4:45 AM wake up call, The Walls are alive

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by cj3, Sep 27, 2007.

  1. cj3

    cj3 New Member

    Messages:
    7
    Tried to figure this one out in the archives but have failed so far.
    At 4:45 every AM for about 15 min the pipes are tapping about once every second. It stops only when water is running or the main shut off into the house is turned off.
    I have turned off the water to the drip system, washing machine, and the hot water heater so far with no effect. I have adjusted the pressure regulator in and out and that also had no effect.

    I am going to turn off the toilets tonight but I am not holding my breath that the toilets are that timely.

    This problem only happens at 4:45 in the AM and not any other time of day and has been happening for at least 3 weeks.

    I called the city today and they had no idea but said they would put a pressure gauge on one of the hydrants around the house if it continues.

    Thanks for taking a look

    CJ
  2. markts30

    markts30 Commercial Plumber

    Messages:
    630
    Location:
    Phoenix, AZ
    Water softener installed recharging at that time?
    City might have a pressure spike at that time... Do you have a PRV?
    Check your T&P valve for discharge when this is happening... might be being tripped and water running out... (eg-city starts up pump at 4:45AM to boost pressure for the day and the excess pressure is tripping an already faiiling T&P valve...)
    Don't really have enough info for a good diagnosis at this time...
  3. GrumpyPlumber

    GrumpyPlumber Licensed Grump

    Messages:
    1,404
    Location:
    Licensed Grump
    Drip system?
    I'm with Mark, or it could be pent up pressure from the water heater causing thermal expansion.
  4. cj3

    cj3 New Member

    Messages:
    7
    Thanks for the reply.
    The drip system is the irrigation system.

    Do not have a water softener

    I believe I do have a PRV where the city supply enters the house. I tried to adjust it while the noise was happening but it did nothing to help with the noise.

    I turned off the cold supply to the water heater also with no luck, the noise was still present.

    Is the T&P valve the one on top of the water heater? If so I cracked it for a few seconds and let some of the pressure out and the noise did not stop.

    I am setting my alarm for another set of tests. Any suggestions on how to troubleshoot this further?

    Thanks
    CJ
  5. Verdeboy

    Verdeboy In the Trades

    Messages:
    2,051
    Do you have a neighbor that gets up at that time? ...Or possibly has a sprinkler system that comes on at that time?
  6. tjbaudio

    tjbaudio Sound and Light Suppervisor for a School District

    Messages:
    162
    Location:
    Wisconsin
    is the HWH electric? if so does it have a timer to run it off peak? it could be heating at that time, closing the cold supply would not stop the noise if it is heating.

    Also what kind of heat do you have?
  7. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,338
    Location:
    Yakima WA
    You say you have a PRV, but do you have an expansion tank? The two go together. If you do not have an expansion tank you need one. If you do hae one, it may be bad.
  8. leejosepho

    leejosepho DIY scratch-pad engineer

    I believe that should be "CWH"!
    Hot water does not need to be heated. ;)
  9. markts30

    markts30 Commercial Plumber

    Messages:
    630
    Location:
    Phoenix, AZ
    If you have a re-circ line then the heater could be called a HWH...
  10. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,534
    Location:
    Cave Creek, Arizona
    noise

    I believe that should be "CWH"!
    Hot water does not need to be heated

    It is only a "CWH" when it is initially filled with water, or all the hot water was depleted. After that it is a warm water heater, or a hot water heater/reheater. But the noise could be your, or a neighbor's, water meter running their irrigation system, depending on how the meters and/or your drip system is installed. Turning off the house valve will isolate your system from the noise, if it is being created externally, so that would seem to stop it.
  11. cj3

    cj3 New Member

    Messages:
    7
    The water heater is gas and it is not running when noise is happening.
    I do not have an expansion tank so apparently I do not have a PRV. What I assumed was a PRV is a valve right after the house shut off. It has a screw with a locking nut that adjusts the water pressure to the house.

    House is heated by forced air.

    All irrigation has been shut off electically and the water has been manually shut off to the system

    It sounds like I need to invest in an PRV and expansion tank.

    This noise apears to be an external source from a neighbor or most likely a pressure increase from the city pumps.

    The time and durration of the occurance is just too precise to be anything other than some daily scheduled event.

    cj
  12. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,947
    Location:
    New England
    A good plumber would install a prv and an expansion tank at the same time, but it is entirely possible you have one without the other. The device you describe is a prv. You should have an expansion tank. The prv may not be working.

    Buy a pressure gauge, attach it to an accessable point, get adapters if you want it to go somewhere it won't screw in (it is designed to screw onto a hose bib). Check that out.

    The noise could be from things cooling off after the WH ran, rather than while it was running. If you habits were consistent, the tank might be running at about the same time during the night to reheat the water.

    Do you have an icemaker in the frig? Most operate on a need basis, but I suppose it could have a timer as well.
  13. cj3

    cj3 New Member

    Messages:
    7
    I have an icemaker that I turned off manually and I also turned off the power to entire house while the noise was happening,, no change.

    I will turn down the water heater to its lowest setting and see if that helps.

    I will get a pressure guage and monitor the pressure durring and after the noise and report back.

    Thanks
    CJ
  14. SteveW

    SteveW DIY Senior Member

    Messages:
    1,052
    Location:
    Omaha, NE
    When you get that pressure gauge, make sure to get one with the extra "arm" which records max pressure - you may be surprised how high the pressure gets overnight if you do indeed have a PRV but no expansion tank.
  15. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,338
    Location:
    Yakima WA
    You don't need to wait all night for the pressure to rise dramatically if you have a PRV without an expansion tank. As soon as the water heater begins to heat the pressure immediately begins to rise. Warning: It will scare the hell out of you to see how much pressure change there is.
  16. cj3

    cj3 New Member

    Messages:
    7
    It is obvious that I need an expansion tank, but I am not sure that the increased pressure in the closed system is making the noise.
    The question is why is it only happening a 4:45 and for only 15 min and no other time.
    Also since the system is supposedly a closed system with the prv Then why when I turn off the water to the house does the noise stop. The increased pressure should be kept in the system when the house supply is off.

    Could the PRV be defective? Allowing the hammering noise to be transmitted from the main.

    Thanks for all the advice I have learned quite a bit about my plumbing system by researching this problem here and in the archives.

    CJ
  17. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,534
    Location:
    Cave Creek, Arizona
    Prv

    That "thing with an adjusting nut", is the PRV.
  18. toolaholic

    toolaholic General Contractor Carpenter

    Messages:
    874
    Location:
    Marin Co. Ca.
    Here's a shot. Do You have a water recirc. pump on the W.H.? Is it set for 4:45
    AM ?
  19. cj3

    cj3 New Member

    Messages:
    7
    I have had my first break wrt a possible culprit. I put a pressure guage on my on my hose bib and it has a 40 -50psi flow or residual presssure and then after the water is shut off the pressure creeps back up to about 100psi. It apears that there is a PRV problem that allows the pressure to creep up. I will be replacing it to see if that will solve the problem.

    The timing of the noise must be associated with some scheduled use of the City pumps.

    Also I have been very curious wrt the lack of use of expansion tanks in the plumbing in CA. Every person who I have asked who is in the trades has rarely if every seen or used one, but no one really new why when I explained the need for them when using a PRV. After looking a the manual for a Watts N5b-M1 PRV I figured out why they are hardly if ever used around here. It states that the regulator has a built in thermal expansion by-pass feature that prevents downstream pressure from rising to more that 10psi above the supply pressure with the only exception being if the inlet pressure is above 150psi.

    Is this safety feature unreliable?

    Are you sugesting the use of expansion tanks as a double saftey feature?

    Are these PRV with the thermal by pass feature not available everywhere?

    CJ
  20. markts30

    markts30 Commercial Plumber

    Messages:
    630
    Location:
    Phoenix, AZ
    THis may be the case but if the city pressure is 100 PSI and you run your PRV at 50 psi, you would have to get over 110PSI pressure in your house for any back-flow to the main to occur - at this pressure the fittings, fixtures and hoses in your house are already at the danger point WRT bursting / breaking...
    The expansion tank prevents this pressure buildup... Your pressure might climb from 50 to 60 max which is very much in the safe zone for plumbing fixtures
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