Splits are much more efficient than window units I believe. They use a lot less juice.
Heat Domes
- Thread starter jamesdeluxe
- Start date
jimk
Well-known member
I made a one hour drive on 4 July 2026 for an indoor party with friends and family. I went from the Washington DC suburbs to the Baltimore suburbs and back. On the return trip around 4pm I looked at my car thermometer and it read 103f. I looked at it again a few minutes later and it read 105f. The official high yesterday in Washington DC was an all time record for the date of July 4th, 102f. Maybe my car was a little off? Maybe being on an asphalt highway skewed things? I'm used to heat and humidity and tolerate it pretty well, but it definitely felt like a special kind of hot yesterday in the mid-Atlantic!
This ^^. IMO, car thermometers are accurate other than during heatwaves.
We hit 101F in the shade on Friday (our humidity was low other than yesterday) and now we're looking at the following. Never a dull moment!
- Today New rainfall amounts between a quarter and half of an inch possible.
- Tonight New rainfall amounts between 1 and 2 inches possible.
- Monday New rainfall amounts between 1 and 2 inches possible.
- Monday Night New rainfall amounts between a half and three quarters of an inch possible.
I find the vehicle thermometer readings are high. Sometimes by 3 degrees C. I blame the metal composition of the car.
Car thermometers work well when you're driving continuously (not stop and go) so the thermometer is ventilated. I think jimk's observation yesterday is within the margin of error.
Western Europe records hottest-ever June as heatwaves intensify
Temperatures across ravaged region 3C above average as scientists warn of risks for people, ecosystems and infrastructure
www.theguardian.com
That graph is for Europe. The worldwide anomaly for June was 1.39C. This fits with a recent article (I can't find today) about the heat wave saying Europe is warming at twice the rate of the world overall. That might imply the rain/snow line in Europe rising by 1,000 feet vs. 500 feet in the past 50 years. I say might because overall warming especially in continental locations is more in summer than in winter.
As we know, if the Gulf Stream shuts down, that'll take care of Europe's warming problem.
EMSC
Well-known member
I'm late to this thread, but was wondering why you would have 2 systems like that.
Part of the silence comes from variable speed motors on the outdoor unit instead of off/on like window or traditional AC models. Those motors are also one reason they are so much more efficient too. Top mini-splits today can have 8 to 1 efficiency ratio of electrical input to cooling output. And in reverse over to 4 to 1 input to output ratios for heating.
Especially with a teenager, our central AC runs constantly all summer long.
jasoncapecod
Well-known member
the central air was put in after the home was built..we are not the original owners..the system does a good job of cooling the upstairs . the downstairs never got cool enough, without making the upstairs too cool. With the additional system we can just run the downstairs system during the day and not cool the upstairs till we go to bed...
The seems so weird. Surely for most homes the sun bakes the upstairs more than the downstairs. It's extremely rare that we use our downstairs A/C. Downstairs is colder in the winter too. Perhaps there is a humidity factor I'm missing here.
EMSC
Well-known member
While I don't live back east anymore, I would guess it depends more on the age and design of the floorplan. Lots of housing stock back east with only a relatively small stairwell connection between the upstairs and downstairs floors. Not going to get much air to circulate if such a design. Also as suspected, humidity also keeps temps within ~15-20F day vs night back east. So often there is no big cooling off at night unlike drier climates (we get ~30-40F drop overnight here in Colo most of the time even when its 100F during the day).
jasoncapecod
Well-known member
The central air system is poorly balanced because it was put in after the house was already sheet rock so they had to go through closets, etc.
Our 1938 house had gravity heat and no central A/C. The return airflow for the upstairs A/C we installed in 1990 had to utilize a space that was formerly a laundry chute. I suspect that duct is narrower than optimal and limits upstairs cooling.
The new heat pump installation took most of September and October to be installed correctly. The heating part worked decently over the winter, costing no more than the former natural gas furnace. The heat wave getting started today will be the first real test for cooling.
berkshireskier
Active member
We're in the middle of a major renovation and addition on our old farm house (built in the late 1700's, around the time of the American Revolution). Needless to say, there was no central heating or A/C in the house originally (other than the three fireplaces on the first floor), so a heating system was installed some time in the 1960's with a huge oil burner in the basement (about the size of a VW bus) and forced hot air through a series of ducts in the basement that fed warm air to the first floor through registers in the floors and then a vertical duct up along side the central chimney to a series of ducts in the attic that fed warm air to the upstairs bedrooms through registers in the ceilings. It was not a very efficient or effective system. The upstairs was always significantly colder than the downstairs (and we had major problems with ice dams on the roof during cold and snowy periods). Plus, our daughter always had allergic attacks when she came home, from, we think, all the accumulated dust, mouse droppings and other junk in the duct work. So, with the renovation, we decided to pull out all the old duct work, replace it with new duct work; get rid of the old oil burner and replace it with a propane burner (one in the basement and one in the attic, to give us two-zone heat) and then we also decided to hook up central A/C to the ducts in the house with two large condensers outside. Needless to say, it was an expensive upgrade to the whole system but they're almost done, so it will be nice to have a whole house A/C system on hot Summer days. We also had our attic completely cleaned out with all the old cellulose insulation vacuumed out and replaced with closed-cell spray foam insulation, so the attic is now hermetically sealed.