Central AC with no 2nd floor return vents?

[tag]

Nice forum here. Thanks in advance for any ideas. Here is my story...

We have a 100 year old 2 story Denver Square with a full basement and one room added on the back. 900 sq ft per floor, plus the 300 sq ft single floor addition off the back.

When we moved in we hoped we could add central AC to the forced hot air heating system when the furnace went. Well, the furnace went one cold winter's day, and it was not until then that we noticed that there were no return ducts from the 2nd floor. The heating system has a supply vent to every room, and 3 return vents in the floor of the first floor. We looked and looked for options in closets, etc, but couldn't find a reasonable solution to get return air from the second floor to the basement furnace. It seems to work fine for heating.

Now we are adding flooring to our attic for storage and thought it might be a good time to update the 100 year old knob and tube wiring and look into central AC "while we're at it". We've had several options offered:

#1 put a big old AC unit in the basement with the current furnace.
#2 put separate AC in the attic for the 2nd floor with new ducting and put AC in the basement system. And
#3 put AC in the attic with new vents for the upstairs, and let gravity take it downstairs and possibly use the fan in the basement system to circulate it throughout the 1st floor. (A la the heating system).

Since we live in Denver, we don't use the AC a lot, and certainly don't need a lot of humidity control, but are interested in quiet. One guy recommended hanging the attic unit from the roof trusses to make it quieter (is that a good idea?).

Because our house is close to the neighbors, we can't put the condensor on the side of the house and we are thinking of putting it on the roof of the first floor addition - thoughts?

Thanks again for any help. Tom

[airman1]

look at http://www.unicosystem.com ... it is the only system that will fit without destroying the old house design ... very small duct

[tag]

Any other thoughts? TIA, Tom

[dave_slo]

All your questions should be able to be answered by a good HVAC contractor.The options you listed, except for letting the cool air from upstairs drift down, could work.
Without seeing your home, nobody can make a really good reccomendation.
The important thing to do is get a good load calculation done, and then get a ductwork design done. These are called Manual J and Manual D calculations.
Once they have this info, a contractor can reccomend a system to cool your home.
Before you get this done, though, you should do all you can to insulate and tighten up your home. You will save money on your air and heating bills, improve your comfort, and cut down the cost of installing a new HVAC system.

[golf junkie]

Tag,

I'm a homeowner from Nebraska, my house is exactly as you describe except that I don't have the addition.

We have a basement furnace with A/C, no return ducts upstairs. This system works for us with the higher humidity here in Nebraska so I think that you could get by fine with option #1.

That's not to say it's the best, but it's all a matter of how much you want to spend, and what comfort level you demand.

Eventually I plan to add ductwork when the brick chimney is removed. For now I works OK and is much better than no A/C.

I'm also considering option 2, if you decide to go that route I would be interested to hear how it works out for you.

[airman1]

all of that is fine but if you are staying here a long time a system that gets you somewhat comfortable is somewhat a waste of money ... imagine haveing a top of the line unico system that gives you absolute comfort and it cost twice as much ... but then last twice as long ... costs less to operate ... makes it a joy to live there ... does not destroy the ambiance that you bought the house for ... the only negative other than the investment is you will have to explain to your friends who visit why your house is more comfortable than any house they have been in ... but then you can always just say "they just dont build them like they use to" and see if they believe it ... as one contractor who does ONLY the highest comfort system money can buy i can describe that level of performance in one word ... "PRICELESS" ... it takes a lot of effort to find someone like that and the unico company engineer works directly with us on all blueprint designs and duct layout for a trouble free installation and standby to assist us with any issues ... unico only does the air side of the system ... with airtight duct designs(less than 5% loss) ...no condensers(outside) ... totally focused ... try finding that in the big boys ... you wont ... they sell boxes only ... figure them out on your own ... at least look in this direction before you jump in the fire ... there is NOTHING WORSE than a cheap lousy air condition system that you though was a good deal ...

[Edited by airman1 on 04-27-2005 at 10:15 PM]

[tag]

Can you explain the Unico system to me? That's the one with smaller ducts? Would the system be separate from the furnace? If it's in one place, I assume the basement, how would we get ducts to the second floor, and how would we get return air from the second floor back to the basement? The first floor is very open with wide doorways between the rooms and one tiny coat closet. I'm not sure how we would get the ductwork between the 2nd floor and basement. Thanks for your advice, Tom

[RoBoTeq]

I'd go with the attic system only and see how it works out for you. You can always do something on the first floor if the attic system alone does not do the job for the first floor. Mostly that will depend on how open the rooms of the first floor are.

Spot cooling can also be added to problem areas such as that room addition. A nice ductless system just may do the trick.

[airman1]

the unico system ducts will fit between the stud joists ... call the number at unico and ask them to refer to one of their recommended dealers ... conventional ac may work and may work fine ... but check it out ... unico uses hot water heat ...reverse chilled water heat ... heat pump that is excellent for heat ... and finally electric heat ... aductless system design may work well also bu it is more obtrusive than a unico less obtrusive than conventional system

[Panama]

How about a fully automatic Australian swamp cooler? They really work well in Denver's hot (95 °F), dry (15% RH) climate.

Of course today you need heat, as it's 26 °F, 91% RH, and snowing.

[tag]

Ahh, Springtime in the Rockies! Tom