Tankless Water Heater (thoughts?)

[DonW]

If you call the guys at aquatic eco they have a calculation that tells you what heater is best based on ambiant temp vs target temp. It would be cool to do some sort of propane type set-up but propane is getting expensive also. Maybe natural gas is an option.

Don

 

[jlehigh]

Thanks Don, I'll give them a buzz. The guys at Aquatic Eco are awesome that way.. If only their shipping/pricing was better I'd send them allot more business.

The natural gas/Propane was the driving factor behind the tankless heater concept as they are predominately offered in gas driven models.

 

[DonW]

I forgot I have a Escobal calculator. What are your tank dimensions and thickness? What is your garage temp when its cold?

Don

 

[jlehigh]

nice!

Display
72X30X30 - 3/4" sides/bttm 1" top
Sump (this makes it a lil tricky)
filled - 60X18X20

The Garage at it's coldest get's down to the low 40's.

 

[DonW]

nice!

Display
72X30X30 - 3/4" sides/bttm 1" top
Sump (this makes it a lil tricky)
filled - 60X18X20

The Garage at it's coldest get's down to the low 40's.

That about 1000 watts with a differental of 25F. @ 38F differential it almost doubles but thats 40F in your garage and 78 in the tank. Bummer, time to start framing in that new room.

Don

 

[MC Lighting]

the tankless hot water heaters I have installed were all copper plumbing I would consider a heat exchanger if you go that route as to not have slatwater in contact with the hot water heater and as stated earlier you could do the same off of your hot water heater that runs your house, I think that it would not run nearly as much as you think the BTU output on those tankless is incredible.... now the question what type of heat exhanger do you use that will tollerate salt water for years to come??? If I ever get a house again I will heat my tank witha solar hot water system they are more than capable of getting up the temps but again a heat exchanger is a must...

 

[dnjan]

heat exchanger
titanium heat exchangers, starting arund $300 ...

 

[jlehigh]

I am not at all familiar with the concept and components of a heat exchanger. Care to give me a 101?

Wiki:
"A heat exchanger is a device built for efficient heat transfer from one medium to another, whether the media are separated by a solid wall so that they never mix, or the media are in direct contact.[1] They are widely used in space heating, refrigeration, air conditioning, power plants, chemical plants, petrochemical plants, petroleum refineries, and natural gas processing. One common example of a heat exchanger is the radiator in a car, in which a hot engine-cooling fluid, like antifreeze, transfers heat to air flowing through the radiator."

So essentially a closed system of heated material/water radiating through conductive coils to exchange heat? So in my case I would use a tankless gas water heater to act as the engine and plumb it to a heat exchange coil.. Pretty cool!

BTW: the 1000 watt+ L-type high grade heaters start at 500.00 and go up to 1200.00 so this is still a viable savings long term in operational costs..

I spec'd out my vapor barrier/tank enclosure. Pretty neat! I'll use barn rails to allow me to slide the primary wall away from the tank for access.

 

[MC Lighting]

you got the idea only thing I am worried about is whether the controller can be set low enough for tank temps I woul dhave to go find a manual for one and see but I am sure there is a way you could make it work with a external temp system because if it fails you will literally boil your tank I would consider the use of a EPO (emergency power off) setup with an independant overtemp alarm so as if the system does not shut off at say 84 deg it kills the power to the WH preventing it from overtemping the tank.

 

[DonW]

I think if I were to experiment with this sort of project I'd look at a drop in Ti exchanger. Pump water from your homes hotwater heater and either shut down the pump or use a bypass connected to a temp controller.

Don

 

[danno14]

I think if I were to experiment with this sort of project I'd look at a drop in Ti exchanger. Pump water from your homes hotwater heater and either shut down the pump or use a bypass connected to a temp controller.

I'm with Don on this.... the Instant hot water heater will not work properly as you outline. As soon as the water circulates, the heater would want to kick on. You would want it to heat, then allow sufficient circ time to fully utilize that hot water.

Look into "desuperheater" tanks- They have a heat exchangeer built into the water tank itself. The smallest possible tank, with a closed loop and circ pump hooked to a controller, along with a titanium exchanger in the sump.... that would do the trick. Still looking at a chunk of $$$ to bring this to fruition.

If you have a high efficiency gas water heater already, it will surpass the efficiency of whatever you try to do with electric.
Good luck, and keep us updated!

 

[jlehigh]

great feedback. The chances are, I'll build the tank enclosure and will only need 1 200watt heater LOL. I am planning to replace my water heater this year though so it may be worth exploring..