Pentair Mastertemp 400 thermal regulator hole blocked

[Portyman]

I have a Mastertemp 400 and it has been giving me issues of starting and running for 20 seconds and then cutting off with the service light then coming on. I have had this issue in the past and was able to fix it by replacing the thermal regulator. When I pulled the regulator out and tested it it worked fine. I then was able to run the heater without the regulator in fine. The control panel does not give any diagnostic leds. I looked inside the regulator hole and it looks like it is blocked. I took a picture looking into the thermal regulator hole. Can anyone help me understand what I am looking at? Do I need to take the manifold off? What parts might I need to get when I take the manifold off. Thanks

Like I said he unit runs fine with out the regulator in and here are no leds on the control panel.

 

[ps0303]

Here is an exploded view parts diagram. What you are seeing is most likely normal as you can see from the diagram. Is the bypass valve still in place? It looks like it might be but double check it with your finger to see if it is secure or not.

 

[Portyman]

I have been looking at the diagram, but it looks like there should an opening for the regulator to sit in. The hole is blocked. I'm not sure how to feel if the bypass is in place. I cannot get my hand in the hole.

Why would the unit work with the regulator pulled out?

thanks

 

[ps0303]

You are looking at the hole it sits in. #7 shows the hole in the plate but then there is another plate behind it, #6.

You sort of have to use a finger to push up on the bypass to see if it is ok. I guess it's easier said than done when you do it for a living.

What does the thermo reg look like?

 

[Portyman]

The Reg looks clean and appears to work. I ordered a new on to try tommorow. We'll see. Thanks for the help.

 

[Portyman]

I replaced the thermal regulator and the heater runs fine until it gets to 89 degrees and cuts off. I restarted the heater and it shut off again. The control panel showed an HLS error.

From other posts it looks like I need to take the manifold off and check the manual bypass.

Is is there any way to test the HLS? I have an ohm meter.

Any other thoughts?

thanks

 

[ps0303]

The bypass is the part asked if it was still in place. It is some work to take the header apart to look at it. You need to make sure you have an o-ring kit handy for when you out it back together. Usually when the bypass breaks, it falls apart and blocks you from removing the thermo regulator. Seems like you were able to remove it easily so not sure if the bypass is your issue.

Are you sure you have good water flow to the heater?