[Richard]

I had an experience where one of the zones in the coach was blowing cold air when the heat was supposed to be on. Quick checking showed the pump motor for that zone was not on. Further checking showed it was not getting power although the relay was getting a signal to close. 

The relays are those three clear covered cubes on the side of the aquahot. Easy to check if you suspect a bad one by moving them to different locations. If the dead pump follows a relay, then the problem is identified. 

They are Dayton part number 1A486M, less than 10 bucks at Grainger. I replaced all three.

Of course I took the cover off of the failed relay just to see what I could see. Green corrosion on both the pins and internal to the unit. Well of course, it's not a sealed unit, and its in an environment that can be wet from time to time. 

Kept the two good ones for emergency spares. 

   

[bryguymi]

I had an experience where one of the zones in the coach was blowing cold air when the heat was supposed to be on. Quick checking showed the pump motor for that zone was not on. Further checking showed it was not getting power although the relay was getting a signal to close. 

The relays are those three clear covered cubes on the side of the aquahot. Easy to check if you suspect a bad one by moving them to different locations. If the dead pump follows a relay, then the problem is identified. 

They are Dayton part number 1A486M, less than 10 bucks at Grainger. I replaced all three.

Of course I took the cover off of the failed relay just to see what I could see. Green corrosion on both the pins and internal to the unit. Well of course, it's not a sealed unit, and its in an environment that can be wet from time to time. 

Kept the two good ones for emergency spares. 

This is good info.....Thank you!