Start-up – Lochinvar CREST 3.5 User Manual
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41
Installation & Operation Manual
9
Start-up
(continued)
Check for gas leaks
Before starting the boiler, and during 
initial operation, smell near the floor and 
around the boiler for gas odorant or any 
unusual odor. Remove the top access 
panel and smell the interior of the boiler 
enclosure. Do not proceed with startup 
if there is any indication of a gas leak. 
Use an approved leak detection solution. 
Repair any leaks at once.
DO NOT adjust or attempt to measure 
gas valve outlet pressure. The gas valve is 
factory set for the correct outlet pressure. 
This setting is suitable for natural gas and 
propane, requiring no field adjustment. 
Attempting to alter or measure the gas 
valve outlet pressure could result in 
damage to the valve, causing potential 
severe personal injury, death, or 
substantial property damage.
Propane boilers only – Your propane 
supplier mixes an odorant with the propane 
to make its presence detectable. In some 
instances, the odorant can fade, and the 
gas may no longer have an odor. Before 
startup (and periodically thereafter), have 
the propane supplier verify the correct 
odorant level in the gas.
Check thermostat circuit(s)
1. Disconnect the two external wires connected to the
enable terminals on the connection board.
2. Connect a voltmeter across these two incoming wires.
Close each thermostat, zone valve, and relay in the 
external circuit one at a time and check the voltmeter 
reading across the incoming wires.
3. There should NEVER be a voltage reading.
4. If a voltage does occur under any condition, check and
correct the external wiring. (This is a common problem 
when using 3-wire zone valves.)
5. Once the external boiler enable wiring is checked and
corrected if necessary, reconnect the external thermostat 
circuit wires to the connection board. Allow the boiler to 
cycle.
Inspect condensate system
Inspect/check condensate lines and fittings
1. Inspect the condensate drain line, condensate PVC
fittings and condensate trap.
FROM CONDENSATE
VENT ON BOILER
FROM CONDENSATE
DRAIN ON BOILER
TO FLOOR DRAIN
OR NEUTRALIZER KIT
1” PVC / CPVC CONNECTION
Figure 9-1 Condensate Trap
ƽ WARNING
ƽ WARNING
ƽ WARNING
