Max-E Therm SR400LP - Control Board LED doesn't come on

[1000RR]

Ok, then you don’t have the ability for RS-485 control of the heater which complicates your IntelliCenter repair if you get this heater running.

I still have the old one, I could throw it back in if needed I imagine. Hard to say it was really bad at this point.

 

[ajw22]

Do a continuity check on the air flow switch.

Confirm it is open when the heater is off.

If the AFS is closed before the heater calls for the blower to start it will not energize TH and throw the AFS error.

 

[ajw22]

I checked for voltage on the Fenwal side at TH, not the yellow/blue tracer wire itself. Should I test the Yellow wire instead?

Was the wire plugged into TH?

Voltage is on the wire from the PCB.

 

[1000RR]

Was the wire plugged into TH?

Voltage is on the wire from the PCB.

I had to unplug the wire to test voltage at TH. I retested, this time on the yellow wire to/from the PCB with the heater calling for heat - no voltage or VERY minimal (like 0.004v). The Fenwal has 27.3v at the top where the yellow wire comes in there to/from the PCB (24 VAC terminal).

 

[1000RR]

Do a continuity check on the air flow switch.

Confirm it is open when the heater is off.

If the AFS is closed before the heater calls for the blower to start it will not energize TH and throw the AFS error.

I unplugged the wires on the Air Flow Switch and checked continuity. There is no continuity, switch is open.

 

[ajw22]

If your PCB is not putting 24V on TH the Fenwal will not energize the blower.

Try installing your old PCB and keypad.

 

[ajw22]

Let’s see if @swamprat69 is around to look at this.

 

[1000RR]

If your PCB is not putting 24V on TH the Fenwal will not energize the blower.

Try installing your old PCB and keypad.

I hooked the old PCB and touchpad back up. Fireman switch still jumper'd. When I flip the breaker on for the heater, the heater PCB boots up with a couple things showing up on the LCD screen, then turns off. When I press Pool or Spa for heat, the unit turns on, reports the temp of the pool and then if I increase the temp setting for it to call for the heater, the "Heater Service" light immediately goes on. The "Heating" light never comes on at all.... straight to the Service Light.

 

[ajw22]

So same behavior, blower not turning on.

The PCB is not happy with one of your safeties and not putting 24V on TH to start the blower.

 

[swamprat69]

As I understand it you have gotten to the point where you have a display and can switch to pool and push the temp up to the point where the heater should start up. Correct?

 

[1000RR]

As I understand it you have gotten to the point where you have a display and can switch to pool and push the temp up to the point where the heater should start up. Correct?

Short answer to your question = yes

Long answer...

Hey Swamprat, thanks for the response/question. It sounds like I have 2 issues. 1) the heater won't kick on 2) the intellicenter won't "tell" the heater to kick on. We haven't dealt with #2 yet. We are trying to get #1 going first. We've jumper'd the Fireman Switch on the heater and I've replaced the PCB and Touchpad on the heater (went from a 5 button to a 6 button). When I flip the main breaker on for the heater, the heater LCD screen now comes on (it wouldn't come on before). The new (6-button) touchpad/PCB I installed shows the heater trying to come on (LED light lights up for a couple seconds) and then the LCD screen says its got an AFS Error (and heater light on touchpad goes out). Shortly after that, the LED red light on the Fenwal blinks once every three seconds indicating the same air flow error. Allen (above) had me do some various testing, you can read above the testing and outcomes.... but now we're at a standstill. In learning from Allen, it seems the PCB should be sending 24vac to "TH" (on the Fenwal) when it calls for heat and that in turn should allow the blower to kick on. I'm not getting 24vac to "TH". And so Allen was thinking maybe there's a safety somewhere preventing the PCB from sending the 24v. Not sure what/where to check next. And then once I get the heater running, I'll need to rehook to the Intellicenter and figure out why that's not sending a signal to control the heater. When the intellicenter sends the heater signal (heater light lights up on the main Intellicenter Board), the heater relay where the control wires attach to is still open (no continuity). If a phone call would be easier, I could PM you my number. Whatever works I'm game. Thanks in advance.

 

[swamprat69]

Do you have the manual for your heater?

 

[swamprat69]

Try working on the heater first with the firemans switch jumped out

 

[ajw22]

Let’s be clear- the IntelliCenter does not “send a signal” for the heater to operate.

All the IntelliCenter does is close a relay that connects the 24V fireman’s switch to power the heater. The relay does the same thing that you did when you twisted the yellow wires together at the heater.

The relay appears to be inoperative on the IntelliCenter PCB and will probably require the PCB to be replaced.

 

[1000RR]

Let’s be clear- the IntelliCenter does not “send a signal” for the heater to operate.

All the IntelliCenter does is close a relay that connects the 24V fireman’s switch to power the heater. The relay does the same thing that you did when you twisted the yellow wires together at the heater.

The relay appears to be inoperative on the IntelliCenter PCB and will probably require the PCB to be replaced.

Thanks for that clarification, that makes sense. Can you also clarify how the heater gets its signal information on what temperature to heat the water to when I use my phone hooked to the Intellicenter? Is there another signal wire to the heater?

On SwampRat's earlier question on the manual.... I do have a PDF manual on the heater and just now noticed pg 49 has a troubleshooting flowchart for the ERR AFS code I have. I haven't gone through that flow chart (didn't even know the manual had one). I'll have to run through that tomorrow morning when I have daylight.

 

[ajw22]

Thanks for that clarification, that makes sense. Can you also clarify how the heater gets its signal information on what temperature to heat the water to when I use my phone hooked to the Intellicenter? Is there another signal wire to the heater?

There is no temperature signal to the heater.

The IntelliCenter does all temperature control. The IntelliCenter turns the heater off when the heat setpoint is satisfied and turns it on when water temperature is below the heat setpoint in the IntelliCenter.

The MasterTemp temperature setpoint needs to be set to 104 when the MasterTemp is being controlled by the fireman’s switch.

On your earlier question on the manual.... I do have a PDF manual on the heater and just now noticed pg 49 has a troubleshooting flowchart for the ERR AFS code I have. I haven't gone through that flow chart (didn't even know the manual had one). I'll have to run through that tomorrow morning when I have daylight.

I think that will lead you to replace the PCB or replace the Fenwal.

Let us know what you figure out.

 

[1000RR]

There is no temperature signal to the heater.

The IntelliCenter does all temperature control. The IntelliCenter turns the heater off when the heat setpoint is satisfied and turns it on when water temperature is below the heat setpoint in the IntelliCenter.

The MasterTemp temperature setpoint needs to be set to 104 when the MasterTemp is being controlled by the fireman’s switch.


I think that will lead you to replace the PCB or replace the Fenwal.

Let us know what you figure out.

Interesting on the IntelliCenter... that makes sense now that you say it. Thanks! If that relay on the Intellicenter is not closing when asking for the heater, do you have to replace the entire board? That's what it sounded like earlier from your post.

On the troubleshooting flowchart, it doesn't look like any of outcomes result in replacing the PCB (plus it's been replaced just today). That said, you mentioned replacing the Fenwal. In looking at the flowchart, I believe I've tested all but the last one (before it says replace the Fenwal). And that is where it says "Disconnect F1 and F2 on the Fenwal and short them together and see if the blower comes on." So it sounds like I just need to jumper those two together and that should directly power up the blower. And if so - then the Fenwal is bad.

 

[ajw22]

Interesting on the IntelliCenter... that makes sense now that you say it. Thanks! If that relay on the Intellicenter is not closing when asking for the heater, do you have to replace the entire board? That's what it sounded like earlier from your post.

Yes.

On the troubleshooting flowchart, it doesn't look like any of outcomes result in replacing the PCB (plus it's been replaced just today). That said, you mentioned replacing the Fenwal. In looking at the flowchart, I believe I've tested all but the last one (before it says replace the Fenwal). And that is where it says "Disconnect F1 and F2 on the Fenwal and short them together and see if the blower comes on." So it sounds like I just need to jumper those two together and that should directly power up the blower. And if so - then the Fenwal is bad.

I think that would be misleading if you don’t have voltage on FN.

F1 and F2 are connected through a relay to turn on the blower. So jumpering them is the same as the relay closing.

You can try and replace the Fenwal. I suspected it may be bad but you saying you get no voltage on FN said it may not be bad.

I can only go by what you tell me.

 

[ajw22]

Looking at the chart it may be voltage on IND and not FN that tells the Fenwal to start the blower. Check for 24V on IND as the chart asks.

 

[1000RR]

Yes.


I think that would be misleading if you don’t have voltage on FN.

F1 and F2 are connected through a relay to turn on the blower. So jumpering them is the same as the relay closing.

You can try and replace the Fenwal. I suspected it may be bad but you saying you get no voltage on FN said it may not be bad.

I can only go by what you tell me.

I don't know what "FN" is... I mentioned I checked voltage at "TH" and I did not have voltage there. I have voltage at the topside of the Fenwal where it says "24 VAC"