Circulator Pump Technology

DOE ASRAC Commercial & IndusPumps Working GroupJanuary 30-31, 2014 
Circulator Pump Definition

 Circulator Pumps (commonly called “Circulators”) 

horizontal, single-stage rotodynamic pumps, with ihousings. Circulator Pumps are characterized by land quiet and vibration free operation and are comutilized in hydronic heating closed loop systems to flow by overcoming system friction loss. They also for potable water (intended for human consumptionrecirculation to provide hot water from a source on 
Circulator Pump History

 First circulator pumps were developed in the 1930s 

the performance of hydronic heating systems . . .

 Early systems relied on gravity (hot water rises) to 

residences. This required very large pipes to move necessary BTUs but system responsiveness was p

 The advent of small circulator pumps reduced the p

and sped the flow of hot water to the areas of the recalling for heat.
Sample of zoning with Circulators

4

Boiler

LOAD LOAD LOAD

Circulator Pumps
Example of zoning with Zone Valv

5

Boiler

LOAD LOAD LOAD

Circulator Pump

Zone Valves 
HI Member: Circulator Pump Manu

 Armstrong Limited Grundfos Patterson Pentair Taco Wilo Xylem (Bell & Gossett)
Types of Circulator Pumps
CP1 – Close Coupled Sealess with Canned Mo

119 18 ** 119 16 2 24 1

*

Item # Part name Def

1 Casing The portion of the pump 

chamber and 

2 Impeller

The bladed member of 

pump, which imparts the 

pu

6 Shaft

The cylindrical membe

mounted and through w

the i

24 Nut, impeller

A threaded piece used to 

s

16 Bearing, inboard

The bearing nearest th

bearing pump but farth

end suction pump or bea

of a sealless w

18 Bearing, outboard

The bearing most‐dista

between‐bearing pump 

of an end suction pump o

impeller of a sealle

119

O‐ring

A radial or 

* Rotor, water

lubricated

The rotor is the non‐s

electric motor, which 

magnetic field generated 

is fluid lubricated and c

** Rotor can

The rotor can encloses t

bearing support and 

contamination of 

6
CP1 – Close Coupled Sealess with Canned Mo

 Typical Product Characteristics (wet rotor)

– Hp: 40-240 Watts– Speed: single & multi-speed– Lubrication: system fluid– Flange Size: 3⁄4” – 1-1/2”– Flow/Head: 130 Gpm/55’ TDH
CP2 - Close Coupled Horizontal In-Line

1

Item # Part name D

1 Casing The portion of th

impeller chamb

2 Impeller

The bladed memb

the pump, which 

to the 

6 Shaft

The cylindrical mem

is mounted and 

transmitt

? Ring, casing

A stationary repla

casing at the runni

or t

24 Nut, impeller

A threaded piece 

o

65

Seal,

mechanical,

stationary

element

A sub assembly c

parts mounted in 

having a sm

80

Seal,

mechanical,

rotating

element

A device flexible m

the stuffing box an

face held against 

119 O‐ring

A radial 

? 24

2 119

6 80 65
CP2 – Close Coupled Horizontal In-Line Pump

 Typical Product Characteristics

– Hp: 1/12 – 2/5 – Speed: 2600 - 3300– Lubrication: permanently lubricated– Flange Size: 3⁄4‘” – 2”– Flow/Head: 130 Gpm/55’ TDH
CP3 – Flexibly Coupled, Horizontal Inline Pum

Item # Part name Definition

1 Casing The portion of the pump that includes the impeller chamber and volu

2 Impeller The bladed member of a rotating assembly of the pump, which imparts the principa

6 Shaft The cylindrical member on which the impeller is mounted and through which po

impeller

* Spring Coupling

24 Nut, impeller

A threaded piece used to fasten the impeller on the shaf

65 Seal, mechanical, stationary element

A sub assembly consisting of one or more parts mounted in or on a stuffing box and 

face

80 Seal, mechanical, rotating element

A device flexible mounted on a shaft in or on the stuffing box and having a smooth

the stationary sealing face

** Sleeve Bearing

*** Cotton Wicking

6

65 80

2 24 1 * ** ***
CP3 – Flexibly Coupled, Horizontal Inline Pum

 Typical Product Characteristics

– The “original” design– Hp: 1/12 – 1-1/2 – Speed: 1750 RPM– Lubrication: oil lubricated– Flange Size: 3⁄4‘” – 3”– Flow/Head: 200 GPM/55’ TDH
Common Applications

1. Hot Water (Hydronic) Heating2. Potable Hot Water Recirculation3. Solar Thermal4. Geothermal
EU Regulations

 EU research into circulator efficiency savings began in 1 EEI (energy efficiency index) developed and introduced  Lot 11 directive created in 2006.  First EEI level implemented in 2013  Only applies to standalone wet rotor circulators less tha
Energy Efficient Circulator Option

 European energy efficient circulator technology is becom

available today in U.S. but acceptance has been slow be

– U.S. hydronic heating installed base is much smaller than E– A very small portion of new homes in the U.S. use hydronic – U.S. hydronic systems typically only run for small portion o– Electricity in U.S. is less expensive– Cost of energy efficient circulators is nearly double traditio

circulators.
Questions