Use Washing Machine Solenoid to control 1/3 hp pump

Thread Starter

Charles191109

Joined Nov 9, 2019
3
I've got a 50 gal aquarium tank to supply RO water to my washer. I want to have a small sump pump turn on when the washer solenoid valve is powered. Would like to keep it low cost if possible. Not sure what current is available through the solenoid power. Can it handle starting a small pump?
Thanks,
Charles
 

AlbertHall

Joined Jun 4, 2014
8,315
I don't think the aquarium has fish in it. It just being used as a water tank.
What is RO water?
How small a pump - how much current does it need?
 

dendad

Joined Feb 20, 2016
2,986
There is no way to know the current capability without looking at the circuit. The max switch current could be a few 100ma to Amps.
You will need to look at the circuit board (with it unplugged!!!) and trace the solenoid switch path to determine what the switch is.
Then the starting current of the motor will need to be determined.
You could just try it and see, but you do stand a chance of popping something.
And if you cannot repair it yourself, that could be costly.
 
I don't think the aquarium has fish in it. It just being used as a water tank.
What is RO water?
How small a pump - how much current does it need?
RO water is reverse osmosis .... but the whole post is not very clear ...

I think TS wants to supply his washing machine with RO water , this has had 90% of dissolved minerals removed and should result in a softer feeling cloths .... but a washing machine needs a feed of water at a fairly high pressure ( perhaps 4 or 6 meters height ) , hence the requirement for a pump to feed in the RO water when the washing machine valve solenoid is activated ...

It maybe best to remove or bypass the water from the solenoid valve (very easy) , then you won't need such high pressure , instead connect the wires to a mains motor which pumps the water from the tank which is slightly lower than the washing machine .... many mains pumps on ebay ....

If you don't want to by pass the valve , the RO tank can be higher than the washing machine , you will need a stronger pump because of the restriction imposed by the solenoid valve . It should be OK to power a small pump by taping wires off the valve.
 

Alec_t

Joined Sep 17, 2013
10,355
It should be OK to power a small pump by taping wires off the valve.
I wouldn't risk that. Domestic appliances are built down to a price, so the solenoid valve controller on the main board is unlikely to be rated generously enough to handle motor starting current as well as solenoid current. If it were me, I'd replace the solenoid valve with a suitably rated relay/contactor to operate the pump and position the tank low, as Oz suggested.
 

Thread Starter

Charles191109

Joined Nov 9, 2019
3
Thanks All, I'll look into a 'mains' pump, also was thinking about an old washer pump for pressure to the inlet, also like the thought about bypassing solenoid altogether as it does restrict flow. Will also research the relay option though I'll have to read again to understand - I can't afford to just run the pump with direct hookup for fear of overloading circuit. The sump pump I'm considering is a 1/6 hp i found on craigslist - not sure of the current requirement to start.
Thanks again,
Charles
 

Thread Starter

Charles191109

Joined Nov 9, 2019
3
Yes RO is reverse osmosis - I have high organic/tannin in my water and the RO filter cleans that up nicely even though it takes patience to not do a bunch of wash in one day. - Thanks again for your comments - Charles
 

MisterBill2

Joined Jan 23, 2018
3,860
At 120 volts a 1/6 HP motor will draw about 4 amps, with an 8 amp starting surge that lasts about 120 milliseconds. So you will want to use a control relay with a 10 amp contact rating to switch the motor on and off. The typical wash machine fill valve draws far less power, perhaps 250 milliamps, 1/4 amp, and so the contacts powering the valve will not last long starting a pump motor. BUT you could put the tank above the wash machine and use a gravity feed and just remove the filter screen on the water valve to allow the flow to be a reasonable amount. OR you could use a relay connected in place of the solenoid valve to control the small pump to fill the washer. But you will only be getting cold water, and that does not clean as well.
 
This side of the pond most washing machines these days are cold-fill only and have an electric heating element.
OK, in that case you should not have a problem with cold water. My situation here in south-eastern Michigan, USA, is different. Electric water heating is avoided as much as possible because it is expensive and relatively slower.
 
The pump sizes being suggested are much too high . When disconnecting the water flow through the solenoid valve you will have noticed how small the pipes are delivering the inlet water , using the large pumps suggested will cause problems ...

The aquarium can be on the same level as the washing machine , usually the water is delivered into a tray where detergent is put , this will stop siphoning when pump is not operating ... a submersible pump is needed since tank is a glass aquarium.....

This is all you need ..12V 0.4A ..I have used these in small hydroponic set ups and they deliver water at sufficient speed .... If you have an old mains to 12V supply just connect to the solenoid valve terminals .....

If you want a mains pump one of these ....
I can guarantee you 8W will deliver fast enough , it has a 1.4 meter lift , and this can just be connected in place of the solenoid valve with no other circuitry needed. ebay.co.uk/sch/i.html?_sacat=0&_nkw=water+pump+240v&_sop=15
 
The pump sizes being suggested are much too high . When disconnecting the water flow through the solenoid valve you will have noticed how small the pipes are delivering the inlet water , using the large pumps suggested will cause problems ...

The aquarium can be on the same level as the washing machine , usually the water is delivered into a tray where detergent is put , this will stop siphoning when pump is not operating ... a submersible pump is needed since tank is a glass aquarium.....

This is all you need ..12V 0.4A ..I have used these in small hydroponic set ups and they deliver water at sufficient speed .... If you have an old mains to 12V supply just connect to the solenoid valve terminals .....

If you want a mains pump one of these ....
I can guarantee you 8W will deliver fast enough , it has a 1.4 meter lift , and this can just be connected in place of the solenoid valve with no other circuitry needed. ebay.co.uk/sch/i.html?_sacat=0&_nkw=water+pump+240v&_sop=15
I doubt very much that any of these pumps will deliver even one gallon per minute. So how long does the TS want to wait for the washer machine to fill and start washing? Also, a centrifugal pump will deliver only as much flow as the pipes will handle, and the pressure will be much less than the mains pressure of 75PSI, which is what the washer machines inlet is designed to work with. The flow limiting is built into the machine.
 
I doubt very much that any of these pumps will deliver even one gallon per minute. So how long does the TS want to wait for the washer machine to fill and start washing? Also, a centrifugal pump will deliver only as much flow as the pipes will handle, and the pressure will be much less than the mains pressure of 75PSI, which is what the washer machines inlet is designed to work with. The flow limiting is built into the machine.
The 8W will deliver 12 liters /min Search shows a washing machine uses about 80liters each wash ... less than 7mins for water transfer ... on mains water supply perhaps 3 mins ?? total wash time is about 45mins? Not much difference . In my house there's no urgency for this ...sort of thing you start , then go out shopping for a few hours ...
 
Top