Imitation is the most sincere form of flattery

Here's a screenshot of a debug console for DZ, published on February 22 2002:




(also, here, here, here, here, and here, and the whole discussion around it here)


Here's a picture of a Honeywell VisionPro Touchscreen Thermostat, released several years later:



Hmm...

Short Take: Unlikely Contender?

Bryant, out of all things, comes out with a zoning system? Interesting... From what I gather, Bryant was always considered to be the low end counterpart for Carrier, just like in Toyota/Lexus and Honda/Acura relationships. And now, the zoning system?

Oh wait, maybe Carrier Infinity was a bit overpriced...

Update Jul 1 2007: Same thing, different branding.

Contractor Grade, adj.

"Contractor Grade". Magic words. The bumper sticker saying "Licensed contractors build confidence" springs up in my mind, and my posture straightens, and my hand is twitching uncontrollably to salute whoever came up with that.

That is, until another phrase pops up. "Shop Talk". Defined as "way to talk about your business in presence of outsiders in a way that only others in the same business can understand".

So what does it mean, really?

"The cheapest product that is necessary to check off the mark indicating a presence of an entity as an integral or optional part of more complicated entity".

Anything even remotely decent will be marked up as an "upgrade".

Go with reputable contractor, they say

More than once I've heard HVAC contractors say that the quality of the equipment is nowhere as important as the quality of the installer. They say, you can buy a cheap Goodman unit, have it installed by a reputable contractor, and have a better result than when you pay three to five times more for a Trane or Carrier unit and have it installed by a nincompoop.

It's all good and well, except for one thing.

Define "reputable".

Do you really think you're qualified to determine whether the contractor is reputable or not? Remember, smooth talk and clean look is not an indicator of the fact that he is either honest or knowledgeable. Neither is jaded look and arrogance, by the way.

OK, suppose you admit it, you aren't. Who do you think is?

Your neighbor Joe must be. He told you that he's really ecstatic with the quality of work that a contractor Bob did last week, and low rates he's charged. So you go and hire Bob, only to meet Joe next week and hear the horror story about how the next contractor he'd hired, Jim, uncovered all sorts of shortcuts, omissions and stupid things that Bob did - and actually, that he's now suing Bob for anguish and mental suffering. Now, that gives you a warm and cozy feeling.

"Check credentials", they say... What exactly do you know about credentials? With all those "get the degree you deserve for the price you can afford" spam messages flying into your inbox by hundreds every day, how can you be sure?

Point is, you really can't know. You can't hire honesty and experience, you may just stumble upon it by sheer luck. But chances are really slim, because uncle Darwin knew what he was talking about when he said "survival of the fittest", and mind you, "fittest" doesn't necessarily means "better" as defined by you, but "better" as defined by competition rules. Racking up enough volume by cutting all imaginable corners to squeeze out those who are spending too much time honestly doing their job to the best of their ability is good enough in that book.

One way out of it? Make sure you know what they are talking about. Only then you can hire a knowledgeable contractor. Hiring experienced (as in street smart, not book smart)? Hiring honest? I'm not in a position to give you any advice about that...

And don't ever make a mistake of thinking that there's safety in numbers and you can cheat by hiring a big company to do what you need done, thinking that you can go after them if they screw it up. All that will happen is they will bleed you to death sending many crews one after another to fix the screwup, each of which will have approximately the same amount of clue (asymptotically approaching zero), requiring you to be at home, say, eight to two, or twelve to five, day after day, week after week, and each crew fixing one thing (optional) and breaking two in exchange (mandatory). Just say no.

Hmm... That turned out acid all right. According to the above, we're screwed completely. As I was thinking this article over and disliking the way it is (all negative), a glimpse of hope sparkled in my head when I thought of reputation systems. But then, immediately, when I googled up "hvac contractor reputation system", this article came out on top... Hmm... I guess some work is waiting to be done.

Short take: Insane Complexity

Look, Ma, it's just a light switch...

Reminds me of the first time I went public with the prototype implementation of the zoning thermostat back in February 2002. The question I asked was, "What would be your questions if you saw this thing on the wall in the house you've just bought"? The first answer I got was, What the <censored> is that?

Honestly speaking, the situation hasn't improved much since :)

On the other hand, you've gotta give those designers credit for making something that complicated looking that simple.

You will never buy a good HVAC unit. Deal with it

To begin with, if you are reading this, you are not a regular person. Either you're a geek, or a HVAC specialist, or recently had, are having or about to have a problem with your HVAC unit. Other people are treating HVAC units as appliances - and I bet that they pay much more attention when they select a refrigerator or even a kitchen faucet than when they select a HVAC unit. If they even acknowledge its existence, that is - usually they blame all problems on the thermostat.

That's too bad, because a proper selection may make your life a bless, and improper one will make it a misery.

HVACs are notoriously difficult to find information about. And, they're complicated (when your HVAC contractor tells you it's rocket science, you better believe it). So complicated, not all HVAC contractors comprehend the complexity. Just ask them what superheat and subcooling is when they are charging your system - just make sure you are able to comprehend the explanations, and keep your bs detector handy. By the way, don't try to fish the answer out of Wikipedia - it doesn't have one for the HVAC subject area, at least as of moment of writing.

To add insult to injury, HVAC system is not even the place you should start at. Heat loss and gain calculation is. But, it is usually very difficult to get. That is, unless you are willing to apply some elbow grease. Don't forget to investigate the sensible vs. latent capacity while you are at that.

But suppose you know the capacity of the HVAC unit you need already. In this case, you're forced to make a decision that basically boils down to this: how much money you are willing to lose.

You see, the reality is a stubborn thing, and face it, ROI is not looking good. High end unit that is able to sustain a house about 2000 sq. ft (about 186 m^2) will cost you somewhere around $8,000..$10,000 (installation included), and even if the installation is perfect (caveat emptor - specs say "up to X SEER", not "X SEER") and the unit never breaks on your dime, you may wait up to ten years until you actually see the first cent of profit.

And make no mistake, all the money that you've invested into a nice air conditioning and/or heating setup is wasted when (not if) you sell the house - for the reason above, normal people care more about a fancy set of door knobs you bought at a garage sale for $5 a piece than for the state of art home comfort system.

Moral of the story?

• Getting a new HVAC unit will hurt.
• The less prepared you are, the more it will hurt (actually, the opposite is true as well because the way potential buyers are treated is guaranteed to drive you raving mad if you have a minimal clue about the problem; it's just the kind of pain that is different).
• The more time you have at your disposal, the better prepared you are, the better your task is defined, the less chance of falling prey to unscrupulous salespeople you have.
• The less you have to lose (30 year old Goettl, anyone?), the more you have to gain.
  
• Or just bite the bullet and buy a house with a good HVAC in it. Actually, if you do have a 30 year old unit, it may be a good time to get out of the house anyway... Unless it is 150 years old.
  

But what if you have carefully weighted all the arguments and decided that you either can't afford or are unwilling to pay that much? Well, the best you can do is make the best out of what you have.

Give Me Back My Air

It's been almost exactly 10 years since I've been exposed to the wonders of air conditioning. Before, the life was simple - you could easily have a $14 (yes, you read that right, fourteen dollars) monthly electric bill for a family of four in Iowa fall, but now it's quite different...

But I digress.

In all those 10 years I've been all around US - with two focal areas being Midwest and Southwest, and going as far west as Ohio and as far south as Florida. Never, ever have I seen a house with a properly designed air return.

You may ask, what is air return? No, that's not the big noisy thing that sucks up cat hair and where your HVAC repairman goes with disgust and tells you to replace the filter more often then once in ten years. That's air conditioner's air return.

Your air return, on the other hand, is supposed to be in every room that is conditioned. Air goes in through the vents, it's supposed to go out somewhere. Done right, there should be not one, but two air returns: one for the heating season, one for the cooling season.

But this is expensive. And cumbersome. And the real estate market is rising (or, should I say, it was until very recently) and every second wasted was worth big $$ - and that couldn't be allowed to happen.

Therefore, you don't actually have one.

Instead, you have (in the best case) a gap between the lower edge of the door and the floor or the carpet. That is, unless you fancied a nice thick carpet and had a carpet guy that was very busy working on ten jobs - so he laid the carpet, plugged the gap, billed you and went out without saying good-bye.

It is very easy to check if you have sufficient air return - when the HVAC is on, see what happens to the door when it is open just an inch or so. If it bangs shut with the walls shaking, then yes, you do have insufficient air return. If air starts hissing angrily when the door is closed, and/or the whole tone of the airflow changes, the yes, you've guessed it already.

So what can you do about it?

Not much.

You can increase the gap by cutting the bottom of the door. This will help somewhat, but will probably be insufficient - you want your air return to be just about the same, if not bigger, than your supply.

You can cut the hole in the door and install nice grills you can buy at Home Depot for ten bucks over the hole - this will help much better. But forget privacy.

And, you can look for the presence of air returns next time you buy a house. But - good luck with that, and please let me know - I will have fingers on my left hand available to keep the count.

Short take: Ceiling Fans & Co

Reading digg, stumbled upon set of Tricks to Keep Your House Cool this Summer. Immediately remembered a non-trivial observation I made in my old house: amount of heat produced by a stock ceiling fan, or a few desk fans, can easily overcome the subjective drop in temperature caused by increased air circulation (the temperature rise was actually measured, it is not a guess).

This is not necessarily always the case - the smaller the room, the more pronounced is the effect. Or, should I say, the easier it is to measure it...

Original observation is a part of the DZ article called Hot Summer of 2003.

Another argument worth repeating - any heat producing device in your house (fans included) makes your A/C work harder, so not only you're not improving situation, you're making it worse.

UPDATE: tangible evidence collected.

A tangent - yes, you can vent the heat generated by your equipment outside, but that opens another can of worms - negative pressure... But that's a different story for a different time.

Who Cares?

The all powerful statistics sometimes uncover quite unexpected results.

I would never expect that the scorching hot Phoenix, AZ takes #13 in the visitor frequency list, whereas first three places are taken by Atlanta, GA, Los Angeles, CA, and Chicago, IL, with London, UK and Toronto, Canada being present in the top ten.

It is natural to see US being #1, somewhat surprising to see that #2 is Canada, even more surprising to see that #3 is United Kingdom, and completely unexpected to see Sweden in the top ten.

It is amazing that there are people visiting DZ site quite frequently as north as Oslo, Norway.

It is sad that New Zealand, #19, yielded more hits than Russia, #20, just as Mexico, #27, is ahead of all of China, #28.

The fact that the whole African continent resulted in 0.48% hits, goes without comment.

Even more interesting the results become if the geek bias (recent hits from Hack A Day) is removed - first place firmly takes... Toronto, Canada (surprise, huh?). Chicago, IL comes second, followed by Atlanta, GA. Phoenix, AZ moves to 19th place.

So I'm thinking - is Atlanta really that bad in the summer? DZ is pretty much a niche project, and the geek appeal of it is barely above absolute zero - only those specifically looking for information on temperature zoning are finding it. Nevertheless, this time the geeks came as soon as the bell rang...

On the other hand, the fact that Phoenix is well beyond the first ten doesn't tell me it's not hot and doesn't need air conditioning - I know it is, and I know it does. It may speak of a different phenomenon, though - population bias. Either a lot of it is Internet illiterate (which certain areas of the Valley definitely are), or a lot of it has enough money to buy it (which other areas of the Valley absolutely do), or both... Or they are snowbirds.

Update Jun 26 2007: Google Setting Up a Presence In Kenya. Wonder how that's going to change the picture - so far, only 2 hits came in over a year.

DZ Live: July 11 2007 at Phoenix Java User's Group meeting

A presentation tentatively named "DIY Zoning: 7 years down the road" will take place at Phoenix Java User's Group meeting on July 11, subject to final approval. Use your chance to find out all things you always wanted to know, but were afraid to ask :)

It would not be a bad idea to submit questions you want answered here. The plan is to have the presentation (with Q&A session transcript, if any) published at the DZ site shortly after the presentation.

Look for schedule and site directions on PHXJUG site.

Shut off the A/C or leave it running?

One of the most frequently asked questions is "Should I shut off my A/C when leaving the house, or leave it running?"

You see, it's not that simple...

This is one of those classical cans of worms that a lot of people (HVAC professionals in particular) have an opinion on, but just try to ask them to quantify the problem, and the result has all the chances to be hilarious.

Suppose, you go on vacation and shut off the A/C for a month. You've just saved a lot of money, except now you have to repair the cracked deck in your sixty thousand dollars Steinway grand piano you absolutely forgot about.

Suppose, you get out to walk the dog and shut off the A/C. I will call you paranoid and probably pound foolish, penny wise (all in all, having a dog is an expense you don't really have to incur if you're so concerned about your financial well being).

Suppose, you send the kids to school and go to work at 0800. Kids get back from school at 1400, you get back at 1800. This is where things get interesting.

Pretend the house is a pool. The HVAC is the hose. The walls are the drain. The drain is constantly open. The hose is open as it is needed to keep the pool filled up.

So when you shut off the hose, the pool starts losing water. The longer the hose is shut off, the more water you have to replenish (note that this is pretty much like cooling the house - yes, there will be a point beyond which all the water is gone, and from that moment on you're purely saving money). On the other hand, the longer the hose is shut off, the less you pay.

When you come back and open the hose, the water level goes up (and the house cools down). The bigger the hose is, the faster it will happen.

In other words, the bigger your HVAC is, the more sense it makes to shut it off or adjust the setpoint when leaving the house.

But wait, this is not the end of the story yet...

The drain is nonlinear.
The hose is nonlinear.

The hotter it is, the bigger is the drain, the sooner the water is gone.
The hotter it is, the more strain is put onto the hose (this is even worse for heat pumps in heating mode, because of the balance point).
It may lead to a situation when the inflow can't keep up with the outflow.


In other words, the smaller (or worse) is your HVAC, the less sense it makes to shut it off or adjust the setpoint when leaving the house. If this is your case, bite the bullet and pay the bill. Which reminds me, by the way, that poor people pay more.

But wait, this is not the end of the story either.

The highlighted cases above are for extremes. As the weather gets milder, efficiency considerations fade because the drain narrows (not as much heat is lost or gained). For this case, the longer you are away, the more sense it makes to shut off the HVAC or adjust the setpoint.

Now, let's remember the rule: whatever you cannot measure, you cannot improve. You may spend days and nights guessing, but you will never know whether you improved the situation or made it worse until and unless you have long term trends monitoring set up.

Which brings us all the way back, right here.

PS: Inquisitive readers will notice quite a few threads dangling here. Detailed explanations will go well beyond the point of loss of interest, but those who care to find out have probably figured out where to go to get the answers.

It is not necessary to read the article in order to criticize it

As I keep watching the hits on the project web site and comments that people leave at blog post pages, one thing never ceases to amaze me: they don't read it.

I mean, how difficult it is, for example, to search for "back pressure" using a search box provided *specifically* for that purpose at every project page before actually making a comment like (name reference withdrawn to protect the guilty) this: "I’ve been told by HVAC people and the local power company that closing the damper (insert opinion du jour)".

Here is the anwser, just in case...
And another, for completeness.

The summer is here

Alas, it appears that this is going to be the hottest summer I've seen in Arizona so far (having come in 2000). Which reminds me that it's been a while since the project this blog will be linked to (DIY Zoning) hasn't evolved in a significant manner for quite a while.

What's changed since the project was created in 2001?

Well, I don't think we've heard about rolling blackouts back then.
The water was near nowhere as expensive as it is now.
I'm not even talking about gas (when I left Iowa, I got a full tank of unleaded for $.73 a gallon, now it costs $60 to fill a tank).
Which makes more people stay at home.
Which makes electricity bills higher. Unless they're actively employing energy conservation measures.
Speaking of which, it appears that today people have become significantly more energy conscious.

Originally , the DZ objectives were stated as: "1. Home comfort. 2. Energy cost savings. In that order."

Well, it may be a time to revisit the strategy and shift the priorities...