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Btabach 05-20-2012 07:50 PM

Hot Water Heater Problems
 
The hot water in my house periodically loses pressure completely and comes Bach after a few minutes when leaving the faucet on. The cold water is not affected. Why is this happening?

Yoyizit 05-20-2012 08:41 PM

Semi-soft calcium plugs are temporarily blocking the pickup tube entrance?

I had this with the WH drain spigot which I periodically use to supply hot water to the basement for cleaning paint brushes, etc.. These plugs were pure white and some were rock hard while others crumbled in my hand.

Homerepairguy 05-21-2012 12:12 AM

Quote:

Originally Posted by Btabach (Post 925382)
The hot water in my house periodically loses pressure completely and comes Bach after a few minutes when leaving the faucet on. The cold water is not affected. Why is this happening?

Every hot water faucet in your house, or one hot water faucet?

Btabach 05-21-2012 10:02 AM

Thank you for the response.

Where are these calcium plugs and how can I resolve this issue?

Btabach 05-21-2012 10:03 AM

Every faucet.

Ryanji 05-21-2012 11:21 AM

Maybe you can try some stainless steel faucets. They are better.

danpik 05-21-2012 01:25 PM

Quote:

Originally Posted by Ryanji (Post 925741)
Maybe you can try some stainless steel faucets. They are better.

Ignore this useless comment.

How old is the tank? The calcium plugs spoke of earlier in the thread are deposits that have accumulated in the tank over years. It is posible they are moving around in the tank causing the infeed and outlets of the tank to clog up. does the water pressure drop off after the water has started flowing or is there none to start with when opening the faucet?

Homerepairguy 05-21-2012 02:24 PM

Quote:

Originally Posted by Btabach (Post 925709)
Every faucet.
(Previous post: The hot water in my house periodically loses pressure completely and comes Bach after a few minutes when leaving the faucet on.)

Since the same symptom is affecting "every" hot water faucet "the same way", I don't think the problem is at the faucets, but at something that affects the entire hot water line.

The most likely things that can affect the "entire" hot water line are heat trap valves on your water heater. There can be one on the cold water line going into the heater and/or one on the hot water line coming out of the heater.

Images from: http://plumbing-leaks-faucets.knoji....relief-valves/
http://knoji.com/images/user/heat-trap-ball-style.JPG
Ball type heat trap valves

http://knoji.com/images/user/heattra...ford-white.jpg
Flap type heat trap valves

First suspect would be a heat trap valve on the hot water line since crud from the heater could partially block that valve as water exits the heater.

But crud could also partially block the heat trap valve on the cold water line going into the heater or even the water shutoff valve on that line if it's a gate type shut off valve. In the latter case, crud could have come from galvanized pipes from the city to your home > to your water heater. Or even if the city did some work on the water lines. --- If the water shut off valve "to your heater only" has a round handle which requires multiple turns to open and close, it's a gate type valve. If it has a lever type handle that only moves a quarter turn, it's a ball type valve. --- If it's a gate valve, try closing and opening it a few times to allow any trapped crud to pass through it. Ball valves won't be the problem as long as they are fully open (lever handle parallel to the pipe).

If you don't have any heat trap valves on your water heater, or it's not crud partially blocking a gate valve on your cold line going into the heater, then it's a mystery.

PS: It sounds like a leaf type blockage (not an actual leaf but an object or sediment like a leaf). When the "leaf" is oriented to block the valve, hot water pressure is lost. Then after a few minutes, the "leaf" turns due to prolonged pressure and then allows water to flow. That's the only way to produce the symptoms you're having that I can think of. I wonder if a flap type heat trap valve could do this?

EDIT: Just had another thought. Looking at the top of your water heater, do you see a pipe connecting the cold input line to the hot output line with a valve in the plumbing? If so, that would be a thermostatic mixing valve which mixes cold water with the hot water exiting the heater to maintain a constant (safer) hot temperature to all of your hot water faucets. Could be that valve is malfunctioning somehow or cold water to the valve is reduced, affecting the hot water output. Here's a link to the Watts website that shows how a thermostatic mixing valve works.

http://www.watts.com/pages/learnAbou...s.asp?catId=64

Look about half way down the page to see an animation of how a termostatic mixing valve works. At the bottom right corner of the animation, click "Cold water loss" to see how the valve can stop hot water flow. Could be your valve (if you have one) thinks cold water is lost and is shutting the hot water off until something stabilizes in the valve and then it allows hot water flow again.

HRG


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