One Size Fits All, or Reflections on EPA guidelines

So here cometh a fresh pair of thermostats (Honeywell RTH7500 and RiteTemp GPMG8085C), both equipped with default schedules taken from EnergyStar ® Program Requirements for Programmable Thermostats: Partner Commitments (look for Table 2: Acceptable Setpoint Times and Temperature Settings). It was summer, and the default settings were too cold for us, so we changed them.

But the defaults for the heating season were left in place.

Now that the heating season is here, and it is eventually getting quite cold outside, several interesting things are popping up.

First of all, let's take a look at default EPA compliant settings.

Wake: 6AM, 70°F.
Day: 8AM, 62°F.
Evening: 6PM, 70°F.
Sleep: 10PM, 62°F.

Then, let's go back and read the long rant about whether you should shut off your A/C or leave it running.

Then, let's take a look at the temperature spread for the schedule above. 8°F.

That's quite a lot.

The very reason I've started thinking about writing this article is that one of my units (Lennox split), being perfectly capable in cooling mode, seems to either hit the balance point, or otherwise severely degrade its performance, when the ambient temperature drops lower than about 45°F - and, as a result, it is unable to bring the zone it serves from 62°F to 70°F in two hours.

Even worse the temperature actually drops to about 65°F by 6AM, and it barely makes it to 68°F by 8AM - forget 62 to 70.

While this is definitely quite uncool, it also points out another fact that is not on the surface: the unit works at the top of its efficiency curve. It doesn't cycle, it spends initial 10-20 minutes approaching the design efficiency and stays there.

That was the positive, now, another negative - since it serves two rooms, one of which is about five times size the other - guess what, by the end of the two hour run the smaller room is HOT. Balancing the dampers manually will not help since it'll shoot the balance for other conditions - like, the evening, when the ambient temperature is significantly higher and the runtime of the unit is very short in comparison.

So, what's the point?

• One should carefully examine defaults;
• You can't get away without actually zoning the house - unless you want to shuffle everything all the day or suffer;
• It would *really* pay back to come up with an idea to figure out to anticipate the *actual* performance of the unit for varying circumstances and make the system issue recommendations to you about what you should do in any particular case;
• Which would imply the knowledge base and rule engines to analyze input and figure out dependencies (homework: see Google's statements how having access to massive amounts of data helps to figure out the trends and make correct decisions);
• It would help to share data between installations (see how Valve managed to make Half Life 2 the most playable game for the same hardware utilizing statistics) and applying some brains;
  

Damn! DZ is going enterprise.

Hmm... Turned out not quite the way I started it - but oh well, I'll just leave it at that.

Books: too obvious to think about

Usually, the Internet is the best source of information - at least, quickest accessible.

But it has a drawback - you won't find the information you're not specifically looking for. Maybe only as a collateral, but even in this case you have to know that it is relevant to the problem you're resolving - and this may not necessarily be obvious.

A while ago, I was trying to figure out whether it is safe to drill a 1 1/2" hole in a load bearing support beam. The consequences of a wrong decision would be catastrophic - the second floor will come crashing down, and no insurance would help. So I started looking for the solution, but, surprisingly, different sources were giving different advices.

It so happened that I visited a bookstore at the same time. By accident, I was passing by the section with all sorts of DIY books in it. Just out of curiosity, I decided to take a look.

Well, now I'm writing this article. Thanks to many of those books, now I know how to do wiring, framing, drywalling, texturing and painting, investigating installing windows and doors, flooring, all kinds of woodworking, will take a look at tiling when the time comes.

It's not that they are the source of ultimate wisdom. It's that there are things in every business that you simply have to know in order to do things - and those books give you the necessary headstart so you can looks ahead standing on the shoulders of giants. Or at least those who passed this road before you.

Another advice - don't rush buying those books - you'll spend a fortune. Each book is anywhere from $20 to $80. Make friends with your local library instead.

Rigid plastic conduit: unidirectional

Good judgment comes out of experience. Experience comes out of bad judgment.

It seems pretty obvious in hindsight, but somehow didn't come to my head that I might have problems running fish tape through a rigid plastic conduit with a few bends. Guess it is not usually a problem, otherwise it would be widely documented - or it may have been just my dumb luck, but...

Turned out that a wide and big 1" conduit run of 26ft with two 90° bends is not passable in either direction.

Took me a split second to realize why - the bell. The one that is at one end of each conduit component. The rest should be obvious.

Two conclusions:

• Do a dry run - works pretty well with plastic conduit, it holds up pretty well and you can probably get away with running it through even though it's not glued together yet;
• Plan ahead and remember that you may not be able to pass a conduit in one direction.

What did I end up with? Well... Had to cut the elbow out and reverse the direction. Don't be like me.

Random Notes: Timing and Blueprints

Random note #1: One thing I have not regretted, in a hindsight, that I've started the wiring project right now - in local mid-season. When the insulation is disturbed, it doesn't function properly anymore, and had this happened in the middle of the summer (or in the middle of the winter for those farther North), it would've been bad.

Random note #2: SketchUp is the best thing since sliced bread for DIY projects. More and more professionals are starting to realize the importance of it (see the article on timber framing, for example). It works for project at almost any scale - the house model I've built, for example, has everything from the yard on the top of the scale to individual screws in places where I've laid conduit, on the bottom of it. Start with 3d Warehouse (Thai House Blueprints is a beautiful example), don't forget the SketchUp Blog.

Doctor, it hurts when I walk this way, or HVAC Checklist

Patient: Doctor, it hurts when I walk this way...
Doctor: Don't walk this way, then...

Buying a house is a major pain.

What I was talking about, again? Ah, the usual complaints people have about the house they just bought.

• A particular register is too noisy.
• Return air grill is too noisy.
• Air handler is too noisy.
• Condenser is too noisy.
• A particular room is too cold or too hot.
• One floor is hotter than the other.
• A room feels stuffy when the doors are closed.
• A/C can't keep up with the heat.
• Heater can't keep up with the cold.
• Air in the house feels musty.
• There are dust traces outside of registers.
• Bathroom walls stay moist forever.
  

The list becomes pretty long pretty fast, but it can grow significantly longer.

For one single reason: people don't pay attention to HVAC. They think about anything and everything except HVAC. And realize they're in trouble just as the train has just departed.

So, how this can be fixed? And who is in a position to fix it? Unsurprisingly, people who can benefit from this, at the same time helping potential victims avoid being trapped - realtors and, to less extent, HVAC servicemen.

It's a double edged sword, though - for realtors, HVAC is just one more hoop to jump through. For both the buyer's and seller's agents, this is an obstacle on the road between today and the moment they cash the commission check. It would take a person of high integrity to step away from otherwise inevitable financial gain - but wait, we're getting into old good argument about reputation...

Theoretically, it should be a part of home inspection report, but I'm yet to see one that would address those particular issues, or even if it did - somehow a $20 register doesn't seem to register, no pun intended, when a typical house could very well cost north of half a million dollars and this is exactly how much is at stake when you are considering buying it (or so you think at the moment. Actually, the stakes are even higher - your well being is at stake). Especially keeping in mind the fact that issues like this will surface well into the process, after you have already decided to make an offer, paid inspection fees and generally are tied up pretty fast.

Another issue is that a person or a crew that will perform the inspection is not necessarily highly proficient in HVAC. Yes, they know the motions (check the supply air temperature, etc.) - but what they do may not be enough. Then again, it is applicable to every possible subsystem in the house (Gawd! Don't ask me about the state the wiring system was in at the house I live in...) So the advice here would be to actually make an extra step and pay a HVAC contractor (yes, and the plumber, and the electrician, and the roofer - the list goes on and on). I don't think you would regret this much, especially in today's market - you may be ecstatic and think you've just coaxed the poor desperate seller and made a steal, but tomorrow will come and you will see that you're already upside down with all the problems you've overlooked.

But let's take a step back and read the complaints above. All of them share one property: they are obvious. All you need to do is pay attention.

There are certain things you can do in order to make those those problems more obvious.

• The most difficult - look for a new house during most unfavorable season. I know, it is difficult, and plans may not work this way, and it would be difficult to have extreme conditions for the heater in the middle of the summer, but at least try. According to 6 years of observations, for Arizona (actually, North Valley, but it may be good enough for all of South Arizona) the coldest period appears to be a second half of January, extending into first half of February. Hottest period is usually the second half of July - immediately followed by the humid period (one thing I can say, though, is that if you have humidity problems in Arizona, out of all places, you'd better start walking away from that house before you finish reading this article).
  
• Next best approximation is to schedule a visit during most unfavorable time of day. Hottest time of day, as far as cooling is concerned is around 5PM. Don't even hope to get the coldest time of day - unless you get to spend the night at the house, which, in this favorable to buyer market, may not be impossible.
  
• Spend as much time at the house as you possibly can.
• Make sure the doors stay closed during this time.
• Open the curtains, don't take no for an answer.
• Shut off the fans. Even if you like them and want them. Fans may mask the problem that already exists.
  
• See where the thermostat setpoint is. Don't be cheap and spend $20-30 at RadioShack to buy a decent digital thermometer, say, 63-1087 or 63-1088 (disclaimer: I haven't tried those. The one I have is 63-1032, but it is wired).
  
• Listen to the HVAC noise.
• Run the hot shower for 15 minutes and see what happens to the walls afterwards. Hygrometer would probably be useless - sensor has too much inertia.
  
• If you feel particularly adventurous, you may even want to shut off the HVAC for a while and then switch it back on and see how it behaves. Keep in mind, though, that if it brings the temperature back no normal within 15-20 minutes, you have a unit that is actually oversized (unless it is multistage, which is very rare).
  

And, again, start paying attention.

SketchUp + HVAC-Calc = ?

Loosely quoted, "Good companies have many great ideas. Great companies know which great ideas to discard".

Alas, I will not have time to implement this, nor ways to approach the Big Guys to make this happen, but I wonder - am I the only one that sees an obvious symbiosis of SketchUp and HVAC-Calc?

Granted, it's not a five minute project, but all the necessary components are already there - and it won't be that difficult (especially for big guys like Google) to implement a real-time heat loss and gain recalculation as one works on the model of the house...

One of the most important features of SketchUp is that it, being a Google application, evolves fast. Plugins are there, too. It would be really interesting to see where it goes - SketckUp Blog is a nice place to keep an eye on it.

More on SketchUp later - it might have many obvious and not so obvious ramifications on the ways home automation, HVAC and general improvements are done. For example, the most obvious side effect of one creating a house model is that all the hidden spaces you've never thought about become obvious, and the task of routing your cable system becomes significantly less intimidating.

to be continued...

Trivia: Not Web Surfing, Blog Hopping

Not that I just realized it, but it's just I have to conduct a lot of research recently, and it is now painfully obvious - the Web as it was before is dead. Static web sites are mostly either brochureware and therefore useless, or product, service or design specifications, or simply abandoned. All current information has shifted to blogs.

Search engines seem to have heed the trend - information contained in blogs is indexed significantly faster than static pages - I won't be surprised to discover that blog hosting sites have feeds to search engines that allow indexing in almost real time.

A corollary: good blog browsing tool is of paramount importance. Web browser is simply inadequate. RSS reader is better, but not much.

Hmm...