I’d stop it now, before you wind up having to rip open walls and ceilings.
Efficiency, reliability and performance all take a hit with hack work.
I'm in the middle of a to-the-studs whole-home renovation plus an addition. Inland Southern California with 100F summers and winters with no worse than 40F overnight lows. Plumbing and electrical have just been roughed out. I'm going through a fancy design/build general contractor, and being an idiot I didn't have them specify anything other than that I'd be getting central air (I had no central air or ducts before this started). It turns out they got a low bid from a guy who owns a plumbing business and an HVAC business.
I've seen the plumbing/HVAC guy once for about 15 minutes so far, right after his guys installed the ducting. My house is on a slope so that the street level is basically the main floor, and there's a 600 sqft basement-like area beneath the kitchen in the rear of the house. I pointed out to the HVAC contractor that there was a supply register (no return) in the basement area where I was told I'd be having a mini-split, and he said his guys didn't know that when he sent them out to run ducts so he'd yank it out. No big deal I guess, but the thing is the whole job looks like it was done without a single thought:
- Before they'd started I asked my general contractor's project manager to have Manual J calculations done and he said it was unnecessary for such a simple house (it's not a simple layout), and that instead they just divided my square footage by a magic number to get tonnage. I'm SURE they didn't run J, S, T, or D.
- 1680sqft main floor with only a single small return in the floor. No one has mentioned any transfer grilles or door undercutting.
- They placed registers where a closet was going to framed and in two other places where my general contractor knew there'd be furniture, so they obvious never consulted with the general contractor.
- There's only two registers in the 800 sqft main room and they're in the middle of the room on opposites side of the 12' wide room pointing at each other.
- There's no registers anywhere near the kitchen (part of that large main room)
- Even though the blower/air handler is at far side of my house, they chose to spider out flex to every room.
- All the flex appears to be the same size and is tightly strapped with metal straps to the point that it's obvious the flex is being squished.
- The general had asked them to install a Goodman, I'll be paying an additional $ at least to get a Rheem (more if I want a two-stage). I don't really have a problem forking over the extra money, but it's just one more small annoyance to deal with. They have not installed the unit yet.
So, my question is, should I just let them finish installing the unit then call up an actual professional HVAC firm and have them rip everything out and redo the ducting for (I'm guessing) $ or so? Or should I wait and see how well the system works, risking an increase cost to redo since the walls will be up? Is there a huge efficiency difference between a good and mediocre install? I figure it will probably be worth the money in the long run. I doubt the guy who did the work is going to suddenly agree that it's shoddy work and needs to be re-ran, and even if he did, I doubt he has guys with necessary knowledge and experience to do it right.
Last edited by beenthere; 10-22-2018 at 04:21 AM.
I’d stop it now, before you wind up having to rip open walls and ceilings.
Efficiency, reliability and performance all take a hit with hack work.
“I haven’t failed. I’ve just found 10,000 ways that won’t work.” - Thomas Edison
“It’s not whether you get knocked down, it’s whether you get up.” - Vince Lombardi
"In this house we obey the laws of thermodynamics" - Homer Simpson
Local 486 Instructor & Service Technician
In general, should Manual J/S/T/D calcs should be expected for any new install, regardless of the complexity? Do most contractors offer them?
Many still don’t, the company owners either don’t understand them, are too lazy, or are afraid the equipment will be too small.
“I haven’t failed. I’ve just found 10,000 ways that won’t work.” - Thomas Edison
“It’s not whether you get knocked down, it’s whether you get up.” - Vince Lombardi
"In this house we obey the laws of thermodynamics" - Homer Simpson
Local 486 Instructor & Service Technician
1. Yes, couldn't get any easier as you have blueprints.
2. They should.
Don't let anyone bs you. I'd stop all work, call everyone in for a meeting, and tell them the hvac system needs to be properly designed and installed as mentioned above. Independently inspected, before any drywall goes up. Then it needs to be commissioned with a full commissioning report showing all calculations-air flow, temp drop, static pressure, etc. before the architect and contractor get paid in full.
If not, you'll end up with an uncomfortable home, they'll all be paid and long gone, and getting it right will be an expensive painful process borne by you.
If I do a job in 30 minutes it's because I spent 30 years learning how to do that in 30 minutes. You owe me for the years, not the minutes.
Helpful Calcs, tips, tricks on my YouTube channel: https://www.youtube.com/channel/UCgm...TUTAdKmqRiTDEg
Thanks for the advice. It looks like this is going to be another battle. My general contractor has just been a nightmare. I'm going to push them to bring a new contractor for the ducting at their expense.
Sorry....just noticed you are in California. Hopefully some of the guys that work there will chime in eventually but from reading their posts, your current HVAC contractor is not even close to meeting the duct leakage requirements and energy conservation requirements. I believe it is called Title 24 or something like that.
I suspect these regulations would be all you need to get your general contractor on board with little resistance.
@lkapigian
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It's funny, I actually read a bit of Title 24 because my terrible general contractor skimped out on the whoppiing $100 or whatever it would have cost them to put a radiant barrier on the new roof in the addition that was framed. I called them on it and they said they'd put one between the sheating and the roof tiles...which is not how radiant barriers work.