Variable Speed & Multi Speed

[martib]

This is my first furnace/ac purchase so go easy. What, exactly, is "variable speed" for the furnace? I have been looking at a Trane XL80 with and without "variable speed". In looking at the product brochure, I see a variable speed draft inducer (listed to the XL90), a two speed draft inducer (XL80), and a multi-speed blower motor. I'm sooo confused.
Also, I'm in a condo unit so the furnace is inside the unit. One installer has mentioned they would be putting extra insulation to make it quieter. How noisy might this unit be compared to a 26 year old General Electric?

[docholiday]

Your not going to like this but odds are its going to be noisier. your old furnace didnt have the inducer motor or inshot burners. It also probably didnt have the drive capacity of the new one.

A 90+ will be quieter for the most part than an 80+ because the combustion is sealed and the combustion air is brought in from outside which allows the cabinet to be closed versus louvered.

VS is simply a motor that varies its speed to maintain a constant airflow. In a two stage unit, it will vary airflow based on the selected constant speed and restrictions in the duct. A multispeed motor is just that but its not automatic. It also costs more to operate than a VS motor. And generally the multi-speed (PSC) offers fewer dehumdification options for cooling than a VS.

[youngoldtech]

I agree with the Doc a 90% furnace will be much better for noise control. And the variable speed blower will help with the noise, as it starts it wont sound like a blast off, it will start slowly making it easier on the light sleepers.

[martib]

I was told that I could not use the XV90 in my unit, only an XV80. I have about 850 sq ft in my condo. Is it a matter of size of my unit or size of the furnace? Or ??

[mayguy]

Both XV90 and XV80 are same in size, and BTU Rating. Only thing i s why the 90 won't work is the venting... Where does the furnace sit now? If it's in the attic, then that's why 90 won't work. if it's up there or in a remote are from the living area, you won't hear the burners.. if it's in the hallway next to the living room, then yes you will hear the burner on 80%

[t527ed]

90% furnace needs new venting system either sidewall or thru roof. some of the condo assoc around here won't let them be installed.

[millerman]

You could possibly run the pvc inside the existing flue pipe however it must be large enough to accomodate 2 2" pipes. You can be creative in terminating the pvc without much exposure.

[t527ed]

most gas heaters in condos around here have water heater venting into existing flue, so thats out.

[millerman]

They're you go.

[ruud-man]

Martib,

You may want to consider the new RUUD GPN 80+. The combustion aree is shielded by a solid front door. It is possibly one of the most quiet 80+ furnaces on the market.

Good luck,

[martib]

Thanks for all the comments. I was told that I could not have the 90. The furnace is in a utility room off my hallway and next to the living room in a 880 sq ft condo. The contractor has said that they will add extra insulation to make it as quiet as possible.
Am I allowed to ask about the difference between union labor and non-union labor - at least in terms of quality of installation? I realize (being a former union person) that union labor is often more expensive and want to find out if a difference in training or education etc. warrants a higher price. Thanks.

[martib]

After reading my first post again, I realized that I mentioned the Trane XL-80 when I'm actually looking at the XV-80. How much different is that unit related to the noise?

[mayguy]

Have they told you WHY you couldn't have a 90%??

XV80 is going to be quiet with the blower motor vs the XL.. They are both still 2 stage heating, just the blower is diffrent.

I still would go variable speed since it's in your home, and not in the basement/garage.

Make sure room has make up air for the 80%

[martib]

No, I didn't ask why - but I will. I thought perhaps it was because of the size of the condo or maybe the size of the unit itself. The area the furnace has to fit in isn't real big however I understand that the current units are much smaller than my 26 year old GE. I'm going to ask why. Thanks.

[Irascible]

Can you even find union shops that do residential out there? Out here union shops have been relegated to the commercial sector. But union or not I personally think it's irrelevant. There are hack union shops, there are very professional non-union shops and vice versa. I'd pick the best contractor irrespective of its union status.

How far from the furnace is the return inlet? There are many components to a quiet system as have been mentioned. One of them is not having a super short return duct. Another is special ordering high quality diffusers. Take a look here.

[martib]

Thanks for the information. I'm not sure what the return inlet is. If it is the large vent near the ceiling in the hallway, then then furnace is right on the other side of the wall. There is another smaller vent opposite the furnace in the utility room.
Regarding the union question, I was curious since the contractor I'm considering has been recommended by a friend who used them but they are more expensive than a couple of other quotes I've had. They do both commercial and residential work.

[Irascible]

Yes. The return is where the suction is. Some furnaces are literally a foot or two from the ceiling vent you describe. In those cases the blower noise if VERY loud. It can be quieted by looping a return duct or by other means. But in your case it doesn't sound like it's that close.

[martib]

It's as close as the thickness of the wall. The furnace is against the wall that the vent is on. The vent is up high near the ceiling. Then there is the old Aprilaire humidifier and then the top of the furnace. When the new furnace is in, as they told me it wouldn't be as tall, the distance will probably be about 3-4 feet to the top of the cabinet. There will be another humidifier installed also.

[Irascible]

So then I imagine you get a significant amount of noise through that vent in particular? If so then you might consider doing something with that duct if the airflow situation and space will allow.

[martib]

Yes, the current system is rather noisy. One of the reasons I don't leave the fan going all the time. The contractor mentioned doing some things that would help to quiet it down. Since the initial post, I went back to him with some questions and he said that the new system would be substantially quieter than what I have now.
Thanks!