Hot water comming out of the cold side

[coastalcruiser]

Just don't know whats going on
I have a duplex with 2 hot water tanks, on one side the cold water starts off hot then just goes warm.
The other side, the cold is warm water unless you run both hot and cold then shut off the hot.
Unfortunately it has a crawlspace so I can take photos and trace the pipes just think its strange could it be a faulty hw heater?

 

[Tubingluvr]

Re: Hot water comming out of the cold side

need a little more info
are we talking about gas or electric heaters?

 

[rolmops]

Re: Hot water comming out of the cold side

This sort of thing is usually connected in a different way then you might expect.
It is quite conceivable that you have a shower or bath tub that has 3 different handles.One for cold ,one for hot and one for actually allowing the water to flow through the shower head or into the tub.Very often people will keep the cold and the hot water faucets open and just shut the faucet that allows the water to come out of the shower head.
What you have in such a situation is an open connection between the hot and the cold while no water streams out.The moment you open an other faucet anywhere in the house the hot /cold open connection will start flowing in the direction of the open faucet and dependent on what has the higher pressure either warmer or colder water will come out of that other faucet.If you run the toilet in another part of the house your cold water will probably have the lower pressure while if you run hot water in another part of the house the hot will be the lower pressure.
I guess you get my drift.

 

[Tubingluvr]

Re: Hot water comming out of the cold side

This sort of thing is usually connected in a different way then you might expect.
It is quite conceivable that you have a shower or bath tub that has 3 different handles.One for cold ,one for hot and one for actually allowing the water to flow through the shower head or into the tub.Very often people will keep the cold and the hot water faucets open and just shut the faucet that allows the water to come out of the shower head.
What you have in such a situation is an open connection between the hot and the cold while no water streams out.The moment you open an other faucet anywhere in the house the hot /cold open connection will start flowing in the direction of the open faucet and dependent on what has the higher pressure either warmer or colder water will come out of that other faucet.If you run the toilet in another part of the house your cold water will probably have the lower pressure while if you run hot water in another part of the house the hot will be the lower pressure.
I guess you get my drift.

I was waiting for a little more info from him before I went there, but you are correct.
Another thing that can cause it if there is a defective mixing valve anywhere in the home.
Single handle faucets can also cause mixing if they have defective seals in them.
Delta single handle faucets are famous for this.
I have also witnessed this problem in hot lines that are under concrete, the concrete slowly eats at the copper and eventually starts to leak and is not always obvious.

 

[coastalcruiser]

Re: Hot water comming out of the cold side

thanks for the replys,
the water heaters are electric. where you notice it is at the kitchen taps. the taps have separate handles for H-C actually not a problem except we use tap water to drink and wouldn't want to be drinking warm water from the water heater.
It's more of an issue on the side I rent out because the cold water is hot at first then changes to warm. Maybe I'll get blamed for someone burning their hand

Single handle faucets can also cause mixing if they have defective seals in them.
Delta single handle faucets are famous for this.

I have a single handle faucet in the bathroom next door, what I can do is shut the water to it and see if that fixes the problem, just shut off the single handle moen in the bathroom sink on my side seems to help

 

[v1_0]

Re: Hot water comming out of the cold side

Unfortunately it has a crawlspace so I can take photos and trace the pipes just think its strange could it be a faulty hw heater?

I would eliminate the hot water heater as a source of the problem. Unless you have something exotic, the cold and hot lines don't both run through the water heater.

Also, hot water wouldn't flow 'backwards' to the junction where the feed to the tank breaks off the 'cold' water pipe.

One thing that I can think of is that it will take less time for the cold water to heat up as you get closer to the source of the cross over. However, it will take a very long time to test all your taps - you would need to let things cool down between tests, otherwise your tests are invalid. (your testing 'loads' the pipes with hot water, which would throw off your results).

By what you have said, it seems like the trouble may be on the rented side... (The water is hotter quicker).

How many shut-offs do you have? You could possibly use them to eliminate areas - for example, if you shut the kitchen's hot water off and the problem doesn't go away you know it isn't from the kitchen. [Unless you have multiple sources... ]

 

[dlindeblad]

Re: Hot water comming out of the cold side

My immediate thoughts were mixer valves. Basically there are two main types. The first is a type of auto temp regulator that controls water temp based upon source temp. It has a bimetalic piece to compensate for long ramp-up times for warm water to reach the showers or faucets.

The second is a full time mixer that can be manually adjusted to allow a constant water temp to be delivered to the source. These are used for toilets mainly to reduce sweating of the tanks in the summer time.

My instincts tell me that you may have the first type in your plumbing system. Something like this: http://news.thomasnet.com/fullstory/464199

More than likely the bimetalic control has failed or fouled. Hope this helps.

 

[coastalcruiser]

Re: Hot water comming out of the cold side

Wow so simple, and cheap to put right.
I believe it's the bathroom single lever faucets. after I closed the shut offs the water is now cold in the kitchen, the shower has basic separate handles like the kitchen.
I will try doing the same on the other side and post back.

 

[Tubingluvr]

Re: Hot water comming out of the cold side

First thing you need to do is verify your water heaters are working correctly.
You heaters have 2 heating elements in them you need to make sure both elements are working.
One will be at the top and one at the bottom you will need to test these with a voltmeter.