Weather conditions for mini-split defrost mode

[Xringer]

Observations for the Last 24 Hours (see pics)


Weather for Friday the 13th !!
Climatological Data


Early this morning 1-13-2012, the dew-point and temp plot lines merged.
As the temperature was increasing, ice was rapidly forming.

I was awakened at 8AM with news of a flashing LED in the den.
After looking out the window and seeing no frost, I shut down Sanyo #2.

Shortly, I went outside and found Sanyo #2 had a very small amount of ice
across the bottom of the coil.
Turned it back on, and it ran fine. It had been at the end of defrost cycle.

The ODU coil on Sanyo#1 was totally covered with frost!
It's compressor was making a funny humming sound.. I shut down Sanyo #1.

After checking the local weather, Last 24 Hours Weather: , I put Sanyo #1 into Dehumidify mode.
That poured a ton of cold air into the house for a few minutes.
I had my oatmeal and returned #1 back to heating mode.

Since the outdoor temp is going up so fast, the frost would have been
gone shortly, without my help..

The Sanyo control firmware avoids turning on the indoor fan while doing a reverse-mode defrost cycle.
It wants to avoid that blast of cold air..
I only use the Dehumidify mode, to speed up melting the ice..


Anyways, these weather conditions are conducive to frosting.
If you live in an area that has a lot of similar weather,
your system will likely experience frosting..

As you can see from the plots, we had a lot of rain an humidity during the last 24 hours.
At the same time, we had many hours of near freezing temps.
Only when the temp shot up early this morning, did we experience
the prefect conditions for ice to build up.

Power use since midnight was normal, abt 1kw on average.
Right now it's almost 11AM and the TED shows 10.8 kWh burned.
The TED recorded a 2.77 kWh peak since midnight.
That likely occurred around the time I was waking up this morning.

[launboy]

Why didn't they just defrost on their own?

Adam

[Xringer]

Originally Posted by launboy

Why didn't they just defrost on their own?

Adam

Sanyo #2, (in the den) actually had just about finished defrosting on it's own.

But, Sanyo #1 was really loaded down with frost over 100% of the coil,
And was making that odd buzzing sound.. So, I decided to intervene
by stopping the cycle and restarting in a faster defrost mode. (Dehumidify).

Not only is Dehumidify faster, it doesn't use a large amount of power to get the job done..

Quoting myself:
"The Sanyo control firmware avoids turning on the indoor fan while doing a reverse-mode defrost cycle.
It wants to avoid that blast of cold air.. "

In the Sanyo docs, it states, "No blast of cold air" during defrost. I guess that's a big selling point.

Since the house has already been warmed up, using the Dehumidify short-cut for a few minutes,
isn't a big problem for us.

Getting the heating mode running again in 5 or 10 minutes,
might be better than waiting an hour for the regular defrost cycle to finish up..

During that time, the IDU is slowly dumping cold air into the house. Even without the fan running.
The short-cut just does the same thing, a lot faster.
This time saver also avoids a total house cool-down from normal losses.

Plus, we have the additional problem of over-current at the end of regular
defrost cycle that causes power re-sets, which makes the process even longer..
http://ecorenovator.org/forum/applia...r-limiter.html


I'm suspicious the buzzing I heard from the #1 ODU this morning,
might have been caused by the current-limiter flipping off-&-on real fast..
Maybe the unit was trying to draw more than 10A, and didn't want to reset.?.

I'm planing to mod the current-limiter/breaker so it shuts the unit
down completely for 53 seconds.. Just in case..