Sunday, December 23, 2007
Tuesday, December 18, 2007
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;
Hmm... Turned out not quite the way I started it - but oh well, I'll just leave it at that.
Saturday, December 8, 2007
Looking outside of my window and seeing a giant plume of steam coming out of my dryer's exhaust.
Immediately thinking that next time I'll be doing remodeling around the laundry room, or building my own house, I'll definitely install an ERV capturing all that heat that is being wasted by the dryer in the heating season, and a bypass allowing it to escape in the cooling season.
Also thinking that it would be a dumbest idea possible to direct the dryer exhaust into the house because of associated humidity and smell.
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.