Engineered Systems Magazine

Draft simulators: Fieldpiece Instruments

October 29, 2012

Fieldpiece-102912-body.jpgAccurately test pressure switches andcalibrate adjustable pressure switches to furnace specifications.

Fieldpiece Instruments introduces the DDSM1 Draft Simulator that allows HVAC professionals to accurately test pressure switches, and calibrate adjustable pressure switches to any furnace. This allows technicians to carry adjustable switches on his truck, instead of switches for a variety of furnaces.

A pressure switch is a safety device that prevents the furnace from running in an unsafe manner.  Until the DDSM1, there were no testing tools available to test the efficacy of a pressure switch, unless it failed completely. 

“It used to be when a furnace was having intermittent problems technicians could only guess if a pressure switch was the problem, or at least part of it.  If a correct replacement wasn’t on the truck, they would need to purchase one, drive back, and then often times find out it wasn’t the pressure switch at all,” said Russ Harju, product manager at Fieldpiece.

“With the DDSM1 the potential for call backs in these situations are low because the tester, when paired with a manometer, can quickly determine whether or not the pressure switch is working correctly, even with the furnace turned off,” added Harju. “And techs only need to carrying one switch because the DDSM1 is the only tool that calibrates adjustable pressure switches to furnace specifications.”

Designed to simulate the negative pressure created by the draft inducer at start-up, when used with a manometer, the DDSM1 produces a consistent vacuum pressure that is adjustable to the furnace pressure, and it will maintain that pressure from 0 - 100 inches of column water, depending on the bleed port.

“Adjustable switches vary, but most sell for under $15.00,” stated Richard McFarland, HVACR pro and developer of the Draft Simulator.  “OEM switches cost considerably more – usually from $25.00 - $50.00,” added McFarland. “Not only that, if a technician doesn’t have the right switch, he’ll need to leave the site, pick one up, return, and install it.  That being said, because of the DDSM1, the adjustable pressure switch now is hundreds of dollars cheaper.” 

To use the DDSM1 Draft Simulator, with the furnace turned off, simply connect it via the supplied leads and hoses to the pressure switch and a manometer, turn on the DDSM1 and slowly adjust the pressure dial. The red LED indicates when the pressure switch closes. Check the reading on the manometer to see what pressures open and close the switch. The amount of pressure to open and close the switch should be within 10% of the manufacturer’s rating.

Like all Fieldpiece products, the Draft Simulator is designed to work in the field for the benefit of the HVACR professional. The DDSM1 features long battery life, sturdy controls, a tilt stand and a rugged reinforced shell for extra grip and protection from drops. The DDSM1 will work with any manometer including the Fieldpiece ADMN2 Accessory Head and SDM5 Stand Alone Manometer. The DDSM1 can also be used to test signal transducers on furnace boards. In addition to furnaces, the DDSM1 can accurately test pressure switches in boilers, water heaters, filter systems, clean rooms, drafthoods, air balance, and zoning.