Classic water heater diversion

Re: Classic water heater diversion

I bought one of them to put in my Geospring waterheater. Couldn,t get any wrench on b back of element to tighten into waterheater without taking off the waterheating insulating foam. Since my insulation is is sprayed on the tank I didn,t want to ruin the insulation. So I tryed to use a flexable oilfilter wrench on the outside of the tin part that holds the thermostat. I couldn,t get element tight enough to keep it from leaking before the can ripped off. If you have a waterheater with removable fiberglass insulation you might be able to get some kind of wrench behind the element to tighten it. Thats my experience. Solarvic

Re: Classic water heater diversion

I am using the waste not output of the Classic and also interested in using the DC output directly. I find that lights flicker when the inverter output is used. I'm thinking that's not necessarily good for both the inverter and sensitive electronics that are down stream. Also, bypassing the inverter will keep the full capacity of the inverter available for use.

Currently, I've been using the extra to run a 1500 watt heater with fan.

Re: Classic water heater diversion

SolarMusher wrote: »

Sounds like we're on the same boat, I would prefer to keep the extra capacity of my inverter available for other loads.
Did you try to tweak Waste not width? What were your Aux2 settings? I was thinking that AC SSR provide good results.
Does the Classic absorb your bank easily when supplying this 1500W waterheater?
Erik

It's actually a space heater that I'm using. I have the heater set at 1000 watts, as my current panel rated output is only 1400 w, but will be increasing the array soon.

The only issue am having is the degree of loading and supply affects the available power/absorb functioning, which requires a bit of tweaking to optimize. Otherwise it works fine. I only have been adjusting the volts and usually works best around -0.3. I haven't tweaked with the pulse width, yet. That is set at the default width of 1.0 V.

Using the batteries directly will also help keep the inverter running cooler, extending it's potential life span.

Re: Classic water heater diversion

Depending on how old the firmware in that Classic is, and I bet it is newer for Erik, you might go (temporarily) into clipper aux 2 mode and make sure it it set
for AC clipper rather than DC. DC clipper mode on older firmware would also make waste not and diversion PWM go too slow (around 20 Hz) and also
make the width much wider. The newer firmware, since December 2012 I think it is, limits the DC PWM to Clipper mode only.

Also, I would tend to pick 1V width. that is around 500 Hz PWM. 5V width is around 100 Hz PWM frequency.

The DC clipper mode slows things down to help eliminate inductive kickback from the load resistors. water heating elements
are evidently not very inductive so they ~should~ be OK either way.

boB

Re: Classic water heater diversion

Solarmusher. I gave up the idea on using that thermostat element for now. I couldn,t get it tight enough into the waterheater to keep it from leaking. Ripped of the can first.

Re: Classic water heater diversion

You might find this thread interesting.

http://www.fieldlines.com/index.php/topic,147132.0.html

Cheers
gww

Re: Classic water heater diversion

SolarMusher wrote: »

Thanks for the link and hints BB and gww, but Chris's thread was talking rather about AC SSR use through inverter and about DC SSR though DC from PV.
My question would be more:
Has someone already "experimented" water heating/preheating diversion using Classic (prefered) or Outback FM60/80 on large PV array through Dc to Dc SSR from batteries ?
Thanks for your inputs,
Erik

I remember this thread from the days of the MX-60 and on their forum a few people did get it to be relaible but not quite as safe as a 2 x 5 foot homemade flat collector, a pump, a dc timer, and thermistor.:grr

Re: Classic water heater diversion

The :grr is there because thats how you will feel after putting in the time. If you do get the system to work safely without low battery issue

I don't understand how what he is proposing is going to cause low battery issues (barring the SSR breaking and getting stuck or some similar failure). The Waste Not Hi PWM function varies the signal voltage, and thereby the voltage the SSR sends to the element, in a user-adjustable way that tracks charging state. So if there's not enough power from the panels, it's off before even one amp hour is drawn out of the batteries (unless you set the voltage offset very wide).

The lukewarm water issue might be a problem if this is his only proposed source of HW and he hits a cloudy stretch. But in my experience using Waste Not Hi PWM with an AC inverter and AC SSR (which is not my only source of HW since one element is grid-connected, in my case), the "problem" has usually been in the other direction -- scalding 170 degree HW on a sunny day before the thermostat shuts the element off.

Re: Classic water heater diversion

northerner wrote: »

Would it be a good option to use the output directly from the PV panels? I know this was brought up on another site, but was just wondering if anyone has attempted that? Of course you will only benefit if your panels are running at a higher voltage than the batteries. In my case, the PV voltage (when they're really producing) is fairly constant around 90 v. Using the PV output will avoid the problem with induction currents when using battery power, which may not be so good for the Midnite CC.

If you want to send all of the panel output to the heater, yes. If you match the panel output voltage to the resistance and power of the heating element. But without an MPPT controller in between the two, that match will only occur for exactly one panel output. Under other light conditions you will not be able to use all the power the panels can produce.
Trying to pulse regulate DC requires a series pass element which can stop the DC, and that will heat up the element (usually a FET) and will cost you some efficiency. With AC you can easily regulate the power to the load using Triacs, which are easy to design with and fairly efficient.

Re: Classic water heater diversion

northerner wrote: »

Actually, what I meant by that, was using the Midnite Classic and the Aux 2 using waste not mode, and pulsing a DC SSR, and then using the PV Panel output through the SSR, to power the heater. My fault for not wording it properly, as this thread is about using the Classic water heater diversion

And there is the rub. When you try to run DC through an SCR, it is very difficult to turn it off again, since the current never goes through zero on its own! If you use a separate SCR for each rectified DC phase from a turbine, then it will indeed turn off. But if you use a full-wave three phase bridge from a turbine or use PV, then the current will be continuous once you fire the SCR.

It is theoretically possible to turn the SCR off again, but the power dissipated in the SCR during the process and the drive current required are usually not practical.

Re: Classic water heater diversion

inetdog wrote: »

It is theoretically possible to turn the SCR off again, but the power dissipated in the SCR during the process and the drive current required are usually not practical.

I know others are interested in using DC to power water heaters. Sounds like it's not the way to go. I was thinking of using a cheap modified sine inverter for this purpose. This would help to keep power available with the main inverter(s), and help keep them running cooler as well, potentially extending their life.