Laars NeoTherm NTV Service Manual

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Laars NeoTherm NTV Service Manual Manual pdf 64 page image

54 Service Manual - NeoTherm 500If the system pressure exceeds the relief valve setting,the pressure relief valve is designed to open and releasethe excess pressure and water. Note - This type of valveis designed to relieve a limited number of times duringits life cycle, so it is not a good idea to “test” the valve bytripping the small metal handle on top. Sometimes whenthis type of valve is opened, it will not re-seat correctly,causing a slow leak. If this happens, and the valve can-not be cleared, it must be replaced.Tools and equipment required:* Plumber’s torch, solder, and flux• Two pipe wrenches• Pipe dope or Teflon® tapeProcedure:1. Turn off power to the system. Use the main discon-nect switch mounted above the front panel.2. Isolate the boiler from the system. To relieve thepressure, open the boiler drain to the right of theheat exchanger.Fig. B35-1 - Pressure relief valve (typical)Note -Normally a drain pipewould run from here towithin 6” of the floor.3. The pressure relief valve is mounted on a pipe that extends up a few inchesabove the top panel of the NT unit.4. Disassemble and remove the drain pipe.5. Unscrew the valve from the vertical pipe using the two pipe wrenches.6. The replacement valve must be the correct size and capacity to match the sizeof the NT unit. Check the old valve for two important numbers:• The capacity of the old valve, listed in BTU• The relief pressure of the old valve, listed in p.s.i.These numbers will be marked on the body of the valve. Check for this beforeyou get a replacement. The replacement valve must have ratings for both BTUand psi which are the same as or higher than the ratings on the old valve7. Wrap a piece of Teflon® tape around the threads on the end of the vertical pipe.Install the new valve using the two pipe wrenches.8. Reassemble the drain pipe.WARNING! Always re-install the drain pipe. If the pressure relief valve wereto open without the drain pipe in place, the boiling water could shoot out, caus-ing personal injury or property damage. Most plumbing codes call for the drainpipe to extend straight down to a point about 6” above the floor. Check yourlocal code.B35 Removing and Replacing the Pressure Relief Valve