Tankless Water Heater (thoughts?)

[jlehigh]

I have been trying to find ways to heat my 300gal system with more efficiency. Titanium and glass heaters just seem incredibly inefficient with inconsistentcies and failures being a annual event. During the winter months heating the tank almost doubles the operating costs of my tank.

Is there anyone familiar with the residential tankless water heaters growing in popularity these days? It would seem to me these could be easily retrofitted with a circulating pump and thermostat to more efficiently stabilize tank temperature..

My initial concerns are:

• Ensuring the internal plumbing is not utilizing copper nor corrosive materials in contact with the water
• Proper heater sizing
• Affects of semi-continuous use (product longevity)
• Any potential code requirements which may negatively impact the heater placement/accesibility

Tankless heaters range from 200.00 to 2000.00. So the pricing viability is there if the requirements can be achieved with the smaller less expensive models.

Assumption: Standard electric heaters would remain in place, set at a lower temp in the event of failure.

 

[Herefishyfishy]

Me thinks that titanium heaters with a good controller are foolproof, cheap and reliable. They need to be firmly fixed in place with top out of the water

 

[DonW]

I think once you have a tank that big you have exceeded the capabilities of hobby heaters. Go to the aquatic eco site, they have heaters more suited to the application. Those are what Mojo is using on his tank.

Don

 

[jlehigh]

Thanks for the input,

I burned through 4 titanium heaters in 4months when I attempted to use them 18months ago..

I'v eye'd the Aquatic Eco units for a while Don, but it just seems to me using electricity to heat material in water with circulation is inefficient. I know I can solve the reliability factor with the higher grade product, but the power consumption will remain.

 

[Herefishyfishy]

I have done well running mutiple higher wattage heaters. Prevents running them at capacity full time.

 

[DonW]

Thanks for the input,

I burned through 4 titanium heaters in 4months when I attempted to use them 18months ago..

I'v eye'd the Aquatic Eco units for a while Don, but it just seems to me using electricity to heat material in water with circulation is inefficient. I know I can solve the reliability factor with the higher grade product, but the power consumption will remain.

I dont recall but is your tank a in wall going into the garage?

Don

 

[jlehigh]

I dont recall but is your tank a in wall going into the garage?

Don

Sure is Don. I keep the sump on a styrofoam pad during the winter, and remove it for the summer (concrete slab chiller).

 

[DonW]

My guess is unless you keep your garage heated 70+F thats where your issue is. Hobby heaters are not designed to run 100% duty cycle thats part of the reason they are so cheap. Since your dealing with the garage you need to factor that in and go WAY up in heater size. Unless your up for spending thousands on a heat exchanger that may be your only realistic option.

Don

 

[jlehigh]

way too practical, easy I have plans to build a vapor barrier around the tank with ventilation, as well as install more insulation in exposed areas which will help..

Regardless of my personal situation, if tankless heaters are 40% more efficient than standard water heaters, I would think is could be a good opportunity for hobbysists with large tanks to save electricity..

 

[dnjan]

I've run tankless heaters for one of the bathrooms in my house since 1998.

First, I doubt you will find heating elements that are rated for submersion in saltwater. Second, I doubt the rest of the fittings would be saltwater-safe either.

So, you would need to use a heat exchanger.

If you are using a heat exchanger, why not just circulate hot water from your regular water heater? People circulate hot water now, so that they don't have to wait for hot water. You would just need to circulate it through a heat exchanger.

 

[dnjan]

Regardless of my personal situation, if tankless heaters are 40% more efficient than standard water heaters, I would think is could be a good opportunity for hobbysists with large tanks to save electricity..

The advertised efficiency of tankless heaters is not in the fact that they heat water with less energy.
Rather, the efficiency comes from only heating the water that you will use right then. With a convertional water heater, you are trying to keep water hot all the time, not just when you need it. So when you don't need it, the water is just gradually losing heat to the surroundings - loss of efficiency.

 

[Katchupoy]

Jlehigh, Im with you with regards to making a wall around your tank with insulation. I have played with the idea of my 2 40g breeders in the garage and it did not work. I ended upi using 4 x 200 watt water heaters connected to a RANCO controller. It works great but my consumption goes really high around 1500 watts with lights just to cope up with heating the water. This was verified using a simple device called "kill-a-watt".

Now that my tank is inside. Not that i only use 1 heater, i save electricity too. The lights also heats up the house in a way.

But i really want it in the garage too like yours. So Im with you with the wall with really good insulation on the roof part.

 

[aquarookie]

I agree with Don (dnjan). On top of that, I do believe that tankless water heaters have copper plumbing...

 

[-=dieseldave=-]

I dont get it why hobby heaters will not work? The efficency of a submerged heater is very close to 100% thats closer than any other device you going to get.
I have been using two 300watt heaters in my tanks the sump is is in the garage as well as a 40 gal breeder and a 20gal long, the sump holds around 30gasl the total system volume is around 300gals.
I run every thing on a controller as well as the cheep thermostats that the heaters came with. I don't see why you could not run three or more all staged on a controller. That way the come on only as needed and not all at one time. by staged I mean on comes one when the tank temp drops by .3 degrees less then the set point heater two comes on at .5 degrees less then the set point and so on. the opposite to turn them off.

 

[DonW]

I dont get it why hobby heaters will not work? I have been using two 300watt heaters in my tanks the sump is is in the garage as well as a 40 gal breeder and a 20gal long, the sump holds around 30gasl the total system volume is around 300gals.

I believe Johns tank is also in the garage for an in wall installation thats quite abit different than a tank in the house and a little sump in the garage.

Don

 

[-=dieseldave=-]

He can alway add more heaters. If he wants to be efficient with the setup as a whole he needs to enclose the tank in the garage by building a small room for it so the heat does not go to heat up the garage. Doing so he will definitely need a dehumidifier if he already does not have one.

 

[DonW]

What I'm getting at is two 250w heater is not the same as running one 500w commercial heater. The 500w is going to heat the water faster and run less that the two 250's. The heaters in water temp is much lower on the hobby units.

Don

 

[-=dieseldave=-]

I guess I don't get it unless the 250s are pulling less than 250 watts. The only way a 500w heater is going to be any different is the surface area of the heating surface. Grater would heat the water faster or less that would heat the water slower. But 500watts is 500watts commercial or not.

 

[DonW]

I guess I don't get it unless the 250s are pulling less than 250 watts. The only way a 500w heater is going to be any different is the surface area of the heating surface. Grater would heat the water faster or less that would heat the water slower. But 500watts is 500watts commercial or not.

Not really. Grab hold of a 250 under water it will never feel more than just warm. Grab a 500 underwater and you will be letting go real quick. The 500w temp difference is big. So even if the 2 250s had close to the same surface area which they dont it would not heat the water near as quick.

Put a pan of water on your stove top across two burners set on medium. Do the same with just one burner on high. The one on high will take less time to boil even though the two are using about the same wattage.

Don

 

[jlehigh]

The efficency of a submerged heater is very close to 100% thats closer than any other device you going to get.

Heater efficiency information is not something I have seen broken down and envalidated. 300 watts submerged to heat a tank does not neccesarily = 100% efficiency.

BTW: I would not submerge a tankless heater I would plumb it on a re-circ pump.

DonW: I think the larger output (1000w+) caliber units will likely be the answer, coupled with a well designed tank enclosure.

As the cost of electricity climbs one evaluates what can be done to drive efficiency. Couple that with a love of this as a hobby and DIY, it is fun to innovate.

Some of my past projects:
Retro L3 to DE:
http://www.reeffrontiers.com/forums/showthread.php?t=8480
Steamer clams for natural filtration:
http://www.reeffrontiers.com/forums/showthread.php?t=6224&highlight=steamer
DIY Moonlights:
http://www.reeffrontiers.com/forums/showthread.php?t=1564&highlight=DIY+Moonlights