The wait for hot water at a far bathroom is not a water heater problem. The heater is full of hot water; the pipe between it and the tap is full of cold. Every time you open the tap, that cold water has to run down the drain before the hot arrives, which in a large or long house can be a minute or more and several gallons. A recirculation system keeps hot water moving through the pipes so it is at or near the tap when you want it. This guide covers the two ways to do that, how the pump is controlled, what it costs in energy, what it costs installed, and how it works with tankless units, which have their own rules.
What hot water recirculation is
A small pump moves water slowly from the far end of the hot water piping back to the heater, so the hot line stays warm instead of cooling between uses. The pump is not there to add pressure; it is there to keep the loop from going cold. How the water gets back to the heater is the difference between the two system types.
| Dedicated return line | Crossover (under-sink) system | |
|---|---|---|
| How water returns | A separate return pipe from the farthest fixture back to the heater | A thermostatic crossover valve under the farthest sink lets hot bleed into the cold line until the hot arrives |
| Pump location | At the heater, on the return | At the heater (tank) or built into the crossover kit |
| Best fit | New construction or a remodel where the return can be run; the cleanest solution | Existing homes with no return line; most retrofits |
| Side effect | None | Cold tap at the far sink runs slightly warm for a moment; more noticeable in summer |
| Energy use | Lower with insulation and a timer | Similar; the cold line becomes part of the loop, so more pipe is kept warm |
| Installed with us | Quoted on site when a return exists or is being added | $649 tank systems; $899 tankless kit |
Why it matters
Three reasons, in the order people usually give them. Convenience: hot water in seconds at the far bathroom instead of a minute. Water: the gallons that run down the drain waiting are clean water and sewer charges, repeated many times a day. Comfort with tankless: on a tankless unit, the pipe wait is added to the unit’s own startup delay, and the cold-water sandwich, a slug of cold between two runs of hot, is more noticeable on long runs. A recirculation loop addresses all three. It also lets a household run a distant shower without leaving the tap open to warm, which is where much of the waste happens.
Pump controls: timer, smart, or demand
- Continuous. The pump runs all the time. Simplest, and the most wasteful, because the loop is kept hot at 3 am. We do not recommend it.
- Timer. The pump runs on a schedule you set, typically the morning and evening hours the house is busy. The usual choice, and what the $649 tank pump includes.
- Temperature and timer. A sensor stops the pump when the return line is already hot, so within the schedule it runs only as needed. Less energy than a plain timer.
- Smart or learning control. The pump learns usage patterns or is scheduled from a phone app. Useful for households with irregular hours.
- Demand (push button or motion). The pump runs only when you press a button at the fixture or a sensor sees you enter the room, and stops when the loop is hot. Lowest energy use; a short wait remains while the loop primes. Best for tankless units, which should not be short-cycled by a timer.
The energy trade-off
Recirculation moves heat out of the tank and into the pipes, and the pipes lose it to the house. A loop that runs on a timer during busy hours costs modestly more in gas or electricity than no loop; a loop that runs continuously through uninsulated pipe in a cold basement costs noticeably more. Three things keep the cost small: insulate the hot and return piping, run the pump on a timer or demand control rather than continuously, and keep the loop short. The Department of Energy lists recirculation among the ways to reduce hot water waste while noting the standby heat loss it adds, which is a fair summary. We do not quote a dollar figure because it depends on your pipe, your basement temperature and your schedule.
Wattson here. The honest way to think about recirculation: it trades a little energy for a lot of convenience and some water. On a timer, with insulated pipe, the trade is a good one for most families with a far bathroom. Running continuously in a cold basement, it is not. Set the schedule and insulate the pipe.
Required, recommended or optional
- Recirculation of any kind: Optional. Code does not require it in a house.
- For a fixture more than about 50 feet of pipe from the heater, or a wait over 30 seconds: Recommended.
- Pipe insulation on the hot and return lines when a loop is installed: Recommended.
- Timer or demand control rather than continuous operation: Recommended.
- Tankless compatibility, check valve placement and crossover location: Verify on site on site.
- Included
- Part of the option you chose.
- Required
- This condition must be corrected for the proposed installation to be safe and code-compliant.
- Recommended
- Not required for the heater to operate, but it improves protection or serviceability.
- Optional
- A comfort or protection upgrade. Your choice.
- Requires field verification
- Priced after a technician confirms the condition on site.
Tankless compatibility
A tankless unit heats water only when flow passes through it, and a recirculation pump creates flow. Two consequences. First, a plain pump on a timer can make the unit fire repeatedly for short periods, which wears the unit and wastes gas, so tankless recirculation needs either a unit with built-in recirculation logic or an external kit designed for it, usually with a small buffer and demand control. Second, some manufacturers void the warranty if a pump is installed in a way they do not approve. Many current tankless models include an internal pump and a crossover valve for the far sink; others accept an external kit. Our tankless recirculation kit at $899 covers the external pump and crossover for units without built-in recirculation. The tankless page and the tank vs tankless comparison cover the rest of the tankless decision.
What it costs with us
| Item | Installed price | Included in |
|---|---|---|
| Recirculation pump with timer, tank systems (crossover valve where no return line exists) | $649 | Not included |
| Tankless recirculation kit (external pump and crossover) | $899 | Not included |
| Dedicated return line piping | Quoted on site | Not included |
Both are available as adders in the quote builder or as a standalone service call on an existing heater. The gas tank page shows what each tier includes without recirculation.
What you can check yourself
- Time the wait at the farthest hot tap in the morning. Under 20 seconds and a loop is a luxury; over 45 and it is a real improvement.
- Look for an existing return line: a third pipe near the heater’s cold and hot connections, sometimes with a small pump already on it. Many older loops have pumps that failed years ago and were never noticed.
- Check for a 120V outlet within reach of the heater for the pump.
- Note whether the hot piping is insulated. Foam sleeves are inexpensive and make a loop cheaper to run.
- On a tankless unit, check the manual or model number for built-in recirculation before buying an external kit.
What we verify on site
We confirm the piping layout and whether a return exists, pick the pump and control that fit, place the crossover under the correct fixture (the farthest on the loop, not the nearest), install a check valve so the loop cannot flow backward through the cold line, set the timer to your household’s hours, and confirm the far tap is hot within the expected time. On tankless units we confirm manufacturer approval for the arrangement before installing. If you are also weighing capacity, the size calculator is a one-minute check, and the mixing valve guide covers the other common comfort upgrade.
Hot water at the far bathroom, on a schedule you set
Add a recirculation pump to a new installation or book it for your existing heater. Or call 844-792-8374, answered 24/7.
Common questions
How long should it take to get hot water at a faucet?
It depends on the length and diameter of pipe between the heater and the tap. A tap near the heater is hot in a few seconds; a far bathroom in a large home can take a minute or more. If your wait is over about 45 seconds, a recirculation loop makes a noticeable difference.
Does a recirculation pump increase my energy bill?
Somewhat. Keeping the loop warm loses heat through the pipe to the house. On a timer during busy hours, with insulated pipe, the increase is modest. Running continuously through bare pipe in a cold basement, it is larger. Demand controls that run the pump only when you ask reduce it further.
Can I add recirculation without a return line?
Yes. A crossover system uses a thermostatic valve under the farthest sink to let hot water bleed into the cold line until the hot arrives, so the cold line serves as the return. It is the standard retrofit and what the $649 tank pump uses. The cold tap at that sink runs slightly warm for a moment.
Will a recirculation pump work with a tankless water heater?
With the right arrangement. A pump creates flow, and flow fires a tankless unit, so a plain timer pump can short-cycle it. Use a tankless model with built-in recirculation or an external kit designed for tankless, which we install at $899, and confirm the manufacturer approves the setup.
Where is the pump installed?
For tank systems, on the hot outlet at the heater or on the return line, plugged into a nearby outlet, with the crossover valve under the farthest fixture. For tankless kits, per the manufacturer, usually at the unit. Either way the visit is a few hours.
Does recirculation wear out the water heater?
On a tank, no; the water is already hot and the pump adds little cycling. On a tankless unit, a poorly controlled pump can add many short firing cycles, which is why controls and manufacturer approval matter. Correctly installed, recirculation is a normal accessory on both.
