Mr. Heater MHVFBF20 NGT, Operating Instructions And Owner'S Manual

14

Installation Instructions and Owner’s Manual

Unvented Natural Gas Vent Free Room Heaters

Burner does not light after ODS/pilot is lit

1. Burner orifi ce is clogged
2. Burner orifi ce  diameter to small
3. Inlet gas pressure is too low

1. Clean burner orifi ce (see Cleaning and 

Maintenance on pages 11 and 12), or 
replace burner orifi ce

2. Replace burner orifi ce
3. Contact local gas company

Delayed ignition of burner

1. Manifold pressure is too low
2. Burner orifi ce is clogged

1. Contact local gas company
2. Clean burner orifi ce (see Cleaning and 

Maintenance on pages 11 and 12), or 
replace burner orifi ce

Burner backfi ring during operation

1. Burner orifi ce is clogged or damaged
2. Burner damaged
3. Gas regulator defective

1. Clean burner orifi ce (see Cleaning and 

Maintenance on pages 11 and 12), or 
replace burner orifi ce

2. Replace burner
3. Replace gas regulator

Burner plaque(s) does not glow [Infrared 
Only]

1. Plaque damaged
2. Control knob set between locked posi-

tions.

3. Inlet gas pressure is too low

1. Replace burner
2. Turn control knob until it locks at de-

sired setting.

3. Replace gas regulator

Slight smoke or odor during initial opera-
tion

1. Residues from manufacturing process

1. Problem will stop after a few hours of 
operation

Heater produces a whistling noise when 
burner is lit

1. Turning control knob to HI position 

when burner is cold

2. Air in gas line
3. Air passageways on heater blocked
4. Dirty or partially clogged burner orifi ce.

1. Turn control knob to LO position and 

let warm up for a minute.

2. Operate burner until air is removed 

from line have gas line checked by lo-
cal gas company.

3. Observe minimum installation clear-

ances (see Figure 4 page 7)

4. Clean burner orifi ce (see Cleaning and 

Maintenance on pages 11 and 12), or 
replace burner orifi ce.

White powder residue forming within 
burner box or on adjacent walls or furni-
ture

1. When heated, vapors from furniture 

polish, wax, carpet cleaners, etc., turn 
into white powder residue

1. Turn heater off when using furniture 

polish, wax, carpet cleaner  or similar 
products.

Heater produces unwanted odors. 

1. Heater burning vapors from paint, hair 

spray, glues, etc. See IMPORTANT 
statement at top of page 14.  

2. Gas leak. See WARNING statement at 

top of page 14.  

1. Ventilate room. Stop using odor-caus-

ing products while heater is running. 

2. Locate and correct all leaks (see 

Checking Gas Connections, page 10) 

Heater shuts off in use (ODS operates) 

1. Not enough fresh air is available 
2. Low line pressure 
3. ODS/pilot is partially clogged  

1. Open window and/or door for 

ventilation 

2. Contact local gas company 
3. Clean ODS/pilot (see Cleaning and 

Maintenance, pages 11 and 12)  

Gas odor even when control knob is in 
OFF position 

1. Gas leak. See WARNING statement at 

top of page 14. 

2. Control valve is defective  

1. Locate and correct all leaks (see 

Checking Gas Connections, page 10) 

2. Replace control valve  

Gas odor during combustion

1. Foreign matter between control valve 

and burner 

2. Gas leak. See WARNING statement at 

top of page 14.  

1. Take apart gas tubing and remove 

foreign matter 

2.  Locate and correct all leaks (see 

Checking Gas Connections, page 10) 

Heater produces a clicking/ticking noise 
just after burner is lit or shut off

1. Metal expanding while heating or con-

tracting while cooling

1. This is common with most heaters. If 

noise is excessive, contact  qualifi ed 
service person

Moisture/condensation noticed on win-
dows

1. Not enough combustion/ventilation air

1. Refer to Fresh Air for Combustion and 

Ventilation page 3 through 5.