Olsen HTL-90D, Installation, Operation & Maintenance Manual

9

MAINTeNANce AND seRVIce

Routine Maintenance by home Owner

Other than remembering to arrange for the annual professional 

servicing of the furnace by the service or installation contractor, the 

most important routine service performed by the homeowner is to 

maintain the air filter or filters. A dirty filter can cause the furnace to 

over-heat, fail to maintain indoor temperature during cold weather, 

increase fuel consumption and cause component failure.
The furnace filter(s) should be inspected, cleaned or replaced month-

ly. The furnace is factory equipped with a semi-permanent type filter. 

If the filter is damaged, replace with filters of the same size and type. 

(See Parts Listing Ref. No. 21). 
During the routine service, inspect the general condition of the fur-

nace watching for signs of oil leaks in the vicinity of the oil burner, 

soot forming on any external part of the furnace, soot forming 

around the joints in the vent pipe, etc. If any of these conditions are 

present, please advise your service or installation contractor.

Annual service by contractor

!

CAUTION

THE COMBUSTION CHAMBER (FIREPOT) IS FRAG-

ILE. USE CARE WHEN INSPECTING AND CLEANING 

THIS AREA.

The heat exchanger should be inspected periodically and cleaned 

if necessary. If cleaning is necessary, SHUT OFF POWER TO THE 

FURNACE and remove the burner. Using a stiff brush with a wire 

handle, brush off scale and soot from inside the drum and flue pipe. 

To clean the radiator, remove the clean-out caps screws, and remove 

the caps carefully to avoid tearing the gaskets.  A wire brush can be 

used to loosen dirt and debris on the inside surfaces of the radiator. 

Clean out all accumulated dirt, soot and debris with a wire handled 

brush and an industrial vacuum cleaner. Before replacing the clean-

out caps, inspect the gaskets. If the gaskets are broken, remove the 

remnants and replace with new gaskets. 
The blower motor is factory oiled and permanently sealed.  DO NOT 

LUBRICATE. Excess oil causes premature electric motor failure.
Inspect the blower fan. Clean if necessary.
Oil Burner Maintenance: Follow the instructions of the oil burner 

manufacturer. (See oil burner manufacturer's instructions supplied 

with furnace or burner). It is advisable to change the oil burner 

nozzle and oil filter on an annual basis.
The venting system should be cleaned and inspected for signs of 

deterioration. Replace pitted or perforated vent pipe and fittings. The 

barometric damper should open and close freely.
All electrical connections should be checked to ensure tight con-

nections. Safety controls such as the high limit controls should be 

tested for functionality. The fan control should be checked to ensure 

that the fan on and off delay function continues to start and stop the 

blower fan at the optimal settings.

before lighting

Open all supply and return air registers and grilles.
Open all valves in oil pipes.
Turn on electric power supply.

To light unit

Set the thermostat above room temperature to call for heat. The 

burner should start. NOTE: It may be necessary to press the RESET 

button on the primary combustion control relay.
There will be a fan on time delay before the circulating fan is ener-

gized. The United Technologies 1158-120 has an adjustable fan on 

time that is set by selecting the dipswitch combination displayed in 

Table 2 

on page 6

.

 This fan on delay can be set at 30, 60, 90 or 120 

seconds. Set the thermostat below room temperature. The oil burner 

should stop.
The air circulation blower will continue to run until the time off 

setting selected on the electronic fan timer control times out.  The 

United Technologies 1158-120 has an adjustable fan off time of 1, 2, 

4,or 6 minutes.
The necessary adjustments to the fan control settings should be 

determined by measuring the temperature of the air in the supply 

air take-off, or within the first few inches of the supply air trunk. The 

OPeRATINg INsTRucTIONs (hTl-D)

side mid point of the transition is usually ideal, providing that the 

thermometer probe is beyond the "line of sight" wherein false read-

ings from radiant heat could be observed. System temperature rise is 

the difference in temperature between the supply air and return air.
To check the operation of the limit switch, shut off power to the 

furnace. Temporarily remove the neutral wire from the direct drive 

blower motor. Restore the electrical power to the furnace and set the 

thermostat above room temperature. 
After three or four minutes of burner operation, the limit control 

should turn the burner off. When the limit function test is complete, 

shut off electrical power to the furnace, replace the neutral wire to 

the blower fan motor, and then restore power. The blower fan will 

start up immediately. Once the temperature has dropped and the 

limit control has reset, the fan will operate until the fan off time is 

achieved. The oil burner will then resume operation and continue 

until the thermostat is satisfied. Restore the thermostat setting to a 

comfortable temperature.

To shut Down unit

Set the thermostat to the lowest possible setting.
Set the manual switch (if installed) in the Electrical Power Supply 

Line to "OFF".