Hot Water Recirculating Loop

How to cut the wait for hot water in bathrooms that are a long way from the water heater. I added a return line from two locations, through a check valve, into the bottom of the heater, setting up a circulation of hot water that does not require a pump.

[JerryNettik]

Thanks! So I watched this video a few months ago. I was replacing old rusty galvanized pipes in my ranch style home with pex, and I decided to make a hot water loop to supply all my fixtures and then return to water heater drain as you explained. I missed the part about the check valve somehow. My water was actually fairly warm all the time but never hot. You could actually take a shower and not turn on the cold water and it was Ok, just OK. On my own, I decided I needed a check valve on the return line and installed it yesterday. This morning, my water in the master bath was cold for the first time in a couple of months. I tracked down your video and rewatched it, and saw the part about the check valve modification, so I'll be drilling the hole in the flapper today. Hopefully, that will fix the problem. Thanks again!! Also, one other modification I'm making is adding a shut-off valve in the return line that can be timer and wifi controlled. That way I can disable the recirculation at night, and when we're away from the house for extended periods, and save a little gas.

[flyme-zb]

Worth reading (IMO): I bought a 2 story 5, 000 sf home with the 50 gallon water heater in the basement and a dedicated circulation line as part of the plumbing system which runs through the ceiling of the basement. The builders had installed a $650.00 Laing recirculation pump with the timer and all the frills. It all worked great for our first 2 years in the home. Then one day the pump started to make some noise so I unplugged it and guess what... We still had all the of the hot water we needed at every sink, tub, shower, laundry and kitchen as needed and never had to wait more than 5 seconds for it. I could not understand why this was still working so beautifully during these past 8 years with no functioning pump but now I know!!! Thank you, Owen, for your wonderfully informative and inspiring video. Keep up the great work.

[MittyNuke]

I installed a system like this, using a pump, and it works great. Very cool seeing the gravity design working. I used a spring-loaded check valve and didn't do the hole (if you can even do that on the design of flow check I used) but I've heard multiple reasons for the hole in the check valve, such as preventing valve chatter on pumped systems (for the hydronic heating loop in my house, there are check valves that were previously installed for whatever reason, and you hear a metallic clanging sound while the heat is running, which may be from these check valves, although I'm not sure), or for preventing an air lock in the system, which could be a concern in your system, since the gravity circulation would probably stop if you had an air lock in the recirculating line. With the hole, you're probably pulling a small amount of hot water the opposite direction while using any hot water at the tap, from the bottom of the WH, to the open fixture, which would ensure any air lock is bled out. The downside of reverse flow for your design is pretty low, since the water is warm anyway because you tee-d into the drain port, so you don't have the risk of cold water bleeding over into the hot line when there's a large enough pressure drop in the hot line. Your design also eliminates the power and design complexity needed for a pump, and keeps the water constantly circulating, which will increase the amount of hot water you have available, as well as prevent the risk of pipes freezing in winter, since the water at the very bottom of the tank will now be warmer than it was before. Cool to see you did it all in copper; I was lazy and used pex on mine 😅

[olddave]

this works great, I've had that system for over twenty yrs on my oil fired hot water tank... yrs ago I wanted to buy a circulating pump and an old plumber explained this to me. nothing to wear out or break down.

[LizRoyable]

I'm getting ready to replace CPVC with Pex and wanted to add recirculating line without a pump. Back in the 70's I built a ranch house and a plumber friend did this for me on that house and it worked great. Thanks for posting this.

[kebo]

Excellent video, thank you sir! This gives me some food for thought, I need to do something in my house as the water heater is in the garage, and BOTH bathrooms are on the opposite end of the house, about 80ft away!!! So yeah, we are wasting LOTS of water!!!! Thanks again!!

[mikeh.]

I bought a single story 2005 home that already had a recirculating pump system installed (probably by the builder). The pump didn't work so I looked online for a new one. $600+ was way out of my price range. Fortunately the hot water naturally circulates through the system just like Owen was saying in his video. It isn't as hot as it would be with a new pump installed but you don't need it to be to wash your hands or even get in the shower. It saves a lot of water and is very convenient. If air is introduced into the system via plumbing repair or the water company fixing a pipe (rare), then you'll need to bleed the air out. All I do is hook a 50ft hose to the bottom of the water heater drain and turn on the hot water at the faucet furthest from the water heater. Then turn on the valve for the WH drain for a minute and it's all good again.

[MoNoShocks]

Interesting. An old time plumber told me about such a system about 30 years ago, but according to his explanation, it only works if the end points are higher elevation than the water heater such as water heater in the basement or crawl space and return lines are eitler level or sloped downward. Based on the theory of heat rises. Very interesting if you can get this to work with water heater on same floor as end points.

[sr.gateau]

Excellent video!
If your water is from a well with a pump, this will save on energy to run the pump and wear and tear on the pump.
Note: if you have a tankless water heater, gravity recirculation might not be enough to turn on the heater.

[FlaGordon]

since I don't have access to any lines, no basement of attic, I think I will add a 2.5 gallon Water heater fed from the hot water supply line at the 70 foot away bathroom... Installed in the kids bedroom closet which backs up to the bathroom.
But I really love your detailed explanation and I will be doing what you detailed for our master, just 20 feet. Electric isn't a concern since I have solar.

[dewaynemartin]

Did this to our house when we remodelled...works great. WH is in the crawl space, upstairs' showers get hot water in 5 seconds or less. Used 3/4" pex on the main loop, 1/2" pex on branch lines and insulated it all well. I always thought the water recirculated due to the temperature differential versus gravity...but I might be wrong. Either way, it works. Nice to not have a pump that can go out.

[huntspoint]

This is brilliant thank you. I was considering installing a recirculating pump, but I definitely will be doing this instead.

[jackt]

Insulating the cold is a de facto requirement, especially with a finished ceiling. If they didn't insulate the cold, there will be a trail of water under every cold water run from water in the air condensing on the cold water pipe, no different than water condensing in an air conditioning system and running out of the drain hose. The hot is normally only insulated if you recirculate.

Using gravity like gravity hot water heat works, but I'm not totally convinced as there are other reasons for that pipe being hot. However, I did find at askthebuilder that they outlined exactly what you did, and I do thank you for your thoughts and the effort you put into making this video.

I notice in the comments that people are trying to come up with a cost basis as to this not costing more or the cost minimized. They need to get over it. You are trading energy money for convenience. To say you are money by saving water is laughable. Unless your house runs on bottled water, that's spending a dollar to save a hundredth of a penny. The only variable is how to get acceptable performance for the least energy investment.

[alanhall]

Coldwater pipes are insulated to keep them from dripping condensate.

[carguy]

Best description I could have hoped for. Thank you!
Looks like you’ve got a lot of time & $ invested into your home - looks fantastic!

[dmcarstensen]

This seems like a perfect thing to use with the Uponor logic system I've been researching.

[shameless]

Genius! I must do this! My wife complains and wastes mass water at the kitchen to get hot water.

[compactc]

I’ve got to install this! One tied in on my Dad’s side sink in the master, the laundry room, and one for the kitchen sink would do it.

[hyster]

I thought the return was mixed in with the cold water inlet. It looks like you supplied it where you empty out the hot water heater

[DJSephEntertainment]

Great explanation. I'm planning on installing a tankless Navien water heater that has an internal recirculation or external recirculation. I'm planning on doing the external.