handling power outages on a well

dennisSA · July 2014

In our location we are subject to

frequent mains power loss of indeterminate lengths of time (4hrs to 6 days), we are

also subject to occasional rise in river levels causing the

municipality to cut off electricity. We are on a well and have a

manual standby generator that powers well and treatment equipment as needed,

as well as and heat/hot water systems as appropriate. However it

also means we have to run the generator for even the smallest amount

of cold water use such as flushing toilets. The well pump therefore

runs for even minor use, as we have only a small well-x-trol pressure tank (the pressure switch is set at about 30/50 range).

The plan is to place a 100gallon intermediate

storage/supply tank, in-line with existing well, filter and treatment

facilities, thus ensuring a 'buffer/bridging' supply of cold water that is

constantly used/refreshed. The TC2364IC-2 100gal polyethylene

storage tank w/side inlet/outlet & top fill capability seems to fit the bill. As the piping in this location is all PEX I intend to undertake this project as a DIY (do the hook up like a water softener or filter station)

SO, the questions are:

1) Is this a really dumb idea in the first place? (A bigger well-x-troll is not an option due to space and accessibility issues).

2) The tank will be placed after well-x-trol/filter/softener stations - any issues?

3) The tank will be isolatable (is that a word?) by use of valves similar to a filter station - any concerns?

4) I would like to have the tank 'refill' to a 100 gallons (ie have the well pump activate) when it's level drops to 70 gallons rather than on every draw however minor - can I do that? How?

5) Am I going to lose house pressure with the tank supplying instead of the well-x-trol? If so, how can I address that? A pump would kind of defeat the purpose, I thought expansion tanks were to relieve over pressure, solution must be valid for potable water).

I hope this is not too wordy and within my humble DIY capabilities, so please be gentle!

Thanks.

icesailor · July 2014

That way?

Did someone tell you to do it the way you describe? Or, is that your own idea?

dennisSA · July 2014

My own idea

This idea came from looking at a hot water heating tank. I took from that arrangement the following:

1) hw pressure out is pretty much cw pressure in

2) the expansion/pressure relief needs come from heating

3) may need a dip tube arrangement inside cw buffer tank if high inlet port

4) 100gal 5ft tank generates roughly 2-2.5psi

5) well pressure tank maintains distribution system psi even in a power outage (assuming no water use/leaks)

6) maybe adding a check valve on cw buffer tank inlet is enough to handle my pressure concerns

7) can't see any health issues since there is constant thruput and tank is specifically designed for potable water

8) used to live in a house where cold water tank in attic supplied whole house acting like a big toilet cistern, even with a ball cock to shut off supply, and gravity fed distribution.

This is an amateurs way of trying to cost effectively solve a high frequency problem.

If I could have replaced my well tank with a larger one I would have done it already - I have to live with things as they are.

If this is giving you a good laugh, I take no offense, but I refer you to Q1 on original post, and I would appreciate any help you might wish to offer.

Thanks for your interest in this problem. After this I have a good one regarding use of an indirectly heated hw buffer tank as supply to an in-floor radiant heating system!

icesailor · July 2014

Your ideas:

If this is YOUR idea and not someone else's, I'll point out a thing or two from my experience. If someone else came up with that idea, they might be right and I'm not.

Regardless of they type and size of your well bladder tank, whatever the pre-charge setting is inside the tank, when the house/pump pressure reaches that, the water stops. You said that it runs at 50/70#. It shouldn't. It should run no higher than 40#/60#. If you want to run 50# cut in, the pre-charge on the bladder tank should be over 50# (55#). Or, the pre-charge tank should be less than 50#. Depending on who you ask. The water in the system will "Pause" while the pump turns on. Because there is no more spring for the tank to push against.

When I/we did off grid houses with gasoline powered well pumps, you used standard hydro-pneumatic storage tanks. NOT bladder tanks. The compressed air at the top of the tank will give up pressure all the way to below 5# pressure. The bladder tank will completely stop when the system pressure and the tank pre-charge are equal.

IMO, if you need to run a generator for your water pump, just add the old standard Hydro-pneumatic tank in series with the bladder tank.

If you have a generator that rums just the well pump, you can 1/2 automate it. Get a pressure switch that "makes on rise" or, when the pressure is as high as you want it, the pressure makes the pressure switch close. Run a wire from the line and load side and connected to some grounded common ground t\and the other end to the spark plug on the generator. When the system comes up to pressure, the switch will close and ground out the plug stopping the engine. If the tank is on the same plane as the first floor, you'll still have adequate pressure at 15 or 20#. But the water will run slower and slower until it reaches zerk.

Jamie Hall · July 2014

ice is right

as usual...

A few other comments, though.

The main one is that your available volume in a power failure will be the effective volume in the pressure tank -- that is to say the air volume between the high and low switch pressures. In your storage tank, that would be exactly zero since you have no air in there! That is if you are depending on air pressure. However, you could have an elevated vented tank, and depend on gravity instead. If you did that you would have the total volume of the tank available. Can you place the tank in your attic? That would give you enough pressure for most fixtures. You would need to isolate the tank under normal conditions as the attic placement would only give you about 10 psi.

icesailor · July 2014

Hydro Vs. Bladder tanks:

Before the development of "Bladder Tanks" on water well systems, they were rated on the amount of water that was removed from the tank, with the air pre-charge that occurred from the first filling of the drained tank. If you had a "Airy" well, the pump outlet was always above the drain by a few inches. The air went to the top. If there was too much air, you needed some type of air elimination device. If the tank would get water logged because it lost all its air, you needed a device to add air. Usually something that added air from when the pump started and picked up air between the nozzle and venturi as pump started. There are calculatable amounts of water that will leave the tank depending on that range of pressure switch you used. If you used a 20#/40# pressure switch, and it was a 40 gallon well tank, there was a listed amount of water that would come out of the tank after the pump shut off at 40# and came back on at 20#. If you went to a 80 gallon tank, more water came out during the range because of the bigger tank. The cut in-cut out pressures are part of the equation too. But water would still continue to leave the tank until the air pressure in the tank went to zero, or a level that wasn't high enough to push it up and out of a faucet.

So when you try to rate a Hydro-pneumatic tank with a "bladder" tank, it is the amount of water that will leave the tank under pressure until it hits the pre-charge point when the water stops flowing out of the bladder tank. Ceiling mounted old style steel expansion tanks on heating systems are rated the same way. Its how much water can flow in and out of the tank during the expansion range of the tank . The bladder tank has NO reserve once the pre-charge setting is reached.

If you understand what I have tried to explain, I would add a large (80 gallon) hydro-pneumatic tank into the loop and leave the bladder type tank as the main source of expansion device.

You sound like a gnarly dude, able to change your oil in the driveway, change a tire, and maybe do many of those homeowner tasks that hiring someone else may be unsatisfactory. And you might even have a portable air compressor around with a air nail gun or two around the shop. If so, put a fitting inline to the hydro-pneumatic tank so that you always have a good "Squish" of air in the hydro tank. If you get clever, you can pre-charge the pressure air in the hydro tank. When the power goes out, if you have 20 gallons of available water in the bladder tank, and the pressure goes to the pre-charge, the water stops. But it will continue to flow out of the Hydro tank until the water/air pressure in the tank is too low to support the column of water.

Hydro tanks aren't cheap. Now, the bladder tanks might be cheaper. But when you get into the larger sizes, the value starts to flip.

I wasn't trying to be WA with my first response. I don't always see solutions like some others. They might not understand my solutions. Your solution to your problem will work OK. Did you come up with it or did someone else come up with that. I'm not wanting to second guess someone else. Maybe they know something I don't know. And maybe they don't know how Hydro-Pneumatic tanks work in relation to bladder tanks. What you asked about would work fine. There is a way that might be cheaper and gives you better results.

There are other positive and negative issues if you are interested. I don't want to get windier than I usually am. Unfortunately, I tend to not be brief.

dennisSA · July 2014

lost the link in my bookmarks

sorry for delayed response to all kind responders.

I am researching the hydro-pneumatic tank option as it seems to meet all my requirements (primarily the provision of normal house pressure potable water during a power outage). Sizing will be based upon physical site constraints but be the largest I can fit and afford - if the tank approaches 'empty' during an outage I should crank up the main genny anyway and at least get the lights/heat on as well as the well pump!!!!

Again thanks to all responders and I will return to let you know how it worked out or if I have further questions. The main items seem to be:

1) type (probably john wood jopr model)

2) usable gals

3) factory preset pressure

this will give me dimensions and pricing....

icesailor · August 2014

Factory Pre-Set:

With a non-bladder, Hydro pneumatic tank, there is no "Factory Pre-Set" pressure. Unless you consider "zero" to be a preset. The whole idea is that the water won't suddenly stop. It will become slower and slower. When you notice that it is getting really slow, it's time to start the generator.

handling power outages on a well

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