Air tight house.
Can anyone tell why using “dual pressure differential valves” for plumbing, 3, in a box with inner and out filters for air movement to release pressure or vacuum inside my air tight house, is a bad idea? The equivalent is a 4.5 inch hole. I also added a fresh air intake system with filter with one-way check valve. Further, I recently installed a Radon gas removal system. The installation compounded the air tightness of my home originally.
Everything seems to work very well. Doors are easy to open and close without slamming. When HAVAC system is running, air passing through dual pumbing checks to outdoors is modest. Outdoors atmosphere changes seem to also be regulated for home. Manometer meter readings for Radon remain the same after dual check valve installation.
The only problem I have is that the system works like a charm. No increased cost in heating and cooling. Has to be something wrong with my little invention. I am not a builder except on a hobby level. Educated guess would be welcomed.
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Your "tight" house just isn't really that tight. There's not going to be pressure or vacuum.
Have you done a blower door test? What did it score?
Thanks DC. I had test done couple years ago. I scored well but honestly don't recall numbers? However, your correct. Many upgrades since two years ago. I should run the test again.
Thanks for the suggestion.
Regular check valves like you use for plumbing aren't ever going to open under the relatively tiny pressure differentials you get betwee indoor and outdoor air pressures. Typical spring-type check valves won't even open under the tiny force of convection flow in thermosyphon hot water recirculation systems -- you have to use "swing type" check valves instead.
Chances are your check valves aren't really operating, and your house is just leaking enough to handle things. If you just want makeup air, you don't need a check valve -- just pressurize the house slightly with a small fan drawing outside air in through a filter. This way all the leaks in the house leak outwards only, so you don't draw in contaminants. If you want pressure equilization, you don't need check valves, just a weighted damper that can swing both directions.
There are simpler ways to accomplish what you're trying to do, if you need to do it all.
Bill
Thanks Bill. I did a pressure test a couple years ago. That is, I had it done and scored well. However, I can not recall the number. Since that time the home has had upgrades for heating and cooling. Costs are below $500 annually. Basement is now part of living space with walk out. Hence Radon remover. Home is now a legal 2000 sq foot livable space. I do not expect much change in costs.
Giving full consideration to your reply, your likely correct. Indeed as a novice, I had my doubts. But I do like damper idea. Continual air replacement is also part of the goal without driving up costs. Air filtration is big for me by choice. So, air filtration for swing damper on both sides.
Thanks. You helped.
I just want to add that the addic has a pretty good thermal barrier that makes a giant difference in the central US.
"This way all the leaks in the house leak outwards only, so you don't draw in contaminants. "
I'm going to question the assumption that air that leaks inward is going to draw in contaminants.
The place to start is by measuring indoor air quality, if you're not measuring you're guessing. If CO2, VOC's or humidity is too high, then you need more ventilation. My recommendation would be to look at a heat recovery ventilator, HRV. While they are sold as "balanced ventilation," with the inflow balancing the outflow, that's only true if the indoor and outdoor air pressure are equal. If they're not the flow will be slightly unbalanced and will tend to correct the inequality.
The "small fan bringing air in through a filter" is supposed to be big enough to maintain a slight positive pressure within the home. This slight positive pressure is what makes all the leaks in the house leak "outwards only". I probably should have been more clear on that. This is the same way clean rooms (and many datacenters) are built, since it makes sure that nothing can get in by sneaking around a seal or filter somewhere. Since you're actively pressurizing the space with the fan, and the fan draws through a filter, you are ensuring no contaminants can sneak in anywhere since all the leaks leak out due to the positive pressure.
I definetely agree that it's best to make measurements and not guess though! Knowing for certain is always an advantage.
Bill