Can you use a recirculating pump with a tankless water heater

Q: Can you run out of hot water with a tankless water heater?

Although a tankless system cant run out of hot water, it can still be overwhelmed with demand. A single tap wont do this: run that single shower all you want, youll keep getting hot water. (But please dont do this! Save water, save energy!)

I installed a tankless 6 years ago and will never install a tank again. I did it myself and will do it again if I am ever in a new house.

Table of Contents Show

GET FASTER HOT WATER
Tankless Keeps Hot Water Recirculating
How do you install a recirculating pump to a tankless water heater?
What is the best practice when installing a recirculating system on a single tankless water heater?
Can you run out of hot water with a tankless water heater?

I have a 120k Noritz unit that performs flawlessly.

I just don't get it guys. Installing a tankless without recirc is like trying to start your car with a half dead battery. Really!

"Your builder is right, it defeats the purpose of tankless" nonsense!

I did not have recirc initially. I learned by experience you do not just replace a tank with a tankless. It is a bad result for hot water supply. Slow and inconsistent.

Internal recirculation tanks might help but never having used one I have no opinion. But unless you circulate water and insulate your pipes to maintain the heat you are really missing the boat. Recirculating inside the heater means your pipes are cold and it takes longer to get to a tap because unlike a tank there is no pressure in the lines to radiate towards the taps. Why store water inside your heater when you need the heat in the pipes for faster delivery? That is just a limited solution to the issue in my opinion.

How much does it cost to keep the lines hot. Depends on heat loss and vol. of water in the lines. Insulate!!!

I would say my pipes take very little in cost to keep hot. Maybe $5-7 a month. I used 3/4 inch pipe for recirculation to store more water for start up and to feed 110 degree water into the heater. I do not have a timer to shut off recirculation at night so I could save a few bucks if I did that.

Its a simple thing to lay out. You go to the last tap in the system and put a return to the heater from there. You need to have a cold water supply for the recirculation. A one way check valve between the recirc and the street supply prevents hot water from pumping back to the street as hot water pressure rises. A second check valve goes between the last tap and where the street supply feeds the recirc line to prevent cold water pressure from the street from back flowing through the hot water lines.

Why any builder would not just put a return line back to the heater is beyond me. Its really not a lot of extra work. Especially with all the cheap Pex being used now. A small grundfos 1/25th hp pump is all that is needed in most cases. I use a Honeywell aquastat to trigger the pump. The pump engages maybe once an hour for maybe a minute to raise the water temp from 105 to 110.

Heat loss? Did you insulate the pipes you say are losing heat from? You can lnstall a timer to turn off recirc in the night so you use no energy at all. You can do the same during the day when you are not at home.

For some families you could have a daily timer that changes recirc to match your schedule. The hot water works with the recirc off, it just does not work properly as iz well known.

Tankless is a superior technology. I did not think the endless supply would matter to me, its noticeably better.

A tank cools as soon as you start using water out of the tank and cold water replaces it. The temp drops and drops the longer it flows. A tankless heats water on demand and it is maintained at the same temp. Its really is an advantage.

But, as has been stated here by users, un managed hot water supply sucks and who cares if it costs a little bit of money to heat and pressurize your pipes so hot water is instant. Its way less expense than keeping 40 gallons of water hot in a tank.

I would never heed the advice by someone on this thread that you don't need recirc.

Have your builder install a true full house recirculation system. Don't pay attention to this "you don't need it stuff."

If the builder balks or talks down to the idea get someone who knows what they are doing to come install it and over ride their obstinate attitude. Just do not listen to the talk of having a better system is not needed.

You are going to great expense to have the best hot water supply you can have. Don't let someone with out your best interests in mind wreck your enjoyment of a great tankless system.

Recirc all the way!!!

Gee people, why would anyone not do this in new construction when its way easier to do.

TANKLESS
WATER HEATER
RECIRCULATION
PUMP

GET FASTER HOT WATER

When a homeowner is looking for instant hot water in their homes, their best solution is a recirculation system. These beneficial systems keep a steady supply of hot water ready for those moments when you need hot water immediately, like a cold winter morning. With the help of an integrated or external pump, water travels from the tankless water heater to the hot water faucets throughout a home without the need to add additional water lines. Homeowners need not worry about going without hot water again thanks to recirculations systems.

Tankless Keeps Hot Water Recirculating

No more waiting for hot water. Noritz can provide you with faster hot water wherever and whenever you need it. It does this by recirculating the water through your plumbing system, so hot water is always available in whatever part of the house that you may need it. the best part is, Noritz can provide this solution regardless of your current plumbing configuration.

TANKLESS
WITH HOT WATER
RECIRCULATING
PUMP

How do you install a recirculating pump to a tankless water heater?

WaterQuick Tankless.

Choose the appropriate place to install the pump and Flow Monitor:.

Turn off water heater: ... .

Turn off water: ... .

Drain the water lines: ... .

Cut the appropriate cold or hot water line and install pump and Flow Monitor:.

Turn on water: ... .

Connect the pump and the Flow Monitor:.

Plug the pump in:.

What is the best practice when installing a recirculating system on a single tankless water heater?

Tips when installing a Tankless & Recirculation System Insulate all hot water pipes to minimize standby energy loss. Minimize the length of the run from the tankless water heater to the recirculation loop (maximum 5' recommended).

Can you run out of hot water with a tankless water heater?

Although a tankless system can't run out of hot water, it can still be overwhelmed with demand. A single tap won't do this: run that single shower all you want, you'll keep getting hot water. (But please don't do this! Save water, save energy!)