Location of furnace?

I am planning to purchase a new house. I found the builder put the furnace in the attic. I guess it might be good for rooms in the second floor, but not so efficient for the first floor. You might feel too cold in winder. I am not sure if the furnace should be in the basement. Some people say putting in the attic is less expensive for builders. It is a single zone heating and cooling system. (forced air.)


Sorry. I got confused with the names of furnace and boiler. It is square box. You may call it AC blower.

Which location is better ?

 

Does this house have a basement or only a crawl space?

The furnace needs to be installed where it is accessable for servicing, if the choice is between a crawl space with only 18 inches of clearance vs. an attic with 48 inches of clearance I would prefer the attic location.

If you have a basement with 78 inch ceilings (or more) then the basement is the proper place for the furnace.

If the duct work is properly sized, insulated and installed then the location of the furnace is of minimal concern in regard to the comfort level in the living areas.

 

Thank you furd. This is a brand new construction with 12 cource brick basement. I just feel curious when most people install furnace in the basement , why this builder chose to put in the attic. Do you need a less powerfull furnace if you put in the attic?
I assume it is not so easy to repair the furnace when it is in the attic.

 

You're going to be sorry. In twenty years in the trade, I have never seen a two story house with a single zone heating & cooling system which was comfortable all year in all rooms. In a nutshell; two floors/two systems.

 

Grady has a valid point but it is more in line with poor design and installation than any inherent flaw in the concept of one heating system for a multi-story home.

I personally do not like forced-air heating systems for a variety of reasons and zone control is near the top of the list. That said, a properly designed and installed forced-air system CAN achieve desired comfort in a multi-story residence. The key word is properly.

Few architects design a home starting with the mechanical systems but instead focus on the outside appearance, the various rooms and traffic flows. The result is that mechanical systems such as heating, cooling, plumbing and the like are placed where they fit rather than in their optimal locations. Builders also take whatever means necessary to fit these systems in "somewhere" rather than their best location.

It is unfortunate, but most architects, builders and homeowners never consider the true requirements on the mechanical systems, I guess they are just not sexy enough. The result is that almost all residences, regardless of the money poured into their design and construction, have less than optimal mechanical systems.

What Grady is pointing out is that the heating requirements of a multi-story house can be vastly different on each level. It is almost impossible to maintain desired temperatures with only one thermostat controlling the heating (and cooling) system regardless of where that single thermostat is located. The answer is zone control but zone control in single-furnace forced-air systems introduces other problems and complications to the point that it is often less expensive initially to install separate systems for each floor. The downside is that the homeowner is left with multiple systems, all of which need periodic service, and (usually) greater maintenance and energy costs.

I know, not really what you wanted to hear. Take heart, though, I'm a perfectionist and most residential heating systems function on an adequate (if less than optimal) level.

 

Thank you two for your detailed explanation. Actually, one-zone system is still quite popular in 10 year old houses in my area -- New Jersey, but not much for brand new construction.

A friend of mine had the same layout. He told me that in winter, he felt too cold in the ground floor while the temperature is OK in the 2nd floor, because the air comes downward from the attic. Someone suggest installing another system in the basement, to supply a baseboard loop for the first floor.

I really do not want this happen in my new house. My another concern is if I want to finish the basement, how we can install supply and return holes. Opening the walls to insert lead new duct pipes down from the attic might be painfull.

By the way, how can I tell one zone from two zones? Do we tell by checking the number of compresser outside? That is for cooling only, right? I saw most new houses have two compressors, but this one has only one.

 

Now I am getting confused, are you having a heat pump installed in this house or a fuel-supplied (gas) heating system in addition to air conditioning?

The "compressor" located outside MAY be for just cooling or it may be the outide unit for a heat pump. If some of your neighbors have two "compressors" then they MAY have two separate systems for upstairs and downstairs areas of their homes. If this is the case then I strongly suggest that you follow Grady's suggestion of installing separate units for the upstairs and downstairs.

 

Thank you Furd,
The compressor outside the window should for AC units, as you said, upstairs and downstairs. We have not installed that yet. I double checked the in-house installation yesterday and found a smaller gas fueled furnace (maybe some people call it boiler,) is in the attic , while we also have a bigger one down in the basement, next to the water heater. Both have supply and return duct pipes. I do not konw it will be called one zone or two zone heating system.

 

If the unit in the attic has a gas line (natural or LP) and a vent stack going through the roof it is a gas-fired unit. The same applies to the unit in the basement.

If either of these units also has (relatively) large ducts then it is a forced-air furnace, if instead of ducts they have pipes no more than one to two inches in diameter then it is a boiler. It is unlikely in new construction but if one of the units appears to have ducts with numerous branch ducts three inches in diameter or less then you have a high-pressure air handler and it most likely is for cooling only.

If you have two gas-fired units (one in the attic and one in the basement) you probably have a two-zone system. The attic unit will serve the upper floor and the basement unit will serve the lower floor.

If you have two condensing units (the outdoors part of an air conditioner) then you probably have two separate zones of cooling, upstairs and downstairs, with one outdoor unit connected to the attic furnace and the other outdoor unit connected to the basement furnace.

If you have only one outdoor unit it could be connected to BOTH the attic and basement furnaces (unlikely) but it will probably be connected to only the attic furnace. If it is only connected to the attic furnace then you will have poor A/C on the lower floor.

 

Great! I learn something everyday here. So we call the outside unit condensor, not compressor. Then what is compressor?

Now I know this new house has two zone heating units, forced air. Let me see how many condensing units they are going to install.

 

The compressor is housed inside the condensor unit. I would assume if you have a forced air furnace in the attic and one in the basement then they will instal a/c into both of them.

 

Yes, that's what I am guessing, too. I do not know how they could divert the pipe to two air handlers (now I know the name) using one condensor.

 

Hi, all,
Eventually, they installed 2 condensing units outside.
So this house has 2 heating and 2 cooling systems. Thank you all for your knowledgable reply.