Hot water in cold water lines

[Rice]

Hi,

I recently noticed that after running my cold water for a few seconds it begins to flow very hot water for a few seconds before switching back to cold. Not just warm water, but straight-from-the-hot-water-heater hot.

I've seen some similar posts on other forums, but nothing quite like this. They all seemed to be related to recently installed mixer valves. I have not modified any plumbing recently. I replaced my washer about 4 months ago, but I don't think that is it. I ran a test and the temperature of the supply lines to the washer didn't change at all.

I notice the problem on all fixtures, including the first sink on the plumbing lines closest to the water heater. The cold water line after the T from the water heater feels warm to the touch. Is there a valve on the cold water supply in the water heater that could be faulty?

Thanks in advance for any advice!

 

[LiQuId]

really water heater hot like burning hot?

water can get pretty hot in the cold lines during the heating season when they are not running and near a heat source. I notice your from denver CO, where i can assume you have your furnace running or means of heating your home?, check for any place where your heating system or ductwork could be influencing the line.

I do the plumbing maitenance in my building, last week A tenant had a fault zone valve and I had to leave it in the open position and.... long story, it wasnt replaced for several days afterwards ( the heat is constantlly running ) during this time I noticed the same phenomonon in my taps, I live on the top floor of these units the unit in question on the bottom. replaced herating zone valve and no longer have the hot water spike in the cold... this suggests to me that my cold water riser is at some point running close to his heating loop.

hope this helps.

 

[Rice]

Hi and thanks for your reply,

My first thought too was that something from the heating system was affecting the line, but that doesn't seem to be the case. When the cold water gets hot, it is REALLY hot - every bit as hot as the hot water.

Whats more is that if you turn the water off, wait 30 seconds or so (less time than it would take for a secondary heat source to heat the pipe) and turn it on again, the same thing happens.

The first fixture (kitchen sink) is almost directly above the main water line and water heater. The main line T's into the water heater and goes directly to the sink and there are no external heat sources along the way. It almost seems like hot water is being siphoned into the line from the water heater.

Is that possible? This is my 6th winter in this house and I've never experienced this. The water heater is old by the way... probably 25 years.

Thanks again,

Ryan

 

[pawel]

Hi.

Judging by boiler schematics, there's gotta be some sort of a check valve and/or buffer on the boiler input line, at some point. It's possible this thing could have broken. If you have it at all fixtures, and if it doesn't happen if you turn off the boilers input line, then it's definitely the boiler.

 

[Rice]

Hi Pawel,

I don't have a boiler. Just a hot water heater and a furnace. Is there a check valve on water heaters that could cause the same affect?

Thanks

 

[JERRYMAC]

no check valve

but if you have a moen single handle faucet it would cause that

effect to test turn off the shut off valves at the washer, and hot

side under sinks if problem goes away then start opening valves one

by one till it starts happening the thats the one that needs a new

cartridge

if you have all valves off and still problem then could be

bathtub/shower valves

if you do go to buy new cartridges be sure to buy the cartridge

puller it will be way worth the few dollars it costs

 

[Rice]

Thanks Jerry,

Sounds like a good course of action. I have a single handle faucet on the kitchen sink, so maybe that's the problem.

I'll try as you suggest and let you know.

Ryan

 

[phishfood]

Does the water heater feed to your heating system, or by furnace do you mean that you have a seperate electric or gas fired heating system?

I have seen hot water heating systems that are fed from the water heater cause such a problem, if the check valve goes bad. But JerryMac has you on a solid diagnostic path, so check that out first.

 

[Rice]

Thanks phishfood. No, I have a completely separate gas-fired furnace.

Just out of curiosity - Since I have this problem on all fixtures would it make sense to assume the problem is with the mixer on the sink closest to the water heater/main water shutoff? Or does water refuse to abide such laws?

Thanks again,

Ryan

 

[phishfood]

Water refuses to abide by rational laws understandable by us mere non-hydraulic engineers. Though the qucker this happens, the more likely it is to be a fixture closer to the water heater.

 

[FlushMasta]

This is my 6th winter in this house and I've never experienced this.

You haven't had any work done to your house or modifications during this time??

 

[Rice]

Update - It seems to the kitchen sink faucet - I think. I followed JerryMac's advice and turned off the hot water there. I waited overnight, tried the cold water upstairs and cold was cold and things in the world seemed right again.

To complete the test, I turned the hot water at the kitchen sink back on and... cold was still cold upstairs. I was sort of hoping cold would be hot again just so I could know definitively that I had isolated it. But I am pretty convinced. If the mixer in that faucet (it's a 'Danze') is flaky, maybe it's back to normal for a bit.

Sound reasonable? Sounds like I need a new kitchen faucet?

Thanks again for everyone's help and contributions.

Ryan

 

[LiQuId]

change the cartridge.

 

[LeakFinder]

What part of the county do you live in? Have you noticed running out of hot water when taking showers, etc.? I have seen this symptom when there has been a leak under the concrete which heats up the cold water lines.