Whole Home Hot Water Circulation

[zmotorsports]

Good morning all. I have a few questions about hot water circulation systems and although it is in my home and not my shop I figured this would be the place to ask and see if anyone has any first hand experience.

I had to replace water heaters in our home yesterday and while I was at it I started thinking about hot water circulation systems again. I spoke to a plumber who was a contact from my contractor a few years ago shortly after moving into our new home as he is installing a lot of these in new builds in our area. He mentioned that with our unfinished basement now would be the time to add the circulation loops if I was even considering it down the road as it would be similar to a new build with the plumbing exposed in the basement ceiling making it an easier install and therefore less costly. Then I could add the pump and final connections at any time thereafter but at least the loops would be installed before finishing the basement.

With all things going up in price lately I thought about not only adding the circulation loops now but maybe adding the circulation pump and connections and getting it all done sooner rather than later. My thinking is that the small amount of electrical to run the circulation pump at certain times of day when we're home and the small amount of gas to heat the water that those would more than outweigh the wasted water as well as frustration from waiting for hot water in the far extremes of the home. The plumber mentioned he added it to his new home several years ago and loves it as he has teenage kids and it is nice to have nearly instant hot water at any faucet in the house and wastes very little water this way. Granted water is still much cheaper than electricity or natural gas, so it is more about the convenience and luxury of having hot water quickly at the far extremes in the house.

At first I dismissed it as I worried about more PEX and more connections could equal more leaks or at least potential for leaks but as I have been around them more I am less worried about the connections and PEX themselves as I was several years ago. The PEX systems seem to be a well proven system of connecting and transferring water throughout homes but I am curious about the pumps themselves and how reliable they are long term and what possible issues people are seeing, if any. He explained that the pump he is now using is considered a "smart" pump and it doesn't require the timer like the old style but rather learns your pattern and adjusts accordingly based on times of day when the hot water is being called for.

Does anyone have any first hand experience with these? Do you like the hot water circulation system? Have you had any issues with the system? If so, which part?

Thank you.

 

[larry4406]

It’s on my list of things to do.

My plan is to use a dumb pump. The dumb pump runs when it gets power.

I plan to enable power by a combination of an aquastat which measures the return temperature in the loop and an occupancy sensor in the bathrooms and kitchen.

Cold return, no occupancy, pump off
Cold return, occupancy, pump on
Hot return, no occupancy, pump off
Hot return, occupancy, pump off

When I get home, I will find link to a user here of the Grundfos Adapt pump that doesn’t work for him.

 

[acer66]

A loop was one of the best things I did when replacing my house plumbing.

Guests/friends often comment how nice it is that the hot water is almost there instantly.

On the flip side it is odd for me now to have the water running at friends places to get hot water.

My GF lives in a old and big fancy house and it takes several minutes to get hot water at the showers even most plumbing was replaced at one point.

 

[zmotorsports]

A loop was one of the best things I did when replacing my house plumbing.

Guests/friends often comment how nice it is that the hot water is almost there instantly.

On the flip side it is odd for me now to have the water running at friends places to get hot water.

My GF lives in a old and big fancy house and it takes several minutes to get hot water at the showers even most plumbing was replaced at one point.

Thank you. That has been my findings as well when speaking to people about these systems. Those that have them love them and those that don't can't justify the cost so don't think they're necessary. Hell, that could be said for many things that we have or don't have but not really based on facts or personal experience so thank you for your actual experience.

I wouldn't say ours takes minutes, although the wife may think that, but it is surely longer than I want to wait so this will be more of a luxury that I may be trying to justify as a cost savings method to the wife.

 

[DGersic]

I recently re-piped my house with PEX. I went with PEX B pipe and expansion fittings. I’m pretty sure that the joints in this system won’t leak.

I ran a passive return (no pump) from the furthest point (bathroom sink) to the water heater, with a check valve to prevent back flow.

This works pretty well, for the cost of some additional pipe and fittings. Yes, there is potentially more gas used, and less water wasted. All things in life are trade offs.

It’s not perfect. The water at the bathroom sink isn‘t immediately “hot”, but it is generally “not cold” and approaches “hot” at about the time you’re done soaping your hands and ready to rinse. For a bathroom sink, that’s pretty good, IMHO, with no moving parts.

I could add a pump and controls to this, if I wanted “hot” to ne immediately availabile.

Edit:

Here is where I modified the water heater.

Post in thread 'Plumbing Project - Re-Pipe the House'
https://www.garagejournal.com/forum/threads/plumbing-project-re-pipe-the-house.509833/post-9983529

 

[zmotorsports]

I recently re-piped my house with PEX. I went with PEX B pipe and expansion fittings. I’m pretty sure that the joints in this system won’t leak.

I ran a passive return (no pump) from the furthest point (bathroom sink) to the water heater, with a check valve to prevent back flow.

This works pretty well, for the cost of some additional pipe and fittings. Yes, there is potentially more gas used, and less water wasted. All things in life are trade offs.

It’s not perfect. The water at the bathroom sink isn‘t immediately “hot”, but it is generally “not cold” and approaches “hot” at about the time you’re done soaping your hands and ready to rinse. For a bathroom sink, that’s pretty good, IMHO, with no moving parts.

I could add a pump and controls to this, if I wanted “hot” to ne immediately availabile.

Thanks. I think if I'm going to do it I want the recirc. pump and the instant (or nearly instant) hot water. I have good data now after being in the house for just over 6 years and I don't actually think there will be much increase in gas or electric usage but I can definitely see a decrease in water usage, or wasted water to be more accurate.

Thank you.

 

[DGersic]

Thank you. That has been my findings as well when speaking to people about these systems. Those that have them love them and those that don't can't justify the cost so don't think they're necessary. Hell, that could be said for many things that we have or don't have but not really based on facts or personal experience so thank you for your actual experience.

I wouldn't say ours takes minutes, although the wife may think that, but it is surely longer than I want to wait so this will be more of a luxury that I may be trying to justify as a cost savings method to the wife.

I absolutely hate washing my hands in cold water. This is especially bad in the winter. After 30 years of walking from the bathroom to the kitchen to wash my hands in warm water, I’m very happy with the luxury of using the bathroom sink.

If you’re considering a return loop, put it in.

 

[LXCam]

Do it Mike, it's really worth it. The house I had over the summer had one but it didn't work initially and it took ten minutes for the water to heat up. Once I fixed the pump it was as close to instant as it get. The home we're in now has one and like I said..

I don't know what your costs are for water but it ain't cheap here and as far as I'm concerned it's worth every dime of the little bit of power the system uses. If I remember correctly that circ pump draws .7 amps so 84W an hour. I think the biggest benefit is for both the dish washer and the washer...ya get hot water and not warm especially if its one of those miser sumbitches that barely use any water.

 

[zmotorsports]

I absolutely hate washing my hands in cold water. This is especially bad in the winter. After 30 years of walking from the bathroom to the kitchen to wash my hands in warm water, I’m very happy with the luxury of using the bathroom sink.

If you’re considering a return loop, put it in.

Do it Mike, it's really worth it. The house I had over the summer had one but it didn't work initially and it took ten minutes for the water to heat up. Once I fixed the pump it was as close to instant as it get. The home we're in now has one and like I said..

I don't know what your costs are for water but it ain't cheap here and as far as I'm concerned it's worth every dime of the little bit of power the system uses. If I remember correctly that circ pump draws .7 amps so 84W an hour. I think the biggest benefit is for both the dish washer and the washer...ya get hot water and not warm especially if its one of those miser sumbitches that barely use any water.

Thanks for the comments guys. I really appreciate them.

I figured with the water restrictions here in northern Utah that the cost is just going to to up and even though we are generally charged the minimum I am thinking this is more of a want at this point in life. Our last home was quite small and the water heater centrally located in the basement so it wasn't too long of a wait until hot water arrived at the faucet. However, even with this home's water heater centrally located, it is much larger than our last and has more bathrooms so it takes just a bit longer for that hot water to arrive at the faucet. I have been thinking about doing it now rather than waiting and just enjoy it.

 

[LXCam]

Thanks for the comments guys. I really appreciate them.

I figured with the water restrictions here in northern Utah that the cost is just going to to up and even though we are generally charged the minimum I am thinking this is more of a want at this point in life. Our last home was quite small and the water heater centrally located in the basement so it wasn't too long of a wait until hot water arrived at the faucet. However, even with this home's water heater centrally located, it is much larger than our last and has more bathrooms so it takes just a bit longer for that hot water to arrive at the faucet. I have been thinking about doing it now rather than waiting and just enjoy it.

You've also got another consideration you haven't considered yet. Right now its just you and the wife. Pretty soon its gonna be grandbaby time and with that comes the great expense of constant cleaning, clothes washing and bubble baths.

 

[zmotorsports]

You've also got another consideration you haven't considered yet. Right now its just you and the wife. Pretty soon its gonna be grandbaby time and with that comes the great expense of constant cleaning, clothes washing and bubble baths.

I'm not gonna lie Cam, that thought was also in the back of my mind when I was wandering around yesterday looking at the plumbing in the house.

And for the record, it's only a matter of days now......

 

[joe_padavano]

I put a Goulds recirculating pump with thermostat in my system. I love it.

 

[zmotorsports]

I put a Goulds recirculating pump with thermostat in my system. I love it.

Thank you for the feedback. I hadn't yet started researching pump brands to be honest as I am only now coming to the realization that I want the recirculation system.

 

[kj_mustang]

New construction home and I had the plumber add the recirculation pex runs during the build. I had to add a couple more sections to the loop as he didn't do all the lower floor fixtures which was easy to do in the basement. I installed a Grundfos pump and plumbed it in to my indirect hot water tank off my boiler. I used a cheap plug in digital timer from Amazon to set up multiple cycle times during the day lasting 10 minutes. Been working great for 5 years, unlimited hot water and almost instantly.

 

[zmotorsports]

New construction home and I had the plumber add the recirculation pex runs during the build. I had to add a couple more sections to the loop as he didn't do all the lower floor fixtures which was easy to do in the basement. I installed a Grundfos pump and plumbed it in to my indirect hot water tank off my boiler. I used a cheap plug in digital timer from Amazon to set up multiple cycle times during the day lasting 10 minutes. Been working great for 5 years, unlimited hot water and almost instantly.

Thank you. I appreciate your feedback.

 

[larry4406]

Mike

Here is the link to the thread where @TT_Vert documented his non-performing Grundos auto-adapt recirc pump.

Grundfos comfort PM 10-16 auto adapt DHW recirc. pump question.

This hot water recirc. pump has an internal and an external temp sensor for the auto adapt and temperature readings. I have a 1/2" return line from the furthest fixture that sends that hot water back to the tank via this pump. I plan to use the temperature control option because my usage...

www.garagejournal.com

 

[zmotorsports]

@larry4406 , thank you. I will definitely read through that thread.

 

[garagenvy]

Lost water while it gets hot is a lot cheaper than heating and circulating water to eliminate a few seconds of waiting. If you do run the hot water through the pipes 24/7 make sure you insulate them to cut the heat loss.

 

[larry4406]

Lost water while it gets hot is a lot cheaper than heating and circulating water to eliminate a few seconds of waiting. If you do run the hot water through the pipes 24/7 make sure you insulate them to cut the heat loss.

Agree on insulating and recognizing that the loop in essence becomes hydronic heating loop like it or not.

However, when water is a scare resource (arid regions) or water disposal (septic) are concerns, then automation schemes tailored to usage/demand make a lot of sense vs 24/7/365 recirc.

 

[jblnut]

When we built a year ago I put the recirc lines in but haven't hooked them up yet. I had a little 5gal water heater from my camper bus we weren't using and put it under the kitchen sink where it feeds the kitchen sink and dishwasher. It uses around $3/month in electricity and the water is hot right now at the kitchen sink. I have the big water heater feeding the little one so the little one is only heating up the little bit of water in the lines between itself and the big one in the mech room.

The bathrooms both have less than 20' of plumbing to get to the main water heater and the slop sink is in the mech room.

Having hot water right now in the kitchen I'd say DO IT now while you can. It is soooooo nice !!!

 

[4 FN 27]

Mike our system has been in play since 2008. It is the last thing I think about as far as Maintenance goes. Other than having hot water right away even in the far corn of the lower garage I don’t even think about it.

Wish I had done it in the shop. Takes 1 full 5 gallon pale of water to get it hot at the sink in the office.

The shop sink takes about a gallon. As the crow flies they are about 9 feet a part. I have tested it.

You won’t be sorry.

 

[rharman]

When we remodeled in 1993, we spec'd recirculating hot water. We HAD two 50 gal water heaters each with its own pump (Grundfos).
Originally, the intent was to have one servicing each floor. Well, the plumber hooked them up in a hitch loop so we ended up with two water heaters, two pumps and one big loop.

The electric bill was staggering as the pumps were running 24x7. Over the years, we tried various timer mechanisms.
Eventually, one water heater died and we just bypassed it - we really didn't need 100 gallon hot water capacity for two people.
Decided to just go with a single 50 gallon WH and one pump. Again, trying various timers.

Some years ago, we finally settled on an X-10 remote setup. We have a wireless keypad in the kitchen and the upstairs master bath. When we know we'll need hot water, we just start the pump and let it go for 5-10 minutes or so before we get in the shower or whatever.

It's worked well for us and the electric bill got a LOT more manageable. Gas bill too with cutting back to one WH.

As others have mentioned, insulating the hot lines is critical.

I'm kind of looking forward to eventually replacing the gas WH with a heat pump WH. I have 240V available from a couple of circuits I ran into the garage 43 years ago when I bought the house. Needed them for my stick welder and my air compressor at the time.

 

[zmotorsports]

Lost water while it gets hot is a lot cheaper than heating and circulating water to eliminate a few seconds of waiting. If you do run the hot water through the pipes 24/7 make sure you insulate them to cut the heat loss.

As I've mentioned, it won't be running 24/7 as it will be on a programmable timer to activate around the times we are home and using it, and also like I've mentioned I am not doing this solely thinking expense or saving money. I mentioned I knew this wasn't a money saving project and that the main driver is the convenience of having instant, or nearly instant, hot water. This IS a luxury and not a necessity but I also want to try and conserve at least some of the water I'm using. I am not what I would call a "greenie" by any stretch of the word but I don't like being wasteful, of anything.

Agree on insulating and recognizing that the loop in essence becomes hydronic heating loop like it or not.

However, when water is a scare resource (arid regions) or water disposal (septic) are concerns, then automation schemes tailored to usage/demand make a lot of sense vs 24/7/365 recirc.

Agreed. I have already insulated my plumbing about a year or so after we bought the new house, so probably about 5 years ago, so this would be no different and then a timer for when we'd be home using water.

 

[zmotorsports]

Mike our system has been in play since 2008. It is the last thing I think about as far as Maintenance goes. Other than having hot water right away even in the far corn of the lower garage I don’t even think about it.

Wish I had done it in the shop. Takes 1 full 5 gallon pale of water to get it hot at the sink in the office.

The shop sink takes about a gallon. As the crow flies they are about 9 feet a part. I have tested it.

You won’t be sorry.

When we remodeled in 1993, we spec'd recirculating hot water. We HAD two 50 gal water heaters each with its own pump (Grundfos).
Originally, the intent was to have one servicing each floor. Well, the plumber hooked them up in a hitch loop so we ended up with two water heaters, two pumps and one big loop.

The electric bill was staggering as the pumps were running 24x7. Over the years, we tried various timer mechanisms.
Eventually, one water heater died and we just bypassed it - we really didn't need 100 gallon hot water capacity for two people.
Decided to just go with a single 50 gallon WH and one pump. Again, trying various timers.

Some years ago, we finally settled on an X-10 remote setup. We have a wireless keypad in the kitchen and the upstairs master bath. When we know we'll need hot water, we just start the pump and let it go for 5-10 minutes or so before we get in the shower or whatever.

It's worked well for us and the electric bill got a LOT more manageable. Gas bill too with cutting back to one WH.

As others have mentioned, insulating the hot lines is critical.

I'm kind of looking forward to eventually replacing the gas WH with a heat pump WH. I have 240V available from a couple of circuits I ran into the garage 43 years ago when I bought the house. Needed them for my stick welder and my air compressor at the time.

Thanks for the feedback guys. I don't plan on running the recirc. pump 24/7, only when we are home and would be using hot water so that chore will be tackled by a timer.

 

[kj_mustang]

Yep, just plan your cycle times around your family's prime usage. My first cycle starts 10 minutes before my alarm goes off since I am the first up, next cycle is about 1 hour later for the wife, and then it skips until I think at 5:00 pm, and a couple more through the evening. Seriously doubt it adds very little to my total energy use.

 

[zmotorsports]

Yep, just plan your cycle times around your family's prime usage. My first cycle starts 10 minutes before my alarm goes off since I am the first up, next cycle is about 1 hour later for the wife, and then it skips until I think at 5:00 pm, and a couple more through the evening. Seriously doubt it adds very little to my total energy use.

When I was speaking to the plumber the other day about this, that was almost my exact scenario that I laid out. Program the recirc. pump to come on just before the wife and I get up then it can shut down when we leave for work and doesn't need to start back up until around 5pm. I think for the weekends we'd probably have it run a bit more as we'd be home during the days much of the time. He said the same thing about energy usage as it would be minimal that way. He said he runs his more frequently because he has a bit larger family that are in/out of the house at various times throughout the day and he still doesn't notice a heavy usage bill.

 

[Rusted Nut]

You may want to look into “tankless” water heaters, as an option for what you want.

 

[zmotorsports]

You may want to look into “tankless” water heaters, as an option for what you want.

Thanks but I'm not interested in a tankless water heater. That still wouldn't address this scenario anyways.

 

[larry4406]

I briefly looked at the timer method, but with our family of 4 all on different work schedules with varying days off for some, combined occupancy and temperature sensor seemed the best method for me. Still on my to do list.

We are on septic and a lot of water gets run down the drain making the kitchen and garage bath hot.

 

[Ole Slewfoot]

The unsung beauty of PEX is it is Lego easy to cut something out or make a change. Aside from money, pump replacement should be a non-issue if needed.

Just don't fall for the cheapout system that returns to your cold supply.

 

[Jackfre]

Rinnai makes a wireless recirc system that is pretty cool…if you have a good wireless signal to the unit. If not, it is a giant pita. Using a wireless motion sensor in the bathrooms and a wireless push button in the kitchen mounted next to the sink up under the lip of a cabinet you can have “on-demand” recirc. For water and energy conservation and your comfort it is a pretty slick system, but again strong wireless. I just moved into our new home and it has a new Navien install. I called the installing plumber to come back and fix the venting and drain line. Freakin’ meathead. The hoouse has a Franke 1 gal elec below the kitchen sink. Not ideal, but for low draws it is instant.

 

[86turbodsl]

I did this in our house, but went a bit further. I installed a thermocouple on the return line, and the pump will shut off when the thermocouple comes up to temp. So the time of day determines when it comes on for hot water, and the thermocouple shuts it down when the line is hot. Turns back on when it cools a bit.

 

[2Fast]

I did this in our house, but went a bit further. I installed a thermocouple on the return line, and the pump will shut off when the thermocouple comes up to temp. So the time of day determines when it comes on for hot water, and the thermocouple shuts it down when the line is hot. Turns back on when it cools a bit.

Grundfos has a clip on AquaStat for their recirc pumps but you could probably wire it into just about any pump. $40. So if you just have the basic mechanical timer, you set the time when you want the pump to run and then the AquaStat will turn the pump on at 85F and will turn it off at 105F, that way the pump is not running continously.

https://www.supplyhouse.com/Grundfos-595444-3-4-Clip-On-Aquastat-Kit-for-UP-Series-Circulators-7-8-OD-Piping-85F-105F

If you don't have a dedicated return line, Navien for one has a Recirculation Valve that you plumb into your hot and cold water lines, usually at your furthest fixture. Once the water in the line gets above 85 F, the valve will close

NaviCirc Recirculation Valve | Navien

NaviCirc Recirculation Valve Designed for Recirculation of Domestic Hot Water in Applications Where a Dedicated Return Line is Not Available.

www.navieninc.com

 

[86turbodsl]

Grundfos has a clip on AquaStat for their recirc pumps but you could probably wire it into just about any pump. $40. So if you just have the basic mechanical timer, you set the time when you want the pump to run and then the AquaStat will turn the pump on at 85F and will turn it off at 105F, that way the pump is not running continously.

https://www.supplyhouse.com/Grundfos-595444-3-4-Clip-On-Aquastat-Kit-for-UP-Series-Circulators-7-8-OD-Piping-85F-105F

If you don't have a dedicated return line, Navien for one has a Recirculation Valve that you plumb into your hot and cold water lines, usually at your furthest fixture. Once the water in the line gets above 85 F, the valve will close

NaviCirc Recirculation Valve | Navien

NaviCirc Recirculation Valve Designed for Recirculation of Domestic Hot Water in Applications Where a Dedicated Return Line is Not Available.

www.navieninc.com

That would definitely be cheaper than what i ended up with, but at the time of build, nobody had fancy controls for anything. Glad to see this sort of thing now.

 

[engineer2]

I put this in many years ago to feed the upstairs bathrooms. Timed to run for morning showers. It has a thermal cutoff. Once the line is full of hot water, it shuts off.
I like the idea of a smart switch I can use with my phone, especially on the weekends.

 

[2Fast]

That would definitely be cheaper than what i ended up with, but at the time of build, nobody had fancy controls for anything. Glad to see this sort of thing now.

My last house, built in 2003, has a recirc pump with that AquaStat on it - that is how I know about it

 

[zmotorsports]

Thanks for all of the comments guys. After discussing with the wife over the weekend it looks like she wants me to move forward with this so I'll probably add it to my house/shop build thread when the time comes.

I appreciate everyone's feedback. Thank you.

 

[mcbane]

It’s on my list of things to do.

My plan is to use a dumb pump. The dumb pump runs when it gets power.

I plan to enable power by a combination of an aquastat which measures the return temperature in the loop and an occupancy sensor in the bathrooms and kitchen.

Cold return, no occupancy, pump off
Cold return, occupancy, pump on
Hot return, no occupancy, pump off
Hot return, occupancy, pump off

When I get home, I will find link to a user here of the Grundfos Adapt pump that doesn’t work for him.

Only thing to consider changing is where you measure water temperature. Point of use is the best place. Imagine someone enters the bathroom and starts taking a hot shower. Eventually the return line gets cold and kicks on the pump, causing the shower to get cold as the pressure balance valve adjusts to the sudden drop in hot water pressure.

 

[larry4406]

Only thing to consider changing is where you measure water temperature. Point of use is the best place. Imagine someone enters the bathroom and starts taking a hot shower. Eventually the return line gets cold and kicks on the pump, causing the shower to get cold as the pressure balance valve adjusts to the sudden drop in hot water pressure.

Since there are multiple points of potential hot water use, where is single point measurement recommended?

I think these are circulator pumps vs pressure pump so I can’t imagine a large differential pressure creating an imbalance but I don’t know.

My basement is unfinished so all hot fixtures will have a short “arm” or branch off the loop. Thus I was thinking to measure temperature after the last hot fixture tap.

 

[Jinks]

Remodeled & added a second story on half of the house back in 2006. Had a problem with the under slab plumbing, so had to re-plumb the house. The new plumbing went between floors, so over the first floor but under the second floor.... While we were at it I added solar water heating & an 80 gal. tank. While the sun heats our water mostly free it took a long time to get hot water from one end of the house to the other, or up to the second floor.

A few years ago I looked into hot water circulation. Having return lines added would have cost a LOT of money along with opening & repairing sheet rock. Way too costly....... Somewhere between 3 & 5 years ago I broke down & bought a hot to cold water recirculating pump from Amazon. Put it under the farthest sink on the lower floor. It monitors the temp at the hot water line, & when it drops to around 70/80 it pumps hot water into the cold water line. At around 85 the pump stops. Even during what we call winter down here it only takes a few seconds to get warm water anyplace on the ground floor, & a little longer on the second.

The pump came with a built in timer that I tried, but since we're retired & home all the time it wasn't worth the effort. I finally just set the pump to run anytime the temp. was low. We now have warm/hot water anywhere with minimal waiting & waste less water. The pump uses negligible electricity, so along with solar water heat the system is easily affordable. If you have return lines, or can add them easily, I'd put in a thermostat pump & just return the water to your heater. The water returned to your heater probably isn't colder than the regular feed line & won't effect your heating bill much.