Burnham US Boiler Alliance LT TPI aquastat

Users who are viewing this thread

Mr Blint

New Member
Reaction score
Yesterday we replaced our badly leaking indirect hot water heater with a Burnham US Boiler Alliance LT, the one with the thermoplastic lining. No sacrificial anode, no corrosion issues. We live in PA, US Boiler is located in PA, and we're shopping local.

The old tank had a Honeywell aquastat and the Alliance LT comes with an electronic TPI with a little motherboard inside. There's no immersion well accessible from outside the unit, just a little wire a few inches long that sticks out the side.

The installers were pretty good plumbers but not electricians. They figured all they'd have to do is move the two wires from the Honeywell aquastat over to the Incoming 24V power connection terminals and call it a day. They did so. The TPI's green light flashes, indicating a call for heat, but the zone valve doesn't open and the pump doesn't come on. The pictures of the TPI in the manual all show four wires not two. There are two additional terminals for Outgoing 24V wires to relay or zone valve.

We have two Taco 3-wire zone valves (one zone for heating the house, one zone for heating the water) on a sideways "T" pipe setup up (├ ) with a single Taco pump pushing water towards the ├ . Up goes to heating the house, down goes to hot water tank. There is a transformer sitting on top of the boiler, and a mares-nest of wires connected together with nuts.

Do I understand correctly from the attached wiring diagram that we need to run two additional wires back to a relay and also connect the Pump terminal on the TPI to the 24V red "in" on the TPI? I should probably hire an electrician and have him move that tangled mess of wires to a relay?

Thanks in advance for helping me to understand how this should be wired up.


  • Wires.jpg
    68.5 KB · Views: 145
  • Transformer.jpg
    79.3 KB · Views: 178
  • TPI Wiring Gray.jpg
    TPI Wiring Gray.jpg
    59 KB · Views: 143
Last edited:


Well-Known Member
Reaction score
Peace valley missouri
Can't open the wiring diagram getting a error can blow it up but can't read it. Honeywell aquastat have any numbers on it? Was the lower right controller on the tank?
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks