Control a ShopVac like a central vacuum - Page 1
Forum section: electronics / beginners

author: tlex
author_rank: Newbie
timestamp: September 03, 2021, 01:27:46 pm
content: Maybe not the best place to post this question but I wasn't sure were to do so...So I reorg my garage and attached my shopvac to some central vacuum pipes in order to make it easier to use it. The setup works well but I had to use a rf remote switch in order to turn it on or off. My goal is to be able to use the wiring and switch already present in the central vacuum hose.I know this can be done using a small ssr circuit but I'm concerned since I'm not a certified electrician and also since the shopvac drains about 12-13 amps, I wouldn't want that ssr to overheat so I was wondering if anyone here would know a ready to use appliance that could fit my need ?I saw a few dry contact input relay circuits but they all need to apply a small voltage in order to trigger the relay... but none of the circuit I found would feed that voltage to the hose switch.Thanks

author: pqass
author_rank: Super Contributor
timestamp: September 03, 2021, 02:12:13 pm
content: Quote from: tlex on September 03, 2021, 01:27:46 pmSince SSRs take 3V to 32V as input at low current you can just use a 9V (or 4xAA) battery in series with the SSR input and existing vacuum pipe wire.I'm not sure about yours but my vacuum pipe outlet just lets a metal ring on the hose attachment short out the wires in the pipe.Also, I'm assuming here that each outlet contacts are wired in parallel to the same wire pair and that no other device/source is attached to the wire pair.See:http://www.alpharubicon.com/altenergy/solidstaterelays2manytoyz.htmThe switch symbol in the image below represents the contacts at each outlet; any one of which can close and turn on the SSR.Put the battery near to the SSR and connect the switch symbol wire pair in the image to the pipe wire pair.

author: tlex
author_rank: Newbie
timestamp: September 03, 2021, 02:19:07 pm
content: I agree, but the problem I think with the ssr I think is heat dissipation.Also I was trying to avoid of using a battery.Do you think that this would work ?https://www.functionaldevices.com/downloads/datasheets/RIB01SBDC.pdfIt's a bit expensive tought..

author: kripton2035
author_rank: Super Contributor
timestamp: September 03, 2021, 02:24:54 pm
content: may be this would help ?http://kripton2035.free.fr/master-slaverepo.html

author: pqass
author_rank: Super Contributor
timestamp: September 03, 2021, 03:21:00 pm
content: Quote from: tlex on September 03, 2021, 02:19:07 pmThat looks to be essentially a [UL listed] relay in a box with a switch for local override of the relay output contacts. You would still need a source of coil power. Relay coils draw much more power than SSR inputs so a battery would not be appropriate.I'd originally suggested an SSR and battery because it's relatively simple to DIY. If the SSR is purchased from a reputable seller (not eBay) then attaching it to the underside of the cover plate of a standard metal junction box shouldn't be a fire hazard. I understand that the SSR does generate heat so an oversided cover plate, or, a standard plate with front-side mounted heat sink may be needed. One SSR datasheet I pulled up requred 2.8°C/W heat sink attached to operate a full power.WRT battery usage, AA batteries have 2400mAh capacity and should last 120hrs @20mA draw. It simplifies the power source.If you built it with a relay you'll need a DC wall-adapter (rated for the relay coil voltage) in place of the battery symbol in the diagram in my last message.

author: tlex
author_rank: Newbie
timestamp: September 03, 2021, 03:39:06 pm
content: Sorry for the poor drawing talent but would that work ?If so, what concerns me is that the max specs are :https://www.functionaldevices.com/downloads/datasheets/RIB01SBDC.pdfContact Ratings:20 Amp Resistive @ 277 Vac 1110 VA Pilot Duty @ 277 Vac 770 VA Pilot Duty @ 120 Vac20 Amp Ballast @ 277 Vac (N/O) 10 Amp Ballast @ 277 Vac (N/C) Not rated for Electronic Ballast10 Amp Tungsten @ 120 Vac (N/O) 240 Watt Tungsten @ 120 Vac (N/C) 2 HP @ 277 Vac1 HP @ 120 Vacand my shop vac they says 6.5hp peak...https://shopvac.com/product/shop-vac-18-gallon-6-5-peak-hp-hardware-wet-dry-vac-catnum:8251800

author: pqass
author_rank: Super Contributor
timestamp: September 03, 2021, 04:07:59 pm
content: Quote from: tlex on September 03, 2021, 03:39:06 pmMy understanding of "dry" means un-powered. That's why I think you'll need a power source in series with the switch and relay.If I'm wrong, and the box does provide a source of power, then your schematic should work.Although the datasheet doesn't say how much voltage/current the box provides, nor, how much the coil requires. How else will the installer know what size "dry contact input" wiring is appropriate? The 42mA spec'd (or 52mA pictured) could be just the LED draw.WRT the 6.5HP, that sounds dubious. 6.5HP=4800VA for maybe a split second; not continously on a standard 15A, 1800W (or VA) circuit. However, the 1HP rating means that the box can only support 746VA. Your Shopvac needs up to 12A (12A*120V=1440VA).I would use a relay/SSR that was at least 15A rated.EDIT: Changed W to VA since its a motor load.FYI: The different specifications on the box is for the type of load expected. Motor loads have a large but brief in-rush current where resistive loads don't so the latter can operate closer to the max. limit.