USPlastics Solenoid Valve Experience?

[JWeb]

Just upgraded my ATO system with a normally-closed solenoid valve that I grabbed from USPlastics. It works perfectly - but I have a question about it's operation:

When activated (opened) by 120VAC, there is a hum or a buzz coming from the solenoid. Since my ATO is set to a trickle, the hum or buzz will persist for 10 minutes or so until enough water is added to open the float circuit.

Is the buzz normal? Any reason it shouldn't buzz for 10 minutes?

 

[NateHanson]

Jeff, what solenoid did you get? I'm thinking of getting one to put on my RODI line, with float switches in my reservoir, sump, and display shutting the solenoid.

 

[JWeb]

Nate, I got this valve from USPlastics.com (1/4" size). It is a well constructed valve and I like the strainer feature (although probably not important when using the valve to control the flow of purified water). I did have a problem getting the John Guest [1/4" pipe] to [speedfit] fittings to seal well on the valve, however - the valve ports aren't threaded deeply and the John Guest adapters were quite long (so the conical threads didn't bottom out to make a good seal). This was solved with a generous helping of teflon tape.

But, I wish I had ordered this valve from McMaster, instead. The USPlastics.com valve above operates with a 120VAC coil - which means you need to either run 120VAC through your float switches, or add a relay to the valve that has a 12VDC coil and switches the 120VAC to the solenoid valve. That way, you can run 12VDC through your floats. I didn't notice the USPlastics valve had a 120VAC coil when I ordered it. Since I still refuse to run 120VAC through my float switches, I chose the relay route. It works perfectly, but it is one more component (relay) that can fail and adds complexity to the wiring.

Just my 2 cents. The bonus is that the McMaster valve is 1/2 the price! I'm sure it is a quality valve although I haven't actually ordered one. And, by the way, I like my top-off arrangement MUCH more now that I have eliminated the bucket, pump and hi/low sump switches. Much simplified - thanks for that suggestion.

 

[NateHanson]

Thanks Jeff. There are a bunch of valves in that link you gave, do you mean the second one from the bottom, 7877K25, for $17.12?

Where can I get float switches? I can't find cheap ones on Mcmaster. They're all over $20 each.

Can I rig this up so all the three switches (mounted to be closed when un-floated) are in series in the +tive lead from a 12V wall adaptor, between the adaptor and the solenoid, and have the -tive lead going from adaptor to solenoid)? That would work to close the valve if any one or multiple float switches got opened, right?

Thanks for checking my plans, Nate

 

[JWeb]

Nate, it's hard to post links to McMaster items since they use frames in the browsing window. Anyway, yes, I meant Part #7877K25.

The float switches on McMaster are expensive, but they are also of really high quality. There are a few that would work in the 10 - 14$ range (e.g., 50195K93 on page 466 or 46515K41 on page 467 - choose if you want horizonal or vertical). Like you, however, I thought that was more than I wanted to spend on 5 float switches. You can find some cheaper ones here. I was bothered by the stainless steel e-clip, so I replaced it with plastic ones I found a Lowe's for 0.02$ each (Lowe's has an excellent hardware section - much better than Home Depot, IMO... but it also seems that each store is slightly different - I mention this because it was hard to find the plastic clips and I stumbled upon them on accident). In the end, I don't think the stainless steel clip is anything to worry about, anyway. Buying switches from this dude, you'll save 4$ each over "comprable" ones at McMaster.

Your wiring plan sounds just fine. Remember, if you reverse the float on the switches I posted in the link, they go from closed contact when un-floated to closed contact when floated - not sure how they will come to you. This is useful when you want to mount the switch in a certain orientation but discriminate between water or no-water. I'm not sure if that is clear, but it will become obvious when you try to set up the switches.

Also, note that the McMaster solenoid valve requires 0.52A to actuate the valve (you are trying to do lots of work with only 12VDC). Thus, be sure to buy or use a 12VDC wall adapter that can supply at least that much power - perhaps more to account for resistive loses. I mention this because there are many 12VDC "wall warts" that are 300 mA - that won't move the valve. Furthermore, many are 500 mA and that will barely be enough once resistive loses are taken into account.

Here to help if I can...

 

[NateHanson]

Thanks Jeff. I picked out a 1000mA transformer on Mcmaster.

I don't understand what you're saying about the float switches : "Remember, if you reverse the float on the switches I posted in the link, they go from closed contact when un-floated to closed contact when floated"

I guess I'll see when I get them.

I thought Rob (robboT) was using even cheaper float switches, no?

 

[JWeb]

1000mA should be plenty!

The float switches in the link above are mounted on a stem. In one orientation, the contacts will close (i.e., switch is "ON") when the float is down. If you remove the float bulb from the stem and flip it over, the opposite will be true: the contacts will close when the float is up. In this way, you can mount the float switch "up" or "down" and decide if the switch will be "ON" when floated or "ON" when not floated. But, yeah, you'll get it once you play with the switches. I just wanted to be sure you were aware that you could flip the bulb over after removing it from the stem to change the float's behavior.

Rob may have found cheaper floats... don't recall the price. But, I think they were the same style.

 

[NateHanson]

Yeah, I figured out what you meant when I took a closer look at the picture. Thanks.

I think I'll use those. Time to keep this water in its place!