Choose the Right Tool for the Job
December 21, 2007
Have you ever had to hammer in a nail with a wrench? Or had to pry open a paint can lid with a hammer? It can be done; it’s just a lot tougher. It’s a cliché, sure, but still true: A job is most easily done with the correct tool.
Drying tools are no different. There is a huge variety of drying tools available, and there is a huge variety of drying problems occurring each day in the field. But what tool should you employ for your drying situation? Here’s a look at some options to consider.
Drying the Inside of Long WallsThe Situation. Water came from above or penetrated very deep into a structure, including the interior of a 100-foot wall. Fiberglass insulation needs to be dried in place. The wall is covered with vinyl wallpaper.
The Tool. Inter-air drying system used in tandem with low-grain refrigerants (LGRs) or desiccants. Carefully pull off the baseboards and place one or two injectors in each cavity. Blow the dehumidifier into the intake of the inter-air dryer. This gives good, thirsty airflow to each cavity and will result in excellent drying.
You might also try carpet dryers rigged with wall-drying attachments. This won’t be as effective, but it will eventually work. Get the demolition tools warmed up if you’re trying to dry the wall from the outside or use low-pressure axial fans – you’re not going to get this wall dry. This is a case where lots of high-pressure airflow is needed inside the wall.
To prove the wall is actually drying, use multiple monitoring techniques, including insulation probes at the bottom of the wall, non-invasive meters at various heights in the wall and penetrating meters along the bottom plate checking for progress.
Crawlspace DryingThe Situation. A crawlspace is wet because of a water loss that occurred above. The vapor barrier and dirt have mixed into a muddy mess. There is about 3 feet of access space.
The Tool. Heat and air exchange drying. Use an indirect-fired furnace positively pressurizing the crawlspace with hot outside air. Always use in tandem with an air mover blowing out of the crawlspace. Overall, the crawlspace should be on negative pressure. This is easy to achieve by making sure the air mover is evacuating more CFM than the furnace is blowing in.
You might also try ducting the output from low-grain refrigerant dehumidifiers into the crawlspace. Because most LGRs are a little too tall to fit in a crawlspace, consider ducting them in from the main floor of the structure. You could open an HVAC floor register or use a dryer vent to gain access. Alternatively, it is possible to place an LGR outside and duct it through the vent access (be sure to secure your dehumidifier and keep rain out of it) Either way, don’t forget to also use an air mover to keep the crawlspace negatively pressurized. Get the mold remediation gear ready if you do nothing with the crawlspace, because you forgot that water goes down. Prepare for major secondary damage if you use air movers alone with no air exchange.
Heated air may not have lower grains per pound (GPP) than the outside air, but it does have low RH and good energy for drying.
The airmover blowing out of a crawlspace during drying is a “non-negotiable” piece of equipment. This negative pressure ensures that there will be no cross-contamination of the crawlspace (nasty!) air into the living areas above.
You can also measure the GPP of the air coming out of this negative pressure air mover. It should be higher than the GPP of the air going into the crawlspace. This proves water is being removed by the drying system
Hardwood Floor DryingThe Situation. The entire main floor of a home is a rare hardwood over plywood. Half of the flooring is affected by Category 1 water and is cupped. The customer wants the hardwood saved.
The Tool. Push-pull hardwood drying. Push air under the floor using high-pressure air movers and manifolds while simultaneously pulling air from the floor using hardwood floor drying mats connected to an inter-air dryer set on negative pressure. Use in tandem with LGR or desiccant dehumidifiers in the area, or even better, ducted into the high-pressure air movers.
If you don’t have high-pressure air movers, manifolds and mat systems, the old fashioned way of drying hardwood still works: tent the floor with plastic and duct in a desiccant dehumidifier. This method is slower, but will eventually work.
If you’re interested in showing off a little and drying the floor ultra-fast, consider doing all of these techniques - push-pull drying used together with tenting and desiccant dehumidification.
Dust off the long crowbar if you can’t do any of the above. I’ve seen restorers try to dry hardwood by blowing air movers across the surface while using conventional refrigerants in the area. This is completely useless. The cupping will still be present when the mold starts to come up in the seams of the floor.
Be sure that all layers of the floor are dry before pulling off the job. This can be done by using a non-invasive meter that reads at least 3/4-inch deep, or by using a hammer probe from below. The least-favored (but sometimes necessary) method of monitoring the hardwood is to make holes in the surface with a hammer probe. Either way, make sure that the subfloor is also dry at the end of the job.
It’s possible to verify that mat systems and tent systems are effectively working by measuring the GPP of the air above the floor and the GPP of the air coming out of the inter-air dryer. If the air coming out of the inter-air dryer has a higher GPP, the system is working. When tenting, the air coming out of the exhaust of the tent should read at a higher GPP than what went in.
Most jobs that restorers run into on a daily basis can be handled with the basic tools of the trade. Air movers, dehumidifiers, and extractors do most of the heavy lifting. When you run into a more difficult situation, be sure to use the right tool for the job.