Radco Drainback Controller

[In Hot Water]

Hi, all-

I'm in hot water over cold water.

I have a solar DHW drainback system that has worked great for almost 20 years.

But the Radco Products Transfer Module that controls everything has stopped working.

In Test mode the pumps turn on, but in Auto mode the pumps do not turn on.

I've tested both thermistors with an Ohm meter & they both tested within acceptable ranges.

So now I'm at a bit of a loss.

Is there anything else I can or should test?

Or is this thing most likely toast?

And what the heck do I order to replace it? Radco is out of business.

Sign me- NOT In Hot Water

[LucMan]

Unless you can trouble shoot down to the component level on the board it's probably easier to just purchase a new controller. Probably a bad relay or a capacitor that is defective.
IMC instruments makes several drain back controllers. There's also Tecmar 156, Goldline GL30.

[In Hot Water]

LucMan OK, I agree, time for a new controller.

This one at Amazon looks like it will work, and the price is right:
https://www.amazon.com/gp/product/B0...HRQ8MAMP&psc=1

But it doesn't have a high temperature shutoff. My Radco would shut off at 180F.

I've read a few places that solar panels heat water as hot as 180F-200F, which makes me think a high temperature shutoff isn't necessary.

So, what do you think? Am I OK w/out the hi temp shutoff?

I'm just balking a bit at paying $180 or so for a controller.