Aqua Hot Circulation pump

[Keith Moffett]

For the last year or so the circulation pump in the bathroom zone has not been working.  Some time prior it did this but rapping on it got it going again for a time.  Not so this time.  We have the small spinning pump with the clear plastic top.  Question is can it be rebuilt?
I considered pulling the top off to see if it might spin by hand but the plastic will likely be brittle.
I searched the AH manuals and everything is there except the circulation pumps internal parts.  I hear that it is magnetic drive so is there a test?
Glad to hear some input.  Vince suggested an amp draw test to see if it is just stuck which I believe is a good start.

[Bill Lampkin]

Don't know if you've seen this:

https://hydronicheatingwarehouse.com/collections/popular-products/products/buehler-400-450-pump-kit


https://cdn.shopify.com/s/files/1/1569/3101/files/450-pump-retro.pdf?v=1607535827

[Frank Bergamo]

Keith,

can you tell if it is spinning by looking through the plastic cap. If it is spinning, then the check valve is mostly likely stuck closed. You can disassemble the check valve and free it up. I had one stuck closed on my 07’ Marquis, after freeing it up I have not had a problem since. I also checked into rebuilding the pump but was unable to get parts from the pump manufacturer. Was told Aqua Hot owned patent on pump and would not sell me any parts. Also, check your Ph of boiler fluid, if it is not correct check valves may stick closed. Hope this helps.

[Keith Moffett]

Frank
After all the whacking on it I looked away and just the the wife saw it spin.  LOL
The rest of the time it hasn’t moved.  I know AH wants to sell you a different pump with a modifier kit.  I am trying all other options first.
The boiler fluid is up to level but I haven’t checked the PH.  My intent is to gather enough new fluid and change it out. 
Good info , thanks.

Bill
Looking into that now

[Keith Moffett]

Bill
You find the very things.  How do you do that?
If I have to change out the pump that is a good one and the price is sure right.
Thanks

[Frank Bergamo]

Keith,

have you checked the two connections at the pump? Are they clean, snug, no loose wires going into plugs? Hope this helps.

[Scott Hinote]

Great information Bill, your very helpful and that information can be very helpful . Thanks
Scott & Cindy

[Keith Moffett]

Ok so with further research the pump works when those connections are removed from the main board and applied direct to a 12V battery.  Problem is it surges.  So does a good pump when hooked directly.
The main board checks good when a good pump is connected where the bad one is now. 
This is strange since it fails when hooked to the original connection on the main board but does work when hooked to 12V direct.
I am considering an exorcism.

[Jim Nichols]

Are you using a different ground when applying 12v direct? May be a bad ground.

[Steve Huber Co-Admin]

Keith,
When hooking up the pumps to the main board check the voltage at the connection point. I suspect the old pump is drawing a lot of current and pulling the 12v supply down so there isn't enough voltage to run the pump. Be sure to ground the meter at the board connection as you want to measure exactly what the pump is seeing.
Steve

[Keith Moffett]

Here's the latest...
The pump test said open. 
The problem is in the spade connectors.  After a continuity check to identify the correct wires the pump began working when reconnected.  This continued until the final check after buttoning up the Aqua Hot and it quit.  Seems like it is the point where the wire joins the spade connector.  Just moving the wire started the pump.  Sadly the pump isn't pumping anything though the motor spins so replacement is next.
Hope this helps someone.