Air conditioner pre-install options

[joelpat]

We are gutting our 95 year old house in sections. CAC is on the menu, but we haven't worked out when to do the install (or how to pay for it).

The attic is being re-finished, but I am going to frame in part of it as a HVAC/storage closet. The closet will be about 15 ft wide by 6 feet deep by 6 1/2 feet tall.

1. How loud will the AC unit be? The closet, as imagined, will be above our bedroom. If floor insulation is the answer, I can do that now.

2. I want a pro to design the system and install the unit, but would they balk at letting me install the ducting as I go. I want to hide the ducting (hopefully no ugly soffits) but the house is going to be gutted and completed in stages.

[rabadger]

6 foot tall equipment room? I smell problems. You could be making several mistakes. Do you have drawing? If so I would like to see them.

I totaly understand what you are trying to do. Doing a little at a time sounds ok but if you start at the wrong place, You will not be able to heat or cool the building this year.

[Sparks]

Floor insulations a good idea. Usually cheap furnaces will be louder than more expensive variable speed versions. Alot of hvac contractors would object to you installing the ductwork because they have to stand behind the job when it's done, some may work with you though. If you object to ugly soffits and ductwork look into the Spacepac setup, duct work is usually pvc pipe. Its a high velocity system but it is noisier. Could be an option for you though, apparently works well when retrofitting an older place and ductwork placement is a concern. Make sure contractor performs heat loss/ gain calculation before signing a deal. Some may object and those are probably the guys to steer clear from.

[rabadger]

Are you going to drop the ceilings? If so how much room will you have to run duct?

[joelpat]

rebadger: the ceilings in the attic are low. Probably about 6'2 or so. Enough that I can stand up, but I pretty much touch the ceiling. My short Cambodian girlfriend is pretty excited to have her sewing room in the attic where she knows I won't take over.

What concerns you about a low ceiling?

As for dropping the ceilings in the rest of the house, no, we won't be dropping them. They are almost 10 feet high, and it really adds to the sense of space. Really the house isn't that big, but with such high ceilings, it feels huge.

I was thinking of running flex duct, but really I haven't done much research. We are planning to endure this summer without AC.

Sparks: Thanks for pointing out Spacepac <edit: I did some looking. Spacepak is exactly what I was referring to as "flex duct">. I'll look into it. I know some HVAC guys won't like the idea of me doing some of the work, but that's just the way its going to have to be (obstinate, I know). I don't have the certainty in my financing or schedule to sub out the whole job. I'm happy to let them design it (heat-loss, etc) and install the unit, and I'll follow their specs for ducting, but I have to do some of the work.


Thanks for the ideas.

[HVACTexas]

Joel you said the magic words, "I want a pro to design the system". I wouldn't worry about a sub balking at you doing your own ductwork. There are companies that won't like it but there are companies that hate doing ductwork too. Just keep interviewing until you find someone that can work with you on that.

Too many times homeowners think that if they call a pro in at the end of the job to do a final check braze the copper and charge the system then everything will be ok. The pro needs to be in on the design in the beginning stages. That is where the real skill comes in. Anyone can learn to operate a torch or shoot in refrigerant.

Equipment noise: Gas heat makes more noise that electric heat/heat pumps but if the equipment is in the attic I don't think it will bother you.

[rabadger]

On the ceiling-

I did a design once on a big old home where the owner wanted energy eff. He started on the outside walls with windows, insulation, doors, roof and worked his way in.

He ripped out the fire places and had a duct chase straight up into the attic. He desided to drop the 10 foot ceilings 12 inches to 9 foot. In the void of 12 inches the contractor ran all the ducts to each part of the home.

The ducts in the basement took care of floor one. floor supplies and high inside wall returns
The ducts in the ceiling of the ist floor supplied the second floor. Floor registers and high inside returns. and so on.

He got all his electric and plumbing through the chases. By adding nice drywall access doors in the chase walls all the plumbing cleanouts and zone dampers were available for servicing. When he was done and everything tested ok the ceilings when in and paint, carpet, trim last.

He ended up with 6 zones and one peice of equipment. I really worked out great.

Try not to use flex duct. It can really screw up the air flow and cause the unit to freeze. Spacepak was designed to handle the flex duct it comes with. Thats why it works so well.

One thing you don't want to do is get the equipment installed and working before you insulate and upgrade windows. If the equipment gets sized for the end result after insulation and windows and it get put in first you could end up in trouble.

HVAC Texas is correct. The design is everything. I have designed systems for owners that are remodeling. They have gone to the city school systems and fire departments to get HVAC maintenance people to help them on the side. Thats how a lot of companies get started. They don't know a lot about design work but they know how to put it in and start it up. All they need are the instructions and map. Some of the best work I have seen was done by a city of Gary firefighter that was also a tinner. He knew how to fab it install it start it up. He just did not know how to size it or design it. His partner was a fire fighter and in the pipe fitters union. He ran the service calls and was the helper on installation.

[Sparks]

Just don't totally confuse the Spacepac system with flex duct. Spacepac is a high velocity hvac system generally used for retrofitting older homes that have limited space available for large ducts. Flex duct is just flexible duct that comes in many sizes and r-values.

[joelpat]

Ignoring my individual case, how does a spacepak system relate in cost to a traditional retrofit?

[Sparks]

Well, check their web site. Could vary drastically depending on alot of factors. Sheet metal prices are high, fabrication of duct is a specialized skill and it's expensive. Theres flex, duct board, combination of the two. Spacepak, like I said involves much smaller ducts because it's high velocity and sometimes is a option for those concerned with duct placement problems. Pros and cons to each. Post a querie on HVAC-TALK. There will be a whole lot of opinions there, the more research you do, hopefully the better the final results.

[giddonah]

Be careful on HVAC-Talk though. Some of those guys don't appreciate homeowners posting questions. Just a warning.

[Cole]

Why post over there when we have HVAC pros here.

[giddonah]

They have more of them. I wouldn't post there though, and I'm even reading a refrigeration text book!

[joelpat]

I don't really want to deal with pros who won't talk to homeowners. Just makes me that much more inclined to do work myself.

If someone asks me for help in my area of expertise, you can bet I will give it.

[rabadger]

I just checked the HVAC-talk site. I opened one forum where the owner was looking to solve his proplem of the furnace being over sized. After scanning the two pages of possible answers to his problem NOT ONE OF THE EXPERTS TOLD HIM TO HAVE LOAD CALCULATIONS DONE ON THE HOME TO FIND OUT IF THE PROBLEM COULD BE FIXED AND HOW BAD THE OVERSIZING PROBLEM IS! It was all about underfiring the equipment, changing blower speeds, keeping windows open etc. I couldn't believe it. :shock:

WELCOME TO MY WORLD !

[Sparks]

But, despite opinions to the contrary, there are a lot of serious pros that frequent that site and will help out. You shouldn't ask for step by step instructions but a question pertaining to equipment choices probably would be answered. They're not all bad but I will admit there are a lot of attitudes there. I wasn't really trying to endorse another site but sometimes the more info. you get the better. Thousands of hvac pros post there on a regular basis so there really is a ton of info there if you're willing to put up with a few jerks. HVAC systems can run into big dollars and I for one would like to be as informed as possible to try to avoid wasting $$ on the installation as well as the effeciency of the system. Just trying to be helpful, not a Benedict Arnold :)

[rabadger]

Your correct, When I started reading the site I thought I was back at the heating counter pulling my hair out. I have to look further into it. It just took me by surprise that that would be the first subject matter I opened. Maybe this weekend when if I get some time.

Happy Easter

[HVACTexas]

I have over 4,000 posts at h-talk so I can shed some light on it's history. The reason that forum grew so rapidly was the owner/moderator (Don Sleeth) drew up a fair set of rules that was properly enforced. He also knew when to let squabbles continue and when to shut them down. You see without some sort of "soap opera" atmosphere there wouldn't be much excitement. So to an extent arguments were a good thing.

I have found that we keep getting the same questions over and over through the years. The most common are:

1. What brand is best?
2. What size do I need?
3. How do you wire a thermostat?
4. What air filter should I buy?
5. What should my installation cost?
6. Heat pump or no heat pump?

The answers are:

1. Installation determines success, not brand. Spend your reasearch time on finding a good contractor and let him recommend a brand to best fit your situation.

2. Square footage only tells you part of the heat gain/loss. Using a square foot per ton rule of thumb is very inaccurate. A full heat load calculation is a must to properly size an hvac system.

3. Most likely your thermostat is not broke. Take it back to Home Depot, put your old one back on the wall and call for a professional service. We get hundreds of posts saying, "I replaced my thermostat and it didn't fix the problem".

4. Let your contractor select the proper air filter. Too restrictive of an air filter will ruin your equipment. If you need your system to clean the air for air quality purposes the filter needs to be part of the design equation in the beginning.

5. Cost varies greatly from region to region. Cost also vaires from season to season and from company to company so posting prices is only asking for a bitter arguement and is highly discouraged.

6. Heat pumps are not tolerant of poor design. They need better air flow and accurate refrigerant charge. When set up wrong a heat pump will give you all sorts of trouble. But when designed and installed properly from the beginning a heat pump is a great investment. It's success (good or bad) will be determined on day one.