Hot water coming out of cold taps in kitchen.

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Old 01-29-20, 07:12 AM
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Hot water coming out of cold taps in kitchen.

So when I open the faucet in the kitchen on the cold side in the kitchen I get scalding hot water (the same temp as the hot water) for about 3 seconds before the water runs cold. I shut off the hot water to that faucet, and it still happens.

on the advice of a plumber I tried shutting off the hot water in the laundry room where I have two faucets which are installed in the wall where water might be mixing, shutting off the hot water there does not help either.

My house has two hot water circuits each heated by a separate heater. This does not happen to the upstairs faucets, nor does it happen in the bathroom on the same level as the kitchen which as a two handle faucet and is on the same hot water circuit (but different cold water line) as the kitchen faucet.

There is are return line for both water heaters plumbed into the drains of the tanks. There is no circulating pump. The water heaters are 2.5 years old and when they were changed, the check valves on the return line were also changed.

The two water circuits can be commuted into one but those valves are closed at the moment (at least I think, theyíre old gate valves that could conceivably have gunk in them)

any thoughts of what I should do next?
 
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Old 01-29-20, 09:14 AM
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Just shut off every hot water valve connected to this water heater. Will wait a while and see if hot water still comes out of kitchen faucet.
 
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Old 01-29-20, 09:57 AM
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Has it always done this or is it a new condition?

My first guess is that your hot and cold pipes are close together somewhere. When cold water is not being used heat transfers from the circulating hot water pipe and heats the cold water pipe that is nearby. When you open the faucet you get that slug of heated water but once it's flushed out you're back to cold water.
 
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Old 01-29-20, 10:52 AM
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It has always done this, just now getting around to take a look at it. Pipes are probably close together, near the sink but arenít touching and also mortared into the walls which you would think would provide some insulation. The water is not just warm itís hot.

These two pipes run in parallel for much further distance than any of the other faucets connected to this water heater which makes me think youíre right. I can deal with this, the one thing that worries me is that the kitchen faucet is also connected to the fridge and I donít know if itís great that itís getting warm water from the pipes.
 
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Old 01-29-20, 11:45 AM
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You can test by turning off your hot water circulation system. That would allow the hot pipes to cool as they do in most homes. Try the cold water of that faucet when you get home from work (after nobody has used water for several hours). If your hot water from the cold tap goes away you've found the culprit.

Don't forget that with a hot water circulation system you are heating that pipe continuously. Mortar is not a great insulator so the mortar is constantly being heated and itself will get hot and pass that heat to the cold water line. This is also why hot water circulation systems are inefficient, especially if they are not well insulated. All of your hot water pipes become radiators within the walls. You save water but waste energy heating the water which heats your walls. Not a total loss in winter but in summer it really bites because you have to air condition more to get rid of the heat.
 
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Old 02-15-20, 05:39 PM
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Most of the time when this happens it means the hot water is going through a mixing valve somewhere and flowing into cold water. Most of the time it's a shower mixing valve or a washing machine valve. This is the only way hit water can make it into the cold water piping.
 
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Old 02-15-20, 05:53 PM
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I have a fairly small split level house. I have my gas furnace and gas water heater in the corner of the basement. For the most part..... the bulk of the plumbing in the house is over this area. After several hours..... and especially overnight.... the hot and cold water pipes are both fairly warm. The hot water heater has also expanded hot water into the cold water system. I get quite warm water out of the cold water faucet for 30-45 seconds.

There is are no mixing valves anywhere in my system.
 
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Old 02-17-20, 01:46 AM
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Reply to pjmaxx

Do you also get your hot water off the boiler from a tankless coil ? If so your saying you dont have a mixing valve to control the temperature of the water that comes out of the coil? If this is the case it's most likely a issue with your aquastat relay control which is the control mounted right on the front of the tankless coil plate. This is the only thing that controls the water temperature if you don't have a mixing valve. If the tankless coil was no good and leaking internally in The boiler your boiler would be discharging water onto the floor from the pressure relief valve the leak would be causing the boiler to over pressurize. So most likely a issue with aquastat relay this has a probe that goes Into coil so it knows when to turn boiler on to heat up boiler.
 
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Old 02-17-20, 07:39 AM
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Is the kitchen faucet set single handle or separate hot/cold handles?

Could there be a tempering anti scald mechanism in or immediately under the kitchen faucet set, that could be malfunctioning and starting off with all hot and then settling down to supposedly proper hot and cold mix?

Starting off with scalding hot out of the cold faucet would not be due to a problem over at the washing machine or even down at the water heater, unless a stretch of cold pipe near the faucet was part of the recirculating loop.
 
 

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