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Superbuuck 03-29-2008 12:49 AM

Hot Water in Cold Water Lines ???
Hi People:

Interesting situation has developed while finishing my basement. I have a helper working to drywall speed progress. He has dry-walled my ceiling of a bath in a basement project. I have been trying to INSULATE my lower bath well before drywall goes up. I have been stuffing insulation in a ceiling where plumbing is above my lower basement bath. NOW, there is HOT WATER coming in my COLD spigots at the UPSTAIRS faucets (it happened within 36 hours of insulating). It's happening at several locations where I have several water lines above new insulation (in the basement ceiling). I have no idea how i have changed the flow of water but all of a sudden heat has been added to our cold water flow. I have been pretty diligent adding the tubular pipe insulation in both cold and hot water lines. I think I may have created some warming pockets within my ceiling insulation. Is it possible to have a hot spot above a ceiling where the water runs HOT when the spigot is set to cold? I can run the water for a few minutes (it turns hot) and then it turns cold as usual. I come back in 10 minutes and the COLD water is as hot as my water heater temp (140 deg). It seems to re-heat up again. Even my toilet water is warm (close to the new basemenet project). Do you think I need to tear out the newly installed drywall and find out if I have "over-insulated" the ceiling of a future basement bath? I am at a loss but it doesn't seem to be critical>



Marlin 03-29-2008 09:19 AM

A few things I can think of
1. So it runs cold, then hot, then cold and stays cold? I take it you have a re-circulating line? If so and the lines are close to each other and uninsulated it's entirely possible to have the hot line heat the cold while the water is sitting. Their isn't anything you can really do about it besides insulate the pipes, get them further away from each other, or remove the re-circulating loop.
2. Did you replace any plumbing? It's possible you crossed a hot and cold line somewhere.
3. For some reason prior to you owning the house the hot and cold lines may have been tied together with a ball valve, perhaps an attempt at a home made mixing valve of sorts. Stuffing insulation may have knocked the handle on the valve open.

majakdragon 03-29-2008 09:50 AM

It almost sounds like you insulated so well that the heat from your ductwork is now serving as a heat source for the piping. The insulation may be trapping the heat and radiating it to the pipes.

Ron6519 03-29-2008 04:38 PM

Was any plumbing done in the basement?

plumber Jim 03-29-2008 08:00 PM

Did you happen to rough in a new tub/shower valve? if so you may have hot crossing over into the cold line. I have seen that happen with the delta valves before they started including those things to plug one side.

Superbuuck 04-01-2008 12:11 PM

Answer for Hot water in cold lines
Thanks so much for your responses. I think I figured it out. Plumber Jim got it right. I just installed a Delta shower valve for a new corner wall shower. The shower valve is only roughed in at the time and I pretty much figured out that the hot water is crossing over to my cold lines thru that valve. I think it will fix itself when I install the rest of the shower valve at the finish stage. Just confirm for me if that sounds right.

Thanks again for your feedback everyone, Superbuuck:yes:

rjordan392 04-01-2008 01:04 PM

I would put money on it. Your problem is simular to one I had with a single lever faucet. I call it hot water bypass. I suppose hot water was able to cross over to the cold side when the internal parts wore out or the wrong ones installed. I originally thought it was stagnant water from not being used and just let it run about 10 seconds before drinking it. But later when I purchased a new fridge with a water/ice dispenser that the water from it tasted lousey. For a couple of years, I thought it was a problem with the fridges holding tank and did not drink from it at all and just used the cold watet faucet. I even bought icecubes for my guests. Then I saw a post on some forum describing this bypass problem and decided to change the faucet to a double lever type and it solved my problem.

majakdragon 04-01-2008 04:53 PM

Sounds quite possible/probable. Be sure to let us know if this is the culprit in the end. It could help other members. Good luck.

plumber Jim 04-01-2008 06:08 PM

If you install the cardtridge it will solve the problem.

guybrush 06-20-2008 10:56 AM

Hi Jim,

I have the same problem with the delta faucets -however, the plumber did his work and there is still one in the basement since the drywall isn't done.

If I buy a trim kit, does this have the cartridge you mentioned that will let me fix this?
I mean the cartridge isn't already inside the rough-in? I thought it was?
Perhaps it is just because it is "ON" right now, since the shower is caped and the tirm kit just lets you turn the valve off?


plumber Jim 06-20-2008 01:54 PM

Yes, If you buy the trim kit it will have the cartridge and you can install it to solve the problem.

mstplumber 06-20-2008 11:08 PM

Jim is correct. Both Delta and Moen now ship their rough in valves with test plugs in place instead of cartridges. These plugs allow water to freely cross between hot and cold lines. The cartridge should be with the trim.

andystlaurent 07-24-2011 04:12 PM

Awesome dude! I was ready to knock down drywall until I read this.

PhillyDIY 07-25-2011 06:37 PM

Cold is Hot and Hot is Hot
I have been having similar problem. It affects the entire branch circuit supplying a 1st floor powder room and upstairs bath. The bath has a Kohl_r single handle mixing valve with a seperate selector for side spray/shower/both. Both sinks cold supply [up and downstairs] run hot for a few minutes. The upstairs toilet fills with warm/hot water. The cold water supply pipe in basement is hot a few feet outside the wall. Happens all day/any time of day. Seems to be getting worse. After hot water is "flushed" out, water runs cold, but after only a few minutes it will be hot again?? It has some sort of scald prevention in the single handle fixtures, downstairs sink and upstairs shower. Upstairs sink is two handle version. All Kohl_r brand. No new work has been done on this branch. The fixtures were all put in the same time and worked fine for about ten years...maybe something in the "mixing valve"?

pixelfixer 08-29-2011 12:21 PM

Hot water in cold lines
I had a similar problem. When I turned on the cold water in either sink in the master bath, I got hot water for a few seconds before it would turn cold. Also the toilet tank was warm. I was baffled. It made no sense to me since I hadn't changed any plumbing. Then, I came to this site looking for an answer and while reading, it dawned on me. I had installed a sprayer on the shower and I wondered if I left the single handle turned on. Yep that was it. That allowed the hot water to cross over into the cold water lines. Just thought I'd post this in case it might help others. I'm sure the same thing would happen if your single handle faucet went bad.

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