE MAXETHERM 333NA.) Fenwal showed 1 blinking light (air fault) and the control board had the "service heater" light illuminated.
I shut power down for 5 minutes and restarted and observed a normal startup sequence but the blower motor didn't start. I disconnected the blower motor harness and restarted and observed 120v from the blk wire pin to ground. I reconnected the harness and restarted again and the blower energized, but the service heater light was still illuminated and the unit wouldn't fire. I restarted multiple times since and neither the blower motor nor the fenwal air fault light have energized again.
I was certain that I was dealing with a bad blower motor but when back probing the blower motor harness, I no longer see 120v after multiple start attempts so now I'm thinking this may be in the control.
I have good water flow, but jumpered the flow switch just in case and no change. I don't think that there is anything else that will prevent the blower from energizing besides a bad motor or a control failure, but wanted to double check with the experts. Thanks fellas.

 

[ajw22]

Read Pentair MasterTemp Heaters - Further Reading

The blower is powered through the Fenwal F1/F2 connections that are a relay.

The F1/F2 relay contacts in the Fenwal are supposed to close and start the blower motor when you have 24 volts between "IND" and the 24 volt ground. If you have 24 volts at these 2 points and the F1/F2 contacts do not close, you would need to replace the Fenwal.

Check for 24V between IND and ground when the heater starts up.

 

[Tony4444]

Read Pentair MasterTemp Heaters - Further Reading

The blower is powered through the Fenwal F1/F2 connections that are a relay.

The F1/F2 relay contacts in the Fenwal are supposed to close and start the blower motor when you have 24 volts between "IND" and the 24 volt ground. If you have 24 volts at these 2 points and the F1/F2 contacts do not close, you would need to replace the Fenwal.

Check for 24V between IND and ground when the heater starts up.

Thank you ajw22. I just went out and rechecked. Here's what I have:
At F1 I have 120v constant with the heater off. At F2 I have 24v constant with the heater off.
When I start the heater I have 24v between IND and ground, and I have confirmed that the F1/F2 RELAY is closing and supplying 120v to the power wire on the blower motor. However the power is not constant. Ill see 120v, hear a click and voltage will drop to zero, then it will power back up to 120v. I believe this may be normal for purging etc. The blower motor "hums" but does not turn. I'm fairly certain now that my blower motor is faulty, however I did see it run for a short time yesterday.
I'm going to go out on a limb and assume that one couldn't purchase the motor independent of the blower housing? Thanks again for your help.

Edit: will the ETI400 blower fit a starite maxetherm 333na? It looks like the same specs but 50rpm higher shaft speed...and about 300 bucks cheaper.

 

[ajw22]

Did you read how to test the blower in Pentair MasterTemp Heaters - Further Reading

Check the capacitor in the blower motor.

If you are going to replace the blower I would first check that your heat exchanger is not leaking. A leaking heat exchanger can cause water to get into the blower motor. Remove the lower left bolt on the manifold and see if any water comes out.

 

[Tony4444]

Did you read how to test the blower in Pentair MasterTemp Heaters - Further Reading

Check the capacitor in the blower motor.

If you are going to replace the blower I would first check that your heat exchanger is not leaking. A leaking heat exchanger can cause water to get into the blower motor. Remove the lower left bolt on the manifold and see if any water comes out.

Thank you, yes I read it in its entirety and it all makes perfect sense.
I just replaced my manifold a few months back, and I had no water on the fire side but I'll check again. Good call.
Regarding the interchangeability of blower assys between the models, all motor specs seem the same?

 

[ajw22]

Regarding the interchangeability of blower assys between the models, all motor specs seem the same?

Dunno, never heard of anyone trying that.

 

[ajw22]

I just replaced my manifold a few months back, and I had no water on the fire side but I'll check again. Good call.

Blower motors rarely fail but if you had a leaking manifold that could have damaged the blower motor leading to your current blower problems.

 

[Tony4444]

Dunno, never heard of anyone trying that.

Roger that. Great call on the capacitor. I can see the thing inside the motor housing but I think the motor needs to come off the volute to get to it. That's probably what it is. There's a motor repair shop down the street. I'm going to see if they'll rewind this thing and replace the CAP while they're at it. If it's less than 400 bucks, I'm winning. Appreciate all your help Sir.

 

[Tony4444]

Well for anyone wondering if you can just change the motor on one of these blower assemblies, you can't. The motor shaft nut that fastens the blower wheel to the shaft is peened so it's not possible the remove the wheel without damaging the shaft and nut. Then once you get the shaft nut off, the flimsy aluminum wheel will take exactly ZERO prying before it becomes completely distorted and unusable.
Looks like I'm getting a new blower assembly. By the way, the capacitor was dead and the motor armature had nothing left. But 18 years of service ain't bad at all.

 

[Tony4444]

Well for anyone wondering if you can just change the motor on one of these blower assemblies, you can't. The motor shaft nut that fastens the blower wheel to the shaft is peened so it's not possible the remove the wheel without damaging the shaft and nut. Then once you get the shaft nut off, the flimsy aluminum wheel will take exactly ZERO prying before it becomes completely distorted and unusable.
Looks like I'm getting a new blower assembly. By the way, the capacitor was dead and the motor armature had nothing left. But 18 years of service ain't bad at all.

Just to close the loop on this issue; I finally ordered a new blower assembly. Replacement was a breeze. The Kit comes with the blower assembly, new lines for the AFS, and a new gas orifice. The price is outrageous, but better than a new heater. After a couple of purge cycles she fired right up.