We still own our condo in Harvard Square (rented out on AirBnB; will sell once coronapanic ends in Maskachusetts and people realize that living in the suburbs while working in the city is intolerable due to traffic (but maybe coronapanic will never end?)). It has a traditional HVAC system with air handler, ducts, and a condenser outside. The contractors in the Boston area that are qualified to do basic maintenance on the system are all too busy to do maintenance (they’re happy to do a $20,000 installation project). But these types of systems need annual maintenance to avoid the risk of a drain backup and massive water leak inside the house.
A contractor here in Florida, where A/C maintenance is much more available, said that he’s never seen a mini-split suffer from a clogged drain. For some reason they don’t build up gunk inside the lines the way that traditional systems do. As the U.S. population grows while the population of skilled laborers stays constant or shrinks (we are growing our population via low-skill labor and/or asylum-seekers who don’t work at all (babies, parents of young kids, the elderly), not with migrants who have HVAC training), the problem of finding qualified service people will only get worse. I wonder if this is a good argument for ductless mini-split heat pumps. As long as there are factories in Japan and China, replacement components will be available and the overall system complexity and annual maintenance needs are much reduced compared to a traditional HVAC system.
(The Florida contractor’s favorite brand is GREE, founded 1991 in Guangdong.)
Readers: What is the argument for installing a traditional HVAC system? Easier to filter and humidify the air if desired? Lower fan noise in the interior?
Mini-splits rely on gravity to drain. If you can’t run a line straight down from the air handling unit, you have to install a small pump inside of it to move condensation, and those are subject to gunk/blockage, and are loud as well.
I’d strongly advise to avoid an install requiring such a pump. If you can do that, they’re quite quiet.
Main remaining arguments against a mini-split I can think of: aesthetics, lack of a smart/central thermostat, and perhaps limited to smaller scale installations.
There are entire commercial buildings built with minisplits. They absolutely can have central thermostats (as smart as you like) and the scale of the installation can be quite large. Variable frequency drives allow these to match the outdoor unit energy consumption to the demand inside with quite high efficiency. You can even get water sourced versions rather than the more common air sourced.
Regarding drains, I believe for any new installs the codes will require some means of shutdown or alarm if the drain fails to drain. The ceiling units from Mitsubishi have this built in from the factory.
I’m almost completely ignorant when it comes to new HVAC systems, but I am kind of surprised that the newest models don’t have a sophisticated monitoring system via the computers that will throw a Hard Stop if the drain clogs and shut it down before The Flood. It seems to me that given the computing power available, a good engineering team could calculate (based on humidity, temperature, etc.) how much water SHOULD be draining from the system and continuously compare it to the ACTUAL amount and set off a Drain Alarm beep and a smartphone app. alert if the values are discrepant for a significant period of time.
Addendum: In fact, given the neighborhood in Harvard Square, it surprises me that manufacturers/installers don’t have some kind of remote dashboard that can monitor and compare the drain rates of all the similar systems in the area. If one gets clogged it should stick out like the proverbial sore thumb, and then you get a phone call from the HVAC folks saying: “Dr. Greenspun, we think your HVAC drain is clogging up.”
I had a mini-split drain plug up and cause a leak at the air handler. This was in Northeast US. I believe it was caused by insects carrying gunk up into the drain from the outside, eventually resulting in a plug. I fixed it myself with a screwdriver and wet-dry vac. In any case, I would be skeptical of your tech’s opinion that they never clog, though maybe it’s a regional thing.
You need a mini split to be a gootube star. The lack of videos on greentube mean you can probably get away with anything. Passive income isn’t really passive. Get back to Boston & manetain the condo.
Case could be made for moving back to Boston. The empirical evidence indicates that once south of the mason dixon line, IQ drops by at least 20, and there is a strong desire to own noisy trucks, pitbulls, and gain a lot of weight.
The schools are better in Florida though:
https://www.wsj.com/articles/the-secrets-of-americas-greatest-high-school-math-team-11657791000
I actually saw a mini-split blockage 2 weekends ago. The drain pipe was cleared by hooking up a shopvac to the drain and sucking out the blob of ‘snot’ which was an accumulation of biofilm. Adding some bleach or something similar every cleaning should help.
Are you sure you can’t find a YouTube video to help you or a local friend, do it yourself?
Phil and DIY anything are incompatible terms
Much as I would love to be working in a 100-degree attic surrounded by fiberglass dust, the attic is in Cambridge and I live in Florida. So it is definitely not the ideal DIY situation.
I actually found a contractor to work on the Cambridge system remotely. They charge $195/hr. The annual service actually ended up disabling the system. The attempt to clean the drain line bunched up the gunk and caused a total blockage. The guy came out again and blew it out with CO2. Now the system is not cooling well at all. I am wondering if the refrigerant has leaked out, maybe as a result of the service attempt or possibly just due to the system being 9 years old.
Speaking of 100-degree attics and fiberglass dust., why isn’t there a national effort to get more Americans who identify as “women” into this in-demand occupation that pays above-median?
How can we let systemic gender discrimination prevent folks in a rainbow of gender IDs, including female, from getting up on ladders and diving into air handlers?
I’ve spent nearly $20K on three Carrier AC systems over the past three years: one 4-ton central ACs at $5500, one 2-ton central AC at $6800, and one 3-head 2-ton split AC at $7900; each including installation and 10-year full parts & labor warranty (which requires the annual $100 AC preventive maintenance service). No drainage problems. Satisfied with all three systems, especially the split system. No problems getting the annual service done in FL.
Mini-splits need routine maintenance also – we’ve owned several houses with both
Mitsubishi and Fujitsu systems. Generally, the blower wheel seems to accumulate dust
and eventually causes the unit to vibrate. Also, we’ve seen leaks in other folks mini-splits,
either due to install issues, or just debris in the drain hole.
Why are there no silent systems? Most manufacturers list > 45-50 db, which is too loud, especially at night. The noise quality is even worse: Often there is a tonal frequency close to a pure sine wave which is immensely annoying even at 30 db.
When the compressor kicks in, add a loud rattling noise. The PC industry has made great steps in producing silent fans etc. Why can’t the AC industry do the same?
To avoid the “plugged drain line” problem in traditional HVAC systems, I put a little fungicide pill (like a slow-release moth ball) in the drip pan once each year. Most big condo/Apt management companies do this for free because it reduces service calls.
There are a number of products, but the one I am using right now is by Diversitech, product number: PROTREAT-151 pan treatment for condensate drain pans. 100 tablets are under $10.
I know the mechanics of minisplits but I don’t have one and thus am not qualified to say how these products would work in pan-less systems. My best bet is that if I get a minisplit next time, I’ll look at the drain line and, if there is condensate hollding tank, either crush a tab to dust or mix it with water and inject it in the line with a dropper or hypodermic needle (I inject B-12 and keep the old needles).
Again, not professional advice but what I do here in Austin and will be doing in Greenbelt, MD when I buy a place there this summer to be close to the NARA research facility in College Park.
100 tablets are $60 on Amazon. Inflation I guess?
Feb 2022, I had to replace a 3 ton heat pump, my final cost was $9,236.
This week, I have to do the same for a second one, this one will cost me $10,489.
That extra $1,253 is entirely price increase of the unit (both are Bryant). So in 5 months, a nice 13.5% increase — hello inflation!
Why minisplits are not universal for the entire house? They are way more expensive to install. One comparison I got is $12K for traditional system vs $40K for a split with 4 in-house units (which is not even enough to cover all rooms). Probably it’s not in “mini” range already, but one way or another you need to serve entire house.
Central and mini and auto systems are all subject to drain blockages by dust and pollen and biofilms.
A quality multi-speed central system is usually running on low and can be almost inaudible, since the fan isn’t in the room with you. Also, filtration is a lot better in a central system, and central or internet connected control is easier.
Mini-splits are good for intermittently used rooms because of the built-in zone control. They can also be more efficient, like SEER 30. I have an old off-brand Chinese unit that sounds like a freight train. I expect a new Bosch would be a lot quieter.
Central unit would be expected to be a cheaper installation if you already have ductwork, or more expensive if ductwork has to go into an existing house.