More For Your Money
Having been in the radon business as a certified tester in 1995 and as a certified mitigator since 1998, I’ve seen a multitude of mitigation systems and with the majority having oversized suction fans.
One of the biggest decisions of the Mitigator is the choice of the suction fan in a sub slab depression system. The largest manufacturer of suction fans offers 13 regular models, with each having different suction specifications. This leaves the Mitigator with the choice of selecting the fan best suited for that unique slab.
Which is the Proper Fan ?
With over a dozen models from which to choose, does the Mitigator install the GP501 or perhaps the RP145. Vastly different fans with vastly different design characteristics.
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| GP501 | RP145 |
| Power Draw: 70 -140 Watts | Power Draw: 37 – 71 Watts |
| Max. Pressure: 4.2″ Water Column | Max. Pressure: 2.1″ Water Column |
| 3 or 4″ Pipe @ 1.0″ WC ?169 CFM | 4″ Pipe @ 1.0″ WC ? 94 CFM |
| Higher Power Consumption 1 & For Non Porous (tight) SubSlab | Small Power Consumption 1 & For Porous Subslab Gravel |
GP 501 (70+140 watts)/2 X 24 hrs X 365 days X $0.079 KWH (Duke Energy) ?$73 for year
RP 145 (37+ 71 watts)/2 X 24 hrs X 365 days $0.079 KWH (Duke Energy) ?$37 for year
Each of the above fans will reduce the radon in the above example of that slab that it’s conditions are producing a 1″ WC (water column) of draw.
The fan selected should produce the necessary airflow while operating in the middle of its operating range. An oversized fan has an additional energy penalty with the system pulling more air than is necessary which includes the cost of the conditioned air out of the building.
If the Mitigator’s only concern is to reduce the radon level, then the easiest approach is to use the fan with the highest suction (built for use w/ nonporous & poor subslab conditions). This is indeed good for the removal of the radon, but bad if the fan is grossly oversized and thus removing a large amount of conditioned air.
With a large number of radon mitigations being generated by Real Estate Closings, unfortunately the final radon reading is the only concern of most buyers and sellers, but the buyers should be demanding a more balanced system. Even after living in the house for years, no blame is attributed to the Mitigation System for high electrical cost due to the excessive removal of conditioned air.
