Water bypass and NRV

[Andrew Dwyer]

Reading the thread “ water issues “ I see that the recommendation for pump/water tank set up is :

 

 

( photo courtesy of Crossy )

 

My set up is identical to this except instead of a NRV in the bypass line I have a manual ball valve.

 

The valve is normally closed and, I was told, is only to be opened in case of no power or a pump issue.

 

If I open the valve then the pump kicks in and the water goes somewhere ??, I tried it a couple of times just to see what happens but shut it off quickly.

 

My question is:

Would I see any benefit of replacing the valve with a NRV or should I leave it be ??

[bankruatsteve]

An NRV would keep the pump from coming on but if you want to control manually (like I do), you need to shut the valve after pump out and then open the bypass valve to allow mains water direct to the house.  (which saves on energy to run the pump).  Reverse the process to use the pump again.

 

BTW:  What you did was pumping water into the tank.

Edited May 31, 2019 by bankruatsteve

[cranki]

Your pump pressure is higher than the water from the mains, so the pump is actually pushing it backwards into the mains supply.

No need for a NRV on the bypass line if you ONLY use it when no power is supplied to the pump....however.....if you forget to close said valve when power comes back on you will empty your tank into the mains water supply.

[Andrew Dwyer]

An NRV would keep the pump from coming on but if you want to control manually (like I do), you need to shut the valve after pump out and then open the bypass valve to allow mains water direct to the house.  (which saves on energy to run the pump).  Reverse the process to use the pump again.
 
BTW:  What you did was pumping water into the tank.

Okay , not sure of what the main water pressure is like, it was pretty p1ss poor when we bought the house but a couple of days later had the pump and tank installed and never had cause to use it .
I can shut valve after pump and open on bypass to give it a go.

I think Cranki nailed it saying the pump pressure water was going back against the mains pressure.

[Andrew Dwyer]

Your pump pressure is higher than the water from the mains, so the pump is actually pushing it backwards into the mains supply.
No need for a NRV on the bypass line if you ONLY use it when no power is supplied to the pump....however.....if you forget to close said valve when power comes back on you will empty your tank into the mains water supply.

Thanks, yes I think you are correct in where the water was going.

I was thinking that with a NRV on bypass I would be getting mains water pressure all the time and the pump would kick in if opening various taps or showers etc hence it would be more economical ??
I guess that depends if the mains pressure is adequate for washing up or flushing one toilet etc ??

[bankruatsteve]

26 minutes ago, Andrew Dwyer said:

I think Cranki nailed it saying the pump pressure water was going back against the mains pressure.

The mains would have to have zero pressure and empty lines for that.  Otherwise, the only place for the water to go is back into the tank (re-cycle).

 

Edit:  As a test, you could close the valve to the tank, open the bypass, and the pump should stay off if there is any mains pressure at all.

Edited May 31, 2019 by bankruatsteve

[Fruit Trader]

30 minutes ago, bankruatsteve said:

The mains would have to have zero pressure and empty lines for that.  Otherwise, the only place for the water to go is back into the tank (re-cycle).

If mains pressure is below pump pressure the pump would attempt to supply the main line. Many water meters have a check valve close by to prevent back flow.

[bankruatsteve]

12 minutes ago, Fruit Trader said:

If mains pressure is below pump pressure the pump would attempt to supply the main line. Many water meters have a check valve close by to prevent back flow.

Actually that's right.  I just did my test and with the current mains pressure being very low, the pump was happily supplying the mains.  Test first, talk later - I'll try to remember that.

Edited May 31, 2019 by bankruatsteve

[Andrew Dwyer]

The mains would have to have zero pressure and empty lines for that.  Otherwise, the only place for the water to go is back into the tank (re-cycle).
 
Edit:  As a test, you could close the valve to the tank, open the bypass, and the pump should stay off if there is any mains pressure at all.

I did that, closed the valve directly to the tank and opened the bypass, the pump stayed off, i then opened the valve to the tank and after a couple of seconds the pump kicked in.

[Fruit Trader]

22 minutes ago, bankruatsteve said:

Actually that's right.  I just did my test and with the current mains pressure being very low, the pump was happily supplying the mains.  Test first, talk later - I'll try to remember that.

There is often a check valve at the meter. Its quite common to fine these partially stuck open restricting the flow. 

 

Edited May 31, 2019 by Fruit Trader

[grollies]

If you open the manual valve on the bypass and your pump kicks-in your pump pressure is higher than your mains pressure and you are simply pumping water in a circuit, round back to your tank. You will initially be pumping water back through your water meter, into the mains - provided the meter has no NRV (ours doesn't).

 

Provided your mains pressure is lower than your pump set pressure:

 

Change the manual valve on the bypass for a NRV and add an NRV to your pump outlet.

Edited May 31, 2019 by grollies

[cranki]

3 hours ago, grollies said:

If you open the manual valve on the bypass and your pump kicks-in your pump pressure is higher than your mains pressure and you are simply pumping water in a circuit, round back to your tank. You will initially be pumping water back through your water meter, into the mains - provided the meter has no NRV (ours doesn't).

 

Provided your mains pressure is lower than your pump set pressure:

 

Change the manual valve on the bypass for a NRV and add an NRV to your pump outlet.

No need for an NRV on the pump outlet for the water to the house.

[grollies]

9 hours ago, cranki said:

No need for an NRV on the pump outlet for the water to the house.

I disagree.

[Fruit Trader]

12 hours ago, cranki said:

No need for an NRV on the pump outlet for the water to the house.

Automatic house pumps linked to public water service.

 

A few years back Mitsubishi service warned about the possibility of high pressures on public water mains during hours of low demand damaging the exposed front end of automatic house pumps. 

[cranki]

Just now, Fruit Trader said:

Automatic house pumps linked to public water service.

 

A few years back Mitsubishi service warned about the possibility of high pressures on public water mains during hours of low demand damaging the exposed front end of automatic house pumps. 

Fair enough, where I am I could pi$$ harder than our mains pressure...lol

[tutsiwarrior]

On 6/1/2019 at 6:55 AM, grollies said:

I disagree.

me too...always need an isolating valve and an NRV on the pump discharge for the best system operating flexibility...