Comments on: How Is a Blower Door Like a Hydraulic Jack? Pascal Knows!

By: Ted Kidd

Ted Kidd — Sun, 29 Jun 2014 00:38:02 +0000

I agree with PJ that programs
I agree with PJ that programs distort solving client problems,but disagree that measuring the problem before to determine importance of fixing, during to determine if fixing is happening, and after to prove (and learn) quality fixing occurred is unimportant.

There is plenty of evidence that when you measure results and provide feedback to all involved, results and skills continuously improve. There are also plentiful examples of where forging blindly ahead leads to disappointing results and terrible consequences.

Its the difference between quick and good, like guessing if your refrigerant charge is correct vs measuring and verifying.

Certainly the quick approach is best for the contractor. But its also the approach that leads to HVAC contractors being perceived as lower on the integrity scale than attorney's and used car salesmen.

If you sell air sealing without measuring and verifying, what are you selling? What kind of person are you?

By: Ed Moore

Ed Moore — Mon, 23 Jun 2014 22:30:06 +0000

Interesting comparison, but
Interesting comparison, but you left out a small detail; air is compressible, while hydraulic fluid is not. When I used to work on large (long) compressed air systems, it was not unusual to a couple of psi difference from one end to another; especially when dumping it for repair. As mentioned above, internal restrictions and the degree of "leakiness" of the house could make a difference. I really enjoy your articles, keep them coming.
Ed

By: Pj

Pj — Mon, 23 Jun 2014 19:03:06 +0000

Hi Allison,
Hi Allison,

Certainly a smart guy like Mr. Pascal would agree requiring a blower door test on every home in every sub division is silly, a complete waste of time and money, and kind of like repeating the same thing over and over and expecting a different result. This Blower door test is in reality nothing more than a dog and pony show that proves repeatedly that houses are leaky.

Treating Home Performance like a science project has prevented any real energy conservation from happening on any real scale, and relegated those involved to a boutique club that only exists as long as they can beg for money to subsidize their excessive time and cost from rate payers or force the issue through codes. It’s ironic that those who claim to be efficiency experts are probably the least efficient group of folks around, have shown little business savvy, and simply an “industry” that evaporates 15 minutes after their subsidies end.

Thanks and, Keep on posting,

Pj

By: Dale Sherman

Dale Sherman — Mon, 23 Jun 2014 17:13:10 +0000
Nice analogy, Allison. But
Nice analogy, Allison. But given the leakiness of so many homes, it is more likely one will observe a pressure gradient as you move further away from the blower door. This is more easily observed in a leaky old colonial house with multiple additions on additions. The last room farthest may be only -45 Pascals while the room with blower door reads -50 Pascals. As David pointed out, flow restrictions of doorways (orifices) combined with leaks to the outside (more orifices) to create this condition. Try jacking up your car with a hydraulic leak on your jack. Of course, once the worst of the leaks are sealed, the house pressure is essentially equalized. A perfectly sealed house would only need a giant extraction syringe in the doorway to reach -50, not a blower door fan. Can you tell us what size syringe?

By: Bill Smith

Bill Smith — Mon, 23 Jun 2014 15:22:50 +0000
Pascal's contributions to
Pascal's contributions to science and mathematics would be remarkable under any circumstance. All the more so when you consider that he did almost all of his scientific work by the age of 31. The last eight years of his short life were mostly devoted to philosophy and religion.
Reading his philosophical writings with a modern perspective could leave you unimpressed. When you consider it in relation to the work of the time, however, it stand out for it's clarity. It served as the basis for many writers who came after him.

By: David Butler

David Butler — Mon, 23 Jun 2014 10:43:30 +0000
Another caveat worth
Another caveat worth mentioning is the impact of restrictive orifices within the house. For example, a small scuttle to an encapsulated attic, or taken to the extreme, the gap beneath a closed door (that should have been opened) will impede equalization in areas beyond the so called orifice.

In a theoretical air tight house, this would manifest merely as a delay in reaching equalization, but in a leaky home, areas past the orifice will never reach the test pressure, thus understating leakage in those areas.