Inconsistent Hot Water

[Mpt1123]

Settle back, this is a long one. A few times a year we have a problem with hot water. The faucets and shower throughout the house have different hot water temps. The kitchen sink is red hot, the powder room and shower is lukewarm. Here's some background. At this point, any of these things may merely be a coincidence, but I'm passing along when I know. The house has a well. It appears it may start when there is a change in water pressure, For instance, we think it may occur when I change the whole house water filter (not always, but sometimes). A few years ago we replaced the well pump and installed a constant pressure water system which replaced the bladder tank. Since then the filters get dirtier quicker. I'm assuming the well pump is too low in the well. The shower has a balancing valve which I've replaced several times but did not fix the problem. At one point I was convinced that there was some sort of 'air pocket' in the system that was keeping the hot water from reaching the faucets. I'm also thinking that there may be dirt in some of the faucet stems. Here's the kicker....without notice, everything just goes back to normal and works fine. The problem lasts for a week or two and then it's gone. I've replaced the elements in the electric heater - even though my meter says they're fine. I even replaced the thermostats on the heater. If it was a problem throughout the house, I'd be pointing to the hot water heater. Keep in mind that while all of this is happening, the faucet in the sink is producing hot water without a problem. I'm stumped big time on this one. Any help is greatly appreciated. Thank You.

 

[Reach4]

Look on top of water heater for a thermal mixing valve. Maybe the kitchen is piped to not go through the mixing valve.

A mixing valve may be located near the bathrooms rather than above the water heater, but that is less common.

Regarding the filters, how big is the crud on the first dirty filter when you replace the cartridge? Can you see individual particles like sand, or are the individual pieces too small to distinguish, like smooth peanut butter?

 

[Sponsor]

 

[Mpt1123]

The filters are dirty but not clogged enough to impact water pressure. Very fine particles, kinda like dirt/mud. There is no mixing valve on the water heater. There is a vacuum relief valve on the cold water side. Looks like this:

Thank You.

 

[Reach4]

That vacuum relief valve is not causing this. You are looking for something that would not affect the kitchen hot.

It could also be an intermittent crossover from cold to hot. Maybe turn off the cold stop valves for the shower or lavatories when not using that device to see if it makes the symptom go away.

 

[Mpt1123]

Since I don't have anything else to do, I went ahead and drained all of the water out of the system. Turned off the well pump. Opened up all of the faucets - to cold and hot - and let the water drain out to a basement faucet. Flushed the toilets, opened the shower valves. Turned the pump back on, refilled the system. Some of the faucets that were lukewarm are now hot - but not all of them. The shower was hot but turned lukewarm. I'm convinced there is some sort of air pocket or mixing going on. It would be great if there was some recent plumbing changes - but nothing has changed in quite a while. No new appliances, faucets, etc. Can you tell me more about this intermittent crossover from cold to hot?
Thanks.

 

[Jadnashua]

Air will NOT prevent pressurized water from flowing...IOW, an air pocket would not be the source of your problem. ANy air will be flushed out when you open the valves. It's a bit different with say a heating system as the pressure is much lower, and there's often not a valve at the top of the line where the air will want to go to purge it, you have to push it all the way through the system...not an issue with a typical potable water system.

When say the shower is only lukewarm, at the same time, do you get full hot in the kitchen sink?

Some valves as their internal seals wear, can create a cross-over that will let the hot and cold mix. It depends on where that occurs. If, say, that offending valve was left in the middle (only on single-handle valves) and was leaking hot to cold, some, maybe not all, hot outlets would then have mixed water as the supply. Water will take the path of least resistance, so it can be different at different locations.

This is a guess, but the kitchen sink may be closer to the WH, and thus, there's less resistance for the water flow, and it doesn't see the mixing.

On any single handle faucet, turn off the cold supply, then check your shower.

Also note, some people put a T on their washing machine supply, and always get mixed, hot cold as a result. That could be your cross-over.

 

[Mpt1123]

After doing some research, what I thought was a unique situation, actually appears to be rather common with single handle faucets. All of the faucets in the house - except for one - are single lever (excluding the showers). After turning off the cold water supply on the faucets it appears that the culprit could be the utility sink in the basement. Since that is not a single lever faucet, I doubt that is the real problem. Nonetheless, the hot water has returned everywhere. Since this problem occurs sporadically, I'm leaning toward sediment in the line to be the problem. Somehow (i.e. changing the water filter), some sediment gets in the system and one of the valve stems in the faucet gets clogged which causes the problem. At least I know now how to look for the bad faucet. In the meantime, I'm going to look into having that well pump lifted a few feet to see if it doesn't pick up so much dirt. Thanks so much for providing much need advice.

 

[Jadnashua]

Do you have a Y adapter on the utility sink? Were the valves actually open?

 

[WorthFlorida]

When the problem occurs again, turn off the cold water at each fixture using the stop valve and that includes the washing machine and the shower.

1. Start at the furthest faucet from the water heater and run the hot water.
2. With the hot water running at temperature, open the cold water valve and leave the faucet in the full hot position. Do not move the lever at all and check the temperature.
3. Keeping the hot water running at this faucet, at the next closest faucet to the water heater, open the cold water valve and do not touch the faucet.
4. Go back to the first running faucet and check the water temperature.
5. Keep checking the temperature at the first faucet while opening the cold water valves at each faucet in line to the water heater. Do not touch any other faucet. All of them needs to be in the off position.
6. Don't forget the washing machine and shower.

Hopefully the temperature will drop at one point and the last cold water valve you opened is the culprit location where the mixing is occuring.

Does this make sense. My whole working career was troubleshooting problems. I've learned that you must "eliminate and isolate" to find problems.

 

[Mpt1123]

There is no 'Y' on the utility sink.
Thanks for the process to identify the problem faucet.
Right now the supply lines to all of the faucets are turned on and the water is hot everywhere. I haven't replaced anything. Clearly something is temporarily causing the problem which eventually clears.

 

[Jadnashua]

On your single-handle faucets, leave them in the middle (where you'd get mixing if they leaked internally). Some brands, Delta is one, force the handle to that central position when it is off, but not all, and it could be all the way to hot or cold.

Do you have a shutoff for your washing machine? Do you mix it to get warm versus hot or cold? The WM internal could be a cross-0ver, but I think, that would be rare.