residential sump pump controls

Hi Sparkstation :

Thanks for the info. As i am pumping high volume for a short time ( one month / year ) i am wondering if the cost of an industrial quality water level sensing system would be cost effective for my application ?

I again submit that whould a simple conversion from a float switch acting as a high current switch to activate the pump motor too a low load switch to activate a relay coil and then have the relay activate the motor ? This conversion should extend the life of a standard float switch to at least the life span of the pump motor .?

What do you think ?

One month a year why bother modifications!

Ok a simple level control can be built using a 55/556 Timer as a level control and instesd of using a light to show level ,trigger an SCR and drive a relay to replace the cheap float switch you are woried about failing after a two year normal operation ; or hook two of the generic float switches in parallel in case one fails open..

Now if you want industrial control an instrumentation bubbler system seems to be replacing the well used probe system for cost /reliability in amodern level control (But TOO costly).

Hey Martin -Electrical :

Sounds really cool with the 55/556 Timer and all but im a working man with no extra bucks to play with and am looking for the least expensive way to prevent an out of sight $ 400.00 pump from cooking off because the cheap ass float switch failed .?

From my experience , we here in Ontario Canada have only the micro switch type of floats to buy ( no mercury ) and they are only good for as many switch cycles as the micro switch is capable of . As a Mech . Tech . for the last 30 years i would offer that micro swithes are everywere and do a good job as long as they are not designed into systems that they cant handle , such as float switches . I have seen this very many times in commercial appliances also. As a matter of fact micro/s and cube relays are the most troublesome fails in most analog control systems . Manufactures will use only what components are barely within paramateres and yada yada .

I was personally surprised that the 1/2 hp pump i bought is a shaded pole motor !

I quess time passes and we all learn things .

Machine Head

Are you saying that there are no mercury tube switches available in Canada? Or do you mean they are not allowed? If it's a mercury float switch you need, let me know, I can get you loads of them.

Most of these mercury tube switches as well as the mechanical float switches using a micro-switch are only rated to handle about 15 amps. Some 20, but those do not last very long. What is the full load amps of the pump you propose? If the amps are high, then use a float switch to energize a magnetic contactor and run the high amp motor load through that. You probably won't need to use a magnteic motor starter since your small pump probably has internal overload protection.

If you install the pump such that it is accessible, the possible replacement of the float switch at a two year interval isn't so distasteful as installing a $1,500 system to operate a $400 pump. Get the pump with the float switch, install it such that you can get it out without a lot of trouble and replace the float switch every two years or so if required. Get a spare float switch and keep it on hand. My guess is that the switch will last longer than two years based on your description of the intended use.

No matter what the micro-switches are rated they can operate a very large capacity contactor/relay. So one more item in series and you have solved the load problem!

Thanks to all for your help and advice .

I now have a plan and thats what i needed .

Hello machine head

You're very welcome.

Kind Regards....