Sequential or random switching

[Engineer54]

Well out of my catchment area sorry to say but maybe we have a more localised Engineer within the forum... and i personally would be one to go the whole hog ....cheaper systems may be fine but it all about what happens if this fails or that fails etc. I've done a similar set-up although not to the same requirements where the operator had full LCD screen overview of tank levels it was fully automated and as it was 24hr monitoring it had multiple redundancy with auto fault clearance. It cost a bit but has already excelled in its use and earned its money by avoiding 2 plant shutdowns.

There you go again!! lol!!

Would you really go the whole hog as above, if this set-up is say, just to water a garden in summer?? lol!!

 

[Darkwood]

There you go again!! lol!!

Would you really go the whole hog as above, if this set-up is say, just to water a garden in summer?? lol!!

I did carry on to say (with edit) we lack info and consequence list... you never know it might be for his prized competition grade Giant Marrows or simply the back up for the local allotment in dry times ...but yes too much of my career designing fail safe that prevent high cost failures

 

[Paul2011]

I did carry on to say (with edit) we lack info and consequence list... you never know it might be for his prized competition grade Giant Marrows or simply the back up for the local allotment in dry times ...but yes too much of my career designing fail safe that prevent high cost failures

Sorry guys. When I posted this I thought an off the shelf easily available piece of kit would be available, and I just hadn't come across it.

For those who are interested we are talking about 3 x 1,500 litre tanks fed by 300+ square metres of roof, to be used for flushing toilets, washing machine, gardening etc. The water to the tanks is pre-filtered and the tanks fill evenly from the roof.

 

[Darkwood]

I take it the toilets use the tanks as primary water source but can be switched back to mains water?
What is the nature of the building (domestic, commercial, industrial) and its use?

 

[Paul2011]

I take it the toilets use the tanks as primary water source but can be switched back to mains water?
What is the nature of the building (domestic, commercial, industrial) and its use?

It's domestic. Large house. Toilets can be switched back to mains but only with a manual intervention.

 

[Darkwood]

Keep it cheap and cheerful then i can only assue you have some sort of header tank in the house thats isolated from the mains system id just implement a secondary water overlevel sensor to ensure you don't get the pump flooding the house if the level switch fails again not enough in ...could go on for days at this rate questions and answers before we get the whole set up.

 

[Knobhead]

I’ve been following this. I was thinking of a PLC that can handle “drum control”. Now I know it’s to flush the bogs I don’t know whether to laugh or cry.

KISS*

*Look it up.

Bath/shower water is a good source of grey water.

 

[DPG]

Hope you can work this out...each time the contacts are closed on your time switch it latches an on/off function......so sequence is
off / pump1 on / off / pump2 on / off /pump3 on/off / then pump1 on again.......hope this helps

View attachment 23629

4017 - an excellent chip. Done many a circuit with those. Still got my Knight-Rider light somewhere - forward/backwards direction using diode logic on the 4017 outputs. And large caps to give the 'trailing' effect. Daz

 

[Darkwood]

I’ve been following this. I was thinking of a PLC that can handle “drum control”. Now I know it’s to flush the bogs I don’t know whether to laugh or cry.

KISS*

*Look it up.

Bath/shower water is a good source of grey water.

Only Fools and Horses sketch -- When you said you had land to furrow i was thinking of acre's not an allotment!

 

[Marvo]

Having the tanks unconnected is making you life very complicated and expensive. I'd seriously reconsider your decision not to connect them together at the bottom, below ground level if necessary.

The advantages are;

• You only need one pump instead of three.
• You only need one low-level safety switch to protect the pump from dry run.
• You don't need a complicated ladder/sequence control to operate the three pumps in order.
• One third of the wiring and cabling, one third the size of control panel and one third of the controls and switchgear.
• More flexibility ie all the collected water is available for all tasks simultaneously.

If your only reason for not connecting them is to be able to isolate tanks individually for cleaning then rather look at just pumping the entire system dry and cleaning all the tanks together. If you really need to isolate individual tanks you could also fit standard 2" plastic ball valves on the balancing pipes and make up some extension handles so they can be operated from above ground level. You also get 12v/24v electrically operated ball valves but the price of these for an IP66 version may be prohibitive.