: Mits AC/Heatpump
2011-06-08, 11:39 AM
Now that the weather has finally warmed up I have had a chance to play around with the cooling aspect of heatpump. For the first couple of days I had the AC set for 70 and it kept the house cool now the last couple of days I just had it set to dehumidify only and I have noticed that the house seemed much cooler and the thermostats in the house shows the air temperature to be 3-5 degrees cooler than with the airconditioning on.
The head unit is at the top of the stairs so the cold air is falling obviously but does not seem to circulating all that well.
The unit seems to be running all the time is this normal?
Also wondering if running it in dehumidify mode draws less electricity than a/c mode.
Are you talking about a mini-split?
In the "dry" mode, the unit doesn't have a set temperature, so it keeps running and you may make it cooler than if you have a set temperature in A/C mode.
The fan runs 24/7 on my mini-split in A/C mode. (The fan switches to "ultra low" in the winter heat mode when it's not actually heating but the unit is turned on)
I have a Blue Line Power Monitor on my home to monitor the power consumption of my unit (along with other items obviously). The "dry" mode may use more power if the A/C keeps the room at a warmer temperature depending on the thermostat setting. The specs for your unit should show the min and max power draws for the various modes...
70F is very cold. I keep mine at 75 and it's more than cool enough in my entire home. Mine is at the top of my stairs and feeds the upstairs, with the air falling to the main floor to keep it cool also. Perhaps your unit is oversized and the compressor is not actually running enough to dehumidify properly. What size is your home? What size is the unit? Many people oversize their A/C unfortunately, thereby creating a clammy condition in the summer with a cool temperature but high humidity because the A/C doesn't operate enough to dehumidify.
2011-06-08, 06:03 PM
The house is around 1000 sq.ft. and the unit is the MSZ-GE15
With the warm muggy day today we just have the dehumidifer going and it`s a chilly 70 degrees on both floors
I looked at the web and this appears to be two indoor units - one at 9,000 (or 12,000) and one at 15,000 BTU. For 1000 sq ft, even if you've only got one 15,000BTU unit indoors, that's probably way more than you need. Let me know if I've looked up the incorrect unit(s).
2011-06-08, 08:51 PM
It`s the single 15,000 BTU unit, the next hot day we have I will try the a/c set to 75 and see how it performs!
Also wondering if running it in dehumidify mode draws less electricity than a/c mode.It wasn't that warm today, but was very humid, so I thought I'd try running my unit in "Dry" (dehumidify) mode. It drew about 4-500W. I switched it to A/C mode and it drew about 2-300W since not much cooling was required. It would have to be quite a warm day for my unit to draw 500W in A/C mode.
^You must have a small cooling load
I wanted to answer the OP's question from post 1 regarding Dry vs A/C mode when it's not hot out, so I chose today, which was quite humid, but not hot. It's cooled down, so the A/C's off now.
On a really hot day (over 40 humidex), my Mits has gone over 1000W, however, most days (say 30-35C) it sits at about 500W during the day and then ramps down to 2-300W at night when it's cooler. The house is well sealed and insulated though. I am very pleased with the performance of this unit in A/C mode. (I have it in the upstairs hallway to cool the upstairs, but it does the whole house with the air that falls down the stairs. 1400 sq. ft. 2 storey) Since purchasing the Mits split, I haven't needed to run the central A/C at all, although I do run it for a few hours every month just to keep it "lubed". The central is a 1.5 Tonne unit from 1990 that draws 2000W when on - quite the difference.
2011-07-06, 05:38 PM
Thanks for the replies, my home sounds similar just a little smaller and I have my unit in the upper hall as well.
I have found that the house seems cooler when the unit is set to dry rather than a/c, today for example it is currently 29c with a humidex of 35c I have the unit set on the dry mode running at the lowest speed and the temperature in the house is 69F on the main floor and 71F on the second floor. I tend to run it at this setting continuously.
You may wish to see if there's some way that you can direct the cooling from the unit so that more of the cooling stays upstairs - so that the upstairs is the same temperature or cooler than downstairs. A higher fan speed may help with that so that the air doesn't "drop" immediately upon leaving the unit?
What temperature do you run your furnace in the winter? As mentioned earlier in this thread, ~70F is quite cool for a home in the summer and is not usually considered healthy or energy efficient. (I'm not trying to tell you how to run your life, just providing some FYI info)
2011-07-07, 05:17 PM
I appreciate the info, No furnace we have baseboards.
Yes 70 is a little cool right now it`s 68 but that`s the temp range I get when the outside temp is 25-30 with 50-70% humidity.
I am still trying to find a setting that is right, I am amazed at how this unit cools the house!:)
You may be able to get the cooling/humidity you want by running the unit in A/C mode, but with a setpoint temperature that gives you the desired result, not necessarily the final temperature.... I usually have my fan set to "auto".
2011-07-07, 08:16 PM
I will try the auto setting!
2011-07-07, 08:42 PM
Slightly higher fan setting did indeed balance the temp! 70 up and down!