Water spike problems in my house.

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I had a new hot water heater installed, and shortly after that, it would discharge water. The plumber who installed it, said that the pressure was too high likely in the house. He looked at the pressure reducer value which he said was old and broken. So he replaced it. He also claimed this would stop the water spike we got in the house. I'm defining a water spike, that at random times during the day or night, when you turn on any facet water will blast out for about 10 seconds and then return to a normal flow. I have not been able to see a pattern for this. I have seen it do this within minutes after using the shower and then getting a drink a water from the kitchen sink.
The plumber, who by the way has a master plumber's licenses was surprised that we still had the water spike problem. Assuming that the new unit might be defective, he replaced it with one that was assemble in the US instead of China, thinking that perhaps the charge in product might have caused the problem.
This didn't solved the problem, still several times a day, without warning water comes blasting out. The plumber said he didn't know what to do, since he didn't think it was likely that both of these pressure reducer valves were defective. I asked if perhaps the ones he was installing simply were robust enough to handle the high pressure and he said that this is a very normal device he has been installing in my area for many years and never had a problem.
This led us to talk with the local water company. Maybe the pressure coming in from the street was so great that this device couldn't handle it when it would spike. After many phone calls I finally got the water company to return my call and be interested in the problem. The last call, I gave him the phone number of my plumber since he was most familiar and understood the system. After all, I'm just a home owner and don't know much about this stuff. I got a phone call back from the water company and said he talked with my plumber and after discussing the problem the plumber agreed with the water company that we should install an expansion tank over the hot water heater. I explained that the water spikes come from the hot water and the cold water as well. How is an expansion tank over the hot water heater going to solve the cold water spikes too I guess, and he said he didn't know. He said the plumber will be contacting me.
I talked to the plumber and he said that about in 25% of the homes that they install new hot water heaters, they need expansion tanks, and that this affects the hot and cold water as well. While I am waiting for a quote to have this expansion tank installed, I thought I would post and ask if others have had this experience or could shed some light on it. Does an expansion tank sound like the solution?
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eastcoastguyz wrote:

Revoke his license.
A thermal expansion tank is required any time a PRV is present on a municipal supply.
Yes, he can get away without one in 75% of the installs maybe because the street pressure is low enough.
The exp tank gets connected on the *Cold* inlet side of the heater. When the water heats up, it expands, raising the pressure in the tank. The PRV prevents the expansion from backing up out to the street. (There are exceptions to this, but not important here.) To absorb these spikes, an expansion tank is necessary.
So, the pressure spikes you see do affect *both* Hot and Cold lines since they are joined by the heater.
Retail on the exp tank is about $40 to $50. Install is easy.
Jim
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I second the notion that it is caused from thermal gain from heating the water. My camper is real bad about this when I use the PRV on it, because a PRV also acts as a check valve.
--
Steve Barker



"eastcoastguyz" < snipped-for-privacy@hotmail.com> wrote in message
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eastcoastguyz wrote:

Yep.
MM
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eastcoastguyz wrote:

Air in the line?
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Yes, with the PRV installed you need an expansion tank. I'd also recommend a check valve on the cold water inlet of the water heater to eliminate the cold system as part of the expansion area and to ensure there's no backflow from the heater into the cold system.
Bob Wheatley
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wrote

(What's the difference between God and a plumber?
God doesn't think he's a plumber)
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"I'd also recommend a check valve on the cold water inlet of the water heater to eliminate the cold system as part of the expansion area and to ensure there's no backflow from the heater into the cold system. "
1. The money would be better well spent on beer and pizza.
2. Some PRV's allow for thermal expansion, eg. Watts AUB series.
3. The thing you need to get is a new plumber, Maybe one that owns a pressure gauge.
kenny b
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What I would guess is: The dynamics of the reducing valve maybe too slow in getting to its steady state regulating position. With no flow the valve is in a closed position. When there is a sudden flow demand (opening a faucet) the valve moves opens to provide flow but actually overshoots its steady state position. For whatever reason it then slowly closes down to regulate the pressure. It's during that time frame that there is high flow out of the faucet. In high performance systems, PRV are fast acting with time constants in the order of 15-20 millisecond. There are many things that slow down the transient response of these type of valves--in many cases it is getting the control pressure to bleed down allowing the valve to respond quickly Usually a damping orifice being too small is one reason. MLD
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MLD wrote:

Just what people need here is more phyco babble bullshit to confuse people even more. When all that was really needed was a plumber with a gauge and a little knowledge on how to use one. Instead you got a plumber that replaces things because they look old so it must be bad theory.
kennyb
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Your response is very refreshing--be so good as to explain just how a gage will resolve the problem. What does the pressure tell you if it's high? or if it's low? Or if it goes from high to low? What it does after or when a faucet is opened? In fact, if it's not bled properly you can't believe anything it tells you other than steady state. In many cases you have to understand the problem before you can fix it. Oh, BTW, sorry if you got confused--but when you have an IQ about the same as your hat size that's easy to understand. MLD
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comment on the issue actually - what a shame a little simple physics seems to have been confused with 'phyco babble bullshit' ...
I agree the guy's plumber sounds flaky ...
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wrote

several PSI day and night. I installed an new water heater a couple of years ago and found that an Xtrol type expansion tank for potable water was necessary to keep the water heater's pressure relief valve from popping every so often. I had tried another relief valve first, but the tank was necessary to absorb the pressure spikes. "Funny" thing is my water meter (in my basement) can be observed oscillating forwards and reverse if you look at the spinner dial on it top while you hear the meters chamber measuring the volume flow while this is happening. What is NOT so funny is that the actual dials on the meter seem not to go backwards (the 1/10 cu ft dial) when the spinner is in reverse. I don't think it adds up to any real dollar amount to my bill. But the frequent meter noise is annoying.
Funny how this thread came up as I was considering installing a check valve in the cold water feed to my hot water tank!
I will put one in for sure now.
Bob (another Bob)
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here's an answer to much of the pressure speculation: www.hdsupply.com this one has a hose female connector: 300 PSI WATER PRESSURE TEST GAUGE 300 PSI Water Pressure Test Gauge THDS Part #: 153000 $7.96
this has a 1/4" MIP [male iron pipe thread] connector 100 PSI WATER PRESSURE TEST GAUGE 100 PSI Water Pressure Test Gauge THDS Part #: 153050 $4.49
eastcoastguyz wrote:

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buffalobill wrote:

Thank You Buffalo Bill, Now if they could just figure out what to do with it, it would answer all their questions.
kenny b
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hand, you must be putting us on because it's hard to imagine you're as dumb as you appear to be. MLD
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MLD wrote:

"I had a new hot water heater installed, and shortly after that, it would discharge water."
why? 1) pressure 2) temp 3) faulty T&P
How are you going to tell if the discharge is either a faulty T&P or due to pressure, you can't without a gauge.
How are you going to tell if the pressure is from a bad PRV, you can't without a gauge.
You can watch the spikes on a gauge and even verify thermal expansion is happening with a gauge.
Only an idiot would come to a conclusion without facts, at the expense of a homeowner.
kenny b
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Good questions, but a very feeble example. First of all, most home systems don't have a point of entry where a pressure gage can be installed. Where would you put one without taking anything apart? Obviously, one can rule out temperature very quickly--not hard to measure or just shut off the water heater and see if the problem recurs. Then there are times when it is just as efficient and cost effective to substitute as it is to try and troubleshoot. In this case, the T&P first since it is the easiest to remove and it is also the least expensive. Maybe you can watch spikes on a gage but in no way are you seeing what's actually happening. Have you ever recorded large amplitude, high frequency pressure pulses with and without a gage installed in the system? I have!! First of all, a gage does not have the capability to respond to a transient pressure pulse; it tends to act as an accumulator. The net result is that it attenuates and dampens out pressure pulses in a system. Finally, you didn't address the prime topic of discussion which is why there is a high flow for approx 10 sec after opening a faucet. Just use some common troubleshooting sense------- If you have a normally functioning PRV how can a defective T&P valve cause high flow out of a faucet for 10 secs? Flow is a function of Supply Pressure and system r esistance. The only component that is responding to the city supply pressure is the PRV. It has to reduce that pressure to it's set point (household pressure) and keep it at that value independent of the flow demand. The slower the PRV responds, the bigger the variation in household pressure and the more the variation of flow out of the faucet. In this case a gage would certainly show a gradual reduction of pressure over a period of 10 secs pointing to the PRV. MLD
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MLD wrote:

Laundry tray, hose bibb, washing maching valve, the water heater drain valve itself. A plumber would know this.
> Obviously, one can rule out temperature very quickly--not hard to measure or just shut off the water heater and see if the problem recurs.
Thats why it was listed but I responded with pressure.

Really, Most professional plumbers not only want to know but need to know what is causing the problem before repairs are made. Someone's paying you for a professional opinion and your guessing. I guess you just defined your self.
As far as the rest, I won't waste my time. A real plumber would have had the problem solved and repaired on the first trip at a fair price. Hey thats why we get paid the big bucks, right.
You can see the real plumbers here responded with thermal expansion, a gauge would prove that in seconds if the system was closed. The gauge would also prove the PRV was working.The thermal expansion causes the spike in pressure equally throughout the system as long as the PRV is working and is closing the system. We're not building a watch here, this is basic plumbing.
Yes an expansion tank is probably needed to solve the problem, but that should of been confirmed from the begining. Instead his plumber followed your play book and changed the PRV twice.
kenny b
In this case, the T&P first since it is the easiest to remove

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Once again you responded by sticking to the simple easy solution of an easy problem and completely ignored and tip toed away from the initial question (and my questions) that started this whole discussion. First, to address your comments: You must be a very unusual plumber--I don't ever recall one that actually measured anything--typically, they replaced or cleaned out, nothing scientific or mind boggling. Thermal expansion: Your comment:*** "The thermal expansion causes the spike in pressure equally throughout the system as long as the PRV is working and is closing the system.*** Dribble, and it surely indicates that you really don't understand what you're talking about. Think of thermal expansion as it applies to the cooling system in your car. As the coolant temp increases, volume increases, pressure increases until it gets to the radiator cap setting and then the coolant spills over to the expansion tank. No spikes in pressure--- it increases along with the temperature. With the PRV and all faucets closed you have a volume of water trapped between them--aka, a hydraulic lock. As the temp is increased, up goes the pressure-what do you think would happen to your piping if there was no escape route via a relief valve built in to the PRV or the water heater T&P valve? No different than if the water froze--something is going to break! Obviously, an expansion tank provides the room to accept the volume increase--that's why it is recommended. Not rocket science. Now once again--would you just stick to the subject--Why do you think there is a flow of water that lasts for approx 10 seconds when the faucet is opened? What do you do to resolve it? Oh yes--you guys do make BIG bucks and in many cases it's justified. One should get paid not only for the actual work but for what he knows. But do you really know what BIG bucks are? Think of the most expensive thing you ever worked on or charged. I worked on a product that sells for 2.5 million dollars. At times I've had to make a judgment call on resolving a problem and replaced a component(s) worth about $50,000 a piece. Early on in the development process (and the need to resolve a problem) required the use of a facility that, with a discount, cost $10,000 an hour with a 10 hr. minimum. Do the arithmetic, it cost $100,000 a day, sometimes for 2-3 months at a time. Finally, our product ended up as a key component of a $32,000,000 machine. In the troubleshooting process there is a difference between shot gunning and selective replacement of components. At times, the least likely of two components might be replaced first because it might only take 1 hour vs. 8 hrs. for the most probable one. Better to waste an hour than maybe 8 hours. Sorry if I got carried away--didn't mean to. MLD

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