We are looking to install central air condintion in a ranch home that has hot water baseboard heating. The home is in northern Ohio, it has a basement and a typical hip roof and attic. I am looking for suggestions and options on were to place the indoor and outdoor coils, blower and the running of the duct work since it does not already exist. Is there a good, better, best system for this type of installation? Would it be better in the basement or attic? So far the plan is to do the majority of the work our self if possible! I have some pevious experience with the typical installation of forced air heating and cooling systems so I am not green on how these sytems work. Just need a little in site and experiences from the board members.
Thanks
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Kwik, I have a ranch with a hip roof and hot water heat. The previous owners had an air handler installed in the attic with a central 20x30 inch air intake in the hall ceiling by the bedrooms. The house has a fairly open floor plan, which helps. In the attic there is a trunk line with 6 inch insulate flex duct coming off it that goes to the registers that were cut into the ceiling. Some of the flex duct runs are fairly long. The condensing unit sits outside with the supply, return and drain going up through a partition wall that sits over the garage ceiling. It doesn't look like a very expensive system like the hi velocity systems and it works very well. -Ed
Thanks for the reply, couple questions if you don't mind, is there just one register per room? How well insulated is the system?
Kwik, there is one register in each room with the exception of the master bedroom and kitchen, there are 2. The system is not as well insulated as could be. I replaced the old flex duct with foil faced duct with an R value of 6.2 and need to put more insulation around the trunk line. The system looks to be fairly old, maybe 20 to 30 years. The house was built in the 50's so there is not much insulation in the walls and I need to blow more in the attic. I live west of Chicago and it's been pretty sticky here the past few days and the house is very comfortable. My basement is completely finished which looks original to the house so I'm sure that's why the attic was chosen for the installation. -Ed
Thanks again for the information, I really like the idea of the air handler in the basement, just figured it would go in the attic. Seems like the attic would be the logical place, allowing the cool air to enter at the ceiling, but that's why I asked the question about the placement of equipment. I guess either way there's still some issues, insulation of equipment or ease of installation.
Thanks for the help
There are advantages and disadvantages to both attic and basement locations.
Obviously, one factor is simple space. If the basement is largely finished, with no good space for an air handler, then the attic is probably acceptable. Likewise, if there's no headroom in the basement for ductwork, or you don't want to tear out finished ceilings for it, then consider the attic.
The attic does make for easier ductwork in many cases, since for a pure AC system you can probably get away with having both output and return registers in the ceiling or high walls. (However, don't assume that ductwork in the attic will be easier if you have trusses.)
The main problems with attic access are vibration/noise, access for maintenance, damage should the drain pan overflow, and winterization. In your area the insulation and sealing of the ceiling is important for comfort and heating efficiency, and with an attic location you are putting several large holes in the ceiling, plus displacing some of your insulation.
One option to consider is one of the high pressure systems that uses relatively small ducts (about 3"). Expensive, but minimal disruption in a retrofit situation.
Another big disadvantage to attic space is that the airhandler and duct work is in unconditioned space.
That can be solved, but it requires GREAT attention to all of the details of sealing and insulating.
A small leak and you are pump your nice cool air outside.
Have to agree with Bill.
One of the recent issues of FHB had a list of ten things not to do in designing, building or remodeling a home. Placing an air handling unit in an unconditioned space was on the list.
For the complete list and detailed explanations, go to Building Science Corp. web site.
Dave
If Possible I would locate the air handler in the basement especially if you have enough headroom for the duct system.
You get into all kinds of problems with equipment in the attic, such as drain pans under the equipment, vibration,and service access difficulty.
I designed systems for Lennox for years and I think the best systems we ever had used 2/1/4 inch by 14 inch floor registers on the outside walls under the windows or large glass areas and about 9inches from the wall to the C/L of the register.
We ran 5" or 6" ducts to these from the unit or from an extended plenum.
In my home using this system I located a closet with a wall facing a central location, built a box in the corner of the closet and cut an opening for the return air grille through the wall into the hall. I located my indoor unit directly under this closet and ran a 16" round flex duct down from the closet to a RA box on the side of the unit.
I built the closet box with 3/4 Plywood and lined it with 1" ductboard on all sides I put a vertical duct board baffle about eight inches behind the grille with space on each side so you don't have a line of sight from the grille to the return duct. This greatly reduces noise from the equipment below and is very important.
As for supply outlets I used twelve 2x14 floor registers on my 2/1/2 ton system. Air comes out of these at a fairly high velocity creating a fan effect which blankets the outside walls which is what you need with a good system.
If a bedroom is large and has two walls use two outlets, all others get one. You can use a 2x12 outlet in the baths. For the rest of the house try to locate the outlets so they cover the glass areas.
My blower motor runs all the time, never quits, This keeps the air mixed and circulating and evens out the temperature between floor and ceiling.Also I don't hear the equipment starting and stopping all night
Running the blower constantly is the secret to a good HAC system Its easy on the equipment(motors are designed to run) and costs less (it costs more to start and stop a motor than to just let it run)
This is my suggestion hope it helps.