Auto Topup System

[Fatty]

Hi,

I have been trying to find a cheap topup system, but there doesn't seem to be one!

I initially was thinking of building a dc circuit with float switch to power an ac pump/powerhead via a relay, but I don't know enough electronic knowhow to do it.

So, I have a 240 Vac float switch with a max switching current of 0.6A. If I wire the float switch in directly in serial with a small eheim 1001 compact pump, the current shouldn't exceed 0.6 A.

Does anyone know if this theory is correct , the pump is an 11w at 240 V so should be 0.05A (11w/240V) .

I have got earth leakage trip electrics as it is but was planning to use a plug in rcd socket to be on the safe side.

The only concern I have is the maximum current a stalled or starting magnetic drive type motor can produce. So if the current for some reason reaches 0.6A this may weld the float switch closed therefore overfilling the tank!

If anyone knows about this sort of stuff and thinks it will work (dependent on the max current) it would be a really cheap effective way to get a pumped auto topup system.???
any feedback is welcome

 

[SkiFletch]

Well you're correct to be cautious, because mixing water with electricity is definitely dangerous. You're also right in assuming/worrying that initial spike current to start a water pump is exceptionally high. That being said your application of the float switch sounds just fine to me. First remember that the 0.6A rating is meant for continuous use when the switch is closed. Often times switches have the capability to tolerate spikes of current. Remember, its really the longterm wattage and heat that will kill the float swith which will not happen with a spike current followed by 0.05A continuous. You should be safe.

One suggestion I have... Clean the float switch OFTEN. As in once a month at least. The LAST thing you want is a float switch that locks up due to calcium carbonate deposits, algae, or detritus

 

[Fatty]

Thanks SkiFletch,

Seems it might be ok then, maybe leave a minimum of water in the resevoir to begin with so no flooding for the first few months just incase.

The float switch I'm using is good for not getting gummed up, it has a significant drop/dog leg in the design so only the actual float sits in the water. So aslong as snails can't jump and the shrimp don't make it a permanent home it shud be bullet proof!

I will post when I get it up and running...