Timer circuit for cooler water pump

[roltex_rohit123]

Hey guys its summer here and temperatures rising as high as 43 degree celcius.. coolers are out. i have a simple plan in mind for saving energy and water usd for coolers. ours is a cooler using 60 L of water in 4-5 hrs. and the water is carried on from a lower tub to an upper tub for draining it on to a special grass fixed on the walls. now this requires a pump of 50 watts at least. and it consumes more energy and water if running continuously. so i am thinking of designing a circuit that would switch the pump on for 2-3 min every 15-20 min. at other thimes it would be off. any ideas??

 

[Hero999]

What about using solar power?

The CD4060 can be used as a timer.

 

[roltex_rohit123]

how could we program it for 10 min break and then 2 min working? solar power would be too costly to use. moreover we need cooling for 8 hrs a day. the total energy consumption is 1300watts per hr, so solar power is a costly option initially. it would need a heavy inverter and a powerful battery. so if we just control the water pump we could save a lot of water and energy. also after every 2-3 hrs we turn of the cooler for 1 hr.

 

[Hero999]

I have another idea: a CMOS oscillator and a CD4017 counter.

C2 needs to be a low leakage tantalum capacitor.

EDIT:
I've just realised that C2 needs to be non-polarised.

Fortunately it's easy to make a non-polarised capacitor by connecting two capacitors back to back, the diodes might not be required for tantalum capacitors which tolerate reverse voltage quite well. You might even be able to get away with using a single tantalum, check the data sheet for the reverse voltage rating. If the diodes are used they should be low leakage.

 

[roltex_rohit123]

how should i actually proceed? i am a newbie and have no ideas.. from 4017? what could be a good design?

 

[MikeMl]

We have "evaporative coolers" in the southwest United States. When the relative humidity is <25%, they work very well. I have large unit on my house that moves ~10,000 cu. ft. of air/hour through my house that I use in the summer. Outside air on the input side can come in at 105degF, while the outflow air is cooled to ~65degF. The operating expense is determined 97% by the blower (1/2 or 3/4HP) depending on motor speed, and the rest (~2%) is the water circulation pump.

If I cycled the water pump on/off instead of leaving it on continuously like it is now, I might be able to save ~1% of the electric power input. Question is: Why Bother?

btw- the evaporative cooler operating expense is less than 10% of what it would take using conventional refrigerated air conditioning.

 

[roltex_rohit123]

its not only the matter of saving energy, its also abt saving water. in general case if the pump is left on then 60l tank which is there for water empties out in 3-4 hrs. we cannot increase its capacity. after that, the air inside becomes humid and I hate that.. Yak! a more to care is the pump itself. if it is left running without water then it burns out. it has happened 2-3 times. overall, it needs some regulation and timer is the best solution for all these.

 

[MikeMl]

Evaporative coolers work by exchanging the entire volume of the air inside your house with cooled air several times per hour. Unfortunately, the cooled air is more humid than outside air, so if you do not allow the air inside your house to be exhausted to the outside (by partially opening windows/doors at the distal corners of the house), the humidity will build up. You MUST allow for circulation/exchange of the air otherwise the house will get damp, and feel like a swamp.

As to saving water by cycling the pump on/off, that depends the degree of water saturation you are getting to pads now. If they are totally saturated, and a lot of the water is dripping out of the bottom of the pads, you might be able to reduce the net water flow without reducing the cooling efficiency. If the pads are already mostly dry, and little or no water is running out the bottom of the pads, then any further reduction in water flow will reduce the cooling efficiency.

 

[Hero999]

how should i actually proceed? i am a newbie and have no ideas.. from 4017? what could be a good design?

I've given you the circuit, what don't you understand?

The 5V can come from a mains adaptor. The power doesn't need to be regulated though so it could just as easily be a 6V adaptor. The relay is used to switch the pump motor which I assume is mains powered?

 

[roltex_rohit123]

I've given you the circuit, what don't you understand?

The 5V can come from a mains adaptor. The power doesn't need to be regulated though so it could just as easily be a 6V adaptor. The relay is used to switch the pump motor which I assume is mains powered?

ok I'l try that