MVHR & Air tightness test - running or not?

[readiescards]

Due to a mistake by me I forgot to turn off the MVHR during the air tightness test - but actually I don't know if it is normal or not to leave the MVHR running during the test?

 

My brick and block house got 2.66 ACH @ 50Pa but was hoping for a little nearer to 2.0 - and have since found a few holes - the air testing guy was not in the mood to allow me any time to chases around with a smoke pencil looking for holes :-(

[Jeremy Harris]

The MVHR should not only be turned off, but the external vents most be totally sealed during the test, otherwise the result is pretty meaningless, as most of the air leakage will be via those vents.

[jack]

Was just going to say the same. Did the tester not say anything about doing this?

 

2.66 with the MVHR on is actually pretty good!

[Dudda]

In Ireland the airtight test cert states if vents are open or not and therefore incorporated into the result. You actually have to state if they're sealed at the incoming and outgoing grills to the unit or each individual vent in each room. Not sure about the UK regs but this tester sounds like someone you should avoid if doing another test.

[readiescards]

Tester just said turn it off but in the process of getting him some power to run the fan (we did not have electric mains connection until later that day) I forgot to turn it off.

 

I can't find a suitable web link saying the external MVHR vents  should be sealed during air tightness testing - does anyone know of a suitable page.  As I wish to send it to the tester to see if he'll come back to do a proper test

[le-cerveau]

Page 11 of the ATTMA (The Air Tightness and Testing Measurement Measurement Association) Air Testing Standards for residential dwellings September 2016.

 

https://www.attma.org/wp-content/uploads/2016/09/ATTMA-TSL1-Issue-3-Rev-0-2016.09.09.pdf