On demand hot water recirculating pump- what brand/model?

[Neilk]

Pelican Braintrust,

I am tired of watching water go down the drain waiting for the water to heat up. I did a search and found these posts about recirculating pumps, but nothing about which model to buy.
Home recirculating hot water heater

Any Pelican plumbing and hot water gurus ?

I would like to put a on demand water recirculating pump under our sink that will work with our tankless water heater. I don't want something running on a timer, but rather a push button. Any one have a recommendation on which pump to buy? This one on Amazon looks good, but the reviews point to a short longevity.

Any tips would be appreciated.

Neil

[look 171]

On demand and tankless do not go together in a sentence.

Inorder for you to have hot water a couple of seconds after you turn on the water, readily available hot water must be near by near by. I mean, within 3to 5 feet. The pump acts as if you were using water but it returns back into the line and recirc. itself. It can be done, but it involves a lot more piping then just screwing in a pump under the sink. I have a recirc on a timer and a thermo. switch hooked up to a tankless heater. That recirc. pump has to be large enough to push water through the tankless unit because it requires a certain volume of water going through it to turn it on to produce hot water.

[jwasbury]

My contractor plumbed a hot water loop in as part of our full gut renovation. Taco circulation pump on a timer is set to run for a several minutes at strategic points throughout the day to help insure there's not a long wait for hot water.

[911boost]

I have on demand and a pump.

It used to take a very long to get hot water from the tank in the basement to my 2nd story master bath. Think minutes.

When we remodeled I added another line from the basement to my bathroom that tied into the plumbing and now have hot water in seconds.

I can look at the brand when I get home.

[911boost]

What the previous two guys said...

[stomachmonkey]

Installed when we built our house.

Won't ever have a home without it again.

[look 171]

Make sure your plumber know what the heck he doing with it comes to recirc pumps. There must be a way to shut off the heater after a hot water cycle. If not it will burn the tankless. Most mfg will void warranty if there's a pump hooked up to it.

[Neilk]

The timer based pumps I have seen turn off after reaching 90 to 100 degrees, so the water is hot within seconds of turning it on. Our schedule is too unpredictable, so I want push button operation.

As I understand it, the pump bridges the hot water to the cold and recirculates the water until it reaches a set temp. Since we are tankless, the key is getting enough water circulating to trigger the pump.

[look 171]

A return line is needed to bring the cold water back to the heater from the faucet to recirculate it through the system keeping all pipes steaming hot. I believe the some of the newer pumps has a temp. sensor built in, so when it reaches a certain temp, pump shuts off leaving hot water throughout the pipe between faucets and heater until it drops to a certain temp., pumps starts up again, another cycle. My system would come on every 15 min for about 20 second keeping the water piping hot. It goes on a little more often during winter but it doesn't get too cold around here. The timer is there so the pump can be completely turned off during a set time such as after midnight to 6 am. to keep wear and tear on the system where hot water isn't needed. Tankless heaters takes an additional 30 -60 second to get water to it source. That's normal. Now, we have hot water in less then 5 seconds.

[911boost]

My system sounds a lot like Look’s.

[tcar]

You do NOT use a recirculating pump with a TANKLESS heater.

[look 171]

Originally Posted by BSiple

My system sounds a lot like Look’s.

That's the way it suppose to be done. I used my own house as trial and error about 15 years ago when tankless heaters started to gain popularity, a time when most plumbers were not used to having a heater shutting off, so they wired pumps to run continuously like a tank unit. They were getting into all kinds of issues. We replaced so many screwed up installs. We finally has to train my plumber on how to install these thing correctly so he can service our clients (thankfully that type of work stopped). Most good plumbers get it now, finally.

[look 171]

Originally Posted by tcar

You do NOT use a recirculating pump with a TANKLESS heater.

A pump sure can be used, but not always cost effective due to the somewhat complex install.

[Evans, Marv]

My circulating pump seems different than what's being talked about. My tankless heater for the back part of the house serves the bathrooms. If you want quicker hot water, there is a button to push that causes the pump to operate long enough to circulate hot water through the loop for whose bathrooms and then shuts off.

[look 171]

Originally Posted by Evans, Marv

My circulating pump seems different than what's being talked about. My tankless heater for the back part of the house serves the bathrooms. If you want quicker hot water, there is a button to push that causes the pump to operate long enough to circulate hot water through the loop for whose bathrooms and then shuts off.

Interesting. Is it automatic or manual only?

We have gotten away from a single tankless due to additional labor for pump times and such. Now, I push for two smaller heater located neat bath and kitchens without pumps.

[fintstone]

I use a RedyTemp ATC3000 Hot Water Circulator on-Demand Circulation Recirculation Pump in my vacation home (regular hot water heater, not tankless). I mostly use it because it keeps the pipes from freezing in the winter. I can remotely turn it on from anywhere (and the hot water heater...also on a wemo switch). I leave both off when I am away and it is not cold out (enough for pipes to freeze). Just place it at the faucet that is farthest away from the hot water heater in the circuit...and it will fix your problem for all in between. It is not cheap to buy, but is safe, well engineered, high quality, easy to install, and saves water and electricity. I use a wemo plug-in to control it from my iPhone, but it comes with a timer if you prefer. You can also use a motion sensor or a switch (if you prefer) to use whenever you go in the bathroom and by the time you get your clothes off...hot water. When I ordered it...it took a few weeks and i began to worry...but then it arrived. Guess the guy sells them out of his house or something.

They also sell a version for tankless water heaters.

[cabmandone]

Years ago a friend of mine plumbed in a gravity loop but he didn't have a tankless heater.
IIRC a tankless needs to see a minimum flow to begin heating so you'd want a pump capable of maintaining that flow rate.

[greglepore]

The newest tankless units come with a recirc built in...my Navient has one.

[hcoles]

I'm using the Watts system from HomeDepot. It uses the cold water pipe as the return. Easy to install works good enough. Saves adding a pipe for the return. Works on a timer.

[Lyle O]

Originally Posted by hcoles

I'm using the Watts system from HomeDepot. It uses the cold water pipe as the return. Easy to install works good enough. Saves adding a pipe for the return. Works on a timer.

I've had a system like this for a number of years (15+). The issue here is that, while the hot water is pretty much instantaneous, if you want cold water, it is not cold (you have to wait for the hot to flush through). For systems that have plumbed a completely discrete hot return line, that's great for new construction, or major renovation work, but more challenging as a more basic add-on. Still, at our house, we use more hot water, and more often, than cold, so the cold return method is still pretty good.