Water Supply, Pump and Pressure Question

[JetsetBkk]

Below is a diagram of my system:

The pump is a new Hitachi "GX series WT-P 200 GX2". The tank is underground and has inside it a normal ball-cock type valve which cuts the water off when the tank is full.

Normally the power to the Pump is off at the breaker box inside the house, and both the Pump valve and the Tank valve are closed. So the tank water is completely isolated.

Under these conditions water comes into the house from the "City Water" supply, through the City Water valve and one-way valve.

But sometimes the City Water pressure is so low that I want to use the pump and use the water from the emergency tank.

So I close the City Water valve, leave the Tank valve closed, open the Pump valve and turn on the power to the pump at the breaker box.

This situation gives me a good pressure of water from the tank, but will only last a few days until the tank is empty.

So what I do overnight is open the City Water valve and Tank valve, and close the Pump valve so that the tank can be filled slowly overnight with whatever pressure there is from the City supply.

I probably don't need to close the Pump valve as I am pretty confident that the One Way valve works: if I leave the Pump valve open and the City Water valve open, the Pump does not switch on, which indicates to me that water is not flowing backwards into the City Water supply (which is my main worry).

But I have one other concern: if I leave all three valves open so that the Tank fills up overnight from the City Water supply, and I can use the Pump to give me good pressure while the City Water pressure is low, is there any danger that if the City Water pressure becomes greater than the Pumped water pressure that City water will flow backwards through the Pump and either cause damage to the Pump or fill the Tank until it overflows?

Of course, if I had a One Way valve between the Pump and the Pump valve, this wouldn't be a problem.

Any thoughts?

.

[Crossy]

These pumps all have a non-return valve built in (so the pressure doesn't leak back to the supply side), no danger at all of any damage or of over-filling your tank. Add another non-return valve on the inlet side of your pump if you're worried.

We have an identical system (OK a Grundfos pump), I just leave all the valves open. City water pressure rarely exceeds the pump pressure anyway, but when the power is off the switch over and back is completely automatic.

[Canada]

Why not just use the emergency system all the time, and use the city water bypass in case of failure of one or more of your components?

That would keep the water in your tank fresh.

[Langsuan Man]

But I have one other concern: if I leave all three valves open so that the Tank fills up overnight from the City Water supply, and I can use the Pump to give me good pressure while the City Water pressure is low, is there any danger that if the City Water pressure becomes greater than the Pumped water pressure that City water will flow backwards through the Pump and either cause damage to the Pump or fill the Tank until it overflows?

As Crossy says, this is the same system that I have and so long as the float valve in the water tank does not stick there are no real problems regarding the pump. Wasted water yes, but it is not going to back up into the pump mechanism. As far as I am concerned this system is set it and forget it

[JetsetBkk]

Why not just use the emergency system all the time, and use the city water bypass in case of failure of one or more of your components?

That would keep the water in your tank fresh.

Yes, I like the idea of keeping the water in the tank fresh. In the past, I have mixed in chlorine (from household bleach) a per here: http://www.cdc.gov/healthywater/emergency/safe_water/personal.html

But regarding the failure of the tank's ball-cock/valve pipe inside the tank, if you saw the resultant mess caused by that failure, you'd be a little reluctant about leaving the tank valve open all the time.

Edit:

Please see my reply to Crossy - the next post - about leaving the tank valve open.

Edited February 13, 2014 by JetsetBkk

[JetsetBkk]

These pumps all have a non-return valve built in (so the pressure doesn't leak back to the supply side), no danger at all of any damage or of over-filling your tank. Add another non-return valve on the inlet side of your pump if you're worried.

We have an identical system (OK a Grundfos pump), I just leave all the valves open. City water pressure rarely exceeds the pump pressure anyway, but when the power is off the switch over and back is completely automatic.

Thanks Crossy. I thought I'd replied to your post yesterday, but it seems I forgot to hit the "Add reply" button.

Here's what I wrote:

Thanks Crossy - I was hoping for a response like yours.

I'll be opening the Tank valve only during the day time if ever I need to fill the tank, as I had a major problem once - the pipe inside the tank snapped releasing the ball-cock and valve and allowing City water into the tank full-bore. It didn't take long to wash away a lot of the top soil from the garden!

[JetsetBkk]

But I have one other concern: if I leave all three valves open so that the Tank fills up overnight from the City Water supply, and I can use the Pump to give me good pressure while the City Water pressure is low, is there any danger that if the City Water pressure becomes greater than the Pumped water pressure that City water will flow backwards through the Pump and either cause damage to the Pump or fill the Tank until it overflows?

As Crossy says, this is the same system that I have and so long as the float valve in the water tank does not stick there are no real problems regarding the pump. Wasted water yes, but it is not going to back up into the pump mechanism. As far as I am concerned this system is set it and forget it

Yes, I do like this idea. I think tomorrow I'll check the tank's internal pipe that holds the valve and ball-cock and - if I can convince myself it's not going to fail again - I may leave the valves open and the pump on. It is nice to have a constant good pressure from the pump.

[Canada]

Personally, I'd leave the tank side running and use city water only as a back up, like I already said. I'd put an overflow outlet on the tank as a safety measure in case your valve does not work properly as you have already experienced. You could pipe that to a close by drain.

[JesseFrank]

Personally, I'd leave the tank side running and use city water only as a back up, like I already said. I'd put an overflow outlet on the tank as a safety measure in case your valve does not work properly as you have already experienced. You could pipe that to a close by drain.

The overflow could also be connected to the house supply pipe with a one way valve between, so he would never lose the water .

[wayned]

No matter how good the cutoff valve is it will occasionally not close completely due to debis in the water. I have a large SS tank on my carport and it does happen and overflows, but doesn't cause too much mess because of where iit's located. I turn off the water remove the valve clean it and it's good to go until the next time. It does have another fitting on the top where an overflow pipe could be fitted but I've never plumbed it.

I've replaced the one-way valve in my system with acutoff vale because the one-way valve would get stuck either in the open or closed position. If open the pump would try to presurize the entire village water supply, if stuck closed we didn't get ant water when the electric was off. So when the electric goes off, often, I just open the valve and turn off the pump so that when it comes back on it doesn't try to pressureize the village system.

[JesseFrank]

I have a similar system where instead of city water my water comes from a borehole.

The well pump fills up a large storage tank, from there it goes through a filter into a smaller tank which provide the house.

Between the small tank and the filter is an electric valve which gets operated by an electric floating switch in the small tank. When the small tank is low water gets pumped from the large tank .

A similar setup could be done with the OP with electric valve between the city supply and the storage tank.

[JetsetBkk]

Personally, I'd leave the tank side running and use city water only as a back up, like I already said. I'd put an overflow outlet on the tank as a safety measure in case your valve does not work properly as you have already experienced. You could pipe that to a close by drain.

Personally, I'd leave the tank side running and use city water only as a back up, like I already said. I'd put an overflow outlet on the tank as a safety measure in case your valve does not work properly as you have already experienced. You could pipe that to a close by drain.

The overflow could also be connected to the house supply pipe with a one way valve between, so he would never lose the water .

Excellent ideas!

[JetsetBkk]

No matter how good the cutoff valve is it will occasionally not close completely due to debis in the water. I have a large SS tank on my carport and it does happen and overflows, but doesn't cause too much mess because of where iit's located. I turn off the water remove the valve clean it and it's good to go until the next time. It does have another fitting on the top where an overflow pipe could be fitted but I've never plumbed it.

<snip>

I had the same problem with debris in the water that caused my toilet cistern valve to allow water in constantly, albeit very slowly, and overflow into the toilet bowl.

So I took the valve apart and found a thin sliver of blue water pipe - a curved piece about 1 cm long - sitting on top of the inlet pipe just where the rubber seal was supposed to come down and stop the water coming in.

This bit of pipe was almost certainly a bit that was cut off by someone who trimmed the end of a pipe somewhere upstream, before joining it to another.

Once this bit was removed it all worked perfectly.

<snip>

I've replaced the one-way valve in my system with acutoff vale because the one-way valve would get stuck either in the open or closed position. If open the pump would try to presurize the entire village water supply, if stuck closed we didn't get ant water when the electric was off. So when the electric goes off, often, I just open the valve and turn off the pump so that when it comes back on it doesn't try to pressureize the village system.

This is my worry - I could be pressurising the whole Rawai water system with water from my tank AND paying for the electricity to do it!

So I think my overall strategy will now be like this:

Normal conditions:

- use the pressure from the City water

- cut power to the pump at the breaker box, as it is not normally needed

- leave Tank valve closed, others open

Low pressure from City water supply:

- turn on power to pump at breaker box, rely on one way valve working

- open Tank valve to keep tank topped up

- periodically turn off power to pump to check City water pressure

- if City water pressure OK, leave power to pump off and close Tank valve

So I only need worry about the One Way valve not working and the Tank's ball-cock & valve not working for the relatively short time that the City water pressure is low.

[callaway]

Jetsetbkk, i have a pressure pump off of a tank due to low pressure from village supply. I have a mechanical shut off valve/ball float so that i can leave water supply to fill tank then shuts off when tank is full. No playing with valves or anything. I have also installed a bypass manifold with 2 gate valves so if we lose power i can still get water. Therefore we run of the pressure system at all times and the tank fills as the water level lowers. Basically never have to touch valves (until lose power to house) and enjoy pressured water at all times. I purchased the ball float cut out from Global Hardware in Surin but i am sure any big hardware shop could supply. I have attached a diagram of the system.Hope this can help.

pressure pump system.pdf

[callaway]

Just need to add Jetsetbkk that this leaves your pressure system independent of the town water supply. Absolutely no fear of supply pressure to the town supply. Water free flows into your tank and you are just drawing from that. Of course this is on condition the gate valve on the bypass line near your pump is closed. In fact i use ball valves due to easier action of opening and closing and the fact that they seal better on the closed position. The bypass can be used in case of pump problems too. Unlike electrical ball valves this is all mechanical so less chance of problems.

[JetsetBkk]

Jetsetbkk, i have a pressure pump off of a tank due to low pressure from village supply. I have a mechanical shut off valve/ball float so that i can leave water supply to fill tank then shuts off when tank is full. No playing with valves or anything. I have also installed a bypass manifold with 2 gate valves so if we lose power i can still get water. Therefore we run of the pressure system at all times and the tank fills as the water level lowers. Basically never have to touch valves (until lose power to house) and enjoy pressured water at all times. I purchased the ball float cut out from Global Hardware in Surin but i am sure any big hardware shop could supply. I have attached a diagram of the system.Hope this can help.

Thanks, callaway. I must start a new topic in the support forum titled "Why don't I get notification emails about my own topics even when I am "following" them?".

So, sorry for not replying sooner as I didn't think there were any more replies!

Thanks for the diagram. My tank is underground, which helps it fill quicker. Fortunately we don't get that many power cuts here, so when the "City water" is off, I usually have power to pump from the tank.

I am now, more or less, on a "set it and leave it" mode regarding the valves. At night time I turn the power to the pump off at the breaker box in the house because the pressure from the City supply is usually good enough.

So my valves all stay open - the one letting water into the tank (the ball cock inside stops it overflowing) and the one letting water out from the pump.

The one way valve appears to do its job, stopping my pump pressuring the local water supply, and the pump doesn't appear to let water in from the City supply.