t.com ECM High-Efficiency Circulators - 34 ft. Head | 50 gpm For closed and open loop hydronic circulation * Rotatable control cover * Recessed flange nut-grabbers * BIO Barrier® protection from system contaminants * SureStart® automatic unblocking & air purging * activeADAPT™ self-adjusting proportional pressure * 0-10V DC & PWM external inputhttp://www.TacoComfort.co