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High Hot Water Pressure - 140 psi

  • 1.  High Hot Water Pressure - 140 psi

    Posted 02-01-2019 10:35
      |   view attached
    I'm beginning to suspect my hot water pressure is too high.

    Another ELBI diaphragm on my brand new Speed Queen SCT machine failed.  This is now the 3rd machine.  Only the hot water diaphragms have been failing on these new machines.

    I installed a pressure gauge last week as recommended by others on this board and left it connected to see what the max pressure would be over the course of the week.  When I installed the gauge, the hot water pressure was 60 psi.  After the ELBI valve failed yesterday, I took a look at the gauge and the pressure was currently at 120 psi and the highest recorded pressure was 140 psi.  See attached photo.

    I'm in the process of buying one more water pressure gauge so I can monitor both hot and cold water simultaneously.  I need to know if the water company has pressure regulation issues.  I doubt it.

    I suspect my hot water boiler causes the pressure to increase on the hot water piping system and that my pressure regulator is bad.

    Can anyone provide input on pressure regulators and hot water systems with boilers?

    At what pressures does your system operate?  At what pressures does your hot water systems operate?

    How effective are pressure regulators with regulating pressures on hot water system that vary temperature from 95 to 135 degrees?  It seems to me that once hot water heats and expands there is no way for a regulator to backflow the hot water in order to reduce pressure.

    Have you experienced pressure regulators that slowly leak pressure between the high pressure side and the low pressure side?  If my utility pressure is indeed high this could be the cause.

    What's the life expectancy of a pressure regulator?  From what I recall, there are rubber diaphragms and springs inside the regulator.  I suspect the moving parts weaken over time and that calcium may affect the valve seats and cause internal leakage.


    Thank you,

    ------------------------------
    Joe C.
    Store Owner
    Happy Bubbles Laundromat
    North Hollywood, CA
    www.BubblesCoin.com
    ------------------------------


  • 2.  RE: High Hot Water Pressure - 140 psi

    Posted 02-01-2019 14:13
    Edited by Larry Adamski 02-01-2019 14:24
    Joe,

    The hot water side is normally the same pressure as the cold water side.  This is because, as the heated water expands, it backs up into a small Xtrol tank located on the cold supply line to the heater.  Here that water pushes against an internal air bladder thus compressing the air as the water fills more of the tank.  As hot water is drawn out of the system via washer demand, the water in the Xtrol  tank decreases thus allowing more room in the air bladder and thus decreasing that air pressure.  So the Xtrol tank will stabalize the hot side water pressure.

    A pressure regulator is a device used to REDUCE pressure for a specific item such as a coffee vender.  This wouldn't work for a large water heater.

    A temperature/pressure valve (T & P valve) is a safety device required on all water heaters.  It has a unique hook shaped lever that can be lifted to manually test the valve.  The T & P valve  will let hot water out of the heater (usually onto the floor) if the gas valve became stuck on and the heater was turning the water to steam.  As very hot water or steam is dumped, cold water will enter the heater through the cold water inlet to help cool it down.  Thus the T&P valve can prevent a steam explosion.


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    Larry Adamski
    Muskegon Laundromat
    Spring Lake MI
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  • 3.  RE: High Hot Water Pressure - 140 psi

    Posted 02-01-2019 16:51
    Larry A. Has really good information. The air bladder also stops "water hammer," the terrible rattling sound as the water is shut off too quickly.

    Pressure should be approximately the same for both cold and hot lines. If you call water department they will provide you with their minimum and maximum water pressures. 140psi is too high, if my memory serves me right.

    Your safety pressure valve should be piped to a floor drain.  Required in LA. The probable cause of diaphragm failure is a bath of bad diaphragms.

    Your installation instructions should also address water pressure issues. The newer machines are sensitive to water pressure and slow fill times.

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    Larry Larsen
    Laundromat123.com
    Anaheim, CA
    Distributor - Insurance - Consulting
    Cell: (714) 390-9969
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  • 4.  RE: High Hot Water Pressure - 140 psi

    Posted 02-01-2019 17:28
    Edited by Joe C. 02-01-2019 17:30
    Thank you Larry & Larry for your input.  I now see what's happening.

    Thermal expansion of the hot water is causing the high pressure.  I probably have a bad pressure regulator and a bad thermal expansion tank.  One thing for certain, I have a good check valve.

    I did some research on Zurn pressure reducing valves, aka pressure regulators.  (Great channel on YouTube by the way).  The pressure regulators are designed to backflow if the pressure is too high on the low pressure side.  However, as I have a check valve installed to prevent backflow, there is no way to reduce the water pressure caused by thermal expansion other than the use of an expansion tank (or a pressure relief valve).  Regulating hot water pressure by means of the PRV is not a smart idea so the expansion tank is a must.

    I have an Amtrol expansion tank.  It probably holds about 5 gallons of water.  I suspect the air charge is too low or the bladder is ripped.  It might also be too small for my tank.  I have a huge tank, maybe 500 gallons.  I'll have to do some math to determine the water capacity.  I'm glad I stayed awake during high school geometry class.

    I'll do some more investigating on the street pressures.  I'm pretty close to devising a solution to reduce the 140 psi hot water pressure and keep my weak batch of ELBI diaphragms from being destroyed.

    Right now I'm planning on draining the hot water system to install a rebuild kit for the regulator.  I'll also investigate the air charge in the accumulator.  Since the system will be drained, I'm going to relocate the expansion tank.  It's sitting on the floor next to the water tank.  Floor space it at a premium in the back of house and this tank could be installed in a better place.

    Many thanks once again.

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    Joe C.
    Store Owner
    Happy Bubbles Laundromat
    North Hollywood, CA
    www.BubblesCoin.com
    ------------------------------



  • 5.  RE: High Hot Water Pressure - 140 psi

    Posted 02-01-2019 17:44
    Edited by Larry Adamski 02-01-2019 17:48
    Joe,

    I'd be really, really surprised if your water pressure actually is 140 psi.  I have never, ever seen water pressure that high anywhere.

    Oh, I did see really high water pressure one time, now that I think about it.  About 25 years ago, I had a 900,000 btu coil type water heater and the 1 1/4" gas valve stuck open.  I knew I had a problem when steam was coming out of the hot faucet on my utility sink out in the laundromat.  As bad as that was, I cannot remember if the T & P valve was dumping water or not.  All I know is I shut down that water heater just as quickly as I could.

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    Larry Adamski
    Muskegon Laundromat
    Spring Lake MI
    ------------------------------



  • 6.  RE: High Hot Water Pressure - 140 psi

    Posted 02-01-2019 22:30
    Typical potable water pressures are in the range of 30 to 85 psi.  Most plumbing valves, pipe, fittings, etc are rated at 150 psi, so a 140 psi supply is probably a bad reading.  The hot water pressure should be very close to the cold water pressure, except for the check valve.  I would remove it if it were my setup.  The T&P valve is probably rated by the BTU of the heater, but every vessel needs to have one; the tank and the heater, generally.  Your local codes rule.  If city water pressure drops below 20 psi the city should be issuing a BWN, a boil water notice.

    The check valve is likely the reason for the high reading on the hw side.  A properly functioning and sealing check valve will 'trap' the water pressure spikes on the downstream side due to valve closings.  That is, when the solenoid valve closes there is a sharp spike in pressure because the water is moving maybe 10 to 20 feet per second, has a good amount of mass, then instantly stops; thus bang, a spike in pressure and the pipes rattle.  One of the problems with water is that it isn't very compressible and so will transmit any shock or spike a long way.  As I recall, water will compress 4% at 10,000 psi at 35 degrees F.

    If you're trying to stop water hammer due to valve closings, the best place to put an air tank is at the source of the spike.  Of course, that's impractical because you may have 100 solenoid valves.  So, the next best place is on the water line behind the machines either at the very end of the run or at the beginning of the run where the line drops in from the ceiling.  I prefer the end of the run past the last washer.  One 1 to 2 gallon tank per water line per row of washers is sufficient.  That tank has an air bladder inside which should be pressurized with clean dry nitrogen at the same pressure as the water line.  The ones that HD sells come precharged at 40 psi, as I recall.  When mounted to the water line to absorb shock it would be called an accumulator.  When mounted to the incoming side of the hw tank or water heater it would be called an expansion tank because it is allowing room for the water to expand as it heats up.  Same air bladder tank, different sizes, different functions in the circuit.

    Please update the forum once you eliminate the problem.

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    Jim Allen
    Store Owner/ Employee
    VIP Laundry
    Orange CA

    Store Owner/ EmployeeVIP LaundryVIP LaundryJimAllenVIP LaundryVIP Laundry
    ------------------------------



  • 7.  RE: High Hot Water Pressure - 140 psi

    Posted 02-02-2019 01:22
    Joe:  140 psi is way high for your plumbing system.  LA probably requires a backflow valve at your water supply.  If your current pressure regulator is not also working as a backflow preventer, then your check valve may have been added to protect the City Water Supply.  A proper regulator setting and proper expansion tank set up should help the problem.  I would do some research on the requirements based on the size and BTU of your water heater.  You also want to be certain you have the correct T&P valve and temperature setting on your water heater thermostat.

    Years back I was called out to fix a water leak at a toilet.  The home had a water heater with a malfunctioning thermostat and no T&P valve.  The home had a pressure regulator with a backflow device on the water supply.  The only way for the super heated water to expand and not explode in some manner was to find an outlet.  The outlet was thru the ballcock of their toilet that had a leaking flapper.  The leak was the condensed steam that was dripping from around their toilet tank lid onto the floor etc.  Good grief.

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    Les Monthei
    Potential Investor
    Redding CA
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  • 8.  RE: High Hot Water Pressure - 140 psi

    Posted 02-02-2019 08:14
    Les,

    ... and that's how the steam heated toilet was invented.

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    Larry Adamski
    Muskegon Laundromat
    Spring Lake MI
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  • 9.  RE: High Hot Water Pressure - 140 psi

    Posted 02-02-2019 11:29
    Joe,

    If indeed you do have a 500 gallon tank, and you do have a 5 gallon expansion tank; it is way too small. The air charge chambers (water hammer arrestors) referenced to not compensate for water expansion as heated, only for the shock wave generated when valves close.

    Here is a chart we provide our distributors for properly sizing an expansion tank; the number on the left of the / is the total tank volume, and the number to the right of the / is the required acceptance volume. All expansion tanks have a specific ability based on internal design to accept a certain percentage of their total volume as expanded water, this is based on the maximum cold city water pressure the system will see (after the pressure reducing valve you reference), and the maximum pressure you can allow the system to see; the pressure relief valve setting (generally 125 or 150 PSI).

    On the left hand side of the chart find the tank volume, and on the top, find the maximum temperature differential from  your incoming water temperature to your stored water temperature.

    Let me know if you have any questions.

    Tank sizing chart

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    Jeff Deal
    Manufacturer Employee
    Hamilton Engineering Inc
    Livonia MI
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  • 10.  RE: High Hot Water Pressure - 140 psi

    Posted 02-06-2019 11:12
      |   view attached
    I've been analyzing this issue for a few days.  I purchased another pressure gauge to confirm the other gauge is good. The read are the same.  Most likely the gauges are good.

    Now that I have pressure gauges on hot and cold water, I can observe in real time how pressure changes during the operation of the laundromat.  Here's what I discovered.

    I have high water pressure supplied by the city.  Cold water pressure is 120 psi during flow to my machines.  The cold water pressure is stable and does not fluctuate much.  Although I have water hammer every time a solenoid operated water valve closes.  The water pressure will spike as high as 160 psi on the cold water gauge.  I cannot find a regulator on the 2" cold water supply.  Yes, it sounds crazy but i didn't build the laundromat.

    (Now that I type this, I just realized there is something that is probably a regulator on the 1-1/2" lines located inside each bulkhead.  I'll investigate later.  I may have regulators within each bulkhead since there's not one on the main line.)

    As far as hot water is concerned, the pressure with flow was only 40 psi.  The static pressure creeps to 120 psi.  With water hammer, the needle pegs to 140 psi.

    I now see that my water pressure is uneven.  I adjusted the hot water supply regulator to 60 psi.  I did a test to see how this affects water flow.  As anticipated, a top loader fills in 2 minutes with cold water, 4 minutes with hot water.  I assume a warm water mix will be uneven, a ratio of 2:1.  That is, 2 parts cold water, 1 part hot water, or put it another way, 66% cold, 33% hot.

    I think I'll increase the pressure on the hot water supply regulator to 80 psi for a couple of reasons.  1) to balance the hot/cold water mix.  2) to fill the washers faster.

    In the meantime, I'll need some surge arrestors to keep the system from spiking to 140-160 psi.  I had another weak ELBI diaphram go bad yesterday.  This one only lasted 5 days.  I replaced it with a used one from my used parts bin.  It seems the old batch is better.

    Any recommendations on a a good water hammer arrestor? 

    I see cheap ones for $20, larger ones for $100.  I'm not opposed to spending money and doing plumbing work.  I just don't want to do a lot of piping work if there's no benefit.

    I found this water hammer arrestor on Amazon.  See photo.  It fits on a 3/4 hose bib.  $50 each. Kind of pricey but the install is super simple.  I'll probably buy a couple and see how it affect the water hammer on the pressure gauge.

    Cheers,



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    Joe C.
    Store Owner
    Happy Bubbles Laundromat
    North Hollywood, CA
    www.BubblesCoin.com
    ------------------------------



  • 11.  RE: High Hot Water Pressure - 140 psi

    Posted 02-06-2019 22:42
    One of my 6 laundries has very high water pressure supply from the city.  I have a regulator which lowers the pressure first thing before it goes anywhere.  I think it lowers it to about 95lbs, but I will double check.

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    Brian DeCoster
    Laundromania
    Iowa City IA
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  • 12.  RE: High Hot Water Pressure - 140 psi

    Posted 02-07-2019 09:13
    Most laundries ideally have the same pressure on both hot and cold water lines. 

    Most often we see 55 - 75 PSI under no load (static) conditions. 

    It will naturally drop down as more washers are in fill mode, but really should not increase "gradually"; if it does it is a sign of improperly controlled expansion occurring when heating or a faulty regulator. 

    The spikes referenced can do tremendous damage to tanks, valves, hoses etc., and should be minimized if at all possible. 

    We have recommended this company for almost 40 years now as they provide great technical support for sizing and designing the proper layout and sizing of water hammer arrestors:     https://www.siouxchief.com/products/supply/arresters-and-trap-primers





  • 13.  RE: High Hot Water Pressure - 140 psi

    Posted 03-19-2019 10:07
    I thought I'd give an update to my issues with high hot water pressure.

    For some reason my laundromat does not have a water pressure regulator on the incoming main line.  There is a 1-1/2" water pressure regulator for the line feeding the hot water tank though.

    My issues was that I keep ripping hot water ELBI diaphragms on my new SQ SCT front load machines.

    The easiest fix, I thought, would be to replace the 1-1/2" pressure regulator that feeds the hot water tank.  The regulator cost me about $400.  To my surprise, it made no difference.

    My city pressure is 125 psi.  Gauges on the hot and cold lines are static at 125 psi.  With water hammer the gauges will hit 140 to 160 psi constantly.

    What I discovered was that the SQ SCT machines have a manifold that connects the hot water and cold water systems together.  If both valves are open simultaneously, high cold water pressure migrates to the regulated hot water system, thereby increasing the pressure from the hot water setting of 60 psi to 125 psi.  When the ELBI diaphragm rips, the hot and cold water systems are essentially connected and the pressures are the same.

    The best solution to this problem is dig up the sidewalk and install a regulator (PRV) on the main line.  This will ensure the entire laundromat is at one pressure and there is no differerential between hot and cold water system.  I believe the pressure differences contribute the weakening on the ELBI diaphragms.

    For the time being, I've installed surge arrestors purchased from Home Depot for $11.00 each.  I've placed them at the back of every SCT machine on both the hot and cold water lines.  Since installing the surge arrestors I have had had no ELBI diaphragms rip and tear.  It's a cheap band-aid fix to a more complex problem.  It buys me time so I can work on more important issues though.

    In a few months I'll work on installing a pressure regulator at the main valve underneath the sidewalk.

    The big lesson for me was that high water pressure and water hammer is a problem that laundromat owners need to consider when analyzing premature component failure.

    Cheers,

    ------------------------------
    Joe C.
    Store Owner
    Happy Bubbles Laundromat
    North Hollywood, CA
    www.BubblesCoin.com
    ------------------------------



  • 14.  RE: High Hot Water Pressure - 140 psi

    Posted 03-19-2019 16:13
    Joe:  Having a regulator on the hot water line is something I have not seen before, even if it's in the cold line before the hot water tank, and if it's not, it does not protect the tank.  With your crazy PSI, I don't think the water hammer arrestors will do a whole lot of good, but won't hurt.


    Be sure to get the right pressure regulator for the main line.  A PR at the meter will start protecting the entire underground system, and that may be needed depending on the materials, age, sprinkler systems, etc.  However, you might find a more convenient spot closer to or in the building water system.

    Be sure to have the spec's on the PR before you plan your job so you know you have the space and proper material to complete the job.  I would install a by-pass around the PR so you don't have to shut down the system to work on the PR down the road.  Might even install a large connector on the high psi side to fight fires, wash building and lot etc.



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    LES MONTHEI
    MT VIEW LAUNDROMAT
    LAKEHEAD CA
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  • 15.  RE: High Hot Water Pressure - 140 psi

    Posted 03-23-2019 14:03
    Why do you need to rip up sidewalk? Install the regulator on the main line when it enters building.
    A plumber should be able to install in a few hours

    Sent from my iPhone




  • 16.  RE: High Hot Water Pressure - 140 psi

    Posted 03-23-2019 15:05
    Unfortunately the main line is under the ground and enters the laundromat from beneath the foundation.  The easiest way to install a PRV is near the water meter located under the sidewalk.

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    Joe C.
    Store Owner
    Happy Bubbles Laundromat
    North Hollywood, CA
    www.BubblesCoin.com
    ------------------------------



  • 17.  RE: High Hot Water Pressure - 140 psi

    Posted 03-23-2019 15:57
    Joe:  Be careful about working on the sidewalk to install your PRV.  I have worked in some municipalities that claim that is their property, and they don't want any private equipment installed.  Others would require a licensed contractor to provide a permit drawing and use their specified equipment and concrete mix.  If you run into this problem, maybe you can install the PRV in a box on your side of the sidewalk in a convenient location with fewer issues.

    Find out what type of piping is underground, so you can be prepared for the issues that piping at that age will reasonably present.

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    LES MONTHEI
    MT VIEW LAUNDROMAT
    LAKEHEAD CA
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  • 18.  RE: High Hot Water Pressure - 140 psi

    Posted 27 days ago
    I just noticed while getting some info at the store today.  Our SQ 40 lb FL Model SCN040 washer dvises "Supply Water: 30-85 PSI.  2-5.7 bar"  Same on the 60 lb Model.

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    LES MONTHEI
    MT VIEW LAUNDROMAT
    LAKEHEAD CA
    ------------------------------