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Thread: Need advice on boosting water pressure

  1. #1

    Default Need advice on boosting water pressure

    My bathroom remodeling in a 1930 apartment building in NYC came to a halt today. When installing plumbing to the new tub we found that we only get 10-15 psi of pressure (through a 3/4" thermostatic valve with a 3/4" line out). We are getting maybe 1.5 gal per minute. By the time I fill a 65 gal tub, the water will be cold.

    I am on the top floor of the building so only about 8 feet below the building water tank, which I guess is the problem. The plumber suggested we install a pressure activated booster pump, but the first quote was around $6,000. This was not in my budget.

    Any advice on the best and most cost efficient way to solve this problem would be greatly appreciated.

  2. #2
    Master Plumber Redwood's Avatar
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    It probably will be your only option.
    Get several quotes.
    Life in NYC is not cheap!

  3. #3

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    Quote Originally Posted by Redwood View Post
    It probably will be your only option.
    Get several quotes.
    Life in NYC is not cheap!
    The truth hurts sometimes!

    If this were just a normal house application, I could put in a pump from the main from the street. Since I am in a building and have separate hot/cold supplies coming into the apartment, do I have to install two pumps?

  4. #4
    Master Plumber Redwood's Avatar
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    Yea you would. and hot water raises issues.
    But an interesting thought is that the building should provide you with useable ressure and volume...
    Perhaps you need to pursue that direction.

  5. #5

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    Quote Originally Posted by Redwood View Post
    Yea you would. and hot water raises issues.
    But an interesting thought is that the building should provide you with useable ressure and volume...
    Perhaps you need to pursue that direction.
    Yeah, I already politely raised that issue with the building. Didn't get very far.

    What issues does hot water raise? Pump problems?

    I'm also concerned about noise. The only place I could put the pump is in a bedroom wall adjacent to the bathroom. I don't really want to be listening to a pump all the time.

    If I had known this to begin with, I probably wouldn't have remodeled the bathroom. The tub and parts are already paid for and delivered though, and the lines put in, so there is no turning back now unfortunately.

  6. #6
    Master Plumber Redwood's Avatar
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    These boosters frequently involve the use of storage tanks. how do you keep that water hot? one of the problems...

    Time to play hardball with property management!

  7. #7
    Retired Defense Industry Engineer jadnashua's Avatar
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    Was the pressure that low before you started? Are you sure that there isn't just some crud caught on the input screens to the valve? What's the pressure and volume on the other fixtures?

    If the pipes are galvanized (possible at that age), the pressure may be great...but the volume is lousy - the interior diameter of the pipe could be a soda straw. Check the pressure with nothing running and let us know what that is. If the static pressure is good, then it is a piping problem that a pump won't solve unless you add your own WH, storage tanks, and pumps.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  8. #8

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    Quote Originally Posted by jadnashua View Post
    Was the pressure that low before you started? Are you sure that there isn't just some crud caught on the input screens to the valve? What's the pressure and volume on the other fixtures?

    If the pipes are galvanized (possible at that age), the pressure may be great...but the volume is lousy - the interior diameter of the pipe could be a soda straw. Check the pressure with nothing running and let us know what that is. If the static pressure is good, then it is a piping problem that a pump won't solve unless you add your own WH, storage tanks, and pumps.
    Don't know about galvanized pipes. Most of the run of pipe is new 3/4" copper, done for this installation. However, the first five feet or so may be sixty years old. So I need to check the static pressure back at the stack where it comes into the apartment. How do I tell if the pipes are galvanized? I never seemed to have problems with pressure in the shower (which is right next to the stack) but the kitchen sink pressure has always been very low. I think the main problem may be that the water pressure for the building is supplied by a tank that is on the floor above me. My floor wasn't originally an occupied floor in the building in 1930, but was added in what was storage space when zoning laws changed in the 1940's.

    My guess is that there just isn't enough vertical drop from the building water tank to my floor to yield decent pressure. Does this make sense?

    So now I have to figure out how to install some sort of pressure booster without much space to work with. I'm thinking maybe something like a variable speed/constant pressure pump like they use on farm wells for irrigation. I have seen systems like this that don't need a pressure tank (which I am not going to have room for).

    The big problem is that I am going to need two pumps, one for hot and one for cold where it comes in from the stack.

    Not a fun problem.

  9. #9

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    Ok so maybe a stupid question, but does copper galvanize? All of the original pipes are copper.

  10. #10
    Master Plumber Redwood's Avatar
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    No! Copper and galv. are 2 different materials. Galvanized pipe is steel pipe with a zinc coating.

  11. #11
    Master Plumber Redwood's Avatar
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    What probably hapens is the water from the tank runs down to a mechanical room where there is something capable of heating the water then it is distributed. The mechanical room may be several floors down. There are probably pump involved that boost it back up. You really need to squeak loud to get them to move on this.

  12. #12

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    Quote Originally Posted by Redwood View Post
    What probably hapens is the water from the tank runs down to a mechanical room where there is something capable of heating the water then it is distributed. The mechanical room may be several floors down. There are probably pump involved that boost it back up. You really need to squeak loud to get them to move on this.
    I would need to do more than squeak. I would probably have to hire a lawyer.

    So Redwood, what's the issue with running hot water through a pump?

  13. #13
    DIY Member msgale's Avatar
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    Default since you have had goodpressure inthe shower,previously...

    the whole probelm might just be corrosion in one of the original pipes, . this isn't necessarily an easy fix, but its a lot less trouble than a booster pump.

    if any fixture in your apartment is capable of good flow and pressure, then the problem is local to your apt., you track down the corroded pipe, replace it.

    is the good flow of hot, or of cold, or do both run well in the shower?

    are we sure the problem is only hot water flow rate, not cold too?

    you need a step by step diagnostic evaluation to locate the problem

  14. #14
    Moderator & Master Plumber hj's Avatar
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    Default pressure

    If the pressure is due to your elevation it should affect hot and cold equally. Therefore you would need two pumps or else the pressure balancing feature of the valve would reduce any increased pressure/volume on one side down to the original volume on the other side and nothing would change. But a hot water booster pump with its storage tank would give ambient temperature water initially until the tank was depleted and hot water started to flow. You could also cavitate the pump if the pipes were not able to supply the necessary volume of water, which would destroy the pump.

  15. #15

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    Quote Originally Posted by hj View Post
    If the pressure is due to your elevation it should affect hot and cold equally. Therefore you would need two pumps or else the pressure balancing feature of the valve would reduce any increased pressure/volume on one side down to the original volume on the other side and nothing would change. But a hot water booster pump with its storage tank would give ambient temperature water initially until the tank was depleted and hot water started to flow. You could also cavitate the pump if the pipes were not able to supply the necessary volume of water, which would destroy the pump.
    Very useful information, thanks. How about a pump like the Grunfos MQ shown here?

    http://www.houseneeds.com/shop/plumb...umpbuypage.asp

    This one seem like it has a small enough pressure tank that it wouldn't take long to get to hot supply.

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