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- #21
Ok guys as promised my Heating and Ventilation unit has been tested and the results are in..................
To remind you i needed at least 12 air changes with an overpressure in my room (GRP house) of 50PA.
I have an HV unit external to the room which supplies the (sometimes warm depending on the thermostat setting) air via a duct with 4 grilles. I had 2 150mm x 150mm weighted vents which was intended to offer the majority of the air changes.
There were two settings on the HV unit - fan 1 and fan 2.
so... see attached...!
As you can see we have the required minimum flow rate through the house! hurrah!
but this is useless unless the pressure inside the house is large enough. This was continuously displayed with a manometer and constantly read around 60-65 PA after the doors (2 off) were shut after 2 seconds or so. So hurrah for that too!
Ultimately this post was started because i wanted to see if my calculation sheet was good for a rough guide as to specifying the duty for the H and V unit (and the vents required)...
A few points to improve the sheet with the glorious technicolour hindsight brings!..
The size of the room in the calcs should be reduced due to the amount of equipment inside it. i will take a 20% reduction in my example.
Leaks. Yes there were lots of them! particularly from the doors (even though sealed) . i have included a leak factor section (to add to the effective vent area) (arbitrary factor figure 2.2)
The vent size is a variable figure. this will change due to the variable/adjustable weighted flaps that are used on the vent. This is essentially where we have the play to try and get the pressure and the flow through correct. I have added a vent factor which it to is a variable so one can have a virtual play as to how open or shut you want the vents . (arbitrary factor figure 0.9 - 10% shut)
both of these affect the "area of leakage" figure. times by 2.2 and times by 0.9
So ultimately and i'm not ashamed to say this! This has been a bit of an experiment and the arbitrary figures above that i have noted make the recorded results match the calculated xl sheet. So in the future if the construction was the same (which is quite likely in the company i work for) then i can use this calc sheet to see what HV duty i need and what vents i could use.
At the end of the day for this project its a billy bonus with tea and cakes for all involved...
PS Thanks for all your input and comments. Any of you guys have any more to add please feel free! Its all working so you cant burst my bubble! lol
Johnny H-S BSc(Hons) MInstMC
Engineers like to solve problems. If there are no problems handily available, they will create their own problems.
To remind you i needed at least 12 air changes with an overpressure in my room (GRP house) of 50PA.
I have an HV unit external to the room which supplies the (sometimes warm depending on the thermostat setting) air via a duct with 4 grilles. I had 2 150mm x 150mm weighted vents which was intended to offer the majority of the air changes.
There were two settings on the HV unit - fan 1 and fan 2.
so... see attached...!
As you can see we have the required minimum flow rate through the house! hurrah!
but this is useless unless the pressure inside the house is large enough. This was continuously displayed with a manometer and constantly read around 60-65 PA after the doors (2 off) were shut after 2 seconds or so. So hurrah for that too!
Ultimately this post was started because i wanted to see if my calculation sheet was good for a rough guide as to specifying the duty for the H and V unit (and the vents required)...
A few points to improve the sheet with the glorious technicolour hindsight brings!..
The size of the room in the calcs should be reduced due to the amount of equipment inside it. i will take a 20% reduction in my example.
Leaks. Yes there were lots of them! particularly from the doors (even though sealed) . i have included a leak factor section (to add to the effective vent area) (arbitrary factor figure 2.2)
The vent size is a variable figure. this will change due to the variable/adjustable weighted flaps that are used on the vent. This is essentially where we have the play to try and get the pressure and the flow through correct. I have added a vent factor which it to is a variable so one can have a virtual play as to how open or shut you want the vents . (arbitrary factor figure 0.9 - 10% shut)
both of these affect the "area of leakage" figure. times by 2.2 and times by 0.9
So ultimately and i'm not ashamed to say this! This has been a bit of an experiment and the arbitrary figures above that i have noted make the recorded results match the calculated xl sheet. So in the future if the construction was the same (which is quite likely in the company i work for) then i can use this calc sheet to see what HV duty i need and what vents i could use.
At the end of the day for this project its a billy bonus with tea and cakes for all involved...
PS Thanks for all your input and comments. Any of you guys have any more to add please feel free!
Its all working so you cant burst my bubble! lolJohnny H-S BSc(Hons) MInstMC
Engineers like to solve problems. If there are no problems handily available, they will create their own problems.
