Variable Speed Delta-T circulators by Taco combine a microprocessor-based variable speed differential controller with Taco’s 00 cartridge circulators. The all-in-one Taco 00 Delta-T Circulator (00-VDT) includes a snap-in PC board, LED status panel, plug-in low voltage wiring terminal for the two strap-on temperature sensors and an optional integral flow check. The circulator shuts off when there is no call for heat. The 00-VDT is fuse-protected, UL-approved and made in the USA. It comes standard in 008, 0012 and 0013 cast iron and stainless steel versions.