Solar water heater controller switch

[markjack99]

I am building a solar water heating system for my house. It will have a differential controller (which I have not purchased yet) that powers the system on when the solar collectors on the roof are hotter than the water temperature in my holding tank.

When the system powers on, I need it to turn on two water pumps - two were required because of my high vertical head - however, once the water is circulating throughout the system (after 2 or 3 minutes), I want to power off one of the pumps.

Is there some type of switch I can buy that will do this for me? Of course, once the system shuts down, this switch will need to reset so it powers on and off again after running for 2 to 3 minutes.

Here is the controller that I am looking at buying: http://shop.solardirect.com/product_info.php?manufacturers_id=&products_id=151

Here are the pumps that I have: https://www.pexuniverse.com/grundfo...343?frommail=44028#write-review-form-expander

Thanks in advance for any info you can provide
Mark

 

[CocaCola]

That controller appears plenty suitable to switch two of those pumps, but why not get a larger pump that has the appropriate amount of head in first place?

Why do you you want it to power off one pump after a period of time?

 

[markjack99]

The smaller pumps have the desired flow rate and a lower operating cost but their vertical head is only 19 feet - I require 30 vertical feet.

 

[CocaCola]

The smaller pumps have the desired flow rate and a lower operating cost but their vertical head is only 19 feet - I require 30 vertical feet.

And why do you want one to shut one off before the other? If you need 30 feet and one will only get you 19, what is the point of leaving one run (essentially doing nothing) when the other shuts off? Are you hoping that the downward siphon effect will keep things flowing with just one pump?

 

[markjack99]

Yes, once the system has been fully charged, one pump can handle the flow rate.

I already have the two pumps in place and the system works as planned - turning the two pumps on manually and then shutting one off manually after the water is cycling through the system.

Now I just need to hook up the electronics for the system.

 

[CocaCola]

How much experience do you have in electronics?

This can be done pretty easy using a 555 one shot timer and some relays...