Gas water heater

[CJDave]

[img]/forums/images/icons/tongue.gif[/img] That's a neat setup, Gary, and retrofittable to existing homes. I lived in a nice home in CA that was on a slab and the H.W. heater was a day's ride from the bathroom. A setup like that would have done nicely. PAT......how about this.....I get a small electric H.W. heater and use one of the thermostats IN THE HEATER to trigger a circ pump. The circ pump keeps the tank full of hot water from my other unit. The other thermostat and heat element in the heater comes on IF NEEDED. Is that a workable setup? [img]/forums/images/icons/tongue.gif[/img]

[Pat]

Gary, I recall your previous detailed description of the system. I used twist timers instead of a thermostat and a recirc pump to serve two bathrooms in my mom's house after removing the small point of use hot water heater which failed just after the one year warranty expired and I discovered a larger one would not fir through the crawl space access door.

Anyway, your system works good for you but it is not ideal for all applications. If you are drawing a bath, no problem. If the "cold" water run is quite long and you charge it with hot water then it will mess with your temperature regulation as you have hot blended with hot that gets colder as the pipe is swept free of hot water. Yours is a good system for your use but for new construction or a remodel if there is access for plumbing runs, I would recommend a separate return line. If you have a main line running the length of the house and feeder lines branching off you will charge the main cold line with hot water which could interfere with other users, say someone brushing their teeth and trying to rinse with "cold water."

Again, yours is a good system for you but other configurations may be better for other situations.

I have noted that the thermostat on the return line in my system does not "make" until the water in the pipe elsewhere has cooled below desirable shower temp. The result is worst case where it takes 30 seconds or more to get hot water to the far end of the house (master suite.) It is a gamble. If the recirc is running or just had run you get virtually instant hot water. If it was just about to run you may wait 30 sec or more. That is why I will incorporate the $6 timer I got at HF and have tested (works fine.) Just need to wire it in. IT will guarantee hot water during our most used showering periods of time. I may leave the thermostat in parallel as well. That would ensure the hot water is never TOO FAR away at any time.

One has to be careful how you mechanize energy conservation measures so that you don't pay more for the conservation measures than you would have paid in energy for several years. As water prices soar and we will be more energetically exhorted to conserve and the recirc for hot water will be sought for water conservation not just comfort and convenience.

By plumbing water distribution via a main trunk with short feeders at points of use you make it dead simple to set up a good recirc system. Just attach a return line and pump to the "far" end of the main trunk or most remote feeder off the end of the trunk. This puts hot ware close to all points of use and right at the one at the end of the trunk to which you connect. It is difficult to use too small of a pump with one of these systems as if the pump is really tiny it just runs a bit longer to satisfy the thermostat. With a really small low electrical consumption pump you may just opt to skip the t'stat and run it 24-7 or put it on a timer and shut it off from about bedtime to nearly get out of bed in the morning time.

Pat

[GaryM]

You make good points as always Pat, but I'm not charging the cold water line with HOT water. When I press the button, chances are that the water in both lines are at about the same temperature. Room temperature almost by definition.

Yes, the pump could be installed to push the "cold hot water" back directly to the water heater. Or the same pump could be installed as a continuous recirculation system. Is that what they use in hotels? Seem you never have to wait for hot water in a hotel. Or maybe it's just that there are so many users that the hot line is always in use.

[Pat]

Gary you are charging your "borrowed" return line with water up to the temperature of the thermostat setting on your system. Not too bad, just something that popped in my head and maybe should have stayed there (if there were room.) In new construction with the available options I would go with a dedicated small diameter return line and pump with timer, t-stat or both. It wouldn't be all that superior to borrowing a well located cold pipe for return but in a system designed to serve more than one location I think the dedicated return is better. You can place the pump by the water heater or other more desirable equipment location than under your personal sink.

The twist timer install I did was quite similar to your setup except for not being a kit and using a separate return line and serving two bathrooms two timers (non-interfering) When I build this house the recirc was designed in from the gitgo. If I had it to do again I would plumb the MAIN trunk for hot water using a larger pipe and route it so that it got close to all 5 bathrooms (distributed on three floors)as well as the pantrility room (contains laundry) and insulated the devil out of it. Then virtually all hot water points of consumptioin would have nearly instant hot water. It isn't bad like it is (no where waits very long (except master bath when the recirc was off wth a screw in the impeller) but making it really good would have been easy.

An alternative to running the main hot trunk near all points of consumption wold be to plumb a return line to all of the locations and use balancing valves to even out the flow.

Pat

[egon]

You folks got this hot water thing complicated beyond all reason.

A very simple effective way is to place two buckets of water on the wood cookstove. One goes on the hot part, the other on a warm part. When both are at proper temperatures [ empirically derived] just pour them in the tin tub and enjoy a the bath. If really fussy use three pails with the last being used to rinse. [img]/forums/images/icons/grin.gif[/img]

Or be men, just use the water as it comes from the well. If colder is desired a few more stokes of the pump handle should suffice. [img]/forums/images/icons/grin.gif[/img]

Egon [img]/forums/images/icons/grin.gif[/img]

[Bird]

Egon, there's probably only a few of us can remember doing that; i.e., bathing in a galvanized wash tub in the middle of the kitchen and we just used one of the same round tubs that mother did the laundry with; couldn't afford one of those genuine bathtubs.

[Pat]

Egon, My wife and I have bathed in waterfalls in the mountains. She has bathed in unheated water in Alaska (I didn't, my mom didn't raise any idiots... mostly I had to care for myself!)

Been there, done that, my goose pimples had goose pimples to show for it I have SCUBA dived in water so cold that exposed flesh only tingled for a few seconds before going numb. I survived 3 winters in Minot ND (-47F) and lately have become accustomed to water above 60 degrees sprinkled on me in my shower. Go figure! I guess I will have to let you drum me out of the REAL MEN CORPS.

Pat

[GaryM]

Not true Pat!

If I were charging the "borrowed" return line with hot water I'd not be running the pump at all. In the morning, when I use the feature the most, I'll bet that the HOT and COLD lines are within a few degrees of one another. They run side by side and with no flow in either for 7 hours why would the HOT side be HOT?

The pump takes the room temp water in the hot line and pushes the room temp water in the cold line away. When the hot line fills with HOT water the pump shuts off. The cold line still has room temperature water inside.

OK there is probably some WARM water in the cold line depending on at what temp rise the pump shuts down. If I wasn't so lazy I'd run a few temp readings in the morning. [img]/forums/images/icons/laugh.gif[/img]

[Pat]

Must be a communications problem caused at my end because I don't think we could disagree very long on very much.

Let me restate part of what I tried to communicate (who knows what I actually communicated??)

After you push your button the systems runs till the thermostat at the pump is satisfied that hot water is there. Up to and until the t-stat is satisfied, the water in your hot water pipe is being pumped into your cold water pipe. The water in your cold water pipe will increase in temp until it gets hot enough to satisfy the thermostat (which is how it was designed.)

Now, right after the pump shuts off and you draw water at your sink you get a mixture of water from the two pipes that can be adjusted continuously from 100% from the hot water pipe to 100% from the cold water pipe.

At first it wouldn't matter which as the water is the same temp from either. Lets say your personal ideal temp would take 1/2 hot and 1/2 cold (after a long run of each.) With your system, the first water delivered will be at the temp of the setpoint of the T-stat no matter how you adjust the faucet(s.) Lets say you adjust for a 50/50 mix. The water starts flowing at the temp of the t-stat set point. The cold side gets colder and the hot side gets hotter (Assumes the t-stat set point is lower than the t-stat of the water heater.) Unless I knew a lot more about your pipe sizes, runs, pipe insulation (if any) and such thermally important information I can't predict just what the temp of the delivered water will do. It could drift up toward an asymptote until the water heater couldn't keep up (and then it would fall) or it could go down toward an asymptote till the heater got behind when it would go down more. Lots of dynamics and variables here but I think I described the gross effects you could sense with your skin.

You said, "When the hot line fills with HOT water the pump shuts off. The cold line still has room temperature water inside."

Gary, I don't believe the second half of this is true. Where does the output of the pump go? Why is the water coming out of the pump more than an infinitesimal fraction of a degree cooler than the water going into the pump?

Why isn't the temp in both pipes near the pump the same temp when it shuts down?? (at least within a fractioin of a degree)

I would be pleased to reexamine my analysis and try to understand any errors if you could be a little more explicit and detailed about your objections to my post other than to say...

"Not true Pat!"

Do you mean the whole thing is not true or some specific part? It wouldn't be the first time I screwed something up that I thought I understood. I find that feedback is a powerful motivator to rethink and examine one's beliefs. Everyone has to believe in something. I believe I will send the dumbwaiter down to get a diet Coke.

Pat

[egon]

Right Bird! That's why I can't understand all these youg'uns with these elaborate plans for hot water when it's all pretty simple! [img]/forums/images/icons/grin.gif[/img]

Egon [img]/forums/images/icons/grin.gif[/img]