[Tran]

For those amongst you who have a solenoid valve that gets too hot and who are concerned, (and who cannot afford a cold solenoid) there is a solution: have it run on on-off cycles during the opening time, what an ordinary domestic power timer cannot support (it cannot have more than a few on-off cycles per day), use a [twin timer], widely sold as an industrial automation equipment. You can program the duration of either the on and off phases from 1s up to...hours. Once set up, it would repeat the on-off cycle as long as it is powered.
Personally, I have found a more rudimentary gear, cheap, match box sized, made by a local manufacturer intended for home use, I doubt it is sold overseas. The wiring is quite annoying, the programming is not as straight forward as with an industrial twin timer but it does work.

For your information:
Công t?c h?n gi? TM3C, Công ty TNHH ?I?N - ?I?N T? TÍN AN

Note that a home version of the twin timer, designed as a plug-socket adapter, is made by a Chinese producer but i doubt it is available in the Western world.

 

[Darkblade48]

I am a bit confused by what you are suggesting.

The solenoids we use are NC and require power to open and allow the flow of gas. If you have them run on on-off cycles throughout the day, you will simply be providing/cutting power, respectively. How does this solve the problem of a solenoid getting too hot (the solenoid is still in the setup)?

Unless the device you have somehow replaces the solenoid, but I also do not see how that is possible.

 

[AKnickolai]

It sounds like the theory is to batch flow CO2 into the tank so that the coil is not energized all the time - allowing some shut off/cool down time during the day. I'd imagine that the cycling needed to significantly reduce the operating temperature of the valve could be problematic. It could be hard to maintain a constant CO2 level, which can cause algae problems. Not to mention, increased wear on the seating seals of the solenoid.

If you're worried about it getting hot, I'd consider mounting some heat sinks on the body first. You can find those small stick on ones designed for Raspberry Pi's and MCU's all over the place for cheap now.

 

[mistergreen]

Yeah, a heat sink is a better solution.

 

[Tran]

A heat sink mounted on a basically cubic valve body that does roughly 4cm² each side...A tricky task....
Basically, most NC solenoid valves are not designed to be open for a long time, but they perfectly withstand frequent on-off. Manufacturers put forward the number of on-off transitions amounting to millions, as a basic specifications. The other specifications being the working pressure and the transition time between on-off states, absorbed electrical power (linked to temp rise) is secondary.
Solenoid valves used for Co2 in aquaria don't need to be fast nor to be reliable through very frequent on-off. But are typically open continuously for hours, and here arises the problem of heat: Mine which theoretically pumps 4.2W, get as hot as at least 60°C in 15'. I have another reputed 3W CKD (Japanese brand) solenoid that gets even hotter in just 10', so hot that it melted the O-ring on the fitting connected to the outlet hole. I don't know the matter the diaphragm is made of, but if it is made of rubber of plastic, the high temperature can seriously impact it.
i don't believe that having the co2 diffused in the water this discontinuous way may disrupt anything. In the wild, plants are not surrounded by a water with constant dissolved co2 rate all day long, they strive though. That being said, I am using a reactor with constant dissolution rate and I maintain an excess of co2 during the open phase (lasting 30"), to dampen the shut phase (30").
My brand new cheap solenoid valve cost me roughly $4, my timer cost me the same price. And there in North America, a used Clippard valve is somewhere above $20.

 

[PlantedRich]

As I think of the $4 solenoids, I think of noise as well as heat so adding power equipment like a more expensive timer to reduce the need of spending $20 for a good solenoid is only a small benefit as I would then have a noisy solenoid and the total electrical use would be higher.
There are many timers which could do the job of shutting off power to the solenoid but I would not want to bother looking for that solution for the small benefit gained. Part of the solution has to be the overall value and enjoyment of using the equipment.
I can stand outside my furnace closet and hear the solenoid humming.

 

[ichy]

As I think of the $4 solenoids, I think of noise as well as heat so adding power equipment like a more expensive timer to reduce the need of spending $20 for a good solenoid is only a small benefit as I would then have a noisy solenoid and the total electrical use would be higher.
There are many timers which could do the job of shutting off power to the solenoid but I would not want to bother looking for that solution for the small benefit gained. Part of the solution has to be the overall value and enjoyment of using the equipment.
I can stand outside my furnace closet and hear the solenoid humming.

I'm with PlantedRich on this one. If I'm worried about my solenoid heat, I'm going to replace it with a low voltage DC one, not add more equipment to deal with it.

 

[sfshrimp]

Just use some ice to cool it down or a computer controlled water cooling system.