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116986-01B

13

We recommend that you install a sediment trap in 

supply line as shown in Figure 12. Locate sediment 

trap where it is within reach for cleaning. Install 

in piping system between fuel supply and heater. 

Locate sediment trap where trapped matter is not 

likely to freeze. A sediment trap traps moisture and 

contaminants. This keeps them from going into 

heater controls. If sediment trap is not installed or 

is installed wrong, heater may not run properly.

 CAUTION: Avoid damage to 

gas  control.  Hold  gas  control 

with wrench when connecting it 

to gas piping and/or fittings.

INsTallaTIoN

Continued 

Installation must include an equipment shutoff 

valve, union and plugged 1/8" NPT tap. Locate NPT 

tap within reach for test gauge hook up. NPT tap 

must be upstream from heater (see Figure 12).

IMPORTANT:

 Install equipment shutoff valve 

in an accessible location. The equipment shutoff 

valve is for turning on or shutting off the gas to 

the appliance.

Check your building codes for any special re

-

quirements for locating equipment shutoff valve 

to fireplaces.

Apply  pipe  joint  sealant  lightly  to  male  NPT 

threads. This will prevent excess sealant from 

going into pipe. Excess sealant in pipe could result 

in clogged heater valves.

  WARNING:  Use  pipe  joint 

sealant that is resistant to liquid 

petroleum (LP) gas. 

*  Purchase  the  optional  CSA  design-certified 

equipment shutoff valve from your dealer. See 

Accessories

, page 25.

** Minimum inlet pressure for purpose of input 

adjustment. 

Figure 12 - Gas Connection

3" Minimum

CSA Design-Certified 

Equipment Shutoff Valve 
With 1/8" NPT Tap*

Approved 
Flexible Gas 

Hose (if allowed 

by local codes)

 Cap  Pipe  Tee
    Nipple Joint

Sediment Trap

Natural Gas

From Gas Meter 

(5" W.C.** to 10.5" 

W.C. Pressure)

Propane/LP Gas

From External 

Regulator

(11" W.C.** to

14" W.C.

Pressure)

CHECkING GAS CONNECTIONS

 WARNING: Test all gas piping 

and  connections,  internal  and 

external to unit, for leaks after 

installing or servicing. Correct 

all leaks at once.

 WARNING: Never use an open 

flame to check for a leak. Apply a 

noncorrosive leak detection fluid 

to all joints. Bubbles forming show 

a leak. Correct all leaks at once.

 CAUTION: Make sure exter

-

nal regulator has been installed 

between propane/LP supply and 

heater. See guidelines under 

Con-

necting to Gas Supply

, page 12.

PRESSURE TESTING GAS SUPPLY 
PIPING SYSTEM
Test  Pressures  In  Excess  Of  1/2  PSIG 
(3.5 kPa)

1.  Disconnect appliance with its appliance main 

gas  valve  (control  valve)  and  equipment 

shutoff valve from gas supply piping system. 

Pressures in excess of 1/2 psig will damage 

heater regulator.

2.  Cap off open end of gas pipe where equipment 

shutoff valve was connected.

3.  Pressurize supply piping system by either 

opening propane/LP supply tank valve for 

propane/LP gas or opening main gas valve 

located on or near gas meter for natural gas 

or using compressed air.

To Gas 
Control

Summary of Contents for Design Dynamics VF-18N-MHD

Page 1: ...pliance Do not touch any electrical switch do not use any phone in your building Immediatelycallyourgassupplierfromaneighbor s phone Follow the gas supplier s instructions If you cannot reach your gas...

Page 2: ...air oxygen from the room in which it is installed Provi sions for adequate combustion and ventilation air must be provided Refer to Air for Combustion and Ventilation section on page 5 of this manual...

Page 3: ...a to cause cancer or birth defects or other reproductive harm IMPORTANT Read this owner s manualcarefullyandcompletely before trying to assemble operate or service this heater Improper use of this hea...

Page 4: ...eaterneedsfresh outsideairventilationto runproperly Thisheaterhasanoxygendepletion sensing ODS pilot light safety system The ODS shuts down the heater if not enough fresh air is available See Air for...

Page 5: ...ystem requires no matches or other source to light log set Air For Combustion and Ventilation WARNING This heater shall not be installed in a confined space or unusually tight con struction unless pro...

Page 6: ...grills between the rooms 1 Determine the volume of the space length x width x height Length x Width x Height __________cu ft volume of space Example Space size 20 ft length x 16 ft width x 8 ft ceilin...

Page 7: ...ption 3 Figure 2 Follow the National Fuel Gas Code ANSI Z223 1 NFPA 54 Section 5 3 Air for Combustion and Ventilation for required size of ventilation grills or ducts Figure 2 Ventilation Air from Ins...

Page 8: ...WARNING Never install the heater in a bedroom or bathroom in a recreational vehicle where curtains furniture cloth ing or other flammable objects are less than 42 from the front top or sides of the he...

Page 9: ...Size Height Depth Front Width Rear Width 18 20 14 35 22 1 2 24 20 14 35 22 1 2 MINIMUM FIREPLACE CLEARANCE TO COMBUSTIBLE MATERIALS Log Size 18 or 24 Side Wall 16 Ceiling 42 Floor 5 Measured at 14 dep...

Page 10: ...Minimum Mantel Clearances When Using Hood Minimum Noncombustible Material 8 Min 12 15 18 All minimum distances are in inches 20 2 1 2 6 8 10 12 Distances to Underside of Mantel Hood GA6050 GA6052 or G...

Page 11: ...ht remove the mantel Floor Clearances A If installing appliance on the floor level you must maintain the minimum distance of 14 to combustibles see Figure 8 B If combustible materials are less than 14...

Page 12: ...ction Purchase the optional CSA design certified equipment shutoff valve from your dealer See Accessories page 25 For propane LP units the installer must supply an external regulator The external regu...

Page 13: ...Purchase the optional CSA design certified equipment shutoff valve from your dealer See Accessories page 25 Minimum inlet pressure for purpose of input adjustment Figure 12 Gas Connection 3 Minimum C...

Page 14: ...e LP gas or opening main gas valve located on or near gas meter for natural gas or using compressed air 3 Check all joints from gas meter to equipment shutoff valvefornatural gas or propane LPsup ply...

Page 15: ...ARNING If fireplace has glass doors never operate this heater with glass doors closed If you op erateheaterwithdoorsclosed heat buildup inside fireplace willcauseglasstoburst Make suretherearenoobstru...

Page 16: ...off with ON OFFswitch thus disabling the remote hand set Setting The Display C 24h and F 12h Press and hold OFF and until display changes from F and 12 hour clock to C and 24 hour clock or vice versa...

Page 17: ...gas Shutting Off Burner Only pilot stays lit Press to decrease the flame height and shut off main burner MANUAL LIGHTING Procedure WARNING Manual lighting mustbeperformedbyaqualified service person Th...

Page 18: ...r knob to adjust flame Knob has a slipping clutch that allows manual flame height adjustment to turn gas off to appliance Shutting Off Heater Press OFF button on remote control to switch off main gas...

Page 19: ...to keep the primary air opening s of theburner s cleanmayresultin sooting and property damage Burner Injector Holder Air Inlet Hole The primary air inlet holes allow the proper amount of air to mix w...

Page 20: ...he burner Figure 25 Injector Holder on Front Burner Tube Burner Tube Primary Air Inlet Opening Injector Holder Injector Figure 24 Removing Front Log to Clean Front Burner Main Log Assembly Front Log A...

Page 21: ...ssure is too low 2 Burner orifice s clogged OBSERVED PROBLEM When and arepressedat the same time there is no spark at ODS pilot When and are pressed there is spark at ODS pilot but no ignition Burner...

Page 22: ...and let warm up for a minute 2 Operate burner until air is removed from line Have gas line checked by local natural or propane LP gas company 3 Observe minimum installation clearances see page 9 4 Cl...

Page 23: ...artially clogged 4 Thermostat on remote is satisfied 1 Gas leak See Warning statement at top of page 2 Control valve or gas control defective 1 Foreign matter between con trol valve and burner 2 Gas l...

Page 24: ...F Switch Soldered Cable Thermocurrent Cable 1 Motor Knob MAN Knob troubleshooting Continued POSSIBLE CAUSE Battery nearly down When signal appears the first time ap proximately 10 ignitions left Cable...

Page 25: ...ct authorized dealers of this product If they can t supply original replacement part s call DESA s Technical Service Department at 1 866 672 6040 When calling DESA have ready your name your address mo...

Page 26: ...llustrated Parts Breakdown Models VF 18N MHD VF 18P MHD VF 24N MHD and VF 24P MHD 1 2 3 4 5 25 22 7 8 18 9 6 10 11 26 34 23 12 21 20 29 28 29 28 27 24 27 24 22 13 19 14 32 30 15 15 15 15 15 15 31 15 1...

Page 27: ...01 117004 01 117004 01 Pilot Shield 1 20 099918 03 099918 02 099918 03 099918 02 Burner Regulator 1 21 116957 01 111803 03 116957 01 Air Shutter 1 22 111824 01 111824 01 111824 01 111824 01 Nut Sleeve...

Page 28: ...d by a qualified installer in accordance with all local codes and instructions furnished with the unit This warranty does not apply to parts that are not in original condition because of normal wear a...

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