View Full Version : I need cold water!!

07-11-2007, 03:35 PM
I live in Phoenix and have a brand new house. All the lines are PEX and run through the attic. I'm sure I don't need to tell you how hot an attic is in Phoenix in summer.
Anyway, I can't get cold water cause of this. I need to have cold water in the shower. The water is even hotter than I like it in winter!
Any ideas? I tried searching for the opposite of a hot water heater, but no luck except for one in south africa.


07-11-2007, 04:33 PM
I live here in Ga and there is no cold water theres lukewarm :) Only thing I can think of that may help is insulate with a radiant barrier. Search online. That will lower the temp inside the attic by few degrees. Maybe also insulate the pipes themselves.

07-11-2007, 05:26 PM
I need more than a few degrees. I haven't checked, but I am sure the attic is 120F+.
They make pool coolers, why not shower cooler?

07-11-2007, 06:43 PM
Funny, I'm in the north...we do all we can to avoid piping in cold area's.
You'd think they'd do the same in your area for heat.

07-11-2007, 11:09 PM
It seems to me that if you ran the water for a few minutes before taking a shower, it would use up the hot water that was in the pipes and you would have cooler water. Is that not the case?

07-12-2007, 07:29 AM
In NH, when I put in a radiant barrier, it dropped the attic temperature about 20-degrees. When I lived in Kuwait, there was a water tank on the roof (gravity fed piping in the house). For about 8-months out of the year, we turned the WH off, and used cold (from the roof) as hot and the stuff in the WH as the cold. Boy was it a problem if you ran out of the water in the WH (air conditioned space), then you had hot on both sides.

More "normal" insulation and a radiant barrier, plus good ventilation of the attic space. www.Solatube.com (http://www.Solatube.com) has some solar panel powered attic exhaust fans that, other than the initial cost and installation, won't hit your utility bill. You may want to look into something like that as well.

07-12-2007, 01:39 PM
It seems to me that if you ran the water for a few minutes before taking a shower, it would use up the hot water that was in the pipes and you would have cooler water. Is that not the case?

That is what I have to do - I find about 10 sec of running the cold solves the problem...
I use the "wasted" water to rinse the shower before use...
In the winter the problem is not so bad...
Insulating the pipes int he attic willl not help - it only slows the rate at which the water heats...
My neighbor and I got into an argument about this and he insisted that it would solve his problem... I got a case of beer out of the deal (OK - at least I shared it with him)...
Cooling the attic (radiant barrier or more/better venting) is the only real solution.

07-12-2007, 01:40 PM
We have the same problem in central FL, but I like the hot shower and haven't felt it necessary to do anything about it.

If you really want cold water, you'll have to cool it somehow. I can think of 2 ways:

1) bury a tank deep enough to stay "cool" (your definition) year-round. See http://www.geo4va.vt.edu/A1/A1.htm for a map showing the approximate "mean earth temperature" in your area. Then plumb your cold-water needs through that tank, taking the water out of the bottom. You might be able to use an old water-heater tank (remove the cabinet and insulation before burying it, and plumb it backwards). Be sure to mark where it's buried, because you'll have to dig it up someday. You may have to go pretty deep in AZ, so you might instead:

1a) Drill a deep hole and place a well casing in it, sealed at the bottom, to make a long skinny tank. Again, water goes in the top, out the bottom.

2) Get a refrigerator with a 55 gallon plastic drum full of water, or better, a drop-in beer cooler, put a few hundred feet of coiled tubing in it, and run your cold-water needs through that.

(1) would be cheaper and greener, but the water might not be cold enough for you. In either case you've got some plumbing to do, and ultimately will be limited in flow rate.

Just thought of (3): Use a conventional hot-water circulating pump, which normally sucks water down the HW pipe and returns it to the WH. Plumb it in to suck water down the cold-water pipe and return it to the WH. I use something called a "Chilipepper Appliance" to do the instant-hot-water thing here. It's got a thermostat on it to shut off when the incoming water is hot enough, so you'd have to see if it could be made to shut off when it's cold enough. Of course, if your cold water NEVER gets cold enough, you're back to (1) or (2).

Just thought of (4): Since you're already using PEX, you've got more flexibility (no pun intended) than the average bear. If the water coming into the house is "cold enough", just run a separate PEX line from the manifold to the shower, keeping it in airconditioned space. How to do that, of course, is your problem, but if you could just run it underneath the attic insulation all the way it would make an enormous difference. If your luck is like mine, of course, the route would cross every joist in the attic. Maybe you could run it inside the A/C ductwork?

07-12-2007, 06:53 PM
1. The water is never cold enough in the summer time. The mains also warm up considerably.
2. Any piping in the attic gets super hot and it doesn't make any difference how long you run it.
3. That is why I, and most plumbers in PHX, (other than those trying to do a quick and cheap installation), prefer to run copper under the floor. That at least cools it down somewhat.

09-09-2007, 04:08 PM
sorry guys, I never got an email responses from this so I never came back to it. hj is excatly right, it's also a problem of the mains. So no amount of running time is going to give me cool water.
One thing I thought of was using a hot water tank as just a water tank and keeping it inside the house, but I don't really have the space. It doesn't have to be 50F water, but room temp would be fine this time of the year.
The reason I heard they are not doing the copper under the house is because of something to do with some type of expanding slab? I don't recall the term.
If I did some sort of underground thing, would I not need a pump as well? Or would gravity do it's thing enough?

What about adapting a pool cooler for this?

Thanks for all the input, even if I am a little late. :o

09-09-2007, 05:01 PM
You could look into one of these. I had a doctor's office request something similar so their whole system was chilled. http://www.classwater.com/products/chillers.html

09-09-2007, 05:54 PM
there were no showers tho correct? Just sinks and fountains?
How much GPH does an average shower use?

09-10-2007, 05:57 AM
a couple minutes under a modern shower head uses a small amount of water, and your usage is not constant, so anything that works for an office where people are constantly taking a little drink or two will be sufficient for you. That is my guess.

Since the temperature of your main water supply is pretty warm to start with, anything that holds a batch of water and lets it cool down a bit is a good step. I'm not there, but from far away I'd say to look into a holding tank (good for the cold water everywhere in the house) and then a lot of attic insulation (good for the whole house). Metal (or foil) is what reflects heat energy back. The sun sends energy, and the invisible energy goes through objects so it gets into your house . The invisible kind can travel through objects only up to a certain point, and that is why caves are cooler than attics. A radiant barrier inside the attic will work. It will send heat back out into space after it penetrates your roof. Your roof is not enough mass to act like the ground covering a cave, so it doesn't keep you cool.

You only need ONE radiant barrier. So, don't wrap the cold water pipe with it while also putting a bigger radiant barrier in the whole attic for the whole house. That is just wasted money and effort.

Adding some of the other kind of insulation, convection-type trapped-air insulation, will help too.

Nobody can calculate in advance or promise a specific number of degrees temperature drop. You are fighting against the sun, and all you can do is to do the right thing and measure the difference it makes.

When you let cold water run for a long time, what temperature do you read on a thermometer? Let water dribble into a glass for as long as it takes for the temperature to stabilize.

Your mission, should you choose to accept it, is to get cooler water stored in advance inside your house, and then run it over to the shower when you need it. The pipe to the shower will be hot initially, but that is inevitable.


09-10-2007, 10:26 AM
I am going to have these guys come and do an energy audit http://www.savenrg.com

Start with that, that should cool the attic down and at the same time lower my energy consumption.

Now if I had a holding tank in the garage and insulate it, would that be enough to keep it a reasonable temp?


09-10-2007, 08:28 PM
Probably not since your garage is probably not conditioned by your a/c...it could be 100-degrees or more in there. Insulation only slows heat transfer, it doesn't stop it. The holding tank would need to be in the house where it is cool.

09-10-2007, 09:26 PM
Ok, what size of tank would I need? Only 2 of us here. Showers are 5-10mins each and we have one regular head and another rain head above.

I found these

Would need some sort of shut off valve in winter since I won't need it. Diverter valve or something maybe?

Just gotta find a palce for it, I just don't know where right now.