Concept for HERMS

Tankless Water Heaters heat water directly without the use of a storage tank. When a hot water tap is turned on, cold water travels through a pipe into the unit and an electric element heats the water (or there are gas versions).... These heaters deliver a constant supply of hot water and have flow rates that vary from 2 gallons per minute to much larger volumes.

I am thinking of trying to use one of these as my HERMS unit vs. a coil submerged in heater water. The investment is going to be a bit more than I have to run to Home Depot this very moment so as I begin my planning has anyone else considered doing this? I can see no downsides to trying this as long as it get's a good clean water flushing immediatly after use.

any thoughts/comments? Any drawbacks I am not seeing? I was originally concerned with the maximum heat that one can produce but it appears that while they may say "max heat of 140F" or something like that others appear to have a maximum heat based on flow-rate (i.e. the elements are on or off) and your incoming water and your flowrate determine the exit temperature.

for example a tankless water heater that produces a 50°F temperature rise at 2 gpm would be good for incoming 60F water, a shower at 2GPM and a desired temperature of 110F



Some of these units are very compact; they have them for the entire house and then for smaller "single point" units such as a dedicated unit for a bathroom sink which is what I am currently looking at.

Eemax SP35 "Single Point" Electric Tankless Water Heater


Specifications:
• Volts - 240V
• KW - 3.5kW
• Amps - 14.6A
• Rise at 0.5 GPM - 48°F
• Wire Size AWG - 10
• Dimensions - 10.75" x 5.25" x 2.125"
• Weight - 3 lbs
• Element - Replaceable cartridge insert
• Connections: 3/8" compression at top of unit

I am thinking a very simple flow control (pulsing solenoid) and some type of controller would make this a kick-ass HERMS heating element.

I am definitly going to put this project into motion - worst case it fails and I have a instant hot water heater to use to get my temps 3/4 there for my HLT.....

Looking for some of the smart-kids to brain storm on this one; I can't think of any negative "cons" to putting this into motion..... anyone think about this, try it before??

Not sure how these appliances are rated/limited in the US. I know that the similar ones that you can buy here have a limitation according to the regulations that comes with hot water plumbing - i.e. so you don't burn yourself when taking a shower.
So that would be regardless of how you would limit the flow to get it hotter.

To me it seems like the same idea as people have in their RIMS rigs where they have a pass-through heater.

Could be a good idea - although more expensive than having a copper coil submerged in water.

I think it has potential, depending if you can override the governor on it, maybe splicing in some kind of other temp controller in a thermowell on the output side of the heater. Keep us informed of your findings.
-Ben

Your concept has more in common with a rims than a herms, where the wort flows past an electric heating element. My concern would be the amount of heat being applied to the wort as it goes past. A 50F increase at .5gpm sounds like a lot of energy, most posts I read talk of a 4F per minute max at a gallon per minute recirc rate so that the grainbed temp rises evenly. You might have scorching or enzyme denaturation if you heat too fast.

Cheers