DIY remote switch

[jasstech]

I rigged this up to preheat my C172. It seems to do well but I hate having to run to the airport to plug it in so usually end up using my Red Dragon. I know you can purchase cellular switches but they seem expensive. Any DIY options? https://uploads.tapatalk-cdn.com/20201105/b05d5b989151610a42b7a02ca8c5fdb6.jpghttps://uploads.tapatalk-cdn.com/20201105/88598016249158982d3256b9c0f8cc5d.jpg

Sent from my SM-G930V using Tapatalk

[Kyle Boatright]

What do you consider expensive? This switch is $115 and works well for me. It does require a cell plan which costs me $3/month.

https://www.amazon.com/GSM%E2%80%91AUTO%E2%80%914G-Opener-Wireless-Controller-Warehouse/dp/B08JZ4FLVC/ref=sr_1_26?crid=R7G02U7XTN4P&dchild=1&keywords=4g+gsm+relay+switch&sprefix=4g+gsm+%2Caps%2C169&sr=8-26

[steve]

I've used one of these to turn on my milk house heater back when I owned my Tri-Pacer. Cost is $13 at Ho De.
https://www.homedepot.com/p/Intermatic-15-Amp-24-Hour-Indoor-Plug-In-Timer-White-TN311K/205478760

[jasstech]

What do you consider expensive? This switch is $115 and works well for me. It does require a cell plan which costs me $3/month.

I'll check that one out! That price is less than half of what I was finding.

[jasstech]

I've used one of these to turn on my milk house heater back when I owned my Tri-Pacer. Cost is $13 at Ho De.

I have one of those. They worked great when I kept the plane 5 minutes away from where I work. But now I'm 25 minutes away so even this requires an extra trip for me.

[Capt Bob]

The GSM remote switch that Kyle shows is a little on the expensive side. The switch cannot operate the outlet directly, you also need a relay. See the December, 2019 issue of Sport Aviation, page 122 for a DIY GSM remote switch that is controlled by sending it a text. The RTU5024 remote switch cost $17.49 and the SSR-25 DA relay cost $3.95, both on eBay. The power supply, outlet, and a box in which to mount the relay were laying around the house and workshop. Not sure if the relay really requires a box, if you have an electrician friend it might be a good idea to ask. We use the same type of heater as in Jasstech's photo with a blanket thrown over the top of the cowling of our PA-12 and the duct hanging on the engine mount in the bottom of the cowl where the cooling air escapes.

Bob

[Kyle Boatright]

The GSM remote switch that Kyle shows is a little on the expensive side. The switch cannot operate the outlet directly, you also need a relay.
Bob

The switch I linked has a built in relay and works as-is.

[Ronald Franck]

Whatever you decide to use please consider mounting your heater up off the floor. Gas fumes are heavier than the surrounding air. A heater at ground level could become an ignition source should your aircraft or a aircraft in an adjoining hangar ever develop a gas leak.

[Airmutt]

In Oct 1970 Lockheed Georgia lost C-5A SN 0001 (AF 66-8303) due to somewhat similar circumstances. Except in this case the heater duct was placed in a fuel tank. Prior to taking a break the crew shutdown the heater. During the break the fuel vapors migrated back down the heater duct. When the crew returned they fired up the heater. The resulting explosion blew the wing off and the aircraft “rolled over”.

[Kyle Boatright]

In Oct 1970 Lockheed Georgia lost C-5A SN 0001 (AF 66-8303) due to somewhat similar circumstances. Except in this case the heater duct was placed in a fuel tank. Prior to taking a break the crew shutdown the heater. During the break the fuel vapors migrated back down the heater duct. When the crew returned they fired up the heater. The resulting explosion blew the wing off and the aircraft “rolled over”.

I remember that from when I was a little kid. You could see the dark smoke plume from 10 miles away.

[Capt Bob]

The switch I linked has a built in relay and works as-is.

Sorry Kyle, I meant that the RTU-5054 requires a relay.

As Andy says in his SA article, the RTU-5014 is less expensive because it does not have a relay, and only works with a GSM network. There is also more DIY effort involved, but Jass said in his original post that he is looking for less expensive. At about $30 all in the RTU-5024 is just about the least expensive way to go, so you pays your money and takes your choice. You will have to buy a phone plan for your remote switch regardless if it is GSM only, or is able to use 4G/5G.

Bob

[FlyingRon]

I still have a GSM auto kicking around somewhere (unless I gave it away to someone). That was my second way of controlling my remote heater when I had the unheated hangar at CJR. It worked just fine except that the hangar was 100% metal and the cell phone didn't work with the doors closed. Fortunately, I had a left over exterior cell phone antenna from a previous project so I just poked that out the eaves of the hangar and connected it up.

My first controller was a combination of a mechanical line-voltage thermostat (like you control electric baseboards with) and an Intermatic seven day electronic timer. I set the thing to come on every Friday, Saturday, and Sunday morning at 2AM (this was a Tannis so it took some time) when the temperature was below 45.