Hello,
This is one of those questions, that if you have to ask, you should not be doing the work. Yes it is simple, but assumptions you make can result in very poor efficiency and in dangerous conditions. Metal is used because it is the best material to use. I can have a box made for $750, and will ship it to you for an additional price of $25.00. OR you can have it manufactured for a reasonable price. This is not a Home Depot product. Ask the supply house where you bought the equipment, they will probably have a source for a plenum. It will not have any duct openings, but this is easy to do. Cut the holes in the side of the box. Poor installation can cause killer problems. If you don't have a clue, don't attempt the install. This is one area that can cause death if done wrong. Death to your entire family if not done properly. This ranks up there with using C-4 and a lighter for stump removal. Jogging after dark in dark clothes on a street without lighting is safer. I am not against HO's doing service work on thier house, but if you don't know,hire someone that does know. Ask questions.

I would take a guess at $200. My entire system is metal and it cost $1400 last year.

Hi baymee, thank you very much for the information, $200 was a very good guess as it is very close to the estimate I got from a fabricator.

Hi Bob, I got an estimate from a sheet metal shop on the box and it came in at just under $200. Thank you for your generous offer to sell me one for 4 times the market price. I will keep that in mind when I read your responses on this message board. I would also like to thank you for your obvious concern for the welfare of my family. I suspect that an electric air handler and heat coil is far less dangerous than you seem to think but no doubt you could site thousands of cases of DIY wiring jobs that lead to mass deaths all over the country. But you know, we are all Do-it-yourselfers, including you. For instance you probably drive a car, odds are you do that for yourself and your family. But are you a professional driver? Have you trained on a track, in all kinds of weather, while tired, with moving obstacles? Did you do your training recently to keep it fresh? Did you train in the car you currently drive? Probably not. You know over 25,000 people die each year in car crashes, tens of thousands more are maimed, in the United States alone, world wide the carnage is unbelievable. For the sake of your family and the other people on the road please sell your car and have a professional drive you where you want to go, you have no idea how much danger you are in from your lack of skill and knowledge in this area.

So what do you think Bob? Kind of silly isn't it? I ask lots of questions Bob, it is one of the ways I find things out. If you don't want to answer them that is fine but please don't waste my time and bandwidth on these condescending warning messages. And learn something about risk assessment, will ya? All that talk about blowing things up is going to scare the children.

Hello,
Ask this type of question and you get a dumb answer. The markup is not 4x. It is probably closer to 15x. I was not concerned about electric issues. You still don't understand. If the questions are about metal vs wood with a product that has always been made of metal or stone, you do not have a clue. Noxious gas is a bigger killer than electrical fires. Electrical fires are a big percentage of house fires, but toxic poisioning is a greater problem. If you have to ask about wood, then the whole gammet of design is beyond your concept of safety. This is if the system uses electricity for heat. If you use gas, the danger is closer to the C-4 analogy.

I have stated many times about the complexity of HVAC. This is not the same as hanging a mirror, or painting a door. Adding an electric circuit is simple in comparison. Learning about the subject cannot be done in a few obtuse questions. Ask proper questions and I will answer as best as possible.

guyinacoldhouse, I think what bob is trying to say is judging from the questions you've been asking in this forum lately it seems that you are sort of using it kind of like a correspondence course. At the stage of the installation you are at now there isn't much of a danger but some of us can see where you are headed here. Believe me, you are going to get to the point where you you will not be sure if what you are doing is correct and if not it can be a safety issue. And you wouldn't even be aware of it. I may not always agree with bob but the man has been contributing to this forum for quite some time and like me and the others of that status you get to know when a person is getting in to deep. Keep in mind, none of us who come here to help the layman want to see anyone get hurt or killed because instructions or advice was misunderstood. Not to mention the liability just for trying to be a nice guy. Maybe bob is a little gruff with his explanation of why you may be getting in to deep,I'm guilty of that myself sometimes. Keep in mind though the advice you are getting is toally free and the people giving it are doing it simply because they enjoy helping others. If you don't care for the advice or how it is given keep in mind "you get what you pay for" and if you do something to endanger yourself or you family, you won't have bob brown to blame.

No Bob, the other poster was able to give an intelligent and helpful answer, and it was very close to what a fabricator quoted me. You gave a dumb answer, everyone responds according to their ability I suppose. You can't force superiority Bob, let your intelligent and helpful answers speak for themselves, they will show the world that Bob Brown knows of what he speaks. The current crop of responses tells a different story.

Hi Mr Havac,
Thank you for your pleasant post, I needed that after the odd ones before it. I do appreciate the people here who try to be helpful, they generally are. I will have to learn to ignore the folks who are working out their own issues.

Normally, you use local sheet-metal shop for this job and that is not too expensive. They will help you all the way because you may have very unique plenum setup. By little leaky plenum, I have not seen any death or fire but just waste of heat! Now you know that it does not weigh $150lb! It is very light!

Hey Guy,

What a snotty response. Two of them, even.

And thank you for your lecture about how people are competent to fix their own heating equipment. The most people I've sent to the hospital with carbon monoxide poisoning at one time was eight, although that was in the kitchen of a restaurant. But what do I know?

But go right ahead and do what you are going to do anyway. I've encountered fools like you many times. As noted, since you have only the haziest idea of how a furnace works, you are not going to be able to recongize hazards that may exist or which you may build into the heating system.

But again, you don't want to hear things like that.

Seattle Pioneer

I suppose I could have thanked Bob for his attempt to cheat me, I wasn't feeling very charitable at the time though. I do feel sorry for the guy, but he has no idea how to judge risk, my electric air handler is the least of my worries. As you say, kitchens are much more dangerous and as I mentioned, cars are deadly. Why someone would try to stop DIY work on HVAC when 25000 people are killed in cars each year is beyond me.

You are welcome, I don't recall the lecture but if it helped you then I am glad of it.

Can you tell me what you meant to say in this post? 8 is the most you have sent to the hospital, were you the installer, the paramedic, the police chief? Why are you sending anyone to the hospital, I never have. Am I to assume that this was a kitchen installed by a DIYer? Odds are it was a professional job and it was dangerous, are you arguing that professionals are not competent to install kitchens? I am not getting the point of this post.

I'm am also not getting why you and Bob keep talking about poison and explosions when I am talking about an all electric air handler, where do you suppose the CO is going to come from? And what part of the electric coils are going to explode?

I can not answer the question of what you know. You might know quite a bit, you might not, there is no way for me to tell. If you know quite a bit then you might find it uplifting to share the knowledge.

I was really surprised at the outpouring of negativity that I found on this forum, I think some people feel threatened by DIYers. The DIYers of this world pose little danger to the jobs of the competent professional HVAC technicians. I would be willing to bet that many pros started out as DIYers on something, probably their cars, enjoyed it and found a profession that valued that kind of problem solving ability.

Anyway thank you for your concern, I will install a few CO detectors.

And thank you for your permission to continue with my DIY projects. As I write this I am listening to the gentle hum of my air handler and enjoying the soft currents of warm air moving through my house. No doubt I will be dead by dawn tomorrow, but I will enjoy my warm fool's paradise while I live.

To answer your first question of Dec. 07 / 06. Metal is used because it is light, strong, and DOESN'T BURN. What you do by building a wooden transision is contribute to the spread of any fire that could start in the furnace and work it's way into the room. A serious code violation up here. If i was the inspector and saw that i'd lock off your hydro to the unit untill it was done properly. God help the person that tries to break the hydro seal. Hope this answers your first question. Nobody else seemed to. I can't believe this forum is still alive.

Hey kalining, do they call natural gas up there "hydro"? Seriously now, no kidding around, I didn't know that. We down here think of fluid when we hear that word,, you know, like hydronics, hydro-electric. Ya learn something everyday!You're right though, some of the advice in here does tend to make the eyebrows raise a little huh?

Mr havac. Unless i'm wrong and i appologize in advance if i
am. Half of the morons that post replies on this site don't read or don't know how to read. The man has an electric air handler. That is HYDRO up here. as in hydro
electric. Electricity produced by water power. ( fluid ).
He doesn't say what makes the heat. Another problem from the poster. " not enough info ". It boils down to a big guess as to what the poster wants. this site is good
entertainment. ( havac, I didn't call you a moron. ) Look
at this site. The poster asks one question and gets ten different answers. Now what the hell does he do now ? Doesn't anyone think that if one question is asked and if it is the right answer there should be one right answer or ten of the same right answers ? I've seen your advice (havac) good stuff for your area but up here some of the advice could put you in the can and have your licence pulled forever. Every area is different. Then there are the nut cases that say HVAC is not rocket science. No it is not, it's more complicated than that. Rocket science can be proven on paper every time for every application and it never changes. Try that with a home HVAC or a commercial one. NOT. Actually the poor home owner might be better off not coming to this site and save themself a lot of grief. I.M.O. they come to this site for FREE info. FREE advice, FREE install information, FREE trouble shooting, and "please help me after my screwed up install because i was too cheap to pay someone to do it properly".
that pulls thousands of dollars out of our pockets. Hay, just a vent and one man's oppinion. Pleae disregard this post if offensive. No offence to all of the many fine techs on this site.

Flat stock 16ga galv steel sheet 2.6 lbs per sgft the shop will charge a full sheet regardless so a 4ft x 10ft sheet = 40 sgft x 2.6 = oh I dont know maybe 100 lbs at a cost of around 65 cents a pound so maybe 65 bones material plus weld costs of say 20 bones now add approx 4 man hrs at around 50 bones so anything under 300 bones should be good for a nice heavy metal plenum box. Wood being a combustible material, should not be used for supply or return duct work, especially close to the heat source. How do these threads get off on such wild tangents??

To those of you who wanted to help me with this project, thank you. Dnt1, if yours had been the first response to my post I would almost certainly have found a metal shop and had my ductwork made for me.

For anyone out there doing their own install, the best reason to go with metal is probably that that is what the inspectors are used to seeing and you don't want to make them uncomfortable. I was just grousing about metal because of the learning curve and the tools, turns out it isn't so bad. Anyway that question has been overtaken by events. My air handler is working just fine. While I got little direct help from this forum, it was useful for some general information and it has been very entertaining. Though much of it is like road kill, it draws the eye but it is kind of horrible to see.

The National Fire Protection Association (NFPA) 90B - Standard for the Installation of Warm Air Heating and Air-Conditioning Systems - 2006 edition (which no one bothers to read) says that wood is fine, it just has to be 25.4mm (1 inch) or more inches thick and perhaps lined with something noncombustible, paragraphs 4.2.1.1& 4.2.1.3. I read something like that and it makes me wonder why they are all made out of metal. Seemed like a reasonable question, the experts see no grave fire hazard, wood is stiff, strong, cheap and easy to work. I naively believed that thoughtful folks on this site would be able to tell me more than the NFPA. Didn't mean to make a scene.

As for HVAC being harder than rocket science, design a HVAC system, now design a rocket to land a man on the moon and get him back, which will be easier for you do you suppose? Just try to design a nozzle and prove that it is an efficient design, that should be an education. Find a book about Goddard, what a guy he was.

One time on Bob Villa (I think) show, one HVAC contractor explained how to build air ducts from 4x8 tuff R foam sheet! It was a very easy procedures to build and connect! So I am sure some HVAC contractors are using that methods!