July / August 2014 ESPCO Newsletter
Did you know that New Orleans is built on a swamp?
I was asked that question at a recent mini split class I conducted at my new friend’s, Tommy Flick, Flick Distributing Company, training facility in Harahan, LA. I think that ever since hurricane Katrina, most the planet knows of New Orleans’ unique structure and its relationship with surrounding bodies of water.
I have to admit the class found me ill prepared for several questions I got that evening about mini splits and humidity removal. Several attendees in that class seemed to have a predetermined perception that inverter driven mini splits do not do a good job of humidity removal…and humidity removal is a critical issue in New Orleans and surrounding areas.
In all my travels over the past three years and all my mini split classes over the last ten years, I had never had this issue come up…at least not in as persistent and consistent a manner as it did in my New Orleans class.
Well, you know me…this became a mission! I don’t like not having the answers and I’m never going to ‘wing it’ so finding the answer to inverter mini splits and humidity removal was my number one priority once I returned to New York.
The following represents my findings…
The first point regarding dehumidification when it comes up in a mini split conversation, (or ANY conversation for that matter), is that unless you have a Koi pond, water slide or hydroponic crop in your home, the source of the humidity is NOT found within the home…humidity issues are almost always the symptom of much larger problems such as a high level of infiltration. An entire industry has sprung up in the US dedicated to such issues…The Building Performance Institute BPI, has a ‘certification’ for such issues and a ‘blower door test’ will determine the source of infiltration.
No matter what type of AC system a structure might have, excessive infiltration must be addressed at its source…and that ain’t got nuttin’ to do with the AC system!
That all said….
I have almost 30 years of experience with Small Duct High Velocity SDHV air conditioning systems…I conducted SpacePak’s training in the NJ / NY market for 20 years. I mention in my inverter mini split class that SDHV is similar to inverter mini splits in that the delta T SDHV sees across their evaporator coil, (25 – 35 degrees), is extreme as compared to conventional ducted systems where a 10 – 15 degree delta T across a standard A-coil would be within specification. SDHV removes 40% more humidity than a standard ducted system and the extreme delta T is one reason why! If you look at the refrigerant coil of a SpacePak air handler, it is six rows deep…the air has more opportunity to have contact with the coil and thus the delta T increases and a secondary result of this is increased humidity removal.
Comfort-Aire & Century mini splits enjoy this same benefit…the delta T of 25 – 32 degrees on their evaporator has the same benefit as SDHV and as a result you see the following published performance:
B-VFH09MA-1 dehumidification = 1.69 pints / hour (wall mount)
B-VFH12MA-1 dehumidification = 2.96 pints / hour
B-VFH18MA-1 dehumidification = 3.80 pints / hour
B-VFH12CA-1 dehumidification = 2.96 pints / hour (ceiling cassette)
B-VFH18CA-1 dehumidification = 3.80 pints / hour
B-VFH24CA-1 dehumidification = 5.28 pints / hour
When placed in the DRY mode the above performance will increase dramatically…I will get into specifics in just a moment but first…
Take a look at this….
Heat Controller / Comfort-Aire / Century is also in the dehumidifier business. Their model
BHD-701 -H has the capacity to remove 70 pints / day or 2.92 pints / hour. This unit pulls 6.9 amps and has an operating sound level of 58.5 dBA. This is the largest standalone dehumidifier they make. The unit is designed specifically for ‘extremely wet’ conditions. It should also be noted that this is an Energy Star rated unit with an energy factor of 1.85 liters/kWH
The B-VFH12MA-1, (12,000 BTU), wall mounted evaporator will remove 71.04 pints / day or 2.96 pints / hour, pull 7.6 amps, (when connected to a A-VFH18DA-1 outdoor unit), and have an operating noise level as little as 21 dBA…and additionally provide the primary benefit of COOLING!
…oh yeah, and it will heat like crazy as well!
The humidity removal performance of the two above is almost identical so I’m comfortable in saying that the B-VFH12MA-1 has equal humidity removal performance to that of an Energy Star rated, 70 pint / day dehumidifier with a 1.85 EF, (Energy Star status requires less than 1.90 EF for a dehumidifier capacity less than 75 pints / day).
OK…time to talk turkey!
I wanted to see for myself just how effective an inverter mini split is at humidity removal so I conducted a test in my lab here in New York. The test and its results have been posted on my website in the form of a video titled, ‘COMFORT-AIRE B-VFH09MA-1 HUMIDITY REMOVAL TEST’. The video can be viewed by going to my website, www.ESPCOtraining,com and clicking on MEDIA in the upper tool bar and then clicking on VIDEOS…it will be the first video listed.
My lab is a 10’ X 20’ prefabricated garage…no insulation and no sheet rock. ..a ‘sieve’ you might say! This actually works in this case as it goes to my earlier statement regarding the source of humidity.
Here are the parameters of the test:
DURATION: one hour
STARTING HUMIDITY LEVEL: 79.8%
STARTING DEW POINT: 78.4F
STARTING WET BULB: 80F
EQUIPMENT: Comfort-Aire model B-VFH09MA-1, 9000 BTU wall mounted indoor unit with
A-VFH24TA-1, 24,000 BTU outdoor unit
I started the test with the system in the COOL mode with a setpoint temperature of 68F. The indoor unit’s fan was producing 327 CFM with a supply, (discharge), air temperature of 59F.
I then put the system into the DRY mode with the same setpoint temperature of 68F. This reduced the fan speed by 43% bringing it to 182 CFM.
25 minutes into the test, the following were the recorded conditions:
HUMIDITY LEVEL: 63.2%
DEW POINT: 59F
WET BULB: 63.6F
The supply air temperature dropped to 55F when placed in the DRY mode.
33 minutes into the test, the following were the conditions recorded:
HUMIDITY LEVEL: 58.5%
DEW POINT: 59.9F
WET BULB: 65.3F
The conditions recorded at the end of the one hour test are as follows:
HUMIDITY LEVEL: 52.8%
DEW POINT: 58.4F
WET BULB: 64.9F
I collected the condensate that the indoor unit produced during the one hour test and it measured 5.75 pints.
The proof is in the pudding…or in the condensate in this case!
The end result of our test was a 43% reduction in humidity and 15F degree reduction in wet bulb all from a 9000 BTU inverter wall mounted indoor unit producing 5.75 pints of condensate.
A couple observations beyond the obvious:
The lion’s share of the humidity reduction took place within the first 25 minutes of the test which is good news for homeowners who work all day and leave their systems off…relief comes very quickly!
The DRY mode is the key here…it increased the published humidity removal, (pints / hour), by 70%!
CONCLUSION: Inverter mini splits remove a boat load of humidity…a ton of humidity…all puns intended!
NOTE: A special THANK YOU to Tommy Flick for what was a standing room only training event in his beautiful facility… Tommy actually BBQ-ed a pig himself the day before the class so we all enjoyed pulled pork for dinner…it tasted so good that it was well worth the risk of possible spontaneous combustion when 30+ men consume pulled pork in close quarters!
Thanks to all who attended for inspiring me to research their question and conduct the aforementioned test.
HAVE A GREAT SUMMER EVERYONE!
See you soon!
The views and opinions expressed in this newsletter are those of the author and do not necessarily represent those of ESPCO’s sponsors and training partners.