How To Save Money With Your Hot Water Heater

[erichtopp]

I had a plumber working at my home recently on a project near my hot water heater. He suggested to me that the outlet pipe of the hot water tank be plumbed down the side of the hot water tank and then back up to the hot water domestic lines in the house. This "down loop" of pipe out of the hot water heater stops the heat from transferring up the lines into the rest of the house hot water lines......therefore radiating heat from the hot water heater. So.......I had him install the "down loop" but we didn't have enough pipe to make the 3 foot drop required for a good "hot water down loop". He says you need to have at least 3 feet of "down loop" for it to stop transferring the heat from the hot water heater. For now, we installed a 1 foot "down loop" of pipe........it makes a big difference in the amount of heat transfer from the hot water heater, but I will have him change it to 3 feet shortly. What are your thoughts???

[Flying Z]

Can you take some measurements and compare before and after temps? Thats the only way you will know if it works. Randy

[Flying Z]

Forgot something: Sounds logical to me, be sure to let us know if it really works.

[terry5732]

He was simply lookig for work. Often these "professionals" come up with such nonsense to increase their revenue. Your extra 6 feet of pipe will lose more heat unless insulated. Best  to have shortest exposed distance to where the pipe enters wall. The wall is somewhat insulative. If buidling new, consider insulating hot water pipe within wall as well. Find a legitimate plumber if you can these days.

[jimjjnn]

By installing the "loop", it prevents heat going up into the hot water pipes due to thermosyphon action until the hot water faucet is turned on. This is an old trick that old time plumbers used to do on early thermostatic controlled hot water heaters. My first house was done this way when I had to replace the hot water heater, Plumbers stopped doing this due to the low price for gas in later years. It was well worth the extra cost to me as it paid off in just a few months in savings. I'm glad to see that some plumbers nowadays are using that method again.

[pyrocasto]

Not nonsense. The loop should help at least some. I never actually thought doing that until now. I may have to have a look at our hot water heater and put in a loop, see what kind of difference I get.

[erichtopp]

The "down loop" really seems to work. My natural gas fired hot water heater doesn't come on as often as it used to. HOWEVER, one of you commented that the piping should be INSULATED. I totally agree an will have this done likely at the end of the month ( November 30th ). But the 12 inch "down loop" just isn't long enough, I agree with the plumber that it should be at least 3 feet long. The plumber is returning at that time due to an RO system problem. I'll get some measurements at that time and post them here on the website. Logically, the law of thermodynamics would indicate that this idea works........not to mention we just had a 64 percent increase in natural gas prices this month. Rgds, Erich.

[hiker]

3 bucks a gallon for propane here--even thou its made just a few miles from my town..

just another scam from the-- >>>United Scam Assoccation<<<<---

time to check out the price of coal[im sure my neibores would just love that]..

[nothing to lose]

It does work. Heat rises, even if water is not actually flowing. Make heat travel down before it can rise and you stop or at least slow the rising.

 Any heat that leaves the tank then of course means the tank has to run to replace it longer, or kick on more often to replace it.

You could sort of test this, but with a chance of less than acurate result though.

Take a Black copper tube capped at both ends, put it in your window in direct sun but with part of the top of the tubbing higher than the window so it is always in the shade. Both ends capped, air can't flow.

 Now after a day in the sun is the top of the tubing warmer, same, or colder than the room it's in. Heat rises and if you did that correct the tube even in the shade above should be warmer than the room. Same thing with a water tank, substitute fuel for sun though.

You could also fill the tube with water for the same results.

If you don't mind bars on your window, a bunch of black copper tube upright letting air flow through can make a dandy solar heater also. Bottom at cold floor, top near ceiling, the rest in the window for sun to hit it. As the center warms, warm air rises sucking up cold air to be warmed. Since it's in the room, not outside, nothing can be lost at night when the sun is gone. Nothing to gain at night, but Nothing to lose

Good use for unneeded scrap pieces of tubbing durring winter

[nothing to lose]

Can't you use like whale blubber or fish oil or something up there??

Just joking of course.

[dinges]

No matter what the leftie greenies say, it IS renewable ;-)

Peter,

The Netherlands.

[kenputer]

Being in the plumbing & heating  business i know that this works and a 1' drop is all that is needed.We put tempering valves on all domestic water heaters now and require the thermal trap so the hot water is not at the thermostatic device when no demand for hot water.

kenputer

[Reno]

This is well known and there are units that can be bought but easilt built. Many how to shows have done segments on this. The pipe does not nedd to run down the side of the heater but just loop down so the hot water which wants to rise can't and the cold which wants to drop also is unable.

http://www.fieldlines.com/comments/2005/11/10/234329/53/11#11

[Laylow]

Heat does not rise, but hot air or water will rise.  Any circulation of water would have to be in the single outlet tube with the hot water traveling upward through the center and the colder water traveling downward around the outside.  I would be more concerned about the heat just conducting through the water which would happen whether you have a loop or not.

If you go the hardware store you can buy heat traps for the inlet and outlet pipes which would be far more effective.  They are simply little short pieces of pipe with a plastic flap that closes when the water is not running.  This would stop any possible circulating of the water and provide a thermal break between the heated and unheated water.

The heat traps and pipe insulation would be your wisest investment.  Forget about the downloop.

[nothing to lose]

Down loops apear to work for whatever reason and don't really hurt anything to have them.

 I would consider this proof enough for me. My water tank has both up and down hot water lines. The line that goes UP is hotter than the line that goes down at the same distances. So if the line went down an equal amount as the other line it should be the same lower tempature, no reason for it to re-heat itself then when it loops back up.

 This is an un-heated room and the tempature difference was greater for the water lines than the differnce in the room itself from top to bottom.

 The line going down is closer to the water tank, so if anything I would expect heat from the tank to be warming that line. But it is colder.

 Moving away from the tank far enough to not get false readings, the wall in the un-heated room is nearly the same temp top and bottom. No water has been ran for at least 6hrs also. The wall is warmer down by the tank than it is above the tank also.

I already wrapped extra fiberglass insulation around the tank, time to add more. Top of insulation on the tank was about 6F more than the room.

I was looking for something to test with my new non-contact thermometer anyway

[Laylow]

I was just thinking, "boy that is one busy guy" right up to where you mentioned the new thermometer.  You'll find out that they are pretty handy for lots of things.  You can point it at light fixtures to see if the ballast is going bad or it is just the bulb.  You could point it at your wind generator to see how its doing.  Or you can take peoples temperature on the bus without them knowing.  What an invasion of privacy, eh?

Anyway, on the downloop, no arguing with experience and hard data.  The downloop works but I think if you get the heat traps it would be redundant.  Could be wrong though.  Maybe you could go buy a couple so you have another excuse to use your new thermometer  :]

[niffa]

Yea, right up until you kill the last one.

Phil

(with a smile on my face)

[nothing to lose]

Might be an idea for me to get some heat traps perhaps, but I already have everything else I need I think for a down loop. Might try both, one at a time later and see how they compare. Test with the toy to see which stays cooler on the pipes then, traps or a down loop. I have to do some water line work for other things anyway soon.

Ya this thing is great, laser pointer so you can actually see what your shooting, no geussing did I get it or something else. Shot the thermometers in the house with it from acrossed the room when I first got it. Walked over and the wall ones and the non-contact said the same temps, pretty accurate even at a distance.

Later I will try the shade side of an old mini van and the inside of it while it's sitting in the sun, perhaps part of a solar heater soon

 Been thinking about cutting it up for parts.

 Hows the fridge doing? Shoot the stove, get the temp, shoot the fridge. Should be the same temps if sitting next to each other right? Mine are pretty close, but if you have pilot lights expect stove to be hotter of course. Center of fridge door is 4F colder than edges of the door on mine

Found a draft in the kitchen while playing too, that needs fixed!

Good thing I bought rechargable batteries for this thing eh

Been checking a bit of solar gain also. Geting a bit of extra warmth.

If these things were less expensive I would be giving them as gifts this year.

Even my daughter (14) and wife couldn't put it down after I showed it to them.

Did you know a dogs nose really is cold? Tempature of a cat's ear?

And I thought I was buying a new tool at the time.

So I'll probably put in a down loop first since I have everything here already for that. Then I'll probably have to make a trip somewhere to get traps later, dought the local store has any. They might. And need more insulation around the tank too.

[electrondady1]

ntl, you might start a trend , use your gage to avoid sick people.

[terry5732]

I guess this wives tale has been told by enough plumbers to have believers. We're usually talking about a 3/4" pipe here. For heat to go any appreciable distance it must be replaced by cold. Any hot water going up would be in close proximity to cold going down and they would necessarily transfer their heat to each other, inhibiting the progression of each. Watch a 10" pot on the stove as you heat it and notice how long it takes until the top is nearly as hot as the bottom. And this is with LOTS of room for the water to move around!

When I purchased my newest water heater last year, there were no models that didn't have a built-in anti-syphon valve in both the in and out ports. No water can flow through these unless there is about a 15 PSI differential and none can go backwards. No cold in = no hot out.

[erichtopp]

Gosh I hope I haven't started a war on "down loops" here on the forum?? Well, at least I learned one thing and that is to insulate the hot water pipes no matter if you have a "down loop" or not on your hot water system. Hummmmmmm, I am still not convinced that a 1 foot "down loop" is long enough, but never the less it sure helps out. As for the pipe traps to keep the water from flowing, I worry that they will stick shut or get slowly clogged over time, restricting the flow. What do you think??.......will they restrict the flow over time?

[Laylow]

Like terry said, you probably can't find a new water heater that doesn't already have the heat traps on it.  Look at the two lines coming out of the top of your water heater.  Do they start out as little 4" long pieces of pipe?  These would be the heat traps.  Everything I know says that the downloop is not necessary but I'm not the one with the laser thermometer.  If there is hard data out there that says it works I'm not gonna stand here and say that it is doesn't.  Sometimes I'm the one missing some key information.  Testing and more testing, that's the thing to do.

Hey NTL, as long as you've got that fancy laser why don't you throw a dielectric union in there and see what that does to your temps (and please tell me that you are using a grounding rod and not your plumbing system for ground).  :]

I guess what I was thinking is that if heat is conducting up the pipe it would have no problem conducting down the pipe.  In any case the water will stratify.  Perhaps the higher temperatures that you were reading just show that the hot water had collected there.  It might not be telling us if the same amount of heat was lost over a greater area.  The only way to know for sure is to do a long term study of how much energy your water heater is using.  So you can either do the world a favor and tell us once and for all what we should do with our water heaters, or you could just insulate your pipes, put in some heat traps and a down loop and get on with your life.

Even better though would be a solar preheater but I'm sure there's another thread for that somewhere.

[richhagen]

If I recall correctly, heat tranfers by three methods:

Conduction, the transfer of heat from colder material to warmer material.  

Radiation, the radiating of energy in the form of electromagnetic waves.

Convection, the movement of matter containing energy

Now, for this loop, I can't see how it would have an effect on the conduction, except that a longer pipe would make it conduct more as there would be more water to pipe and pipe to air boundry area.

For Radiation, the same thing, it would actually hurt a little I think.  

The convection part of it seems the most interesting.  Cold water, like air, but to a lesser extent, is more dense than warmer water, and would have a tendancy to sink to the bottom, while warmer water would have a tendancy to rise.  This happens in the Ocean for example.  If the pipe has enough area for water to circulate, and I don't know the answer, then a trap, or loop of sufficient height would probably eliminate that.  Such convective losses might or might not exist to any great extent.

I'm curious, but not enought to research it further right now.  Rich

[nothing to lose]

Ya know another thing is not all tanks are plumbed the same either. My tank the lines go into the sides, not the top. Hot line comes out the side at the top, cold line goes in the side at the bottom. Close to the drain valve but I think a bit higher.

Most of the scrap tanks I drag home, the cold goes in the top and a plastic tube inside pokes down towards the bottom, hot just comes out the top.

"Do they start out as little 4" long pieces of pipe?  These would be the heat traps."

If they are the heat traps? I do get scrap tanks with just plain 3-6" galvanized pipes at the top, or other fittings. Not knowing what the heat traps look like, would I even see a difference there? Maybe I have some out in the yard and never even knew it? I just toss them untill I need something then go look for it.

Grounding rod? I just clamp a zip cord to the PVC pipe, ain't that good enough

Just a joke of course, and yes I do have a ground rod.

 "dielectric union" off hand not sure what that is, but I am about half asleep, long night.

I normally have my pipes insulated best I can. I like cold water on a hot summer day, don't like condensation either (very humid here at times), and might as well try to hold heat in the hot lines also. Awhile back I was working on stuff and removed insulation so I do have exposed pipes now that normally are not exposed.

 I do have alot of the old grey plastic lines here also. I like those, they can freeze solid and never break, unlike PVC, copper, or steel. Having extra tubing now I will probably be replacing the other stuff with more tubing soon as I can get around to it. Also will need less, moving the tank.

 Got a good deal on new rolls at a garage sale awhile back, several sizes.

 Don't tell me this stuff contains lead or something and that's why it's not sold any longer .

Anyway I won't be doing any long term studies I geuss. Been thinking about it for along time. Pretty stupid to have the water tank on one end of the house when bathroom and kitchen are in the middle of the house. Since it's electric not a big deal to move it. I'd like to get an on demand tank to install, not sure what they cost though.

  So, I can save a about 20' (maybe more) of each pipe moving the tank closer to the facets and that should also save on hot water losses. Less pipe to heat when using hot water, less standing water to lose heat when you turn it back off. That should add up to some savings also. Bathtub is used about 3-4 times a day not that big a deal, sinks are always on and off all day long. Everything will be closer.

 Why are tanks often installed far from the facets? Any reason for it?

When I move the tank all the lines will go down anyway to get under the floor or straight through the wall, no over head lines any longer either. Loop won't be needed with no upward lines. Still may try the traps if I find some though, geuss it can't hurt anything.

[nothing to lose]

"The convection part of it seems the most interesting. "

Kinda my thought. If in a cold room a pipe is hot when water has not been run for 6 hrs or so, then I think that heat had to come from somewhere fairly recently.

If the only source of heat is a tank of hot water below the pipe, that would be my best geuss as to where the heat came from

 I think it was said somewhere here, forget who, that heat does not rise, water or air rises when hot, but conducton does not. Would that be correct?

 I can't test it to be sure right now, but it seems to me that when working with hot metals, like when I weld tanks together, the the upper side does get hotter and for a further distance than the bottom. I don't think that is just hot air rising around the metal tank. I think it's the heat conducted in the metal tank itself rising. I'm reffering to the sides of the tanks still, not right at the top or bottom ends.

 What do you think?

Anyway I am going to move my tank closer to the facets and all lines will go down or straight through a wall. Kitchen has an unused closet right next to the unused electric furnace. Short run through wall to bathroom sink, equal distance to bathtub and kitchen sink, opposite directions, same distance.

Should be more heat savings there than either traps or loops, far less pipe to heat and cool for the 3 hot water facets.

[asheets]

At the laundromat my parents owned while I was growing up, there was a return loop to the tanks (main out at the bottom, return to the top).  It wasn't for saving money, but to keep the water pressure and temperature fairly constant.

[richhagen]

That doesn't seem right to me.  The heat should conduct either way I would think.  It is just the vibration of the individual molecules, which are held in place in a solid.  I don't think gravity would play much role.  Rich

[nothing to lose]

Ok, perhaps it's an illusion then. I had never really checked it speciffically.

 Should be welding on a tank again soon, perhaps I will try to set it up vertical and horizontal weld it, then check with the non-conact thermometer and see if I find any difference.

Could be too that the air inside the tank heats from the welded area causing the top to be a bit warmer. A sheet metal pannel might be better to check than a tank.