Who Needs A Thermostat?

I've been pondering about this question for a long, long time - starting in about 2001 when the only way to control DZ available was a debug panel, and last time in an essay about SWMBO Compliance Certification (Squeezebox is still a good candidate), but it seems that there's been a new development that might if not put an end to the fruitless search, then significantly widen the options available.

I'm talking about Android.

It remains to be seen how viable the platform is and how many hardware manufactures will jump on the bandwagon. But for now - having worked on different Google APIs (Checkout and Calendar in particular) I can say that it's sure going to be a hell of a fun ride, and I'm about to get busy installing the Android SDK and tinkering with it to see how well can a user interface for a HVAC system work on a cell phone.

Now, who needs a thermostat on the wall, really?

SketchUp + HVAC-CALC, part 3

(part 1)
(part 2)

Now, Official Google SketchUp blog reports that the beta version is available for download.

Hurry before they change their mind.

SketchUp + HVAC-CALC, part 2

You've read it here first. Now someone closer to the subject area implemented it: Energy Analysis Tool for SketchUp.

Told you.

I'm waking up, too

Those who have been following this project since days long gone may have noticed that nothing really significant appeared here in about last two years or so.

There were many reasons for it - I've changed the house (couldn't staple those nice looking blue cables to white walls any longer), changed the job (free time have become scarce), and all the things that could've been done to the project itself were essentially done - there was no significant itch to scratch anymore.

All of this changed again recently - energy prices are going up, kids are growing up, conditions change, and my last electric bill was whopping $420. Twice of what it was two years ago.

So the itch is there again.

And the last straw, I've made a mistake of undertaking a wiring project - and of course, as soon as I've opened the walls, I've realized that this is a perfect opportunity to install DZ again - and as soon as it is installed, two years worth of unimplemented ideas will start begging to be implemented and perfected.

So, the short term plan goes like this: Finish wiring, install sensors, install dampers, install DZ and roll on. Will not be fast (a simple speaker wiring project turned out into an exercise in advanced framing, insulation, conduit installation, drywalling, texturing and painting; plus, a new server room will be built to accommodate everything) - but it will be thorough.

Stay tuned.

Big guys are waking up

At last (seven years later), there are signs of companies that manufacture and install zoning systems and components for living waking up and paying attention to their Internet literate customers. First time ever, links from them (as opposed to mere installers) appear on the first page of Google search for related terms.

Eventually.

It appears, though, that they have to pay for listings to have them above DIY Zoning - which was the purpose of the project to begin with.

Let's see what the future holds.

Look, Ma, The Zone Control Blog!

Not this one. The one Jackson Systems created, here. Fresh one, too - started on September 24 2007.

Don't know about you, but I'm definitely looking forward to reading it. I sincerely hope it's not going to be an another clog.

---

Clog, n - a type of website where entries are made (such as in a journal or diary), displayed in a reverse chronological order. Clogs differ from Blogs because the content is typically aligned with a marketing or press release strategy in order to promote the company or corporation. -- Wikipedia entry on Clog

Short take: two HVAC units vs. Zoning System

Talk about outsmarting oneself.

The whole point of The Dual Nightmare article was to convince the reader that there's no way two HVAC units can serve the house as good as one zoning system. Alas, the subject didn't click together with what people were looking for. Let's see if this one is better.

Short Take: Where's My RTH7500 Manual?

Exactly where you put it, dummy.

Correction: I am the dummy.

So here I am, trying to figure out the way to configure the hysteresis and, at the same time, save myself a long walk to the shelf at the second floor where I *think* I put the plastic bag with the manual and spare parts. Also, it's middle of the night, it's dark, the light switch is out of the way, everyone in the house is asleep and I don't want to step on the cat strategically placed somewhere down my path.

So I'm thinking: it's 2007, let's google it up.

Yeah, right.

I guess my patience is thinned by previous encounters with HVAC machinery and service, unlike one of this gentleman.

Mind you, all configuration settings in this thermostat are not described by words. They are described by numbers. There's no way in hell I can remember numbers I have to use once in a few months, if not years. And the paper manual is nowhere to be found. And what other companies usually put up (a printable PDF document) is nowhere to be found, either.

Nice.

Another score for Rite Temp.

And don't lose your manual, otherwise you end up with a quite expensive brick on your wall.

Update: I've found the manual...

The Dual Nightmare

There is an ongoing heated discussion among homeowners and HVAC professionals about what solution to the problem of properly balancing the house is better - zoning the house, or having multiple units installed. There are all kinds of arguments on both sides.

The proponents of zoning are usually saying that it would be silly to use one switch to turn on or off all the lights in the whole house, whereas the opponents are pointing out that it is silly to pump the amount of air intended for all ducts together through one.

The opponents of zoning are usually saying that it is more reliable to have two simple HVAC units than it is to have one complicated HVAC unit and one complicated zoning system, whereas the proponents are pointing out that maybe HVAC professionals may be simply out of their depth and are trying to cover that up by silly arguments.

The opponents of zoning are saying that having two units is an adequate solution to the balancing problem and point out to the fact that existing commercial zoning systems are rarely extending "affordable" options beyond four zones, to which I say they are completely nuts and give the room (read: zone) count for three quite average houses that I've lived in: roughly 11 zones in Iowa farmhouse (2 levels, 4 bedrooms, full basement), 14 zones in one house in Arizona (3 levels, 4 bedrooms, game room, library) and 13 zones in the house I live in now (2 levels, 3 bedrooms). Oh, I do include bathrooms, too.

But I digress.

Sometimes you just have two units - for example, when you simply buy the house with them installed - it would be silly to rip them out, wouldn't it? So one just has to deal with it...

Whereas having two units is certainly nice, it is by no means a guarantee of any improvement whatsoever. Like it was pointed out before, all your luck depends on having the job done right.

Sometimes your luck is improved by the fact that the house was designed with heat exchange physics in mind (little heat transfer between floors, narrow staircases).

Sometimes it is degraded by the fact that aesthetic considerations took priority over common sense - wide open floor plans with walls being mostly glass, rooms spanning several floors vertically, and different floor count in different parts of the house.

Which is exactly the situation I have to deal with right now. The north side of the house (1 floor, 2 rooms + 2 bathrooms) is served by a nice powerful variable speed high SEER Lennox split unit. The south side (2 floors, 4 rooms + bathroom + kitchen + laundry room) is served by a puny rooftop Trane and a set of drinking straws they called ducts.

So let me skip the rant about how unthoughtful that was, and get directly to describing various interactions between two units that may happen. Let's assume for simplicity that we're talking about cooling season behavior.

Unhappy Load Meter

If both units kick in at the same time, and you are on a load controlled electrical billing plan, you're not gonna be happy. Neither is your electrical company, but that's a completely different story for a different time.

Cold Spots

It may happen that both units serve the same room[s], directly or indirectly, and the room has enough or more than enough supply and return capacity, and neither of the thermostats is in it. If both units kick in at the same time, the room will get uncomfortably cold.

Hot Spots

It may happen that the cold air supplied by unit A drags down the temperature at the thermostat controlling unit B. In this case, it will not get unhappy and cause unit B to switch on until unit A is off. Which will cause the rooms normally served by unit B to become uncomfortably hot.

The Skew

To add insult to injury, it is quite possible that the layout described above also makes unit A serve, at least partially, the zone that is supposed to be served by unit B - and in this case, unit A will keep running and running, possibly not even catching up with demand - and it will not get any help from unit B because the effect described above robbed unit B of necessary control input and is preventing it from switching on. You end up with one unit trying to do the work of two, for which it is clearly undersized. To further aggravate the situation, it is possible that the overworked unit will go beyond its normal design range, and then you have a dead unit (ask me how I know).

For more than one floor, The Skew is rather a rule than an exception.

Ask yourself a question, don't you always have to set the thermostat downstairs a couple of degrees lower than upstairs, otherwise it feels hot and stuffy? The scenario above explains it vividly. All there is is a leak of cold air from upstairs through the staircase (or a tall room) that causes the thermostat downstairs to make the unit stay off.

Catch-22

To prevent The Skew (further defined as one of the units working significantly longer than the other), you need to carefully balance the thermostats in such a way that the race never starts. This will usually mean that you will have one of the thermostat set below the comfort level, and the other above. Also, this is going to cost you, because the difference between "comfortable" and "balanced" positions of thermostats is going to make a significant contribution to your electric bill. Also, it robs you of comfort. Also, it will make you fiddle with controls all the time, unless you have monitoring set up, in which case you'll just spend half of the time fiddling.

It would be interesting to know what side of argument described at the beginning of the article you are now...

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.