04:21PM | 11/09/04
Member Since: 11/08/04
2 lifetime posts
I have a gravity fed hot water recirculation system in my house that has given us great, fast hot water. 75G Bradford-white hot water heater; 2 storey house with hw heater in basement.

However, we've discovered that hot showers can turn lukewarm pretty fast with the return line open -- especially for the person who is second in line for the shower.

With the return valve closed, we don't have this problem -- hot water is plentiful. But we have the "3 minutes to hot water" problem, which is why a return appealled to us in the first place.

It is weird, the 1st hour rating on this 75G water heater is great, so it is hard to imagine that we could be out of hot water in 10 minutes of showering (primary shower head is not a 2.5 gpm head, but shhhhh, don't tell anyone...).

I wonder if the balancing valve in the shower is somehow mixing hot water with cold and sending the mixture down to the hot water heater?

So diagnosing help would be great.

But, I'm also wondering if I can kill this problem at the hot water heater, since I know that with the valve off there I enjoy long hot showers. Could I install a valve on the return line that would shut off the return when the water fell BELOW a certain temperature, yet stayed open when the water was pretty hot? All the thermostatic valves I've seen work the other way around.

Thanks for any help in diagnosing and fixing this problem!



05:48PM | 11/09/04
Sounds like your system is not circulating. That when you shut the system off you have plenty of hot water from the tank. But with the system on you are not pulling all hot. I doubt it is the shower valve. It is often hard to get a gravity system to work.

I presume your system must be designed correctly and that it has worked for several years. Was the heater changed recently or the temperature lowered on the heater? What event may have occured around when you started having the shortage of hot water?

I am not aware of a valve that shuts the flow down but there may be one. I have not worked on a gravity system in twenty years so my knowledge is not the best.


06:07PM | 11/09/04
Member Since: 11/08/04
2 lifetime posts
Lonny, thanks for your reply. House is new and builder was pretty good. Codes in my town are unbelievably strict, (copper required, cast iron no-hub required, galvanized sump required, etc.) So hoping the system was well-designed, but no way for this novice to know.

So when you say the system is not pulling all hot, what do you mean?

Would a recirculation pump fix this, provided it was designed properly? Does that typically mean you have to add other items, too?



08:42PM | 11/09/04
If your new house is still under warranty you should call the builder. Has this system ever worked? Yes a pump would cure gravity recirculation problems but it's about $200. for the pump. and maybe the same each for the plumber and electrician. You shouldn't have to do that if it's a simplier matter of getting your system to work correctly.

Oh, do you have a check valve on the circulating line? I think you should post your question on There are two threads on recirculating lines going on now and there are plumbers there more experienced than I am on the circulating lines. Perhaps one of them have gravity knowledge. You can say LonnythePlumber sent you.


Post a reply as Anonymous

Photo must be in JPG, GIF or PNG format and less than 5MB.


type the code from the image


Post_new_button or Login_button

All bookworms need a good bookmark that inspires them to keep reading. To make this colorful bookmark, cut a rectangular p... It turns out that many bath and kitchen cleansers contain chemicals that are dangerous to the skin and eyes, and often pro... So often we paint tiny nooks white to make them appear larger, but opting for a dark, dramatic wall color like this one—Be... Chocolate-colored walls and large window frames allow the exposed wood beams to take center stage in this small screened p... If you're not crazy about the idea of commingling plants and pool, this modern variation may be more to your liking. The s... Yes, a freestanding garage can become its own tiny house. Artist Michelle de la Vega has all the comforts of a modern resi... There’s nothing like a new set of cabinet hardware to refresh a room. The possibilities are endless: Go modern, rustic, or... Pursue what's known as the stack effect. To achieve it, open the windows on both the upper and lower floors, and as warm a... Like no other floor type, a checkerboard design works wonders to underscore the retro kitchen theme. Vinyl flooring, ceram... Twine lanterns add pops of crafty—but sophisticated—flair to any outdoor setting. Wrap glue-soaked twine around a balloon ... When securely fastened to a tree or the ceiling of a porch, a pallet and some cushioning make the ideal place to lounge. V... Incorporate nature into your lighting scheme by securing a dead tree in a concrete mold and draping your pendant lamp from... For the cost of a can of exterior paint , you can totally transform your porch. Paint the floor a hue that complements yo... In this urban apartment, a standard-issue patio became a serene and green perch by replacing the typical concrete with gro... If you put the washing machine in the mudroom, you can stop the kids from walking through the house in dirty, grass-staine...
Newsletter_icon Google_plus Facebook Twitter Pinterest Youtube Rss_icon