There's a water witch in your plumbing. Are you asking for the reason it happen's or do you plan to roll up your sleaves and get your hands dirty checking the possabilities we tell you about?

Both.

Well alrighty,you'll need to help ,this water witching business take's a village.

How long has this been going on?

Does it happen at kitchen sink,bath basin and shower?

Have you noticed it's worse or only happens when the laundry washing machine is in use?

Does it happen ONLY when using both hot and cold to get warm water,when hot only is on or both?

It has been going on for months, seems to be getting worse. Yes, it happens in every sink, tub, and shower. Happens when hot only is on and both hot and cold are on. Recently has changed and hot water does not get completely hot at first, didn't even have to turn on cold to take a shower, then gets completely hot after a few minutes. About every couple of minutes it turns cold for a few seconds with just hot and with hot and cold on. What is a water witch? Thanks for your help, I'm desperate.

Water witch = evil demons = gremlins=bad plumbing karma=bad plumbing juju -- it's very scientific.

Do you have a tank type or tankless hot water heater?

Do you have a tempering valve?

A few pictures of your hot water system may be helpful for remote diagnosis.

Ramona ask's good questions regarding tempering valve and tank vs tankless. If you aren't certain what you have,just say so. I can't say as I've run across this exact set of circumstances so knowing about tempering valve and type system need's to be cleared up before digging deeper.

Sorry to be away so long. Ramona- I have a Rheem 40 gal. tank water heater that was installed Aug. 2018. I don't think it has a tempering valve, maybe you can tell from the pictures. I don't know if this is relevant but right after we moved in the faucets stopped up with rusty metal chunks. First well guy replaced the water pump and installed an under the house water filtration. Common sense told me this was not the problem (boy did I get screwed). I had another well company dig me a new well and moved the new pump over. We tried draining the water heater last weekend in case the metal chunks had got inside causing problems. My son was under the house the other day looking around, wondering if we should try replacing the pressure switch and noticed that the gauge on the pressure tank was as far as it would go. Don't know if it's broken or what. The tank was also replaced in 2018. The water pressure inside seems pretty good but when I try to use my expandable hose outside it comes and goes. Could this be caused by a pressure problem? I have tried to find info on cold and hot water mixing too. I also noticed the other day that when I was running water in the bathtub, every time it would do it's two minute interval of cold blast of water I could hear what sounded like a rush of water under the house, It only happened when the water turned cold, every time. No sign of it running out under the house, maybe just a rush through the pipes, maybe the pump cutting on and off? Thank you for any help you can offer, I can't afford to call a plumber right now.

"We tried draining the water heater last weekend in case the metal chunks had got inside causing problems."

And,,,,,,,,,,,,,,,,,,,,, you trird but then what happened? Was the tank full of rust or wut? I don't see a tempering valve but who knows,there could be one under the house with the pressure tank. Meanwhile I want you to have someone turn a hot faucet on and feel temperature as it flows. You stand by at water heater keeping your hand on the hot/out flow line seeing if temperature jump's around as water flows out. Have helper let you know if faucet temperature is jumping around. Report back.

First water out was rusty. We drained it completely, then added some water, then drained again to stir up anything settled in the bottom. Did that several times. It continued to run clear after the first rusty water. Put holes in a bucket to drain and put a piece of a cotton sheet over top but didn't see any chunks come out in the sheet. I'll try holding pipe at water heater, didn't think of that, thanks klem1. Will report back. Also, my son took pictures under the house of the tank and switch, I'll have him send them to me and post them.

Could the thermostat be broken or rusted out?

I forgot to mention heating elements. If you have a vom and clamp on amp meter and know how to use them,both elements and t-stats need to be tested.

Hi,

From your picture it looks like your water heater is on the ground floor (the window). The Pipes go up, Maybe the attic? Maybe tempering valve up there? I would doubt it valve should be by the heater. Another guess, go to a sink that gives you a problem. Take the aerator off and give it a try. Sorry I couldn't be more help but some times a good guess fixes the problem.

Good Luck Woodbutcher