Navien CH-180, Service Manual, Page: 66 / 155

64
Check method
Failure
mode
Cause Check method
1. Check if the gas valve is open.
2. Check the gas supply pressure.
NG: 6 ~ 10.5 inch WC
3. Check the flexible pipe dia. (3/4 inch or larger)
4. While the static pressure is normal, a large difference of
dynamic pressure may cause drop of gas pressure. Therefore,
it is required to check the dynamic pressure.
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Static pressure: Gas pressure at the stop of the boiler.
Dynamic pressure: Gas pressure at boiler max combustion.
5. Excessive force in fastening nuts at installation of gas pipe may
move the packing and block the Teflon sealing, causing a drop
of gas supply pressure.
6. Check the gas meter class.
425 CFH (or higher) : Combination Heater/Boiler (195 CFH)
+ Furnace (58.8 CFH) + Domestic gas range (63.7 CFH)
ú 1 CFH = 1,020 Btuh
Gas supply
error
Defective
electrode
gap and
shape
Ignition
failure
Defective electrode gap and shape disables ignition.
Appropriate electrode gap: approx. 3~4mm (replace if defective)
An ignition failure may occur due to improper gap, while
discharge seems normal when checked via the flame monitoring
window. Therefore, it is required to check the gap after disassembly.
<Moved packing narrows the inner diameter.> <Check gas supply pressure>
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© Navien Ameri c a I n c . 20 1 0 CH series servi c e Manua l Version 1 .0