Variable Speed/ Capacity Air Conditioner in practice...

[UncleDave]

This is a day and morning showing the effect of what a variable speed and capacity 5 Ton AC load looks like to your houses electrical load

It's a lennox signature series 20 Seer unit that can vary the compressor speed as well as the fan speed.

The first morning bump in the left is from space heaters and coffee maker.

The middle bump is the mid day run that shuts down totally at 4PM when the electric rate goes to 49C KWH, this exhibits quite a different ramp curve than the night shift.

The bump on the far right Is the 9PM-5AM AC run to cool the whole house back down.
This exhibits very pronounced step down plateaus.

The blue curve is solar productivity but this isnt about that.

The Lennox control system is what I would call - good but not great, leaving me unable to control the system as finely as Id like with the T stat I have - maybe there is an upgrade maybe not?

 

[SHOZ]

This is a day and morning showing the effect of what a variable speed and capacity 5 Ton AC load looks like to your houses electrical load

It's a lennox signature series 20 Seer unit that can vary the compressor speed as well as the fan speed.

The first morning bump in the left is from space heaters and coffee maker.

The middle bump is the mid day run that shuts down totally at 4PM when the electric rate goes to 49C KWH, this exhibits quite a different ramp curve than the night shift.

The bump on the far right Is the 9PM-5AM AC run to cool the whole house back down.
This exhibits very pronounced step down plateaus.

The blue curve is solar productivity but this isnt about that.

The Lennox control system is what I would call - good but not great, leaving me unable to control the system as finely as Id like with the T stat I have - maybe there is an upgrade maybe not?

View attachment 163956

View attachment 163957

What's the indoor temp swing?

 

[thastinger]

If you are a net exporter, why do you care what time you run the AC unit?
Maybe I'm missing how net metering works out there

 

[UncleDave]

If you are a net exporter, why do you care what time you run the AC unit?
Maybe I'm missing how net metering works out there

Because the rate you pay in and take at isnt 1-1 on our plan, but subject to both rate change and tiering.

 

[UncleDave]

What's the indoor temp swing?

6 degrees both up and downstairs between shutoff at 4 and turn on at 9.

 

[IndyIan]

Are you running the AC at night and then space heaters in the morning? Looks pretty good otherwise though.

 

[UncleDave]

Are you running the AC at night and then space heaters in the morning? Looks pretty good otherwise though.

Yes, thats what that graph shows.

Mrs. Uncle Dave suffer from a degenerative disease called reynauds and it's hard on her mobility and the heat makes it better so we run the heat in her office.

In addition to space heaters
a coffeemaker that run from 5AM -about 1PM
2 heated toilet bidets (water and seats)
Well pump, a septic xfer pump, orchard and landscape irrigation and 2 full fridges and a wine fridge.
Modems, wifi, 4 monitors.

 

[loneryder]

The Lennox control system is what I would call - good but not great, leaving me unable to control the system as finely as Id like with the T stat I have - maybe there is an upgrade maybe not?

My GF had one of those high seer units installed and it may save electricity but does do a good job of keeping her 2 story colonial warm or cool. I runs whatever speed it needs to fulfill the thermostat setting, the rest of the house be ****ed. She had a warranty call and I asked the service guy about it and he simply said "the latest and greatest isn't always the best." He said it in a way that indicated he didn't care for these new high seer units.

 

[Rand]

The Lennox control system is what I would call - good but not great, leaving me unable to control the system as finely as Id like with the T stat I have - maybe there is an upgrade maybe not?

My GF had one of those high seer units installed and it may save electricity but does do a good job of keeping her 2 story colonial warm or cool. I runs whatever speed it needs to fulfill the thermostat setting, the rest of the house be ****ed. She had a warranty call and I asked the service guy about it and he simply said "the latest and greatest isn't always the best." He said it in a way that indicated he didn't care for these new high seer units.

Is there a typo in there or a missing letter I'm not getting what you are saying..
if its doing a good job of keeping it warm or cool why is the rest of the house be ....ed
service call? I think maybe you had minor typo that changed meaning.

 

[IndyIan]

Yes, thats what that graph shows.

Mrs. Uncle Dave suffer from a degenerative disease called reynauds and it's hard on her mobility and the heat makes it better so we run the heat in her office.

In addition to space heaters
a coffeemaker that run from 5AM -about 1PM
2 heated toilet bidets (water and seats)
Well pump, a septic xfer pump, orchard and landscape irrigation and 2 full fridges and a wine fridge.
Modems, wifi, 4 monitors.

Oh I see, well that's quite good you are still a net exporter, gas hotwater heater I guess? We use propane for hot water and the kitchen stove.

 

[loneryder]

Is there a typo in there or a missing letter I'm not getting what you are saying..
if its doing a good job of keeping it warm or cool why is the rest of the house be ....ed
service call? I think maybe you had minor typo that changed meaning.

I'm sorry. It doesn't do a good job of keeping the rest of the house comfortable. Once it gets close to satisfying the thermostat it slows down speed and the rest of the house (except for the t-stat room) suffers. So you have to adjust setting way lower to keep the rest of the house comfortable.

 

[UncleDave]

The Lennox control system is what I would call - good but not great, leaving me unable to control the system as finely as Id like with the T stat I have - maybe there is an upgrade maybe not?

My GF had one of those high seer units installed and it may save electricity but does do a good job of keeping her 2 story colonial warm or cool. I runs whatever speed it needs to fulfill the thermostat setting, the rest of the house be ****ed. She had a warranty call and I asked the service guy about it and he simply said "the latest and greatest isn't always the best." He said it in a way that indicated he didn't care for these new high seer units.

Seems there is two kinds of places - those that embrace the latest stuff and those that dont.
They take dedicated training and non common parts.
Im only 3 years onto this thing, but so far so good.

 

[UncleDave]

Oh I see, well that's quite good you are still a net exporter, gas hotwater heater I guess? We use propane for hot water and the kitchen stove.

Yeah not being fungible kind of blows, but I still have a pretty fair deal with the contract I have.

Nat gas for the hot water, 20K backup gennny, clothes dryer, stove/ cooktop and furnace.

Id probably get a 6-7 year ROI if I upgraded this to a 5 ton heat pump.

 

[Davejam]

How hot does it get by 9PM.
That just wouldn't cut it for me, that's the hottest part of the day and I'd hate to find out how hot my house could get.

 

[Rand]

I'm sorry. It doesn't do a good job of keeping the rest of the house comfortable. Once it gets close to satisfying the thermostat it slows down speed and the rest of the house (except for the t-stat room) suffers. So you have to adjust setting way lower to keep the rest of the house comfortable.

sounds like the tstat room has too much flow.. shut down some registers?
I have opposite problem.
If I set the living room on 70f rest of house main floor would be 67f, upstairs would be 90f and basement would be 50f.

tstat is in an end corner.. about 5ft from tv which heats up that corner.
I use a fan on the only vent in the room.. and house has a central return collector.. pretty bad design.

What i need is about 33% more cold air out of the living room register and to get it to dislodge the hot air in tstat corner.

Upstairs I fix with a midea u shaped window ac.. last month cost me 4.50$ and kept it livable.

At night when the tv is off its much more accurate but the bedroom is hot.

If you have 2 levels.. they should have separate systems no way will an upper story be cool enough it gets all the sunload.

 

[UncleDave]

How hot does it get by 9PM.
That just wouldn't cut it for me, that's the hottest part of the day and I'd hate to find out how hot my house could get.

On a 90 degree day by 9 PM the house creeps back up from around 72 to 78 degrees.

 

[PimTac]

Have you considered a thermal pot for the coffee instead of keeping the coffeemaker on? Zojirushi has some excellent pots that keep coffee hot for all day if you need.

 

[SubieRubyRoo]

13kw exported AFTER 35kW consumed? Holy cow, how big of an array do you have?

If this was a typical day, does the 13kW exported not offset the increased rate during the day? If this was me and space was available, I would add more panels until the net export offset the cost to maintain the AC all day.

Nice work overall!

 

[UncleDave]

Have you considered a thermal pot for the coffee instead of keeping the coffeemaker on? Zojirushi has some excellent pots that keep coffee hot for all day if you need.

I went from thermal pots to super automatics about 20 years ago.

(Definition being whole beans go into a hopper and each individual cup is ground and prepared on its own automatically from espresso, to latte, to cafe aulait at the push of a button.)

For sure a good thermal pot can keep coffee hot, but it cannot make every cup its own fresh cup like an automatic does. I usually start with a big old cup of Americano and switch to a latte or espresso later in the morning.

I'll pay the electric fee to keep it running, Ive never actually put a kilowatt on it, but Im tempted to.

 

[UncleDave]

13kw exported AFTER 35kW consumed? Holy cow, how big of an array do you have?

If this was a typical day, does the 13kW exported not offset the increased rate during the day? If this was me and space was available, I would add more panels until the net export offset the cost to maintain the AC all day.

Nice work overall!

Correct -

Not as big as you'd think. It's 8KW on its face 20 X 400 watt Qcell and Enphase IQ8 inverters.
I get pretty good yield out of this setup.

The 13 KW exported is turned into a dollar credit a variable rate. The higher cost electricity eats into the dollar credit . Would I still be up - sure, but the timing games saves me a few bucks so I play it.

I can add more panels, but I typically yield closer to 20 exported because I dont run the air conditioner very often anymore due to the effectiveness of the combo of upgrades- whole house fan, cool roof, attic fan, and insulation upgrades I installed last fall.

On some nights it doenst cool down enough for the whole house fan to work or in the case of a fire within a 500 mile radius the whole house fan brings in smoke.

The AC unit uses a most impressive 25x20 x5 MERV 16 + carbon filter (best Ive seen for home use) with 85 square feet of material and can isolate and scrub out smoke from a forest fire a few miles away.