Where is the most effective location to apply vacuum during a sub-slab communication test?

In a sub-slab communication test, the primary goal is to assess the effectiveness of the vacuum applied in creating a sufficient pressure differential to draw radon gas and other soil gases into the collection system. The most effective location to apply vacuum is at the proposed suction point location. This is because the suction point is specifically chosen based on its proximity to areas that are expected to yield the highest radon concentrations. When vacuum is applied directly where the radon extraction system is anticipated to be located, it allows for an accurate measurement of how effectively the system will perform under real operating conditions.

By applying the vacuum at this strategic location, practitioners can better simulate the conditions that will occur when the radon mitigation system is activated. This direct application helps to identify possible communication pathways and assess the efficiency of gas flow into the suction point, thereby providing valuable data to inform system design and installation. The other locations, while they may offer some data, do not simulate the conditions at the proposed suction point as effectively, leading to potentially less accurate insights regarding radon mitigation system performance.