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Residential Circulator Pumps

Recirculation pumps are the answer to waiting (and waiting and waiting) for the hot water to arrive where you need it, and can also provide energy efficient heating for your home. These excellent quality pumps from Grundfos are economical, easy to install, low-maintenance and they save valuable resources, too! On this page you can view some "typical" hot water and hydronic heating system installation designs. We also have a guide to recirculating systems and some helpful FAQ's at the bottom of the page to help you find answers for many questions you may have.
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What is the difference between union mount and flange mount?

Grundfos UP Series Heating / Cooling Circulator Pumps - for Closed Systems

These Grundfos circulating pumps operate whisper quiet for sound sensitive applications. 3-speed pumps offer more flow rate flexibility than single speed pumps and are manually adjusted to the preferred speed by the user as needed. Speed adjustment of 3-speed pumps should not be done while the pump is in operation.

The UP and UPS series pumps are a canned rotor type. The motor and the pump are made as an integral unit without the need of a shaft seal and only two gaskets are used for sealing. The pump has a ceramic shaft and radial bearings with a carbon thrust bearing. The bearings are lubricated by the pumped liquid. Pumps housings are made in cast iron, bronze or stainless steel for use in appropriate liquids and water conditions. The impellers are made of a durable, corrosion resistant, PES (30% glass filled).

The maximum allowable liquid temperature of these pumps are determined by the ambient or surrounding air temperature around the pump. If any UP pump is equipped with a timer, the maximum liquid temperature is 150° F (66° C) even if the pump specifications show a higher temperature. The UP and UPS 25, 26, and 43 pump types can be used with chilled water due to their motor construction, which is suitable for 32° F (0° C) as long as the pump housings are compatible with the pumped liquids.

example of a Grundfos 3 speed circulating pumpUPS15-58FC

Cast iron pumps are excellent for use in radiant heating systems, hydronic baseboard or floor heating systems, fan coil heating systems, heat recovery/heat pump systems, geothermal heating systems, closed solar heating systems, air conditioning systems and other chilled water applications.

Grundfos cast iron pumps are intended for use in closed systems with potable or non-potable water, softened water or with a 50/50 mixture of water and propylene glycol. If water conditions exist that are not compatible with cast iron, then Grundfos recommends the use of a bronze or stainless steel pump. These can be installed in both vertical and horizontal lines.

For a new recirculation system setup, you will need a flange or union adapter set - sold separately below - to properly install your pump. If you are replacing an old Grundfos recirculating pump, you may not need new adapters.

Standard Flange Mount Pumps

Model # Description Flange Mount GPM @ 5' Phase Price for 115V Price for 230V
UP15-10F 1/25 HP Cast Iron Pump GF 15/26 1 1 speed $162.08 Not Available Enter a quantity and
UP 15-42F 1/25 HP Cast Iron Pump GF 15/26 15 1 speed $142.89 $149.63 Enter a quantity and
UP 26-64F 1/12 HP Cast Iron Pump GF 15/26 25 1 speed $349.31 $355.82 Enter a quantity and
UP 26-96F 1/12 HP Cast Iron Pump GF 15/26 21 1 speed Not Available $371.89 Enter a quantity and
UP 26-99F 1/6 HP Cast Iron Pump GF 15/26 30 1 speed $373.81 $379.99 Enter a quantity and
UP26-116F 1/6 HP Cast Iron Pump GF 15/26 35 1 speed Not Available $396.76 Enter a quantity and
UP 43-75F 1/6 HP Cast Iron Pump GF 40/43 39 1 speed $451.85 $457.77 Enter a quantity and
UPS15-58FC 1/25 HP Cast Iron Pump GF 15/26 5/10/15 3 speed $144.33 Not Available Enter a quantity and
UPS26-99FC 1/6 HP Cast Iron Pump GF 15/26 13/21/28 3 speed $401.25 Not Available Enter a quantity and

Rotated Flange Mount Pumps

Model # Description Flange Mount GPM @ 5' Phase Price for 115V Price for 230V
UP15-10FR 1/25 HP Cast Iron Pump GF 15/26 1 1 speed $161.07 Not Available Enter a quantity and
UP 15-42FR 1/25 HP Cast Iron Pump GF 15/26 15 1 speed $154.50 $168.07 Enter a quantity and
UPS15-58FRC 1/25 HP Cast Iron Pump GF 15/26 5/10/15 3 speed $156.78 Not Available Enter a quantity and

Union Mount Pumps

Model # Description Flange Mount GPM @ 5' Phase Price for 115V Price for 230V
UP26-120U 1/6 HP Cast Iron Pump GU 125 18 1 speed $383.08 $389.97 Enter a quantity and
Timer Control fits any 1 speed UP 115V pump
Note: Click here to see timer installation info and specs.
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Grundfos UP Series Hot Water Circulator Pumps - for Open Systems

Grundfos Bronze and Stainless Steel circulating pumps are used for hot water recirculation and open systems because these materials are not effected by air and oxygen released into these types of systems through the constant introduction of fresh water. They're made for whisper quiet operation for sound sensitive conditions. These pumps are of the canned-rotor type, i.e. pump and motor form an integral unit without shaft seal and with only two gaskets for sealing which helps to extend pump life by keeping foreign debris out. The bearings are lubricated by the pumped liquid.

The maximum temperature of liquids to be used with these pumps will vary by pump and the maximum liquid temperature will be directly effected by the ambient or surrounding air temperature around the pump. If a UP pump is equipped with a timer, then the maximum allowable liquid temperature is 150°F (66°C). The Grundfos UP and UPS pump types 25, 26, 43,and 50, can be used with chilled water because their motor construction is suitable for temperatures as low as 32°F (0°C) as long as the pump housings are compatible with the pumped liquids.

3-speed pumps are adjusted manually by the user to the preferred speed as needed offering more flow rate flexibility than single speed pumps. Speed adjustment should not be done while pumps are in operation.

Grundfos pump UP 15-18SUUP 15-29SU

Variable speed and mixing-reset control pumps are used to customize heating systems to increase user comfort. Variable speed pumps can be set for variable speed operation or can be set manually to operate at one speed. The motor output can be set to run at a variable speed by either voltage or current. The motor output is set by adjusting 4 switches (called "dip switches") located on the pump, in a predetermined sequence by the manufacturer, to control by Voltage: 0-10V(DC) or 2-10V(DC); Current: 0-20mA or 4-20 mA.

These pumps are excellent for open solar heating systems, domestic hot water recirculation, and circulation of liquid in cooling and air conditioning systems. Grundfos bronze and stainless steel pumps are manufactured for use with potable or non-potable water, softened water or with a 50/50 mixture of water and propylene glycol. These pumps can be installed in both horizontal or vertical piping installations.

For a new recirculation system setup, you will need a flange or union adapter set - sold separately below - to properly install your pump. If you are replacing an old Grundfos recirculating pump, you may not need new adapters.

Stainless Steel Union Mount (GU 125) Pumps

Our Most Popular Models - union adapter sold separately
Model # Description GPM @ 5' Phase Price for 115V Price for 230V
UP 15-29SU 1/12 HP Pump ONLY 6 1 speed $282.38 $302.55 Enter a quantity and
UP 15-29SU/LC 1/12 HP Pump with Line Cord 6 1 speed $295.54 Not Available Enter a quantity and
UP 15-29SUC/TLC 1/12 HP Pump with Timer & Line Cord 6 1 speed $381.82 Not Available Enter a quantity and
UPS 15-35SUC 1/15 HP Pump ONLY 2.5/5/9 3 speed $322.28 Not Available Enter a quantity and
UPS 15-35SUC/TLC 1/15 HP Pump with Timer & Line Cord 2.5/5/9 3 speed $519.35 Not Available Enter a quantity and
UPS 15-55SUC 1/12 HP Pump ONLY 5/10/14 3 speed $528.53 Not Available Enter a quantity and
UPS 15-55SUC/TLC 1/12 HP Pump with Timer & Line Cord 5/10/14 3 speed $578.88 Not Available Enter a quantity and
Timer Control fits any 1 speed UP 115V pump
Note: Click here to see timer installation info and specs.
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Stainless Steel Flange Mount (GF 15/26) Pumps

Model # Description GPM @ 5' Phase Price for 115V Price for 230V
UP 15-29SF 1/25 HP Stainless Steel Pump 6 1 speed $281.97 Not Available Enter a quantity and
UP 26-96SF 1/12 HP Stainless Steel Pump 16 1 speed $557.90 $563.38 Enter a quantity and
UP 26-99SF 1/6 HP Stainless Steel Pump 27 1 speed $585.70 $590.81 Enter a quantity and
UPS 15-35SFC 1/25 HP Stainless Steel Pump 2.5/5/9 3 speed $321.61 Not Available Enter a quantity and
UPS 15-55SFC 1/12 HP Stainless Steel Pump 5/10/14 3 speed $485.74 Not Available Enter a quantity and
Timer Control fits any 1 speed UP 115V pump
Note: Click here to see timer installation info and specs.
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Bronze Sweat Mount Pumps - 1/2" Copper Pipe

Model # Description GPM @ 5' Phase Price for 115V Price for 230V
UP 15-10 B5 1/25 HP Bronze Pump ONLY 1 1 speed $330.19 Not Available Enter a quantity and
UP 15-10 B5/LC 1/25 HP Bronze Pump with Line Cord 1 1 speed $351.06 Not Available Enter a quantity and
UP 15-10 B5/TLC 1/25 HP Bronze Pump with Timer & Line Cord 1 1 speed $427.67 Not Available Enter a quantity and
UP 15-18 B5 1/25 HP Bronze Pump ONLY 7 1 speed $330.90 $336.60 Enter a quantity and
UP 15-18 B5/LC 1/25 HP Bronze Pump with Line Cord 7 1 speed $349.68 Not Available Enter a quantity and
UP 15-18 B5/TLC 1/25 HP Bronze Pump with Timer & Line Cord 7 1 speed $441.95 Not Available Enter a quantity and
UP 15-42 B5 1/25 HP Bronze Pump ONLY 9 1 speed $449.09 $457.96 Enter a quantity and
with Integral Check Valve
UP 15-10 BUC5 1/25 HP Bronze Pump ONLY 1 1 speed $369.70 Not Available Enter a quantity and
UP 15-10 BUC5/LC 1/25 HP Bronze Pump with Line Cord 1 1 speed $364.27 Not Available Enter a quantity and
UP 15-10 BUC5/TLC 1/25 HP Bronze Pump with Timer & Line Cord 1 1 speed $473.29 Not Available Enter a quantity and
UP 15-18 BUC5 1/25 HP Bronze Pump ONLY 7 1 speed $370.86 Not Available Enter a quantity and
UP 15-42 BUC5 1/25 HP Bronze Pump ONLY 9 1 speed $488.76 Not Available Enter a quantity and
Timer Control fits any 1 speed UP 115V pump
59.54-43 1/2" Copper Clip-On Thermostat Control (85°F - 105°F, not adjustable) $37.75
Note: Thermostats are somewhat (but not perfectly) temperature accurate. Click here to see the timer and thermostat install info and specs. We do not recommend ordering thermostats for use with Line Cord models - click here to learn why.
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Bronze Sweat Mount Pumps - 3/4" Copper Pipe

Model # Description GPM @ 5' Phase Price for 115V Price for 230V
UP 15-10 B7 1/25 HP Bronze Pump ONLY 1.5 1 speed $349.10 Not Available Enter a quantity and
UP 15-18 B7 1/25 HP Bronze Pump ONLY 7 1 speed $350.06 $357.06 Enter a quantity and
UP 15-42 B7 1/25 HP Bronze Pump ONLY 9 1 speed $450.57 $454.88 Enter a quantity and
with Integral Check Valve
UP 15-10 BUC7 1/25 HP Bronze Pump ONLY 1 1 speed $379.40 Not Available Enter a quantity and
UP 15-10 BUC7-LC 1/25 HP Bronze Pump with Line Cord 1 1 speed $391.81 Not Available Enter a quantity and
UP 15-10 BUC7-TLC 1/25 HP Bronze Pump with Timer & Line Cord 1 1 speed $471.97 Not Available Enter a quantity and
UP 15-18 BUC7 1/25 HP Bronze Pump ONLY 7 1 speed $380.28 Not Available Enter a quantity and
UP 15-42 BUC7 1/25 HP Bronze Pump ONLY 9 1 speed $495.60 Not Available Enter a quantity and
Timer Control fits any 1 speed UP 115V pump
59.54-44 3/4" Copper Clip-On Thermostat Control (85°F - 105°F, not adjustable) $41.69
Note: Thermostats are somewhat (but not perfectly) temperature accurate. Click here to see the timer and thermostat install info and specs. We do not recommend ordering thermostats for use with Line Cord models - click here to learn why.
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Grundfos Dielectric Flange Adapters with Isolation Valves

Image of Dielectric Flanges with Isolation Valves
  • Can be used with cast iron, bronze, or stainless steel recirculating pumps that have GF 15/26 connections
  • Isolation valves shut-off water supply at the site so the pump can be removed from the system or serviced without turning off the main water supply
  • Safe for use with potable water systems
  • For new installations, 1 complete set required per pump (flange adapters may not be needed if replacing existing pump)
  • Each set includes:
    • 2 - rotating flanges
    • 2 - lever handle full ported ball valves
    • 2 - EPDM gaskets
    • 2 - dielectric sleeves
    • 4 - 7/16" x 1-3/4" bolts with nuts
NPT Dielectric Flange & Isolation Valve Set
Solder Dielectric Flange & Isolation Valve Set
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Grundfos Flange Adapter Sets

NPT Cast Iron Flange Set for use with cast iron pumps
  • Sets available for cast iron, bronze, or stainless steel pumps in a variety of pump connection sizes and pipe sizes
  • Safe for use with potable water systems
  • For new installations, 1 complete set required per pump (flange adapters may not be needed if replacing existing pump)
  • Each set includes:
    • 2 - flanges
    • 2 - gaskets
    • 4 - 7/16" x 1-1/2" bolts with nuts
NPT Flange Adapter Set
for Cast Iron Pumps
NPT Flange Adapter Set
for Bronze & Stainless Steel Pumps
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Grundfos Bronze Union Adapter Options

Image of Grundfos 519852 Bronze Isolation Valve-FIPS- Union Set
  • Designed for use with Grundfos cast iron, bronze, or stainless steel recirculating pumps that use GU 125 union connections
  • Safe for use with potable water systems
  • For new installations, 1 complete set required per pump (union adapters may not be needed if replacing existing pump)
  • Each set includes:
    • 2 - standard unions OR 2 - isolation valve unions with screwdriver stops
    • 2 - gaskets
Bronze Union Adapter Sets
Part # Description Pipe Size Pump Connection Price & Quantity
529912 NPT Bronze Union Set 3/4" FIPS GU 125 Union $39.48 Enter a quantity and
529913 Solder Bronze Union Set 1/2" sweat GU 125 Union $33.74 Enter a quantity and
529911 Solder Bronze Union Set 3/4" sweat GU 125 Union $32.79 Enter a quantity and
519850 NPT Bronze Isolation Valve Union Set 1/2" FIPS GU 125 Union $44.47 Enter a quantity and
519852 NPT Bronze Isolation Valve Union Set 3/4" FIPS GU 125 Union $44.29 Enter a quantity and
519851 Compression Bronze Isolation Valve Set 3/4" Nominal (7/8" OD) GU 125 Union $44.48 Enter a quantity and

Related Items & Accessories



Frequently Asked Questions

Q. "Does a hot water recirculating system use up a lot of energy?"
A. Both options use energy. But not as much as most people think. On the recirculating system we highly recommend insulating all of your hot water pipes. Also having a timer and/or a thermostat will use even less energy. An electric tankless water heater doesn't use any energy when you're not drawing hot water.

Q. "Is the thermostat adjustable?"
A. The thermostatic control automatically turns the circulator off when the temperature exceeds approximately 105°F and back on when the temperature drops below approximately 85°F. The thermostat is not adjustable. You can click here to read more info about the thermostat.

Q. "Your timer seems expensive. Is it necessary?"
A. Most three-prong wall timers should work, but Grundfos makes a fantastic timer for their most popular model (#UP15-18SU). It can be set in 15-minute increments, mounts right onto the pump, and is the best timer we have ever seen. You can click here to read more info about the timer.

Q. "On your cast iron pumps you say that they are only for a closed system. What is a 'closed system'?"
A. A closed system is a recirculation loop for water (or other liquid) where once it is set up and running, no new liquid is introduced into the system. If new liquid is brought into the system it will bring air with it and over time this will rust out a cast iron pump.

Q. "Why don't you recommend ordering thermostats with the line cord pumps?"
A. Due to these pumps being pre-wired, they would require re-wiring in order to use the thermostats, so we recommend you purchase the pump, thermostat and timer separately when you want to use a thermostat.

Q. "Why do I need flanges/unions?"
A. The threads on the pumps are designed to attach only to the flanges or unions. There are many different sizes and types of pipe. Using flanges/unions means they don't have to make a different pump for every different size & type of pipe.

Q. "I am purchasing a replacement Grundfos pump. Next to the pump it states: 'one set required.' Must I (am I required to) order flanges/unions along with the pump or can I just order the pump?"
A. If it is an identical replacement Grundfos pump you certainly don't need to purchase flanges/unions again. The ones that you currently have "should" fit fine.

Q. "How is the quality of a Grundfos brand pump?"
A. We know of no finer made pump. Having said that we do want you to realize that every pump has a specific function. Meaning, for example, a circulating cast iron pump isn't generally for domestic drinking water. Every pump also has a specific flow rate, etc. so please don't assume that you can simply order the lowest priced Grundfos pump and that it will work for your situation. Grundfos is top quality but recognize that a $20,000 bicycle might not go as fast as a $15,000 car.

Q. "On your flanges/unions, what does 'ISO' mean?"
A. The ISO (isolation) flanges have a screwdriver shut-off built into them so the pump can be removed from the system without turning off the water supply.

Q. "Which pump would you recommend for most residential recirculation systems?"
A. Our most popular unit is the #UP 15-29SU (formerly the #UP15-18SU). It's a very quiet unit and uses less electricity than most light bulbs (65 watts!). For even more savings you can also incorporate a timer and/or thermostat.

Q. "You offer/show such a great selection and since I need the pump right away am worried that it won't ship right after I order it. How's your inventory on these?"
A. Over 95% of the pumps are always in stock and ship within 24 hours of us receiving your order (Mon-Fri).

Q. "What is the benefit of installing an optional timer or thermostat?"
A. Either one will save energy (and money). The timer only allows the pump to turn on at certain times. So if you only need hot water in the morning, you could set the timer for 6am to 8am. Then the pump would only recirculate the hot water during that time. The thermostat turns off the pump when the water in the pipes reaches a certain temperature. So once the water in the pipe is hot, the pump turns off. When the timer and thermostatic controls are installed together, in series, the circulator operates ONLY at the preset clock times specified by the user AND ONLY when the temperature conditions of the thermostat are met. That is, if either the timer control or the thermostatic control switch is open (off), the circulator will not operate.

Q. "What else would I need to install a hot water recirculation system?"
A. You'll need the pump and flanges/unions of course; a swing check valve, and pipe and pipe fittings to run the return line back to the pump. A timer and/or thermostat are optional. (click here for instructions and more info on these).

Q. "Are the Grundfos stainless steel pumps specified for potable hot water?"
A. Absolutely. They are an excellent choice for drinking water.

Q. "I want to install a hot water circulation loop so that I can get hot water quickly at my taps. My problem is that I have to pump it up about 20 feet and I only have 40 psi. Will a 1/2" return line work ok?"
A. You could even use 3/8" on the return line (after the last fixture). Best to go with 1/2" but there is no reason to use 3/4" pipe. When your system is entirely under pressure, while the Grundfos pump is "pushing" up, the water is also "dropping" down. Just make sure to get rid of ALL of air in your return line and design your system so that no air will be in your line.

Typical hot water system before a recirculation pump.

Common recirculation pump installation.

Close-Up of pump installation.

Notes on installation:

Now that you're going to have hot water in your pipes all the time we strongly recommend insulating your hot water pipes as well as the return line to avoid stand-by heat loss.

A 2" clearance should be kept between the hot and cold water lines.

Branches off of the main hot water supply should be kept as short as possible.

Local codes may require the installation of a hot water expansion tank for secondary pressure relief on cold water supply lines with check valves.

The pump should be installed with the motor shaft horizontal.

It is very important that there is no trapped air in the pipe or the pump. Unless you have extremely oversized the pump (which wastes a lot of energy), trapped air in the return line can damage the recirculation pump. With these Grundfos recirculating pumps, air removal from the pump can be accomplished by releasing air from the chrome slotted plug located on the front of the pump. IMPORTANT: This chrome plug must NOT be removed. This chrome slotted plug is to release air from the pump only, not from the entire circulation piping system. After the system is charged with water make sure the power to the pump is turned off. Position a bucket under the pump because water will begin to stream from the plug as the air is released. Slowly unscrew the chrome slotted plug counter clockwise, until small bubbles of air and water appear. As soon as tiny bubbles or water appear, stop unscrewing the chrome plug any further. Allow all the air to escape. When only water streams slowly out of the pump then you will know the air has been purged. Tighten the chrome slotted plug clockwise. To prevent air from collecting in the return line, slope all the pipes so air will flow to the high point in the return line and then put an air vent there so you can release the air periodically.

The return line can be installed either under the floor or in the ceiling.


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