Tankless Water heater to heat 1200g

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MyGiants

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Been kicking this idea around in my head recently. this summer plan to build a 1200g tank. I need a economical way to heat it during the winter months. My idea is to circulate tank water through a Tankless water heater run on NG. The water flow would be controlled by a digital controller. The heater is pulse activated so gas turns on automatically when water begins to flow through it. Tankless heaters operate when 45-50F cold water from the tap enters. The heater kicks on and heats it to 100-120F exits at 2-4gpm depending on the size of the unit.
Now I don't need 100F water but lets say I want to maintain 80F. The heater can adjust the temp and the flame down so the water exits at 80F. Once the tank is up to desired temp and controlled to activate a pump when water drops to 78F the Tankless heater would only run till tank water gets back to 80F.
The tank water would be filtered of course first and possibly run through a UV light before it enters the heater to keep bacterial slim from building up in the heaters tubing.

What are your thoughts on this idea?
 
I like the creativity, but it honestly sounds more expensive than it would be to heat it with intank heaters. I really have no idea if it would be beneficial or harmful but I'd like to find out, haha. I assumed you looked into the high wattage titanium heaters? I think about 4 or 5 500w heaters would be needed to heat a 1200 efficiently. Did you price it to see if it would cost you more or less to do the out of tank heater idea?
 
Tankless water heaters and digital controllers don't exactly sound economical, and electricity is usually much cheaper than natural gas. To pull this off you'll need a pump feedding the Jeter once it the tank temperature falls below a set temp and shuts off once a desired temp is reached, think how a tstat controls a furnace.
 
It takes 6 300w heaters to maintain my 300g at 80F. If it only took 1 300w heater then yes it would be cheaper. The tankless heater runs on battery couple D size only to ignite the flame.There is no constant pilot light the flame only ignites when water begins to run though it. It is pulse activated. So when tank is at temp the water pump is not running to activate the heater. I only need a 300gph pump so not much electricity there. So my feeling is the heater will kick on and off several times a day much like a electric heater does. The amount of NG used would not be much to maintain 80F.
 
Alright then, sounds good to me. Let us know if you ever get it running. Before you set up the 1200, I would test out your tankless heater to see if it's even practical.
 
Electricity cheaper than NG? No way. Natural gas is by far the most economical way to do it. I'm building my shop right now and will be using tankless water heater to heat over 5000g of water. I don't recommend you running tank water into the heater. You should use a heat exchanger or just coil up a bunch of pex tubing in the sump. There's a bunch of way to do it. Since you are doing a single system/zone, your implementation is pretty easy. If you are doing a close loop, make sure that you install an expansion tank to prevent system pressure overload. Good luck
 
bbortko;4928751; said:
and electricity is usually much cheaper than natural gas.
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While I can't speak to all municipalities, it's typically the other way around.
 
Ocean Blue;4928815; said:
Electricity cheaper than NG? No way. Natural gas is by far the most economical way to do it. I'm building my shop right now and will be using tankless water heater to heat over 5000g of water. I don't recommend you running tank water into the heater. You should use a heat exchanger or just coil up a bunch of pex tubing in the sump. There's a bunch of way to do it. Since you are doing a single system/zone, your implementation is pretty easy. If you are doing a close loop, make sure that you install an expansion tank to prevent system pressure overload. Good luck
Click to expand...
Well I seen a setup done with a water to water heat exchanger using water from your house water heater to heat tank water. This is what got me on my current idea of using tankless water heater directly instead. The system would not be closed or sealed as you imply. Water coming from the tank the tank water is not sealed off. The exit water might be split 4 ways into the tank to spread the heated water better. Is there another area where pressure would build. I can't see any..
 
Is this going to be in a relatively small room? If so, have you thought of heating the room with a wood stove? I use a wood stove, and my basement is never under 78 degrees, and for the month of January I burned a total of 33 gallons of oil (heat and hot water).
 
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