How to size a booster pump?

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Old 05-01-17, 02:46 AM
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How to size a booster pump?

In question is a six unit (six family) tourist accommodation. I need to determine a booster pump performance specification.

Each unit will include a shower, toilet, and wash basin; but no kitchen. The pump size specification will need to accommodate peak usage, (presuming that all six bathrooms will be in use simultaneously.) All units are adjacent, and single-story.

Can someone please give me some guidance, and/or direct me to a calculator tool?

Thank you very much for any assistance,
~~z
 
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Old 05-01-17, 02:58 AM
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Where are you located? What is your water source? A booster pump will increase pressure, but will do nothing for continuous volume. You will need a pressure tank to hold water and disperse it at a prescribed pressure. Six units is a lot of water at certain times.
 
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Old 05-01-17, 05:20 AM
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Hello Chandler, thank you for your reply.

To answer your questions, I am in Thailand; but I'm not sure that helps much. I should have mentioned that the water source is a 10,000 liter holding tank, adjacent to, and at the same height as the bathroom units. (Actually, it is about 1-1/2 meters higher than the bathrooms but I'm not taking credit for that.)

What I was hoping for was a constant-pressure pump, (that speeds up or slows down depending upon the demand.)

My understanding of all this is pretty shallow, so don't be shy to tell me that I don't know what I am talking about !
 
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Old 05-01-17, 06:18 AM
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The first step is to add up the gallons or liters per minute that you must provide. Then pick how much water pressure you want. Then with those two bits of information you can look at the performance charts and pick the right size pump.
 
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Old 05-01-17, 12:02 PM
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Thank you for the reply Pilot. Got it ! I was/am just hoping that there is a calculator somewhere that would allow me to input the above "consumption variables" and it would output some "standard estimates" of the min, max, and average flow rates to be expected for "the average user". (With those estimates, I would intend to go into the performance charts.)

However, as you imply, Chandler, six units of demand may be unachievable -- but at this stage I haven't yet even the vaguest estimate...
 
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Old 05-01-17, 12:24 PM
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I still say pressure storage will be your best bet when using a pump. You should have some pressure with the fall you have, but probably not enough. Adding the pump and a subsequent pressure tank will ensure each constituent will have enough volume and pressure for nominal activities such as a shower and flushing.
 
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Old 05-02-17, 06:28 AM
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A general calculator may not be your best bet. Here in the USA showers and other fixtures are restricted by law to a maximum flow of 2.5 gallons per minute. Fixtures in others countries do not have that restriction and may flow considerably more water so you really need to look at the items you have to feed to come up with a flow calculation.
 
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Old 05-02-17, 02:54 PM
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Thank you, Pilot. I really haven't a clue as to real numbers though. It sounds as though I will have to go take a shower with a 5-gallon bucket, and then deploy wifie's kitchen measuring cup in the toilet reservoir. I can do that, but I would welcome anyone's even ballpark estimates to compare against. (For example, I could just try doubling them and see which pumps that leads to.)

Thank you, Chandler. Your idea of a pressure storage tank is intuitively appealing. However, that kind of brings me back full circle: How then do I size this tank? (I know -- bigger is better. But what would be a practical size for my set of circumstances ?)
 
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Old 05-02-17, 03:53 PM
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I should think for that number of users a 62 gallon tank would suffice. That's over 10 gallons per unit at a constant pressure, and it will be replenished as the demand is there. Water Worker 62 Gal. Pressurized Well Tank-HT62B - The Home Depot
 
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Old 05-02-17, 04:13 PM
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A water saving misting (spittting) shower head may use about 1/2 gal/min (1.9 liter/min). A standard US shower head consumes about 2.5 gal/min (9.5 liter/min) while a old, non-water saving one can be 4-5 gal/min and I recently had a shower in Hong Kong that had to be at least 10 gal/min from the overhead rain head. So, there is a tremendous range in what a shower can use. You'll have to test your shower heads to get a useful number as anything else is just guessing.

A pressure tank can be a good way to keep water constantly available to guests without the pump having to run continuously. Keep in mind that the tidal volume (the amount of water used between your pump's turn on and turn off pressure) is about 15-20% of the tank's stated volume. The tank size refers to the volume of the outer steel can while what you use is the smaller volume of the rubber bladder inside. This 82 gallon tank works with 12.7 gallons when your pump is set to turn on at 20 psi and off at 40psi.
 
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Old 05-08-17, 04:00 PM
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Big apologies for not acknowledging your detailed responses Chandler and Pilot ! I have just returned from an emergency trip to south Thailand with no internet access.

You have given me some real numbers to chew on, and I will -- thank you very much !

I will report back with progress, as available.

Thank you again !
~~z
 
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Old 05-08-17, 06:29 PM
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Oh, so good to know where you are located. I took my first trip to Thailand in November. Most of the time was in Bangkok and I really wish I could have spent more time outside the city.
 
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Old 05-10-17, 10:02 PM
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Hello Pilot, Yep, your intuition is correct. Bangkok urban almost leaves the opposite impression from that of the rest of the country. Try to get out of there next time !

I've already strayed way off-topic, sorry; but maybe you or someone might find these interesting:

Thai Visa is the expat forum, which discusses every conceivable topic from an expat point of view: https://www.thaivisa.com/forum/

Bangkok Post is the primary english-language newspaper: http://www.bangkokpost.com/Bangkok Post
 
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Old 05-22-17, 09:23 PM
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Hello again, Chandler,

Could you please re-click your link from your post #9 above:

Water Worker 62 Gal. Pressurized Well Tank-HT62B - The Home Depot

I have tried it quite a few times and have even had other people try it -- but no joy. My tecchie says he thinks it is a problem within Home Depot's server.

I am still trying to get myself educated on this topic !!

Thank you very much,
~~z
 
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Old 05-23-17, 03:05 AM
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Link works fine. You may have a problem being in Thailand. Not sure what your local home depot store carries.
 
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Old 05-23-17, 04:34 AM
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There is noting special about the tank he linked. It is a pressure tank that is commonly available in the US. I have no idea what is available to you in Thailand. Tanks in the US have an internal rubber bladder that separates the air and water which helps keep them maintenance free. In your case probably the biggest tank you can get might be the best.
 
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