EKO Power Consumption

[Nofossil]

I finally got around to making actual power consumption measurements for my complete system as I revamp my battery backup system.

The EKO running at full fan speed with circulator on high speed, two open zone valves, 24VAC transformer, thermostats, relays, EKO controller and NoFossil controller all together use about 145 watts. That's a good deal less than I had expected, and should yield about 12 hours run time on my two deep-cycle marine batteries - enough for 24 hours heat on the coldest day of the year.

 

[jebatty]

Did you check VA? Most motors and electronic circuits operate at less than PF of 1. Your battery backup needs to be sized for the VA draw, not watts. If you can't easily check VA, you could check amps drawn from the batteries during operation. That will give you an accurate read on battery draw.

Also, what is the cutoff voltage for the battery backup system? And will your system maintain output voltage or will you brown out as battery voltage drops? Will that adversely affect your system? If voltage is maintained, then draw on batteries will increase as battery voltage drops.

Although in an emergency you may not care, for normal deep cycle operation you don't want to draw your batteries down to more than 70-80% of capacity; 50% is the normal do not go below point without beginning to have a material adverse effect on battery life.

You can get a pretty good read on battery capacity remaining by doing an open circuit voltage check. If after some use, let the battery rest some before checking voltage. For a 12 volt deep cycle battery (this will vary a little depending on wet cell, gel or agm) at 80F: open circuit voltage/capacity remaining -- 12.73/100; 12.62/90; 12.50/80; 12.37/70; 12.24/60; 12.10/50; and 11.96/40. Be sure to do an open circuit test, not a voltage test while in operation. These numbers change as temperature changes. Approximation: at 70F drop down one level, example: 12.62/100, etc.

Best would be to actually put your system through several power outage tests, say for 3, 6, 9 and 12 hours. Check battery open circuit voltage after each test. This will give you a good read on actual emergency operation preparedness.

My Tarm with its controller circuitry, draft fan, Taco 007 and Taco 009, 2 line voltage aquastats, and Automag draws 300VA. The Taco 009 is an energy hog compared to the 007, but I had it on hand and used it rather than buying a new circ.

I have 2 - 104ah gel cell 12v batteries with an inverter for a manual switchover in the event of a power outage. I had these wired to a computer UPS for automatic switchover, but found that the brief switching period frequently, not always, would shut down the Tarm controller and to start it I had to do a manual reset. Maybe someone who reads this can explain to me why this happens. The same thing is true if I manually cut the power to the Tarm and then turn it back on. Sometimes, not always, I have to do a manual reset.

 

[Nofossil]

Thanks for the details and the battery info - I'll do all of that. My expectation is that in 90% of cases, the power will be out for less than 30 minutes. In the 20 years we've lived here, we've had three times when the power was out for more than an hour. Only once was it more than six hours, and that was five days. Not building a battery backup for that!

Point of clarification: I thought watts measured the actual power consumed, and thus was appropriate for sizing the battery. I thought that VA measured the peak output needed, and was appropriate for sizing fuses, wiring, and peak load inverter capacity. Am I close, or am I missing something?

 

[jebatty]

For an AC circuit, and a pure resistive load (like an incandescent light bulb or space heater without a fan), then watts = VA. For a DC circuit, watts = VA.

AC circuits: If you have an inductive load, like motors and most electronic circuits, then watts almost always understates the actual draw on the supply. This is the power factor (PF). If PF is 1.0, then watts = VA. Typical PF, though, is about 0.7 for many circuits, so a 120 volt circuit with 100 watts (0.83 amps) may have VA = 143 (1.19 amps equivalent). If being supplied by battery/inverter, the battery draw will need to meet 143 VA, not 100 watts.

 

[Nofossil]

Thanks. I'm planning on using an inverter that's rated for 400 watts peak and 320 watts continuous. Hopefully that's enough safety margin. It sounds an alarm at 10.5 volts and shuts down at 10.0 volts.

My thoughts at present are to keep the battery on a 2A float charger and power my controller directly from the battery all the time. My controller draws less than half an amp at 12 volts.

I would then use a 110vac relay to switch the EKO and 24vac transformer from inverter to line whenever there is 110vac line voltage available. This means that the EKO would see a power glitch that might reset the controller, but that shouldn't cause any problems other than potentially resetting it's internal 'fire is out' timer.

I have a pair of deep cycle marine batteries that I plan on connecting in parallel. They're rated at 1000 watt-hours each. My inverter claims a 90% conversion efficiency. If I use the .7 power factor and 90% inverter efficiency, I end up with about 230 VA, which works out to a peak load of about 10 amps per battery. Seems like this is all within the capabilities of my components.

Actual run time will hev to be determined by experiment, but I'm pretty optimistic that I can get many hours out of it - enough to cover all but the most extreme power failures, and certainly enough to safely burn out any fire that's active when the power goes out.

Does this make sense?

 

[jebatty]

Looks good to me. Give it a test and see what happens.

Good idea to power the controller continuously from the inverter. What about also powering the internal Eko circuitry continuously from the inverter with a separate relay controlled inverter circuit to power the circs, zone valves, etc.? Then there never could be a power glitch to any controller circuitry. With line AC to relay coil, DPDT, energize line contacts; AC fails, relay energizes inverter contacts.

I hadn't thought about this for my own purposes but now will consider.

 

[Nofossil]

Looks good to me. Give it a test and see what happens.

Good idea to power the controller continuously from the inverter.

What about also powering the internal Eko circuitry continuously from the inverter with a separate relay controlled inverter circuit to power the circs, zone valves, etc.? Then there never could be a power glitch to any controller circuitry. With line AC to relay coil, DPDT, energize line contacts; AC fails, relay energizes inverter contacts.

I hadn't thought about this for my own purposes but now will consider.

'Controller' is ambiguous in this context, and I wasn't clear. My controller, the infamous NFCS, runs on nominal 12vdc (actually, 5 to 20vdc). I plan on running it directly off the battery rather than use the inverter to make 110vac and then run that to a power supply to turn it back into 12vdc.

I thought about running the EKO controller directly off the inverter all the time, but the EKO controller drives the fan directly with a varying AC voltage so the EKO controller can draw a bit of power. As delivered, it also drives the circulator directly. I could interpose a relay to take the circulator load away from the EKO controller, but I figured that the consequences of cycling power on the EKO controller aren't too serious - I do it every time I refuel.
There's been a lot of discussion about wood boiler and power failure protection, so I figured I should clean up, test, and document my approach so that folks can learn from it - whether it works or not. Thanks for your help.

 

[DaveBP]

Are you Battery/Inverter backup guys using pure sine wave inverters? Are they necessary for the controllers on the boiler's sake? The only issue of concern to me is the considerably lower price of the modified sine wave models. I wouldn't even consider a square wave inverter. My whole house used to be Photovoltaic so I'm used to living with motors that are slightly noisy and maybe a little warmer running on MSW. Just looking around the web it seems like the relative price of the sine wave models has come down a bit. They were pretty exotic stuff 25 years ago, at least on the consumer market.
So is there a concensus on this?

 

[jebatty]

I have both a UPS pure sine wave inverter and a UPS MSW inverter. My issue was controller shutdown on power out and switch over to the UPS. It occurred with both. Also, both operated my system just fine on manual reset. I believe pure sine has more "power" per cycle, as MSW is clipped square wave output, I believe. I don't know whether it makes a material difference to system performance.

 

[Vtgent49]

I appreciate the dabate here. But, shouldn't we have a plan for the 100 year Ice storm? I've seen the 4 day power loss twice in 29 years here in VT.

My present system can be modified to run well on thermosiphon. I just crank open one 4 way valve manually, then the whole thing takes off. I do have to manage the fire so that I don't overheat, but that's a normal task it seems to me. I have a second 4 way valve for the second floor that I could open, but I hardly ever circulate to that floor anyway.

No offense to the Nossil fans, of which I am one, but there may be a point where all this control/analysis is counterproductive. I'm kinda a do-it-myself/prefer the 1880's method/elimate carbon etc by getting back to basics kind of guy.

All of these old wood/coal boilers ran for a century without electricity.

Could be another thread, sorry.

Al

 

[Nofossil]

I appreciate the dabate here. But, shouldn't we have a plan for the 100 year Ice storm? I've seen the 4 day power loss twice in 29 years here in VT.

My present system can be modified to run well on thermosiphon. I just crank open one 4 way valve manually, then the whole thing takes off. I do have to manage the fire so that I don't overheat, but that's a normal task it seems to me. I have a second 4 way valve for the second floor that I could open, but I hardly ever circulate to that floor anyway.

No offense to the Nossil fans, of which I am one, but there may be a point where all this control/analysis is counterproductive. I'm kinda a do-it-myself/prefer the 1880's method/elimate carbon etc by getting back to basics kind of guy.

All of these old wood/coal boilers ran for a century without electricity.

Could be another thread, sorry.

Al

For me, there's a constant tension between simplicity and technology. My goal is to refine the technology to the point where it's as close to invisible as possible. Doesn't mean that it's simple, just that it appears simple in operation. Some of the places where I feel as though I've approached that goal:

1) My domestic hot water gets heat from four sources:
- Preheat coil in storage
- Solar
- Wood boiler
- Oil
All those sources contribute their portion automatically, and hot water is always available - no human interaction is needed.

2) Wood boiler operation is as simple as it can be: Look at the control panel. If it says 'build a fire', then do so. If it says 'add wood', then do so. Otherwise, have a beer.

3) Heat source priority is completely automatic. If the wood boiler is active, then heat comes from there. If it's not and the storage is hot, then heat comes from storage. If the wood boiler and storage are both cold, then the thermostats set back automatically and heat (if needed) comes from the oil boiler.

I get a lot of enjoyment from tinkering, so I spend a lot more time and effort than necessary on refinements. Really, all I have to do is build a fire now and then. This whole deal with battery backup is so that I can avoid having to put down my beer just because the power went out.

I do have a generator for extended power failures.

Despite my boundless appreciation for the good old days, I'm very happy that I can keep a big house comfortable with four cords of wood, no oil, and virtually no smoke. Technology really does make things better once we understand it. I get my kicks out of the 'understanding' part of the process.

Even the 1800s' axe head carries in it a vast science of metallurgy which is invisible (and simple) to the user. Big improvement on the flint axe, though ;-)

 

[mpilihp]

SAMS club or other generic generator. We have a 4Kw pull start that we bought during the ice storm of 98 here in Maine and used it for about 10 days. Now if the power is going to be out for more than an hour it comes out, quick and easy.

Granted it doesnt help while we are away during the day but we dont have a gassifier and the boiler will shut itself down on its own, tried it already and it it didnt blow the pressure release.

~ Phil

 

[Kipstr]

Thanks Nofossil, that is just the info I was looking for. Monday my guy from Washington Ele Co-op droped off a meter to measure my power usage of my EKO. Rushed home just to plug it in, the damn thing didn't work. Every thing I tested read 192 volts and 1.52 amps.

I think I will try this inverter with auto switching and battery charger.http://www.theinverterstore.com/the-inverter-store-category.php?cat=TSW

Strap on a 100 amp hr deep cycle battery. All I want is back up if I have a full load of wood.