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Hot Water · RecirculationHot Water Recirculation Pump Installation
Hot water recirculation pump installation ends the wait at the far tap by keeping hot water moving through the pipes instead of letting it cool there. There are two ways to do it: a dedicated return line back to the heater, or a retrofit crossover valve under the farthest sink that borrows the cold line as the return. Choose the return line when the piping is exposed and the crossover when the walls are finished, and put the pump on a timer, aquastat or demand button so it runs minutes a day, not all day.
The wait is plumbing geometry: when a hot tap closes, the water left in the line cools, and the next person has to push all of it out before heated water arrives. In a 2000s two-storey with the mechanical room at one end of the basement and the ensuite at the opposite corner upstairs, that is a long run of pipe. A recirculation pump replaces that cooled water before anyone opens the tap. How the water gets back to the heater is the design decision.
A dedicated return line is a third pipe from the end of the hot line back to the heater, with the pump and a check valve on it near the tank. Every fixture along the loop gets hot water quickly and the cold line stays cold, but the pipe has to be run, so it suits an open basement ceiling under a bungalow or a renovation with the walls open. The retrofit uses a thermostatic crossover valve under the farthest sink instead: the pump pushes cooled hot water through the valve into the cold line until the valve senses warmth and closes. No pipe goes into finished walls, and the trade is a cold tap at that sink that runs lukewarm for a few seconds.
Left running around the clock, a recirculation loop is a radiator: the heater keeps reheating water that loses its heat through the pipe walls. Controls limit that penalty: a timer runs the pump for the morning and evening blocks, an aquastat stops it once the return reaches temperature, and an on-demand button or motion sensor runs it only when someone is about to use hot water. We insulate the accessible loop piping and use a bronze or stainless pump rated for drinking water, never a cast-iron heating circulator. The recirculation pump glossary entry defines the terms.
Tankless heaters need more care, because a tankless fires only above a minimum flow and a small comfort pump may not trigger it. Some models are built for recirculation: Navien's NPE-A series carries its own pump and a small buffer tank, and Rinnai's RUR models include a pump and can work with a crossover valve. A tankless without those features needs an external pump, a control that limits run time, and often a small buffer tank so the burner is not short-cycling all day. We read the model's installation manual before quoting, since an unsupported loop can shorten the heat exchanger's life; the units themselves are on our tankless water heater page.
A recirculation pump is worth installing when
- The far bathroom or kitchen takes a minute or more to run hot, every time
- The basement ceiling is open or a renovation has the walls open, so a return line can go in without drywall repair
- The house is on a private well or a septic bed, where every litre run to drain while waiting has a cost
- You are already replacing the water heater, so the pump, check valve and outlet can be done in the same visit
- A tankless unit went in and the wait got longer, because the burner has to light before the pipe even starts to warm
How it works
We find the farthest fixture, see how the hot trunk and branches run, check for an outlet at the heater and note the heater's make and model. That decides return line or crossover.
The pump goes on the return or at the heater outlet with isolation valves and a check valve, the crossover valve goes under the far sink if that is the design, and the timer or aquastat is set to your household's hours.
With the loop cold we run the pump and time hot water at the far tap, then confirm that cold taps run cold and the heater is not cycling needlessly. Send the heater model through our contact page and we can say which approach it supports.
Common questions
What decides the price of a recirculation pump installation?
Three things: whether a return line has to be run and how much of it sits behind finished surfaces, how many crossover valves the layout needs, and whether there is a 120-volt outlet at the heater for the pump. A tankless loop adds a buffer tank or a model-specific kit. We look at the piping and give a written quote, and the quote visit is free.
Will a recirculation pump raise my gas or hydro bill?
Somewhat, and the controls decide how much. The pump itself draws about as much as a small light bulb; the real cost is heat lost from the loop while it is hot. On a timer or demand button with insulated pipe the penalty is small. Running continuously through bare pipe, the heater fires far more often, which is the setup we talk people out of.
Does the crossover valve make my cold water warm?
Briefly, at the sink where the valve sits. The valve closes at roughly body temperature, so the first seconds of cold at that tap come out lukewarm before fresh cold arrives. Most households do not mind it at a bathroom sink. If you want cold water cold at every tap, a dedicated return line is the design that delivers it.
Why does my tankless take longer than my old tank did?
A tank has hot water sitting ready; a tankless has to sense flow, light and bring its heat exchanger up to temperature before hot water even enters the pipe. That adds seconds to a wait already set by pipe length. Recirculation fixes it when the unit supports it, and why a tankless takes so long to get hot explains the delay.
Does hard water affect the pump or the valve?
Yes. Halton and Hamilton water is hard, and scale builds in the crossover valve's thermostatic cartridge and on the pump's rotor over the years. A valve that sticks open leaves warm water in the cold line; one that sticks shut ends the benefit. Both are simple parts to swap, and isolation valves at the pump mean it can be serviced without draining the heater.