Recirculation system, worth it??

[Eman85]

Doing some reno on my house and putting in a new 40 gallon electric AO Smith WH. Master bath is about a 30 ft run of 3/4" PEX from the WH. Is it worth it to put a recirculation system in? I know having faster hot water to the shower is nice but aside from the convenience does it work out in savings in not wasting water vs running the pump and heating more water?
If it's worth it which style system?

 

[Tuttles Revenge]

The only selling point I make when up-selling a recirculation pump to a customer is the convenience of having hot water within 5 seconds of opening a faucet or shower. We run the hot water main lines as close to each fixture so that the return draws water past as many fixtures as possible.

Pretty sure they're not an energy saver since we're now having to install them on an "On Demand" basis for energy code. No timers or aquastats allowed. Based on Washington state laws of course..

 

[Sponsor]

 

[Bannerman]

A recirculation pump does not need to run continuously to be of benefit. The pump could be activated when you anticipate hot water will soon be required, such as when you first enter the bathroom, kitchen or laundry room. While preparing to shower, loading the dishwasher or washing machine, will provide opportunity for hot water to arrive to those locations.

Navien offers a Hot Button accessory package for it's tankless WH systems, but I anticipate it or similar could be adapted for use to control an external circulation pump.

https://www.navieninc.ca/accessories

Momentary contact controller board

 

[Eman85]

As I said the convenience would be nice but if there's no $$ savings in the long run I guess it's not worth it. I was looking at the Watts system and it does have a timer so I would only have it run around shower time. I could run a dedicated return line if it was worth it.

 

[Tuttles Revenge]

As I said the convenience would be nice but if there's no $$ savings in the long run I guess it's not worth it. I was looking at the Watts system and it does have a timer so I would only have it run around shower time. I could run a dedicated return line if it was worth it.

Run a dedicated 3/4 line no matter what.. We always do and our customers thank us when they change their minds after sheetrock is installed and we tell them we've already got the line behind the wall.

 

[Fitter30]

How much is instant hot water worth? 50' of 3/4" copper 1.075 gallons.

 

[Eman85]

How much is instant hot water worth? 50' of 3/4" copper 1.075 gallons.

It's not worth anything, what's worth something is the wasted water waiting for hot water. That's the basis for my question, if there is any savings in the long run. Sounds like it's just a convenience.

 

[John Gayewski]

It's not worth anything, what's worth something is the wasted water waiting for hot water. That's the basis for my question, if there is any savings in the long run. Sounds like it's just a convenience.

No there is no savings. You either waste water or waste energy.

 

[John Gayewski]

The only selling point I make when up-selling a recirculation pump to a customer is the convenience of having hot water within 5 seconds of opening a faucet or shower. We run the hot water main lines as close to each fixture so that the return draws water past as many fixtures as possible.

Pretty sure they're not an energy saver since we're now having to install them on an "On Demand" basis for energy code. No timers or aquastats allowed. Based on Washington state laws of course..

I'm curious how this will play out over time. The "energy savings people" vs the "legionella protection" people seem to be at odds here.

There's no question when it comes to large systems in Healthcare facilities or even most all commercial plumbing systems that legionella mitigation and circulating water at 140 degrees is the priority. At least in my experience this has been the case for a while now. But in homes somehow energy savings (and a very small amount at that) seems to be getting the priority over the health of the water supply, at least in Washington state that seems to be the case. I just heard a story a few months back about a legionella outbreak killing around 15 people at a hotel (the details are fuzzy on this memory) and a semi local facility for veterans was re-engineered and rebuilt with legionella mitigation as one of the primary focuses for the design. So through my lens legionella would seem to be getting the attention, but it seems other lens' are focused on energy savings.

 

[LLigetfa]

It's not worth anything, what's worth something is the wasted water waiting for hot water. That's the basis for my question, if there is any savings in the long run.

For a cost analysis, one would have to know the installation cost of the recirc system balanced against the cost of the water and the energy to heat it. Then of course, the frequency of use also factors. I don't think anyone here would do the analysis for free so you need to add the cost analysis as well.

 

[Eman85]

Don't know anything about the legionella risks. I do know that water is and will be a big problem in the future. I don't drink the municipal water I pay for, they never pass the annual tests and I can't have a well as the groundwater has been contaminated by dumping.

 

[John Gayewski]

Don't know anything about the legionella risks. I do know that water is and will be a big problem in the future. I don't drink the municipal water I pay for, they never pass the annual tests and I can't have a well as the groundwater has been contaminated by dumping.

Life is short, live comfortably. Will a recirc save you money? No. Neither will a Ferrari. It's a luxury item meant to make life better.

 

[Master Plumber Mark]

Life is short, live comfortably. Will a recirc save you money? No. Neither will a Ferrari. It's a luxury item meant to make life better.

It will wear out the water heater faster....
it will thin down the copper pipes and eventually you will get pin holes in the copper
it cost more energy to constantly heat the water

Also, it will spoil your wife and kids and they will come to expect it.... The next thing
you know they will want endless hot water to stay in the shower all day long...


be happy you live in a time when you have running water... hot water is a luxury you
take for granted....

It all depends on what you want to teach your family I guess.... when your kids move out
some day, will they think their life is hell if they have to wait 20 seconds for hot water??

 

[Eman85]

"So through my lens legionella would seem to be getting the attention, but it seems other lens' are focused on energy savings." Let's talk about Legionella. Does turning the water temps up to 140* help prevent it? Does a recirculating system help prevent it?

 

[Reach4]

While 140 F water heater will prevent Legionella from growing, it would be very unlikely that it would be there in the first place. It occurred in some places where the water was not chlorinated and was sent thru the air. So that could occur in cooling towers, or even non-pressurized building water tanks. Those exist in some places.

If chlorinated water is coming into your house thru a pipe after being treated, I cannot see it having Legionella to grow.

 

[EricE]

Doing some reno on my house and putting in a new 40 gallon electric AO Smith WH. Master bath is about a 30 ft run of 3/4" PEX from the WH. Is it worth it to put a recirculation system in? I know having faster hot water to the shower is nice but aside from the convenience does it work out in savings in not wasting water vs running the pump and heating more water?
If it's worth it which style system?

A button or trigger for on demand to run a set period of time is definitely the way to go. In my last house I had a home automation system (zwave switches and outlets, homeseer providing control logic/coordination) that provided on demand triggering and it worked really, really well. I had it tied to the light switches in the bathrooms/laundry room and a motion sensor in the kitchen. Turn on any of the lights or detect motion and Homeseer turned on the pump for 30 minutes. My one bathroom/laundry room was about as far away from the water heater as it could be - must have been 80 feet of pipe from the corner of the basement to the opposite 2nd story of the house and it could take literally 3 minutes of running water to get hot water there - what a waste. I'm in a new house on the other side of the country and I haven't gotten around to setting the system back up here yet but it's high on my to do list. I'm also using the watts pump - I just set the timer to be always on and use a zwave outlet to turn it on and off as needed. In my last house I used the under sink returns watts provided to run the return back down the cold water supply and they worked just fine. A little warm water in the cold supply but not too bad. This new house has a return already plumbed in so it's just a few connections to the water heater for the pump and return and I'm good to go. Heck I don't even have to make any connections as everything is threaded. I'm now in the desert - conserving water is a much higher priority than conserving natural gas - but even if I was still back east, clean potable fresh water is still a valuable resource and not nearly as plentiful as people assume.