ProDave

Understanding my air test results.

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IIRC manometer fluid for the sensitive inclined filter loss gauges is basically white spirit with dye in.

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On 13/10/2021 at 08:05, SteamyTea said:

Have you used a manometer?

Then worked out the pressures.

 

 

Anyone know what calculations are needed?

I understand you seal up and put the fan on and regulate the fan speed to get a differential pressure of 50Pa.

What I don't understand is how you work out the air change.

Is that related to the speed of the fan and the extraction rate of the blades? Or is it using an aneometer and cone similar to balancing MHRV?

I can see the benefits of rigging up a DIY test after the airtight membrane is installed. It would be better if I could get some figures as well.?

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What I did is used an anemometer to measure the speed of airflow flowing past the fan to achieve equilibrium at 50Pa.  then knowing the area of the fan you calculate the volume of air flowing past the fan in a given time and that Vs the volume of the house gives you ACH.

 

Just a case of scaling to get airflow units and volume of house units the same.  So if you want ACH calculate the volume of air flowing past the fan in an hour, and compare that to the total building volume.

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1 hour ago, ProDave said:

What I did is used an anemometer to measure the speed of airflow flowing past the fan to achieve equilibrium at 50Pa.  then knowing the area of the fan you calculate the volume of air flowing past the fan in a given time and that Vs the volume of the house gives you ACH.

 

Just a case of scaling to get airflow units and volume of house units the same.  So if you want ACH calculate the volume of air flowing past the fan in an hour, and compare that to the total building volume.

What I would do.

Just take several readings across the diameter of the fan and take the average airflow.

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the flow would be too turbulent for the average anaemometer to deal with IMO

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