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I prefer the off setting.
It's just like my leaf. Saving a trip, combining a trips, planning ahead saves more power than using B mode, cruise control, etc and it keeps run time hours off my machinery.
If you want to "save energy" by running your gear 24/7 by all means be my guest.
If I can leave my machine off for 12 to 18 hours a day I'm going to do that.
 
LeftieBiker said:
Eventually, as more users realize that maximizing late night/early morning usage actually helps the "grid" and as a result, they are able to save usage during the peak afternoons, that less "peaker" energy (think very expensive) is required - at least here in the ERCOT system which is likely similar to most grid systems.


We've been doing this for 20 years: greatly reducing our grid consumption during peak loads (hot weather here) and doing more cooling in the morning and late at night. I remember poring through the regional ISO logs about 20 years ago, to get a feel for when local demand was highest and lowest, because they never made (or make) any effort to inform consumers about this issue.

Yeah during the hottest part of the day, peak grid time I'm at work. No reason to A/C an empty house while I'm at work for 13 hours.
I'm with you, run that A/C in the evening.
 
Oilpan4 said:
LeftieBiker said:
Eventually, as more users realize that maximizing late night/early morning usage actually helps the "grid" and as a result, they are able to save usage during the peak afternoons, that less "peaker" energy (think very expensive) is required - at least here in the ERCOT system which is likely similar to most grid systems.


We've been doing this for 20 years: greatly reducing our grid consumption during peak loads (hot weather here) and doing more cooling in the morning and late at night. I remember poring through the regional ISO logs about 20 years ago, to get a feel for when local demand was highest and lowest, because they never made (or make) any effort to inform consumers about this issue.

Yeah during the hottest part of the day, peak grid time I'm at work. No reason to A/C an empty house while I'm at work for 13 hours.
I'm with you, run that A/C in the evening.
.
Read again; that is not what Leftie is saying
You should get a clue about home conditioning. They heat up (or cool down) regardless of whether you are at home. Time shifting conditioning is affected by Newton's law of heating/cooling but the more important factor is the machine load efficiency curve. Your behavior is the poster child of how NOT to use a heat pump.
 
I'm going to leave it off.
If air conditioning an empty house all day makes you feel more Al gore like, go for it.
 
Oilpan4 said:
I'm going to leave it off.
Of course you are...until you turn it on full blast and then run it inefficiently. And you will continue to whine that heat pump use is expensive, never knowing that your ignorant behavior is the problem.

Trumper
 
Oilpan4 said:
I'm going to leave it off.
If air conditioning an empty house all day makes you feel more Al gore like, go for it.


You already know that the heat pump works best when it's nearly loafing, so unless you have a very under-insulated house that heats up very quickly to ambient in the daytime, it makes more sense to do what we do: set the thermostat higher rather than turn it off. If you set it to 78F then the HP doesn't need to work as hard to get it cooled. I think you mentioned having to replace a unit that was basically worn out after 10 years; that was probably in part because of the frequent heavy loads you create...
 
Actually I don't know how old it was. 10 years was a guess as the manufacturer serial tag was weathered away.
I removed the split today and found the stucco was pushed in around the lines coming through the house.
Well last year I was talking to my neighbor about when the roof got put on and when it got the last coat of stucco and he said it was done at least 15 years ago.
So the split was put in before the house was stuccoed "at least 15 years ago" as of last year.
I moved in there late 2017 and cut that tree down 2 weeks ago.

It likely wore out because it was around 15 years old, had been oversized for the application and when I cut the huge 63 year old rotten tree down that was providing shade to the split and that whole part of the house it was already going out and that finished it off.

When the central heat pump was blowing up my power bill 2 years ago during the winter, back before I got the coal furnace I was leaving it running all the time as it was the only source of heat.
So what's your excuse now smart guy?
 
So you haven't lived there long, and you know that the 15+ year old heatpump unit was dying. While it obviously wasn't you that overworked it (if that happened) it apparently wasn't something that you (or I) can diagnose, either, as you didn't live there for most of the unit's life. Is that correct? Getting back to the central point: just try setting the thermostat to 78 in the daytime. If nothing else your fridge will thank you.
 
The split is a 18,000btu unit covering less than 400 square feet.
Normally 18,000 btu units are used on double that square footage. So it was never over worked, just over cycled.
The inverter split won't cycle on and off like the old fixed speed unit. It should be able to throttle down to about 6,000btu and run nice and easy.
I would have to say that part of the house is well enough insulated. I stuck an inefficient 2 year old barely used 8,000btu window air conditioner in there now and it doesn't have any trouble keeping the space nice and cool.

My central A/C has been off since Wednesday afternoon. There's no way running it for the last 2 days would have "saved electricity" or helped it last longer.
That's normal for me to leave it off for up to 2 or 3 days at a time in summer.
I will probably run the centeral some this weekend.

Last time I checked my refrigerator with a Kill-a-watt plug in meter it used about 2.5kwh a day. If it's 10 degrees hotter inside the fridge might use 2.6kwh. While it would take dozens Kwhs of air conditioning to cool off the house to save maybe a few hundred watt hours on the refrigerator....
I found the fridge used about the same amount of power in the winter (2.1kwh) or summer (2.5kwh) and that is probably mostly due to opening the freezer and fridge a lot more in the summer. The house is around 20 degrees cooler in the winter and I turn the ice maker off in the fall and don't turn it back on till it warms up.

I found that the people telling us to run our air conditioner all the time are almost always the same people trying to sell new ones or service our broken ones.
 
LeftieBiker said:
You already know that the heat pump works best when it's nearly loafing
Not so ! It works most efficiently when load is ~ 50% of maximum. That is why it is so important to to size the heat pump correctly: maximum load is inefficient, low load is inefficient. All hypermilers should know this.

Oil-y has "figured out" how to size and run the heat pump in the most inefficient way possible :?
 
I don't know too much about the history of mini split heat pumps. I think Oilpan4 says he had an old fixed speed heat pump. Assuming like central air ones these have come in 2-3 stage and infinitely variable for a while now. There are probably some nice load efficiency charts on these things out there.
 
iPlug said:
I don't know too much about the history of mini split heat pumps. I think Oilpan4 says he had an old fixed speed heat pump. Assuming like central air ones these have come in 2-3 stage and infinitely variable for a while now. There are probably some nice load efficiency charts on these things out there.
Quite right. The new gen inverter based heat pumps have a much wider range of efficient loads but the advice to size the heat pump for close to continuous operation at moderate load still holds. The old 1-stage pumps would cycle incessantly between off and full load since it was better than running low load.
 
I don't have to filter anyone or require any any kind of modification to the world around me.

I don't "just turn it off for a few hot hours" usually I turn it off in the morning when I get up at 4:30am and it stays off till I get home around 7. That's typical and I can leave it off for 2 up to 3 days in the summer, but that is not typical.
I wouldn't call 430 to 7 a few hours.

It depends on the type of air conditioner.
They are all not created equal.

My central is an older R410a system fixed speed compressor and mechanical thermal expansion valve when used in A/C mode. Pretty sure its not staged because of how old it is.
The manual says it gives up on trying to be a heat pump a +5F, starts using minimal electric heating at 38F.

Old central systems, some old splits and most window units run a fixed orifice and fixed speed compressor.
The fixed orifice and speed units need to be ran full blast for extended periods. If it were over loaded that wouldnt really be a bad thing.
Trying to do things that you think would save power really have little effect, such as slowing down the fan or cooling the condenser coils with cool water only reduce power consumption by around 10%.
Most of the power reduction you see when turning the fan speed down is just from the fan running slower.
The inside and out side fans may have 1 or 2 speeds.
These are your 10 to 12 seer machines. They're cheap above all else, efficiencywas an after thought.

The most common central air systems and most splits now use a single staged fixed speed compressor or 2 fixed speed compressors usually a big and small one, this has been around for ages on large commercial installs and use a metered expansion valve, usually a mechanical one.
These can be throttled down, be extra cooled on the condenser side during AC mode with say a ground based hest sink and it will reduce power consumption dramatically up to 75% for winter heatpumping, but usually only 1/3 to 1/4 for summer A/C.

Now we have variable speed compressors with thermal expansion valves on premium central units and splits. These give the best efficiency.
The compressor can slow way down to match the heat load saving the power of running the compressor at full speed when it's not needed. These can slow way down and go into high efficiency mode, not even needing the condenser fan to run, cooling off a big room with around 400 watts of power during the hottest part of the day.
They also don't try to start at full speed like a fixed speed, pulling a bunch of start up amps.
Good for if you want to go off grid.
The violent jerk to full speed is what helps wear out fixed speed compressors.
 
LeftieBiker said:
We've been doing this for 20 years: greatly reducing our grid consumption during peak loads (hot weather here) and doing more cooling in the morning and late at night. I remember poring through the regional ISO logs about 20 years ago, to get a feel for when local demand was highest and lowest, because they never made (or make) any effort to inform consumers about this issue.

Griddy got caught with proverbial "pants down" as many of their customers quit after one or two days and quickly signed up for the typical fixed rate contract. They have gone on quite an informational/educational campaign after that. If the majority of users where educated and gave a damn, the ERCOT grid would likely never have such an excursion. It has been hot, but not much more than expected. Rumors are that ERCOT does this periodically to drive "generators" to install more capacity. With $1.5 billion in three days, seems they can afford it!!
 
Got my new 18k BTU inverter split installed.
It draws 10 amps at 240v when heating.
It does not appear to have backup heat and gives up heat pumping at +4F according to the manual.
Still going to use the wood stove as much as possible.
I will probably set the heat pump for 60F and if I want it warmer use combustion and run the heatpump to keep it from getting cold late at night after the fire goes out.

I have a 9k BTU premium efficiency split on its way for the bedroom. This one will try to heatpump down to -22F. Also 240v. I installed this exact unit in my rental house in 2016 and it has a backup heater grid. I'm curious to see if the latest version still has a backup heater.
The 9k BTU premium efficiency unit cost almost as much as a the 18k that went in the living room.
 
My mini split has proven to be better as a heater than as an A/C unit (except that it's more powerful as the latter). I get smaller swings in room temperature, although the remote thermostat still reads too high by 2 degrees (except for when it decides to be accurate and throw off my corrections). The built-in thermostat continues to read too high (it is near the ceiling) but still also wanders both ways, making it impossible to maintain a single room temp. So whichever thermostat I use I have to correct it at least twice a day. I also got a heat shortage this week, at about 18F: it was still providing heat, but only on the low fan speed - I couldn't raise it. I had to open my furnace duct for enough additional heat to keep my room warm. I deliberately (and with some misgivings) oversized the unit for my room, going with 18k instead of 12k, specifically so I would get the rated 9k of heat in the upper single digits. That seems to have been optimistic by at least 10F. My opinion remains that it wasn't really worth the huge amount of installation work...
 
The one in the 9k btu split in the bedroom is supposed to be able to deliver 9,000 btu down to I think the manual said -10F.
I'm a little skeptical. It would appear my skepticism is well placed.
But I have a propane space heater just incase.
On that bedroom I can maintain 65F inside with a mere 5,000 btu heat input down to around 10F outside. So I shouldn't ever need the space heater unless the power goes out.
 
Well the 9k btu inverter split in the bedroom did it, kept the room warm no problem down. To +5F out side.
The coal furnace has knocked off $100 per month off the winter electric bill every month for the last 3 years and the inverter splits at least another $50 for 2019.
 
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