electrifying a Sep 4

hot_rod

Looking for an electric option for my shop system, LP at $3.79 with tax, .11 Kwh in winter months here. I brazed a 1" nut to the top, hole sawed thru it.

First attempt with element on top was not so successful, probably an air bubble took out the element. So I moved it to the bottom, and also fired up the radiant pump. I also got the air removal function back with the element at the bottom.

I will build a protective non NEMA protective enclosure at some point

Solid_Fuel_Man

Interesting, I know some wood boiler guys do something similar with a water heater element in an iron Tee. Used for boiler backup/freeze protection. 

I'd be inclined to use a pair of aquastats one a high limit manual reset. Wire them in series and use them to control a 2 pole contactor to control the element. That way if the operating aquastat failed then the high limit one would kick the system off. Or maybe a flowswitch in there as well in case of pump failure. 

hot_rod

I have a flow switch in the plan, maybe a RIB to break both poles. I think it will run up to temperature and shut off without flow, via the water heater control?

ratio

I wonder how fast the water heater control would respond. IIWM, I'd want an immersion well, packed with heat transfer compound, immediately above the element. But that might be overkill.

Larry Weingarten

Hi, I like all that water heater tech! Agree that heat transfer compound between thermostat and housing would be good. Maybe insulation over the thermostat too? Keep kids away from those wires, unless they only use fingers on one hand to test for voltage ?

Yours, Larry

hot_rod

ratio said:

I wonder how fast the water heater control would respond. IIWM, I'd want an immersion well, packed with heat transfer compound, immediately above the element. But that might be overkill.

Not a bad idea.  

it’s a steel tank not unlike a water heater and the springs keep good contact. I’m only running 110F

EBEBRATT-Ed

Is that UL approved LOL

pecmsg

EBEBRATT-Ed said:

Is that UL approved LOL

Was!

mattmia2

Is that open to the relief valve without a valve?

GroundUp

I have done something similar with wood boiler systems in the past, for backup. Most OWB have substantial water storage and run 24/7 circ so the flow through the element controlled with a Ranco controller in a thermowell works great to keep it from freezing when set down at 40 degrees with a 5 degree differential.

ratio

I'm thinking there's a race condition between the high limit shutting down the heat & the element burning up due to lack of flow. If there was a suitable margin of time, the water heater limit sounds like the cheapest solution. How fast it can respond to a lack of flow condition, IDK. There's not much volume of water in that Sep 4 compared to how long it'll take to boil a portion of the element dry enough to overheat.

Solid_Fuel_Man

At least control the element with the pump, so when the pump is off the element is off. 

I'm not 100% on the water heater contold being used as a limit due to the fact it is not actually in the water and just on the outside of a steel vessel. A water heater has a lot more volume and would be much slower to respond. 

hot_rod

Plenty of small volume electric boilers I've seen with only snap disc control and safeties, Thermo 2000 shown below, for example. Their small 5-9KW are 1 gallon capacity. I had a small one in a tiny home I built where the boiler ran all the time up to temperature , t-stat triggered on circulator.

Maybe thermal discs respond faster than a cap tube control on a thermal well?

I did build an enclosure this morning since I'll run with this hybrid option.

I ran it all afternoon with no flow. Set at around 115F, it creeps to 140 when the discs clicks off. About 45 minutes later at 105F or so it kicks on. It seems to work fine, but a flow switch is a simple add on safety. I'll insulate the tube also for faster response.

A conceptual prototype, don't try this at home kids

Larry Weingarten

Hi, It would have been interesting in the early days of water heater manufacturing, to be in the manufacturer's labs and see equipment being developed. I imagine that those folks would have been quite comfortable with @hot_rod 's work, maybe even envious of the curved tubing!

Yours, Larry