Building Reserve and Using KWH

Thank you.

Just wondering if you had noticed any correlation between HVAC usage and daily/weekly/monthly (inside-outside) temp. diff., or correlation with other factors such as conservation measures.

BTW, Happy New Year.

J.P.M.

My POCO updates a 30-day span online report each morning with the last day's activities. It 's a quick reference for graphing Net Energy, Generation and Usage. It also overlays the average temperature for the day. I can also view it by the week or by the year. Pretty handy reference to glance at while eating my bowl of oatmeal each day.

On the Net Energy screen you can certainly pick out a cloudy day instantly.

Webp.net-gifmaker.gif

I do write down several numbers once a day, but not average temp. Inside temp not uniform and not recorded.
I hate to think of what J. P. M. would say about my thermostat settings. The PoCo is trying to get me to have
an online account with them, auto pay, but I am not playing. Bruce Roe

[QUOTE=bcroe;n389644]I hate to think of what J. P. M. would say about my thermostat settings. /QUOTE]

Why? First and foremost, NOMB.

Besides, some of my cold climate thermostat shenanigans would probably make you shake, or at least scratch, your head. But I learned or confirmed a lot of book learning by doing stuff.

My sense is that you and I are about equally eccentric in residential energy matters but with different emphases. I think my ways of approaching the situation are more useful for more people, and, without being critical, I believe I'm better versed in cost effective ways to kill a utility bill and I think you leave money on the table ion that respect, but I feel that ignoring your experiential knowledge and/or what you write about with respect to the finer points of PV electronics and practical ground mounting is not in my, or others', best interests. I don't agree with you on everything, but I sure take what you write seriously and I believe you are sincere and well meaning.

Pretty much right, different objectives. Bruce

Just read through most of this thread. Part of my job is installing Mitsubishi mini splits. Sounds like you did your research and did a good job installing. One thing: if you didn't use nitrogen to pressure test the lines, I would check all of the connections for signs of oil. Leaks can sometimes occur only under pressure, not under vacuum. If theres no oil, you're all set. When the refrigerant leaks out it brings oil with it and then evaporates.

I have 3 units at my house. (FH-15, FH12 and FH-09)
Even though they're rated to -13f, I've seen them running at -20f. Great units! Just make sure you keep the filters clean.

Ben

Seriously, it's nice to get some intelligent feedback from someone who sounds like they possess common sense and experiential knowledge. Thanx for the reminder/refresher.

Thanks for the feedback. With welding and other gasses here, they did get pressure tested. A leak
was and remains my biggest concern, and great care was taken to avoid them. None were detected.
The below zero weather has not arrived, that will be the most serious test. Bruce Roe

OcHpN.JPG

Got the PoCo bill today, well into winter, and this time covered some serious cold (below zero F)
temps including a couple record breaking days. The general experience has been, the 3 mini
splits (around 3 tons total heating) will handle any cold down to zero F. What I needed to know,
is what to expect for below zero. More equipment will be needed, but how much?

Jan included below zero, and even a couple record breaking -30/-31 nights. The minis seemed
to be still putting out serious heat down to -12F, but losing effectiveness below that. As we
headed down to -30F, some 3 tons more heat was turned on of the previously unused resistive
heat elements. This seemed to do the job, in fact it was more comfortable than years the minis
were not helping. I know, this is far from laboratory precision.

Seems like the mini outdoor units tended to make more noise with extreme cold, defrosting
themselves I think. Sort of like the engine of a rather distant heavy truck.

Available is a 2 ton mini with a -25F capability. Given these result, I will see about getting one
going in what she calls the Garage Mahal. The idea is to keep it in the high 30s all winter, with
a quick blast of propane to bring it up to 62 F for serious work (transmission overhaul,etc). It
would be better for things like keeping the 44 inch snow blower completely melted off for the
next use, and so on. Some summer cooling, and maybe justify the size of the array.

The -25F mini may not be quite as efficient as the -14F units now operating, but when added
could lower the temp of completely automatic operation of the house. If we break the latest
cold records, I might need to turn on the electric stove.

The summer generated KWH reserve started a bit down (14,000 KWH) from past years, but is
now higher than ever before this date, near double the average over several years. The reserve
has been dropping about 62 KWH a day, was around 100 in past years. Total consumption is
about 99 KWH a day, the difference being solar generation over the month.

Bruce Roe

Who makes the -25 mini split? I've been running my new pellet stove a lot this year, mostly when its below 20f, so haven't run my mini splits nearly as hard. I've been getting very bad feedback from the hyperheat multi zone Mitsubishi units (MXZ-C series) people have been reporting a COP of near 1.4 for heating.

I would expect the heating COP would drop with outside temp, do not have all the numbers. From
what I see its better than 1.4 above zero F, at some negative it could drop to 1 which is still as good
as resistance. Even if it reached that level, having the system take care of every temp with no
action from me would be valuable. I am quite sure the best COP possible is delivered at any time,
winter temps go all over here.

The pump was part of the family of Fujitsu RLS3 rated -21F 16000 BTU heating 29.3 SEER.
RLS3H rated -25F, maybe they added a heater because no SEER listed. That is fine, saves
me turning on a heater. Bruce Roe

Here's some data I just found from heat pumps in VT. I haven't read the whole thing yet, but very interesting stuff.


https://www.google.com/url?sa=t&sour...dqgYrRPKJcGjqI

That is a lot of info and processing, for a smaller sample. More than some of us want to know.
I was sorry to see that hardly anything was said about outdoor temps lower than -5F. Interesting
that a 9000 BTU unit put out as much heat as a 12,000 BTU unit. And, the largest indoor head
could put out a maximum of 15,000 BTU heat.

Meanwhile, the PoCo seems to have stopped sending me those messages that my energy use
is very high or very low compared to the neighbors. Useless since they only saw inflow, not my
net metering outflow. But I am getting messages about putting in new heating plants that are
very expensive and half as efficient as what I now have. The rebates would not begin to save
what DIY would, with no rebates allowed. Apparently these are just ads passed along from the
HVAC industry under their name. And some other appliances. Bruce Roe

The PoCo bill for 28 Feb 19 shows an energy reserve of 58% of my peak of 14,000 KWH
after the beginning of the cold. It is pretty obvious I am not burning through all that in the 31
days of March before my 1 April reset day. Rather than humbly give such a generous gift to
the PoCo, I installed a 7.5KW electric heater in the car shop, setting it to keep the temp
about 42F. That had been done in other times with propane, but I am trying to limit that.
This makes the building so much more pleasant to pop in and out of in winter, than 0 F
temps seen so much lately (as a consequence of global warming I hear). Snow and water
dragged in by the 44 inch snow blower soon disappear. From there a quick blast of propane
achieves the desired 65 F when serious vehicle work is to be done. Turns out this heater
really does not run that much in most weather.

In the house the mini split heat pumps made this the easiest winter to get through since PV
solar went in. The propane furnace functions only as a generator powered emergency
backup. No need to turn on every incandescent bulb in the house 24/7 for the worst below
zero temps. From this learning experience, I will probably install a couple of minis rated to
cover -25F in return for slightly poorer efficiency. The exact ducting arrangement is still
being contemplated, using multiple indoor air units for a compressor might be the best, but
is another adventure into areas I have not visited. Another -25F mini may find its way into
the car shop, then only turn on the electric 7.5K as a supplement rarely used.

Looking back a bit, methods here are close to the reverse of the usual recommendations.
Most of the examples I see exalted are brand new construction using the very latest tech
to avoid losses. Fine but everything here is old, I did spend a lot of resources reworking
things up to my version of Energy Star performance. Then I should put in super windows,
run around turning off LED lights, and learn to live like a monk in my sweater. Then I am
allowed to put in barely enough PV solar to cover minimum annual consumption, and
save as many $ as possible to be invested for my descendants.

I do not see it that way, solar should go in right away to start providing energy. That
energy should be large enough that I can enjoy year around temps anywhere I set,
operation of a dehumidifier, and a much higher minimum temp in the occasionally
occupied car shop (she calls it the Garage MaHall). It should be large enough to
entirely free me of all the utility manipulations of one of my largest costs, keeping
warm. My electric energy budget went up by a factor of 5 with solar.

Zero carbon footprint for house heat and electricity was achieved a while ago, have a
lot of other projects (mostly not energy related), not sure when these awful windows might
get replaced. The interest saved by never being in debt has been a big investment.

Overall, I think I am much closer to the end, than to the beginning, of achieving sustained,
green, automatic, generous home energy use. Bruce Roe

7500heater2.JPG

My solar system is proclaiming the spring equinox. The inverters were up for almost exactly
12 hours. And also, production (130 KWH) exceeded consumption for the first time in 2019.
Hope I can average that balance in April after my net metering reserve is reset to zero. Today
there is still plenty left over from last year. Bruce Roe