New gas furnace/AC recommendations?

[Vic Smith]

Strange that Canadians do that. Maybe makes sense for that multi-story condo building. Wouldn't make sense for my house. Small 3-bedoom, no "zoned" heating. Though you can "zone" by closing vents and doors to some extent. In some situations a blower always running during heating cycle would work that works - to distribute fireplace heat is one. In my house the thermostat is located in the hallway adjacent to where we spend most of our time - bedrooms, bathroom and kitchen. The dining room and living room are cooler. Maybe a degree or 2. And they are as big as the other rooms combined. This suits us fine.

When we have company and are in the living room/dining room body heat and sometimes cooking heat spilling from the kitchen keeps those rooms comfortable. When it's hot though I have to lower the thermostat to keep those rooms cool. I could reverse all that by moving the thermostat if I wanted to, but it works how it is.

What would happen if my blower was constantly running during heating and cooling times is this. In winter heat would be lost through living/dining room walls and windows, and when the A/C is running heat would be gained through the same. All of this come down to personal tolerance for uneven heat in different rooms, and how much you want to pay.

There's absolutely no question that in my house a constantly running blower would cost me both in electricity and natural gas. Because it would move heat or cool air to places it's not needed. I used to argue with my wife all the time about heating and cooling. She can't take it cool in the winter, or warm in the summer. I gave up the argument. You got to know when to fold 'em. But I never even started an argument with the laws of thermo dynamics, and don't intend to.

BTW, this reminds me how car A/C compressors kick in on defrost mode. I used to pull the A/C plug when winter rolled around because I never had a problem defrosting with just undried hot air and didn't wait to waste a couple/few HP all winter just to blow dried air on the windshield. I stopped that when I heard the compressor seals could suffer from disuse, but mostly because I lost my "need for speed."

--Vic

[ransley]

On only the coldest or hottest days do I run the fan 24hr just to balance things out. 24x7 will sure wear out a motor faster

[.p.jm.]

Actually, the worst thing for a motor is frequent starts.

[clare]

With the DC blower it's only about 100 watts to run the blower on low in my house - a 2 story with finished basement and no doors between floors. The house is quite well insulated, but the upstairs is still cooler than the main floor, and the basement is very comfortable year round.With the blower running on low constantly we do not get condensation on the patio door on extreme cold days like we did without the blower running, (RH is steady at about 35%) (one register is at the corner of the door)

My daughter's place is a 6 level split, basement, entry, living room, kitchen/dining, 2 BR and bath, and master bedroom. Built like a ruddy silo - definitely no place for old men!!!! We just insulated the basement and attic, and right now, with temps down to -17, the only cool area is the entry level (built on concrete slab - 3 outside walls)

[clare]

The only motor I've had fail was the single speed belt drive. I replaced it with the 2 speed just under half way through the life of the furnace. The original was a 1/3HP, the replacement was 1/2 and

1/6. The new furnace is a multispeed brushless DC motor

[Home Guy]

[e-mail] improperly and unnecessarily full-quoted:

Look - I live in Ontario too. And I just got dumped on with 3 feet of snow, and it's like 16 to 24 F around here lately.

I live in a drafty 1976-era house. I can tell you that there is no reason to run the blower constantly in the winter. When I switch my HVAC from summer to winter mode, the only time my blower fan comes on is when the furnace is on. There is just no need for a constant breeze inside your house in the winter.

Running the fan constantly in the winter, even at a low speed, is not efficient from a heating point of view. By keeping a constant breeze, you're helping interior heat loss by causing interior air to constantly come into contact with your walls and windows, which are the coolest parts of the interior and from which heat is transfered out of your house. When the fan is off and there's no air circulation, a temperature gradient will set up in the air near the surface of the walls and that air will be cold but you won't get as much heat loss through this gradient as you would if the air was constantly mixing.

In the summer (late may to maybe late september) yes my fan is on quite a bit, and even if I had a low-speed option I would not use it - I would still be using the normal hi-speed mode for circulation and comfort.

And I still say that having the ability to draw return air totally from a dedicated outside duct in the summer and force the normal return air out of the house through another duct is more energy-efficient at cooling your house vs using an AC during those times when the outside air temp is lower than the current inside air temp, which frequently happens in the late afternoon and evening in the spring and late summer.

[Home Guy]

[e-mail] unnecessarily full-quoted:

Which are glorified stepper motors.

In my house, the only place these wimpy DC motors will ever be is in my hard drive and DVD players.

[Vic Smith]

I totally agee with that. Probably isn't done because of issues with ducting to the outside. For my basement furnace it wold take a up window, not counting the ductwork and diverters. So we open the windows when it's cooler outside than in. But if there's no breeze you really need fans in the windows to make that work well.

--Vic

[Steve]

ECM motors are *NOT* stepper motors. If you had a half a clue, you would know this.

Its too bad you have your mind made up and can't be confused with the facts. If ignorance is bliss, you must be in a constant state of euphoria.

[clare]

London area? You poor guys - Waterloo Region dodged the bullet this time!!!

You can say what you like. I heat my 1970's (1974?) 2 storey for $700 a year in Waterloo with natural gas.

Only use the AC on the really nasty hot/humid days. This last summer that was about 2 weeks

[clare]

They are a heck of a lot more efficient than a crappy split cap induction motor!!

[trader4]

I'd say it depends on how much cooler the outside air is. And even then, you have the issue of humidity which is a major concern in many climates. Pulling humid air from outside that happens to be 5 deg cooler than the house inside wouldn't seem to make a lot of sense to me. And here in the NYC area, the few days of the year you would do that, ie some Spring and early Fall days, it just isn't worth it comared to the addional ducting. Besides, I thought Home Guy was all about simplicity. At a minimum such a system would require actuators, more controls, etc. To do it right you'd have to measure outside temp, outside humidity, inside temp, inside humidity and then have a mircrocontroller decide what to do. Sounds exactly like the complexity that HG wants to rip out of a new high efficiency furnace.

If you want to go that route, a whole house fan to pull air in from outside is an option. But it too has the above problems and being in the upstairs ceiling/attic interface, you now have something difficult to seal and insulate perfectly for the entire winter. Meaning what you gain in a few days that you use it could be more than lost.

[trader4]

I have 57 years of service experience with conventional blower motors that cycle on and off with the furnace/AC and have not had one fail yet. So, I'd say using them only during heat or AC vs running them 24/7 is a non- issue in terms of longevity.

[Vic Smith]

You don't need microcontrollers. Just go to the basement and pull a lever or crank on a chain fall (-: Where I live, and the house I live in, it makes sense to draw in outside air at night about 10-30 days a year, depending. My house is brick, with little or no insulation. Haven't torn off any drywall on the exterior walls, but I know from drilling the drywall is on furring, maybe 1", not 2x4's. Never picked up any fluff when drilling. Surprisingly, my gas bill isn't bad. But it can absorb a lot of heat during the days of high sun and the heat migrates in if the nights aren't sufficiently cool. Better to have the night air working on both sides. Adds up to 10-30 days a year, depending. The same was true of my last brick house. Besides, if it's not too humid, outside air is good.

--Vic

[Home Guy]

Sometimes durability and longevity trumps efficiency.

Even if electric heat (on a per-therm basis) is twice the cost of natural gas, that extra energy used by a PSC motor is beneficially used by my house in the winter, and my PSC fan is running only maybe 25 to

33% of the time, not 100% of the time. In the summer, when my fan is running more often, it's running at full speed - something that I would also ask an ECM motor to do, and for which the ECM motor does not have as much of an efficiency advantage over a PSC motor.

So I'll pay the net $100 a year in additional energy cost and never have to worry about my PSC motor failing me for several decades - if ever.

Even after gov't rebates, forking out a minimum $2000 for a new furnace is going to take years to recover that, with the ECM motor delivering just $100 a year and the burners / heat-exchanger *maybe* giving me an additional $200 a year in savings. And by the time I've made those savings the furnace will be near the end of it's reliable life-span.

[Steve]

I have 57 years of service experience with conventional blower motors that cycle on and off with the furnace/AC and have not had one fail yet. So, I'd say using them only during heat or AC vs running them 24/7 is a non- issue in terms of longevity.

--------------------------------------------------- Running the blower on continuous for A/C here in the deep south will actually raise the indoor humidity, but during the winter I do ust the "circ" function on the system control to keep the temperature mor even between the 3 floors. The "circ" function brings on the blower for 15 - 20 minutes an hour, just to circulate the air in the house.

[Steve]

So your saying that the "reliable life span" of the new furnaces is only 6 -

7 years?? This may be true when installed by John Q Homeowner, or the lowest bidder, however when correctly installed, properly adjusted, and with correctly sized ductwork, the normal lifespan is 20 - 23 years.

You still cannot buy a new furnace today that *DOESN"T* have electronics controling it. Furnaces with PSC motors are still available, but only in the cheapest, lowest efficiency, "builder grade" models.

Maybe thats why your so against the new furnaces... your got the cheapest POS furnace you could find, you got what you paid for, and now your not happy with it.

[bud--]

Some systems for commercial buildings do use all outside air when economical. They need, if I remember right, 10% outside air when occupied in any case. Makes it more practical to go to 100%. Duct control is with "damper motors".

They don't just use outside temperature. They likely use an "enthalpy" controller, which combines temperature and humidity. If you don't take in air with humidity that is too high you don't have to worry about inside humidity, and control on temperature. One I remember had a temperature "set point" control in the supply air duct, that was a potentiometer output, which connected to the damper motor that controlled the amount of outside air that came in.

[The Daring Dufas]

I've rented old buildings in the past that had an interesting hollow tile like building block construction for the walls. The material looks like the red roof tiles and with no heat in the warehouse area, the temperature never got into the low 30° range, nothing ever froze. I don't know what the material is but it seems like the designers knew what they were doing around the turn of the last century. :-)

TDD

[clare]

Up here in Central Ontario when it is hot enough that you would want to draw in the outside air, the humidity is way too high to make it an acceptable alternative most days.

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