Acceptable Furnace Install in Sealed (foamed) attic

No thanks. You…and know-it-all contractors like you…keep screwing it up so that good inspectors can find it and write it up. You make us look good.:smiley:

Tell us some more about how sucking air from one closed off area of conditioned space does not create a negative pressure in it. That’s my favorite.

I as well be speaking with a box of rocks I truly feel sorry for your clients if you ever have any. Why don’t we just agree to not agree

Because you are wrong. Besides, you started with the insults. I just followed suit.

Better goback to school, man, or stick to photographing horses with your new infrared camera. Better yet, do some research before you start slamming people.

Tell us some more about how sucking air from one closed off area of conditioned space does not create a negative pressure in it. That’s my favorite.

Just in case you were sleeping the suction side of any blower draws air from the path of least resistance. Put a closed door in the path of resistance with a 1 inch gap at the bottom and you will not and I stress will not draw enough air from that room to create a negative pressure. Have you lost your mind think about what you are saying

I would have done the same Kevin. :smiley:

So…a bedroom with a return drawing air from it, and a closed supply vent, and a door that seals tightly…will have…what?

A third grader would correctly conclude the answer to be…a negative pressure.

And he would also be able to tell you that the same room with no return, air blowing from an open supply, with a sealed door would have…a positive pressure.

And he would be right.

That is why any newby with the education of a third grader will advise his client who has no return in his bedroom…in order to avoid a positive pressure (and restricted flow of hot or cold air from the vent) to have a one inch gap under his door to equalize the pressure so that the room will properly heat and cool.

Again show me where you said the bedroom had its own return or do you just make this up as you go along to suit you

LOL…you tap dance very poorly.

What does your question have to do with this…

We are talking about negative pressures within a house that could draw air from an unventilated attic through an air bypass that could compete for the combustion air… You said that such a premise was “crap”. You said that a central system will not create a positive or negative pressure in the home.

I think the “crap” is coming from you.

Normal operations.

One can also make water flow up hill if so desired


So…pretend you are a home inspector for a minute. Would you encourage your client to totally rely upon “normal conditions” in all matters that could result in serious illness or death if “normal conditions” were to change for a few hours?

I mean…under “normal conditions” a gas water heater in a bedroom will operate just fine, won’t it?

Your thinking, I thought I could smell wood burning. You don’t have the equipment for that.

Yes I stand by my statement a normally operating central system that is a closed loop system will not put a home in the negative or positive situation by its self. I did not say anything about dryers and or exhaust fans removing air from the home.

LOL. I don’t blame you for trying to save face by “standing by” a statement that you never made. We’ll just keep this to ourselves.:wink:

By the way…to most folks… operating the dryer or exhaust fan, opening or closing a door to a room, or opening and closing vents…would be considered “normal conditions” under which a “normal operating” heating and cooling system would create different levels of positive and negative pressure in different parts of the house.

All the petty arguing and name calling on a post I started and have my name and links attached to is not appreciated. This is a PUBLIC forum and that behavior does nothing to create a positive PROFESSIONAL image for the profession that I take very seriously and use to make my living. Take it somewhere else.

Thanks to those that gave serious replies. I reported the issues, they have been verified by a licensed HVAC professional and my clients are extremely happy with my service.

If this is what one can expect from fellow members of what is supposed to be a PROFESSIONAL organization, I am going to have to give serious thought to continuing any association with INACHI. It is a shame that there cannot simply be constructive and PROFESSIONAL discussion about topics that could be learning opportunities for everyone involved.

Belong…or not…to whatever association you wish.

When contractors begin their posts by bashing the guy they don’t agree with, they get it back in the nuts from me. If that bothers you, I will just have to live with that.:wink:

Some guys can’t be smart. Instead…they have to show how others are “dumb”. It’s like the contractor your client calls because you called out a service panel full of double taps who tells your client that you don’t know what you’re talking about…he sees this all the time and never saw a house burn down, yet…and crap like that.

People who can’t take it should not dish it out.

I have seen negative air created with a clothes dryer several times.
What Charlie is saying is true to some effect. Each and every room would have to have a return vent and the furnace blower would need to be keep running. Also the ductwork in the attic would have to be sealed. We would still have trouble with high moisture into the unvented/unconditioned attic though.

Kevin we have guys on here putting out false information that he has no clue as to what he is talking about just trying to make himself look big to whom I know not. Some one has to police people like that and some times calling someone a knuckle head is the only way to get their attention sorry you were offended maybe you need to toughen up a bit.

With this sealed and insulated attic, the attic is essentaially now conditioned space…my concern: Is the foam a high density closed cell type that essentially forms an air/vapour barrier? If not, in winter, moisture may diffuse through the foam to reach the roof/wall sheathing.

If this furnace is not a sealed combustion, direct vent unit, there are potential combustion air issues. Simply adding an air supply vent to the exterior will not solve the problem in all conditions…if the outdoor hood of the supply air ducting is ever in the lee of strong winds, it will actually be sucking air out of the attic, not supplying it! In Canada, the WETT Association has a video taken by a homeowner of smoke emitting from the supply air vent to an airtight wood stove during very high, gusty winds!

If this house is very airtight, by having 2 or more exhaust fans (dryer, range hood, bath fan) on at the same time may create enough negative pressure within the building shell to cause backdrafting.

I have been working a job on a high-efficiency “huge house” sitting on top of a hill.

When there is a fire in the first floor fireplace, smoke gets sucked down an adjacent flu (in the same chimney) from three stories above and discharges smoke into the master bedroom through the fireplace there.

Contractors have yet to come to grips with this new technology without abandoning old construction technique.

Also, last week we had a report hit the newswire were someone’s kid had a hamster that died. They replaced the hamster and it died two days later so they got a mouse which died in two hours! Hazmat was dispatched to find high levels of CO2 (enough to kill a small rodent). Not CO, CO2. There was no fossil fuel appliances anywhere in the building. The house was built to high-efficiency standards and obviously a design to ensure rodents will not infest the residence! :slight_smile:

We have yet to fully see this high energy efficiency technology rare its ugly head.
As far as this situation is concerned, anyone that spends the effort and money on a high-efficiency home and installs an 80% furnace in this manner is a total idiot. This furnace does not have a supply air connection that can be piped to the exterior.
Installing combustion air vents from the attic to the exterior wipes out the entire principal of insulating the roof versus the ceiling. It will also produce the moisture issues at in the attic as those who misunderstand a sealed attic design pointed out concerning moisture entering attic from the finished space below. Adding vents into the attic is not a proper method of mediation.

If properly installed, a sealed attic will not have any problems with moisture levels from the interior of the house, if these moisture levels are properly maintained and someone doesn’t do something else stupid. Improper use of humidifiers, failure to use installed ventilation equipment in bathrooms etc. Buy the way, HVAC equipment does not produce moisture inside the house when installed inside the house unless it’s leaking all over the place.

Kevin, I think you did good by reporting what you saw, even though you did not have the tools to determine if this is actually a hazardous condition. This evaluation is not part of home inspection and not your job. In principle, this could be a very hazardous situation if we take into account other conditions built into the house.

Whenever I see a high-efficiency home or building, the hair automatically stands up on the back of my neck!

I have not been doing many home inspections since Thanksgiving, but I have been booked up with building performance issues. Surprisingly the majority of them are high-efficiency homes that are improperly built. Maybe it’s just that those homeowners expect more and recognize these problems, however I find it interesting at the ratio of buildings with problems in relation to the efficiency standards that the buildings are built by.

So how does moisture get keep out of a sealed attic?
I have heard of installing a moisture barrier between the living area and the attic, but my concenr is what does the moisture do when it hits the moisture barrier?

If you do not have High Moisture in the Home then you will not have high moisture in a sealed attic .
Unless you send it there from Dryer Bath vent Ect.
No moisture Barrier on any homes I do if they are older and the ceiling has been painted twice then it is no longer a concern unless there are holes.