Best hot water recirculation pump: the makers' own manuals compared, and the three things every crossover kit admits in print
Watts' 500800 manual prints 120 VAC, a 15-minute timer, a 140 F maximum and not for tankless; Taco's Hot-LinkPlus-e prints 44 W max. Who should skip both.
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OwnerSpec compares published manufacturer specifications, certification listings and sourced technical documents. Unless a page explicitly states otherwise, OwnerSpec has not laboratory-tested or used the products it compares. Editorial policy
Short answer
For a tank water heater with no return line, the pick is the Watts 500800, because it is the one recirculation kit whose maker prints the whole spec: the IOM-WQ-500800 manual lists a pump made by Grundfos, 120 VAC at 60 Hz, a 24-hour timer switching in 15-minute increments, a 140 F operating maximum, a UL classification to ANSI/NSF 61 and 372, a cord to a grounded outlet at the heater and a 1-year warranty. The runner-up is the Taco Hot-LinkPlus-e, whose page prints a 44 W maximum, 0–11 GPM, 0–13 ft of head and a controller that learns a 7-day pattern instead of a dial. Both makers say the same three things in writing: not for tankless heaters, warm water in the cold line is by design, and the pump runs 24/7 if the switch is left on ON. Skip every pump here if the wait-time calculator puts less than 0.5 gallons in your pipe, EPA’s WaterSense benchmark.
The picks
A tank heater, no return line, and a routine the timer tabs can follow
Watts 500800 hot water recirculation system with 24-hour timer (0955800)
Watts IOM-WQ-500800: pump made by Grundfos, 120 VAC 60 Hz, 24-hour timer in 15-minute increments with OFF, TIMER and ON modes, a cord to a grounded 115 V outlet at the heater, 140 F maximum operating temperature, UL classified to ANSI/NSF 61 and 372, not for tankless heaters, 1-year warranty
A tank heater, no return line, and no wish to program a dial
Taco Hot-LinkPlus-e ECM instant hot water system (HLPe-1)
Taco's product page: ECM motor, 44 W maximum operating power, 0.54 A, 120 V 60 Hz, 0–11 GPM, 0–13 ft head, 150 psi, 203 F maximum water temperature, 3/4 in NPT union, 6 ft cord, SmartPlug with Smart (7-day learning), Pulse (5 minutes on, 10 off) and Vacation (after 36 hours) modes
No outlet at the heater, but one under the far sink
A. O. Smith APCOM UT1 under-sink instant hot water system (kit 100306289)
APCOM's page and dontwaitforhotwater.com: installs under the sink with no pipe cutting, stainless steel pump, for a standard tank or indirect heater on a single-pipe system, pipe runs up to 250 ft, needs an outlet at the sink; no wattage, listing mark or warranty term is printed on either page
If hot water reaches the tap before you have finished filling a glass, this page is not for you: run the hot water wait-time calculator first, and under 0.5 gallons in the pipe insulate the run instead.
How was this shortlist built?
Every figure on this page is a manufacturer’s published specification, read on 2026-09-27 from the manual or page named beside it. Nothing was installed or run by this site. Listings were shortlisted from current Amazon listings, kept or rejected on the maker’s document, and confirmed buyable the same day.
The units were compared on return type, control, voltage and maximum power, flow and head where printed, lead-content certification where printed, maximum water temperature, the tank-or-tankless statement, where the outlet has to be, and warranty term.
Two names from the brief are missing on purpose. Grundfos’ current pages describe an ALPHA Comfort System for homes without a return line and repeat a “12,000 gallons” per year claim, but every Grundfos product URL tried on 2026-09-27 returned 404, so no Grundfos model has a spec here. Laing’s AutoCirc and Taco’s older Hot-Link HLS were listed scarce or under a different model number from the maker page, so neither is a pick.
The recirculation guide explains the four families; this page puts named units against three of them.
How do the units compare on paper?
Manufacturer figures. “Not printed” means the cited document carries no value.
| Unit | Return type | Control | Power | Flow and head | Materials or listing printed | Tankless | Outlet |
|---|---|---|---|---|---|---|---|
| Watts 500800 | Crossover valve under the far sink, pump at the heater | 24-hour mechanical timer, 15-minute tabs, OFF / TIMER / ON | 120 VAC 60 Hz; “less than a 25 watt light bulb” (product page); no wattage printed | Not printed | UL classified to ANSI/NSF 61 and ANSI/NSF 372 (pump and valve); adapters marked lead free; 140 F maximum | “Does not work with tankless water heaters” | At the heater, grounded 115 V |
| Taco Hot-LinkPlus-e HLPe-1 | Crossover (bypass valve), pump at the heater; “no dedicated hot water return line is needed” | SmartPlug: Smart (7-day learning), Pulse (5 min on / 10 off), Vacation (36 h) | 120 V 60 Hz, 44 W maximum, 0.54 A, ECM | 0–11 GPM, 0–13 ft, 150 psi | 3/4 in NPT union; 203 F maximum water; no listing mark or lead statement printed | Page names tank water heaters only; no tankless statement | At the heater, 6 ft cord |
| Taco Hot-Link HLS-2 (maker page; Amazon lists the HLS-1) | Crossover, pump at the heater | Analog clock timer, peak hours or continuous | 115 V 60 Hz, 1/40 HP, 0.52 A maximum | Not printed | cULus badge on the page; valve 220 F maximum, 125 psi | Knowledge base: the valve “can Not be used with a Tankless Water Heater” | At the heater |
| A. O. Smith APCOM UT1 | Under-sink pump, cold line as return | “Fully automatic” (APCOM); no timer or thermostat detail printed | Not printed | Not printed; runs up to 250 ft | Stainless steel pump; no listing mark printed | For a standard tank or indirect heater | Under the sink |
Watts 500800: buy it or skip it?
Buy it if the heater is a tank, there is a grounded outlet near it, and your mornings repeat. Watts’ IOM-WQ-500800 manual prints 120 VAC at 60 Hz, a 24-hour programming ring with quarter-hour tabs, three switch positions (OFF, TIMER and ON), a 140 F operating maximum and a 1-year limited warranty. The cover carries the UL classification MH26400 for the pump and Comfort Valve to ANSI/NSF 61 and ANSI/NSF 372, and names Grundfos Pumps as the manufacturer of the pump.
The flaw is in the same manual, twice. The cover says “this is not an anti-scald device. You may have some warm water in your cold water line under the sink where the valve is installed.” The troubleshooting table lists hot water in the cold supply as problem 4, with the first cause being the manual switch “set to ‘ON’ which will cause it to run 24/7”.
Watts prints no flow rate and no wattage anywhere; the product page’s only energy sentence is “uses less energy than a 25 watt light bulb”, and its “saves up to 12,000 gallons per year” comes with no method. Both are Watts’ claims, not measured figures.
Skip it on a tankless heater: the manual’s first warning is that the system “does not work with tankless water heaters”. Skip it if a warm cold tap at one sink is a deal-breaker.
Taco Hot-LinkPlus-e: buy it or skip it?
Buy it if you want the pump to work out the schedule. Taco’s page prints an ECM motor with a 44 W maximum operating power at 0.54 A, 120 V 60 Hz, 0–11 GPM, 0–13 ft of head, 150 psi and 203 F maximum water temperature, a 3/4 in NPT union, a 6 ft cord and flex hoses. The SmartPlug has three modes: Smart learns 7 days of usage, Pulse runs 5 minutes on and 10 off, and Vacation shuts the pump down after 36 hours without a draw, exercising it for 10 seconds every 7 days.
The flaw is what the page leaves out. It prints no listing mark, no lead-content statement and no warranty term for the HLPe-1, where the older Hot-Link HLS-2 page shows a cULus badge. Taco’s “up to 85% less electricity” claim names no comparison pump. And the bypass valve is the same idea as Watts’: Taco’s knowledge base answers “why is my hot water coming out of the cold water line?” for this family.
Skip it on a tankless heater. Taco’s knowledge base says the Hot-Link valve “can Not be used with a Tankless Water Heater. It does not allow enough flow through the valve to activate the Tankless Heater.”
A. O. Smith UT1: buy it or skip it?
Buy it if the only outlet is under the far sink. APCOM’s page lists the UT1 as kit 100306289, a stainless steel undersink system with all fittings, and its distributor page adds that it installs under the sink with no pipe cutting, suits a standard tank or indirect heater on a single-pipe system, handles runs up to 250 ft, and requires an electrical outlet at the sink.
The flaw is documentation. Neither APCOM page prints a wattage, a flow rate, a listing mark, a lead-content statement or a warranty term, and the Amazon listing is the only place a thermostat and timer are described. A pump under the sink also uses the cold line as its return, so the warm cold tap applies here too.
Skip it if the heater has an outlet beside it: the Watts and Taco kits put the pump and its noise at the tank, not under the kitchen sink.
Measure the pipe before you buy a pump
Do not buy any of these until the wait-time calculator has your number. EPA’s WaterSense guide recommends no more than 0.5 gallons stored between the heater and any fixture; a 2.5 gpm shower clears 0.5 gallons in 12 seconds, and that run wants insulation, not a pump. Over it, on a tank heater with an outlet at the tank, the Watts 500800 is the kit with the manual to match. If the heater is tankless, close this page and read the recirculation guide: the fix lives inside the heater.
What goes wrong?
The switch stays on ON. Watts’ manual states that the ON position is “continuous operation” and lists it as the first cause of hot water in the cold line. EPA’s hot water delivery guide says timer- and temperature-based systems “can increase energy use due to frequent use of the recirculation pump”, and rates demand-initiated systems, started by a button or motion sensor, as the more energy-efficient kind. Watts’ own advice is to set the tabs from 30 minutes before the first shower to 15 minutes after the last.
The valve fails warm. Watts’ test: close the cold angle stop, open the cold faucet, wait about a minute for a drip; if the water is above 100 F, replace the valve. The replacement is Watts’ own sensor valve , not a new pump.
The power goes out. Watts’ manual says the timer does not keep time through an outage, so the ring has to be reset to the current time or the pump runs on the wrong hours.
The outlet is wrong. Watts requires a grounded receptacle wired to the National Electrical Code, and says to route the cord away from the flue of a gas or oil heater. A new receptacle at the tank or under a sink is electrician work, and codes are adopted locally and vary.
The cold tap runs warm. Every kit on this page uses the cold line as the return. EPA’s guide calls that a convenient retrofit that “may not achieve the same efficiency or performance of dedicated returns”. If the house has a return pipe, buy a circulator sized to it and skip the crossover valve altogether.
Frequently asked questions
Why is my cold tap warm after installing a recirculation pump?
Because a crossover kit uses the cold pipe as its return. Watts' 500800 manual says so on its cover: it is not an anti-scald device and you may have some warm water in the cold line under the sink where the valve is installed. Its troubleshooting table adds that the timer switch left on ON runs the pump 24/7 and is a cause of hot water in the cold supply.
Can I use a Watts 500800 or Taco Hot-Link with a tankless water heater?
No. Watts' manual opens with the warning that the 500800 does not work with tankless water heaters, and its product page repeats it. Taco's knowledge base says the Hot-Link valve cannot be used with a tankless heater because it does not pass enough flow to activate it. Tankless makers sell their own built-in pumps and bypass valves; the recirculation guide covers those.
Does a recirculation pump cost a lot to run?
The makers print small figures: Watts says the 500800 uses less energy than a 25 watt light bulb, and Taco prints a 44 W maximum for the Hot-LinkPlus-e. The larger cost is the heater. EPA's hot water delivery guide says timer- and temperature-based systems can increase energy use because the pump runs often to hold the loop hot, and rates demand-initiated systems as the more efficient kind.
Do I need an electrical outlet for a recirculation pump?
Yes, and where it sits decides the kit. Watts' 500800 plugs its cord into a grounded 115 V outlet at the water heater and needs no electricity under the sink. The A. O. Smith UT1 is the reverse: the pump sits under the far sink and needs an outlet there. A new receptacle is electrician work under the National Electrical Code.
How do I know if the crossover valve has failed?
Watts' troubleshooting table gives the test. Close the cold angle stop under the sink, open the cold faucet, and wait about a minute for the flow to slow to a drip. If it does not, check the water: it should be around 90 F plus or minus 4, and Watts says to replace the valve if it is above 100 F. Watts sells the sensor valve on its own.
Fact sheet and how to cite this page
- Answer
- For a tank heater with no return line, the Watts 500800 is the documented pick: its IOM-WQ-500800 manual prints 120 VAC, a 24-hour timer in 15-minute increments, a 140 F operating maximum and a UL classification to ANSI/NSF 61 and 372. The Taco Hot-LinkPlus-e is the runner-up at a maker-printed 44 W maximum. Neither works on a tankless heater by its maker’s own statement.
- Comparison basis
- Manufacturer-published installation manuals and product pages: return type (crossover valve on the cold line, under-sink pump, or dedicated return), control (mechanical timer, learning controller, thermostat), voltage and maximum power, flow and head where printed, materials and lead-content certification where printed, maximum water temperature, tank or tankless statements, cord length and outlet location, and warranty term.
- Assumptions
- A single-family house with one storage water heater and no dedicated return pipe, which is the retrofit every kit on this page is sold for
- The reader has timed the wait with the wait-time calculator; EPA’s WaterSense guide recommends no more than 0.5 gallons stored between the heater and any fixture, and under that volume insulation is the answer, not a pump
- Grundfos’ current Comfort System literature could not be opened on 2026-09-27: grundfos.com and its product-selection site returned 404 for every product URL tried, so no Grundfos model is compared on specification
- Method
- OwnerSpec read the Watts IOM-WQ-500800 manual and 500800 product page, Taco’s Hot-Link, Hot-LinkPlus-e and knowledge-base pages, APCOM’s recirculation page and dontwaitforhotwater.com, and EPA’s Best Practices for Efficient Hot Water Delivery in Homes on 2026-09-27, and confirmed each listing buyable the same day; it did not install, run or test any pump.
- Primary source
- Watts, Installation and Operation Manual, Hot Water Recirculation System Model 500800 (IOM-WQ-500800, PDF) (manufacturer or vendor document)
- Facts verified
- Last updated
- Cite as
- OwnerSpec, "Best hot water recirculation pump: the makers' own manuals compared, and the three things every crossover kit admits in print", https://ownerspec.com/plumbing/reviews/best-hot-water-recirculation-pump/, facts verified 27 September 2026.
Every figure above also appears, with its source, in the article. All sources · How OwnerSpec verifies numbers
Sources
- Watts, Installation and Operation Manual, Hot Water Recirculation System Model 500800 (IOM-WQ-500800, PDF) (manufacturer or vendor document)
- Watts, Hot Water Recirculating Systems, Model 500800 product page (manufacturer or vendor document)
- Taco Comfort Solutions, Hot-LinkPlus-e ECM High Efficiency Instant Hot Water System (HLPe-1) (manufacturer or vendor document)
- Taco Comfort Solutions, Hot-Link System (HLS-2) product page (manufacturer or vendor document)
- Taco Comfort Solutions, Knowledge Base: Residential Circulators (Hot-Link valve FAQ) (manufacturer or vendor document)
- APCOM (A. O. Smith), Recirculation Systems (manufacturer or vendor document)
- APCOM, Don't Wait For Hot Water, distributor page (UT1 kit 100306289) (manufacturer or vendor document)
- EPA WaterSense, Best Practices for Efficient Hot Water Delivery in Homes (PDF, 2026), section 3.1.4 Recirculation Systems (government or regulatory source)
- Grundfos, Give homeowners the efficiency and comfort of instant hot water (manufacturer or vendor document)