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E. Burns

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Does anyone use a Manometer?

The reason I'm asking is we have in the Florida Building Code requirements for pascal movement in sleeping rooms with the doors closed.

Here is the code:

§M601.4 Balanced Return Air. Restricted return air occurs in buildings

when returns are located in central zones and closed interior doors impede

air flow to the return grill or when ceiling spaces are used as return

plenums and fire walls restrict air movement from one portion of the return

plenum to another. Provisions shall be made in both residential and

commercial buildings to avoid unbalanced air flows and pressure

differentials caused by restricted return air. Pressure differentials

across closed doors where returns are centrally located shall be limited to

0.001 inch WC (2.5 pascals) or less. Pressure differentials across fire

walls in ceiling space plenums shall be limited to 0.001 inch WC (2.5

pascals) by providing air duct pathways or air transfer pathways from the

high pressure zone to the low zone.

Visible provisions are not present in all jurisdictions. It was suggested to us from a a/c contractor to purchase a manometer. Rather than state visible provisions have not been made IE: Transfer grilles, Return ducts, 2 1/2 inch undercuts.

If anyone is using a manometer what capacity are you using it in? What model are you using?

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Don't, wont, never will. (I hope)

Most of us are already beyond the scope of a visual inspection. This is certainly way beyond that. Where will it end? Will the next thing be measuring gas pressure both up stream and down stream of both the gas meter and every gas valve? Clocking the firing rate of gas appliances and checking the "balance" of the air distribution systems? Maybe calculate the adequacy of the duct work?


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Hi Ellen,

I agree with George. It's one thing to be able to speak to the physical condition of something as you observe it, but there is plenty in the home that you can't observe. Air pressure balance is a good example.

I think for electro-mechanical systems of a home it is up to us to educate ourselves to the point where we can recognize the tell-tales that tip us off that something isn't quite right. We then reveal those tell-tales to our clients, explain what we think 'could' be happening, what the negative consequences of that are, and then we refer it off to a specialist to investigate, whereupon the specialist, being the subject matter expert in that particular trade, either confirms or refutes our suspicions.

Try this analogy. We're just the team doctor being paid to screen the potential new player for illnesses and to inform the team owner/coach of whether the player is fit to play. The team doctor is supposed to just look for the tell-tales. And, if the player hasn't concealed them, hopefully can find them all. So, we don't diagnose any illness we suspect, but we make sure the team owner understands whether tell-tales are tipping us off to minor ills that can be handled with an over-the-counter prescription, leaving the player fit for duty in short order, or it is something that needs to be take to a specialist, and therefore something that might not make this player such a good choice for our team. If the team owner decides that he/she is willing to take a chance on the player, despite a potentially significant health issue, he/she needs to know what the 'potential' consequences could be of that decision and which specialist to send the player to in order to get the player healthy.

In your own example, if there are no returns in every room, you'd naturally look to see if the doors had been undercut or had ventilation ports in them. You'll probably also notice that when the heat is on doors tended to be sucked closed by themselves. You might even listen to the home when the door to a room is closed to see whether you could discern an audible drop in blower RPM when doors are closed and the air handler is starving for air.

Those are a few tell-tales I use, and because they don't require any special testing, they fall within the category of a non-technical/visual inspection. When those tell-tales tip me off that something just doesn't seem right, I refer the issue off to an HVAC guy for further diagnosis. As far as I'm concerned, he can stand there all day with his manometer and test to his heart's content. I don't have time for it and I'm certainly not being paid for that.

If someone ever trys to haul me into court for missing something like that - claiming that I should have found it when there are no tell-tales - I'll be using that same analogy in court to make the judge understand exactly what it is that we can, and can't, do.



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Thanks for the reply George.

We will rethink that type of testing. Just thought if it was easy enough we can take a quick measurement.

Currently we document the lack of visible provisions and recommend having the a/c contractor measure the pressure and document his findings. If we don't see the provisions for return air.

Would you personally not mention it at all?

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No, I don’t. But if my local code said what yours does, I might. (In fact, I know I would on new construction inspections.) Sadly, my local code is entirely silent on the matter.

The thing is, I don’t believe you’re going to find a manometer that reads down to one or two or three pascals for anything like a reasonable amount of money. Maybe I’m wrong, but that’s a *really small* amount of pressure. Most manometers I’ve seen measure in ‘inches of water,’ a much more gross measurement that won’t do you much good.

If you find one for a couple of hundred dollars or less, let me know.

- Jim Katen, Oregon

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Well, I never thought I would, until I had a client quite upset that the bsmt. FR didn't receive enough air movement to provide adequate heating in extremely cold weather. Somehow, me telling her that it was "beyond the scope of my inspection" didn't placate her.

The harsh reality is that we can, & will be held liable if a particular client thinks we should be. I now subcontract suspect installations to a certified air control technician.

That really blows......

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While I don't use a manometer I have utilized the services of a womanometer on occasion. I bring Leslie with me on inspections and if she says it isn't right it flat out isn't right. Getting serious now I believe, at least from my perspective, the use of such monitoring devices is so far fetched from reasonable standards of practice, not to mention standard of care, that it is not warranted. If we go to far in this direction then we will soon set up laser particle counters in order to inform our clients that there are too many airborne particles in the indoor air which could contain fungal spores, dust mites, bacteria, viruses, and a whole plethora of other contaminates which may or may not have an effect on them. Keep it simple and accurate and you won't go wrong. Go too far and it doesn't end.


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  • 4 weeks later...


Just to split airstreams (or hairs) I believe that the numerical data is incorrect.

2.5 pascal should be .01 wc not .001 wc. Sorry, just learned those # from a mold class.

Using a manometer for our work is just Waaaay out of line. Whatever happened to "normal user controls"?


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