DIY Drip From Hot Water Heater

[mjovic]

Has anyone done a drip water change system using the hot water directly from their hot water heaters? Seems like you'd be killing two birds with one stone. You could dial in the flow to get to 2-3 degrees below your desired temp and then have a heater handle the difference. Would be substantially lower cost than running 1500W+ heaters for larger tanks. Been looking, haven't sen it done, just using cold water (as I already do for my smaller tanks). Thoughts?

Edit: I should have mentioned this would be for a fresh water setup.

 

[Doctorgori]

I’m not picturing that very clearly , can you explain the setup?

…..on a side note
… I don’t think heaters burn that much juice anyway,,,besides I tossed heaters years ago for tanks above 50g … risk/ reward isn’t there IMO

 

[Gtinnel]

I’m not into freshwater tanks, but do people just use untreated tap water for water changes?

 

[mjovic]

I’m not into freshwater tanks, but do people just use untreated tap water for water changes?

For cold water I run it through GAC. For this setup I was thinking maybe dosing with prime. Again not sure if this is even a thing since I haven’t seen it done this way. But in theory I think it could work.

 

[mjovic]

I’m not picturing that very clearly , can you explain the setup?

…..on a side note
… I don’t think heaters burn that much juice anyway,,,besides I tossed heaters years ago for tanks above 50g … risk/ reward isn’t there IMO

Literally was thinking as simple as tapping the hot water line with 1/4” copper tubing right into the sump. Simultaneously dosing with prime.

 

[Gtinnel]

I don’t see why it wouldn’t work in theory, but balancing the amount of water going in/out seems like it could be problematic.
Also depending on if you use a tankless water heater they don’t work unless there is enough flow so for a small amount of water it won’t be heated. Not an issue for a normal hot water tank.

 

[QuickrdenU]

That doesn’t sound safe at all to me. Too much to go wrong and wouldn’t it need to be dechlorinated?

But there are posts on here that use the hot water line to heat your water instead of a heater. Saves a ton of money in big tanks I’m sure. The new water will come into contact with the hot water plumbing through a small heat exchanger that is hooked up to some other parts. Probably no more than $400 in total. If you have reliable heating, and you’re only dripping water in, I wouldn’t worry about preheating the water. But that’s just me.

 

[Kodski]

You wouldn't want to just drip unfiltered water into your tank. Plus hot water heaters are chocked FULL of sediments. I could see no reason to warrant doing this.

There are several people who have used their hot water to heat their tank though, but not adding water directly to their tank. I have a system designed and will eventually implement it to utilize this method. I bought a titanium chilling coil, a temperature controller, and a water circulation pump. The idea is to submerge the chilling coil in your sump, and then plumb it inline to your house plumbing. Essentially as follows. Water heater outlet --> circulation pump --> titanium coil --> cold water input to the water heater. The circulation pump plugs into your temperature controller which then circulates warm water only when needed. Since your loop dumps directly back into the water heater, you're not using water unnecessarily, and since a water heater will be running most of the time anyways to always have hot water ready, its a very efficient system. Even more so if your water heater is natural gas. Propane is still more efficient than electric but not as much due to the cost per BTU.

I’m not picturing that very clearly , can you explain the setup?

…..on a side note
… I don’t think heaters burn that much juice anyway,,,besides I tossed heaters years ago for tanks above 50g … risk/ reward isn’t there IMO

That's a perk of living in Florida. For those of us in colder climates, I'm in Wisconsin, my house usually sits around 67*F during the winter. My basement where my sump room is located is even colder, probably 63-65. Last year for about 150 gallons of water volume I needed 750 watts of heaters and they were pretty much on 24/7. Heck even in the summer my heaters kick on because my basement is usually only 72 even on the hottest days.

 

[DIFish]

Drip systems with freshwater are common, but you need to run through a chlorine block at the minimum, probably through a sediment filter too if you are bringing it in from the water heater. You either need to figure out your minimum evaporation rate or have a sump overflow to a drain to handle excess water. Most large freshwater tanks do auto water changes through dripping in new water and having a drain for excess old water. The heated water won’t change much imo, not enough there to Get away from using a heater.

 

[theatrus]

Depending on your cost of energy (electric vs burning hydrocarbons), use a heat pump. On solar energy, using a heatpump for tank heating would save significantly.

If you’re burning hydrocarbons, use a titanium heat exchanger coil and a recirculating pump on a temperature controller from your boiler/tank. Treat it like a radiator. You can find titanium coils of decent quality with compression fittings on AliExpress.

 

[Doctorgori]

Literally was thinking as simple as tapping the hot water line with 1/4” copper tubing right into the sump. Simultaneously dosing with prime.

I may have missed this in earlier post but the word “ copper” jumps out at me and kills the entire project IMO

 

[Gtinnel]

I may have missed this in earlier post but the word “ copper” jumps out at me and kills the entire project IMO

Does a trace amount of copper matter for a freshwater tank?

 

[theatrus]

Does a trace amount of copper matter for a freshwater tank?

Could be a shrimp tank, in which case it will present a problem depending on the water parameters kept.

 

[KrisReef]

Location of the tank is key for heat transfer. A long line of 1/4” tube would be losing heat on the way.

A heat exchanger in the floor is how they used to warm up homes in Alaska.

I would recommend using cold water and a heat exchanger to accomplish the job without bringing the hot water sediment into the equation.

What fresh water fishes are going to enjoy this sauna tank?

 

[mjovic]

Thanks everyone. Seems like the consensus is don't do it, but do the heat exchanger method instead. The goal with this was two fold: design a system to utilize less energy to heat the water while eliminating one more failure point (heater). Adding a circulation pump would negate one of those goals, but would probably be more reliable in the long run.

The system will contain approx. 330 gallons. My ambient temp ranges from 66-70 year-round and I'd like to heat the aquarium up 10 degrees or so above ambient. How much heat realistically do submerged return pumps produce and how much do you all think it would raise the temperature of my system?

Thanks for the input. I agree there are a few variables to account for. Even with flushing out my hot water heater regularly there likely will be too much sediment and potential heavy metal contamination that would make balancing the water treatment out very difficult and not exact enough over time.

 

[mjovic]

Location of the tank is key for heat transfer. A long line of 1/4” tube would be losing heat on the way.

A heat exchanger in the floor is how they used to warm up homes in Alaska.

I would recommend using cold water and a heat exchanger to accomplish the job without bringing the hot water sediment into the equation.

What fresh water fishes are going to enjoy this sauna tank?

It will be a mix of South American cichlids.