Running hot and cold water together for insulation?

cc-rider · #1 04/07/10, 05:58 PM

I just read an interesting concept. It said to run your hot and cold water lines together for at least 20' and insulate them together, to keep your cold water line from freezing in the winter. I'm going to run lines up an exterior wall....do you think it would be worth the bother of trying it? I'm using PEX, so it wouldn't be that difficult to run them side-by-side and throw insulated pipe cover over them.

Whatcha think???

Hank · #2 04/07/10, 06:10 PM

I don't see that it could hurt anything. My only thought is that the hot line is only hot when running. The water in the line will cool down when not in use. So, a hot water line, if not used often, can also freeze.

Hank
http://www.doublemfarmandchuckwagon.webs.com

rancher1913 · #3 04/07/10, 08:11 PM

you will end up using more energy and the cold water will be warm at times when you want a cold drink, but if it prevents a freezeup that might offset the drawbacks. it won't hurt your pipes unless they are copper, when copper from two differnt pipes touch they cause a reaction and will corrode from the outside in. the plumbing code says copper lines have to be 4 inches apart.

cc-rider · #4 04/07/10, 08:26 PM

I'm using pex, so corrosion won't be an issue. I'm curious, though...how will it use more energy? I'm thinking of only doing it in the bathrooms, so having cold water (to drink) won't be an issue, I don't think. (I use warm water to brush my teeth.....I know, I'm odd!)

countrygurl · #5 04/07/10, 10:50 PM

we live in the south but had a very unusual cold winter this, it smowed 4 times with the last snow we had 6 inches. we had 5 straight days of below freezing temps our home is off the ground of course we ran the cold water at but never thought of the hot water, well on the 4 day it finally froze, wont let that happen again!

texican · #6 04/07/10, 11:05 PM

Why an exterior wall vs. an interior one?

Bearfootfarm · #7 04/08/10, 12:25 AM

Quote:

how will it use more energy?

If the lines are touching, the cold line will be absorbing heat from the hot line

cc-rider · #8 04/08/10, 06:58 AM

Texican - all the sinks are on the outside wall.

Even the tub lines will be an outside wall. Luckily, most of it will be through a basement, but will still have a few feet of exterior wall.

Bearfootfarm - I'm still confused. The hot water tank controls how much energy is used to heat the water in the tank. Once it leaves there.... hmmmm.... I just can't wrap my arms around why it would use more energy. I'm not USING the water, other than what is already in the line is being used to help provide heat. How would that draw more water, and/or energy? Please 'plain me!

Tarheel · #9 04/08/10, 08:26 AM

Quote "I'm not USING the water, other than what is already in the line is being used to help provide heat. How would that draw more water, and/or energy? Please 'plain me! "

Hot water radiates up, so the warm water will radiate into the cold water line thus causing the hot water heater to come on more often.

cc-rider · #10 04/08/10, 08:32 AM

So, besides keeping the water hot in the tank, the tank also keeps the water hot in the lines??? Even when they aren't turned on? That doesn't make sense to me. When I turn a hot water line on that hasn't been run in awhile, the water is cool. It's not constantly hot.

Still not buying that one.

Michael Kawalek · #11 04/08/10, 08:45 AM

Quote:

Originally Posted by cc-rider

So, besides keeping the water hot in the tank, the tank also keeps the water hot in the lines??? Even when they aren't turned on? That doesn't make sense to me. When I turn a hot water line on that hasn't been run in awhile, the water is cool. It's not constantly hot.

It's a special recirculation system designed to always have "instant" hot water on demand. A recurculation loop is built into the design so that an electric pump can circulate hot water out of the tank, through the pipes, and back into the tank to reheat. When you turn on your tap, the already hot, recirculated water immediately comes out. Of course, this is much more energy intensive than just keeping the tank hot, and more so than a "on demand" water heater.

By the way, one important detail. Even though PEX pipe is freeze resistant (I'm using it myself) remember that fittings are all brass and are just as damaged by freezing as any other metal component. So, if you are placing it in an exposed location, make sure that only the PEX pipe itself is exposed and not any fittings.

cc-rider · #12 04/08/10, 08:53 AM

But I have a regular water heater. $199 at Menards. It isn't a special recirculation system, is it??

None of my lines are actually "exposed"...they are insulated within a 6" wall, with 2" foam between them and the outside sheathing and fiberglass around them. Thanks for the heads-up about the fittings, though!

Bearfootfarm · #13 04/08/10, 09:21 AM

Quote:

I just can't wrap my arms around why it would use more energy.

Because you will have to run the hot water LONGER to get the temps up at the faucet due to heat transferring to the cold water line.

cc-rider · #14 04/08/10, 09:27 AM

Ahh! An answer I can understand. Sorry I'm so dense! I kept thinking it was somehow pulling energy while it was sitting there.

Thanks!

blooba · #15 04/08/10, 09:34 AM

Quote:

Originally Posted by Bearfootfarm

Because you will have to run the hot water LONGER to get the temps up at the faucet due to heat transferring to the cold water line.

I see where you are coming from bearfoot but in NW Ohio temps can get to be -10+° with a stiff 50+ mph wind in the open like she is. The slight increase in energy consumption would definitely outweigh a frozen pipe. I would be more worried about placing the pipes as close to the interior wall as possible(i think 1-1.5 inches is code) I would run them together and insulate well. Are you using spray foam insulation or fiberglass?

||Downhome|| · #16 04/08/10, 09:36 AM

Quote:

Originally Posted by Bearfootfarm

Because you will have to run the hot water LONGER to get the temps up at the faucet due to heat transferring to the cold water line.

and all the hot water you pull out of the tank is replaced with cold, the more of it the longer the tank will take to hit operating temperature.

I also see the cold line working as a passive heatsink in general.

are you on a slab,crawlspace or basement?

cc-rider · #17 04/08/10, 09:53 AM

I'm on a basement (10" walls), and the house walls are 6" thick. I'll have 2" pink foam BEHIND the pipes against the exterior wall, and then fiberglass batts around the pipes. And probably foam pipe wrap AROUND the pipes WITHIN the fiberglass batts.

Like Blooba said....it's REALLY windy and cold out here. In fact, my chicken coop is STILL upside down! Any suggestions on flipping it back over? LOL

||Downhome|| · #18 04/08/10, 10:19 AM

Im farther north then you ? wind well so-so. cold ya we have our share.

but if your on a basement and insulate the basment walls and condition it,add a heat register that is. though Im pretty sure most basements stay 45-50 by themselfs) that space, I would only worry about insulating the pipe in the wall, and maybe some heat tape on the pipe where you can access it from the basement. as close to the exterior wall as possiable.

as far as the chicken coop just wait for the wind to blow the other way.

ronbre · #19 04/08/10, 11:17 AM

live in Michigan where it gets way below zero for most of the winter..never had a frozen pipe and never let the water run..59 years and no frozen pipes..

some people wrap a wire heating cable around their pipes up this way..or let the water run..but that is mostly people with city water.

blooba · #20 04/08/10, 11:25 AM

Quote:

Originally Posted by cc-rider

Any suggestions on flipping it back over? LOL

Hey, your on Rt. 12 aren't ya? take a chain and tie it to the top girder at the opening and drive slowly into the field. Can't let the wind blow it around anymore or it will be in the road. You should call Fairpoint Communications and ask if you could get a telephone pole or 2 and tie it down to them for the added weight. Probably will still flip the next big storm but its worth a shot. Make sure the opening is facing east.