Home (built in 94) is in Texas and attics tend to get a bit warm 6 months out of the year. 2 HVAC units for 3300sf home are in attic, along with 2-40 gal water heaters (yup, I said the same thing, WH in the attic?), Anyway, HVAC could be near replacement stage, now 15 years old.
Need your “expert” opinions – If you were to replace HVAC units, prior to new installation, would you . . . build an insulated cavity in attic for the HVAC to help new not work so hard to cool home? Other ideas to increase energy efficeincy?
Thanks for your opinion.
Replies
Yeah. I live in Texas too. HVAC and WH in attic pretty much standard fare. Not sure about WH's now. Seem like in the code (at least Ft. Worth) that no WH's in attic anymore.
As to your question. (IMHO) I don't think much would be gained by enclosing the HVAC units. Biggest problem usually is conditioned air leaking from the units and the duct work. Make sure new installation is tightly sealed and the ducts are well insulated and sealed. Not just tapped.
You can get more for your buck with better/more insulation where possible and eliminating air infiltration. In other words, sealing cracks etc. around opening etc. Check with you not so "Texas" friendly local utility company. I think some of them will come out and do an energy survey.
The ultimate would be to have the roof (not the attic) insulated by applying foam insulation to the underside of the roof deck. This would be very expensive and evolved as you would then need to seal off all of the existing attic vents that were originally required. This in effects makes your attic conditioned space similar to the living area.
As to your WH's, just rap them with you wife's fur coats. On second thought, maybe it would be better if you run down to the big box store and get a WH insulation kit. Just make sure there is a pan under them and the drain is not stopped up and any exposed water lines are insulated. Good Luck
Are the condenser/compressor units in the attic, or just the evaporators and air handlers?
Generally you want the condenser/compressor outside of the "building envelope", and with good airflow. (And you certainly don't want the airflow mixing with inside air.) The evaporator/air handler should ideally be inside the "building envelope".
Any air-handling equipment or ductwork that's outside the building envelope needs to be scrupulously air-sealed and, ideally, insulated.
Sorry to butt in but:
Standard installation around here is: Condenser located outside, Evaporator & air handler/furnace in attic and duct work in attic. Actually, most installations now days are heat pumps.
No evap. coolers in this part of the country. Too humid. (+50% humidity & 105 in the shade) Got to go further west before swamp coolers do any good.
Builders/owners don't want to put the time, space and money into putting everything in the condition space. I have designed homes for clients and then have the builder convince them that it is a waste of space and money and proceed to stick it in the attic and show them show them what a nice closet he got them.
I have heard of installations where the condenser/compressor is in the attic space, along with the AHU.Around here you hardly ever hear of airhandling equipment in the unconditioned attic space. And never a water heater.
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
How do you deal with the noise and vibration right above your head?
The kids moved out, so I don't have to anymore.
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
Unit is suspended from roof rafters.
I was referring to DanH. He was saying that his condenser was also in the attic. That's a big difference than having the furnace &/or the airhandler in the attic. I have one of my units in the attic. It's just the way it's done around here.
I did it in the past when I didn't know better. I have built many houses that way.
But if its already there, there is not easy way to change it. Have you read my previous post?
Not mine. I said I've heard of it being done. Down south. (Seems like a dumb idea to me.)
The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
I have never heard if the condenser in the attic (in Florida) but a package unit on the roof was fairly common for a while. Roof leaks and servicing problems seemed to make that go away. I haven't seen one installed like that in years.
My county in Florida had just added something in their building code requiring an insulated enclosure in the attic when the unified building code wiped out all local amendments and it was a mistake to lose that one.
An attic mounted air handler may save some interior space but they are inefficient, a bear to work on and sweat like a pig for most of the day. Be dam sure you buy the secondary drain pan and a condensate cut off switch!
Insulating your attic with radiant barrier insulation (do a google search) and making sure you have adequate attic ventilation either at the ridge or the gables will help cool the attic in the hot weather. This will help not only the efficiency of the HVAC system itself but the performance of the entire building.
Have you looked into foaming the roof deck?
Now I wish I could give Brother Bill his great thrill
I would set him in chains at the top of the hill
Then send out for some pillars and Cecil B. DeMille
He could die happily ever after"
Yeah it is maybe the best option to add more cavity in the entire insulation area. The more of it the more the temperature get enclosed.