Domestic water pressure question

VivaVegas

VivaVegas

This has nothing to do with heat but

I don't think it really matters considering a lot of you guys are plumbers by trade.

Recently I built a concrete holding tank (2000 Imperial) to offset the problems created by a slow producing shallow well. I am about to install a submersible well pump in the low producing well and use that to pump water over to the holding tank.

I am also installing a 3/4 HP submersible deep well pump in the holding tank and this will provide the water for the house via a one inch line directly to the 80 gallon pressure tank.

The total head for this pump will be less than twelve feet (distance between the floor of the holding tank and the shower head). I am fond of really good water pressure. So, what are your thoughts about what constitutes good water pressure? I am leaning toward 40/60 psi for cut in/cut out settings as a minimum and am wondering if I can go higher.

As plumbers, you guys know what municipal systems run at and what is ideal when it comes to pressure.
VV

jackchips_2

Most plumbing

codes do not allow an excess of 80 psi for a domestic water system.

Raising your pressure up to or near that could cause other problems in your system, such as velocity noise, erosion of the pipe or water hammer, depending on the sizes of your cold and hot water pipes.

A normal residence, properly piped, should work well at 50/55 psi.

[Deleted User]

your well system pressure will never equal your city pressure..

unless you want to get into some serious booster pumping products..what concerns me more is your desire to use a holding tank..is this board of health recognized in your area? here is why i ask- in the navy we obviously used holding tanks on the ships, and the water lab had to test the water in the tanks daily, and the hospital corpman than treated the water based on the waterlabs findings...just a thought.

Jack, CVMS

Water pressure

There's nothing wrong with going a little over the 40/60 setting so long as you don't get too wild. 50/70 should give pretty good pressure at the fixtures. Be sure to install a 75psi pressure relief valve near the pump discharge to protect the rest of the system in case the control contacts weld together.

Unless you use a tremendous amount of water, it sounds like you're commiting a bit of overkill. I've seen small hotels run on a 3/4hp submersible pump, at over 100' depth. With no suction head, and an insignificant static head, your pump will have much more capacity than you need, and for that reason will probably be cycling off and on frequently. With a 1/2hp pump you could probably use a 60/70 pressure setting to keep from having noticeable pressure fluctuation (such as causes temperature changes in the shower) without excessive pump cycling. The cycling is harder on the motors than constant running.

Also wondering why you didn't just install a large steel or plastic storage tank for your water. Something that can be fairly well sealed - with just a screened air vent - and will keep your water relatively clean

hr

Why a submersible

A basic booster pump/tank combo may supply your needs. Grundfos and others offer them. Or a shallow well pump/ tank combo. If it's in the tank you will need acess.

Actually flow, and proper pipe diameter will give you plenty of water at 45psi, keeping in mind virtually all faucet and mixer valves have flow restrictors.

Unless you have a huge gpm demand body shower?

Pressure above the 45psi gets harder on faucet washers, seals, ballcocks, solonoids on wash machines and dishwashers, etc. Pressure tank capacity goes down with elevated pressure also.

hot rod

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Dave Yates (PAH)

CP booster pumps

Constant pressure booster pumps are now available too. Much like a modulating boiler, they will match the "load" placed on them. This eliminates bulky expansion tanks and offers more of a steady-state pressure. You'll get spoiled(G).

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Rich C._3

There are several solutions .....

for the type of appilication you describe.

A traditional pressure tank/booster pump will work. We manufacture an integrated solution called the MQ which integrates the pump and pressure tank into one unit.

The application you describe would be ideal for our Smartlfo system. It's a constant pressure solution that uses a variable speed submersible well pump and controller to deliver the desired performance.

I hope this info helps, feel free to email me directly for more information.

VivaVegas

There was no doubt in my mind

when I posted this thread that I would get excellent response. Thank you, one and all.

The consensus seems to be that running my pump at 40/60 at the outset would be advisable and then raise it to 50/70 only if the situation demands it.

Yes, a 3/4 horse deep well submersible pump capable of delivering a contant 12 gallons per minute probably is overkill but I would rather have overkill then underkill. I have always been of the mind that you get to do these things once, the right way. The second attempt is always more expensive if you have to scrap the first attempt.

HotRod: I recently redid all the copper for both hot and cold. The line coming from the pressure tank is 3/4 inch and it supplies the hot water tank as well as being a main trunk supplying half inch branches leading to the kitchen, the bathroom and the laundry room. The hot water lines are all in half inch and the two exterior faucets are on a separate half inch feed running off the 3/4" cold trunk line. All pipe are foam insulated from end to end. And no, the shower is just one standard head.

Jack: Yes, I will be putting in a pressure relief valve right at the tank "just in case". The decision to go with concrete was simple. I could build it myself. When it was finished, I could cover it with two and half feet of dirt and drive a truck over it without fear of any damage. It i six inches thick all around with rebar and remesh everywhere. It does not leak, so contamination from ground water is not an issue. Oh, and it does have an access port that is three feet square internally that sticks above grade by two feet. I am building an insulated locking cover for this access.

Your comment on the cycling has me puzzled. My understanding is this. It is the trapped compressed air in the pressure tank that actually moves the water through the system. The size of the pressure tank dictates (for the most part) how many gallons of water can be drawn down before pressure in the tank drops to the pump cut in point. The larger the tank (under identical circumstances) the more water can be drawn down prior to the pump being activated by the pressure switch.

Therefore, if a one third horse pump delivers eight gallons a minute and a 3/4 horse pump delivers 12 gallons a minute, all that will happen is that the tank will come back to full pressure quicker with the bigger pump. Doing so, would mean that they system pressure would, on average, be maintained at a higher pressure with the larger pump.

I think I understand what you are trying to get at, in that the smaller pump would not have the ability to easily override the demand and would continue to run for longer time intervals if one was watering the lawn or washing the car. The question would then be whether jumping in the shower while the washing machine was also being used would cause fluctating water temps or not.

As I further understand it by reviewing the charts at Diamond Pumps, the larger hp pump has an easier time at achieving higher line pressures. I would be interested in hearing further discussion on these issues if anyone has experience on pump output vs. pressure tank sizing.

Gerry: the issue here is whether this is true "potable water" or not and the answer is no. Tests on this well in the past have shown some mild fecal contamination. Nothing outrageous but who wants to drink water that has this confirmed problem? Water for drinking is pushed through a diatamaceous filter and I probably spelled that wrong but you likely know what I am referring to.

When the system gets up and running it will be sanitized with a gallon of bleach. The water will be monitored on a regular basis to make sure that it is not going stagnant and breeding any nasties. If that happens, then the health department will be consulted to see how much bleach should be added and how often.

To help with this decision, I am installing an old Neptune mechanical water meter on the pipe coming from the well so I can monitor how much water is being pumped over on a weekly basis. Thanks for pointing this issue out.

As for those who mentioned the other type of constant pressure systems, I was recently made aware of a pressure boosting pump for homes on municipal water systems that delivered low pressure. The ones I saw came in at $800.00 to $1000.00. These pumps were already being pressure fed by the municipal supply and so I do not believe that the system I saw would work for this application.

As for the Grundfos system, I will check that out. One joy I was looking forward to was NOT having to listen to the jetpump everytime water was being used. Oh, and along with never having to prime the system again was my second joy.

VV