Circulator pumps move water through the boiler and system loop. Lochinvar applications include:
- Internal combi pump — built into NOBLE/KNIGHT combi for the heating loop
- External SQUIRE indirect-loop pump — separate pump moving water between boiler and indirect tank coil
- External system pumps — additional zone pumps in larger systems
Common OEMs (external pumps)
| Application | Common OEM | Replacement options |
|---|---|---|
| SQUIRE indirect loop | Taco 007 cast iron / Grundfos UPS 15-58 | Direct OEM swap; ECM upgrade to Taco 007e or Grundfos Alpha |
| Small zone pump | Taco 007 / Grundfos 15-58 | Direct OEM swap |
| Larger system | Taco 0011 / Grundfos UPS 26-99 | Higher head/flow as needed |
Symptoms of failure
- SQUIRE tank not heating: indirect circulator may be off, seized, or failed
- No water movement noise on call (listen at pump body)
- Hot pump body with no water flow = seized impeller, motor running
- Cool pump body with call active = motor not running
- Leaks at pump flange or coupler
Replacement (external pump on SQUIRE loop)
- Power off circulator
- Close isolation flanges on both sides of pump
- Drain residual water from pump body
- Disconnect electrical (typically 120V single-phase)
- Unbolt pump from flanges
- Install new pump with new flange gaskets
- Verify pump direction arrow matches flow
- Reopen isolation flanges; restore power; bleed air from pump body
ECM upgrade consideration
Replacing a fixed-speed Taco 007 with a variable-speed ECM equivalent (Taco 007e or Grundfos Alpha) reduces electric consumption 60-80% — meaningful savings on always-running indirect loops. Cost: $200-350 OEM vs $80-130 for fixed-speed. Payback in 3-5 years for continuously-running pumps.
Cost
- Taco 007 / Grundfos UPS 15-58: $80-130
- ECM equivalents (Taco 007e / Grundfos Alpha): $200-350
- Contractor labor: $150-300
Bottom line
External circulators are widely available — Taco and Grundfos are interchangeable on most Lochinvar indirect setups. Internal combi pumps are OEM-only contractor work. Always verify flow direction on replacement and bleed air after install.