I take that back, Kiturami Co. does make boilers https://krb.co.kr/english/products/products_view_m1s3.php and your boiler is a rebadge of that, none the less, yours is probably a rebranded one by Rheem similar to mine which is rebranded by Noritz.
Is this a Rheem Prestige Series? Can you provide the actual specific model number? The photo you took is of the heat exchanger and it is not the manufacture of the boiler. "Kiturami Co." is just a manufacture of heat exchangers, this same heat exchanger is used on Noritz CB-199/180 models...
I have a recently installed Noritz CB-199-DV-NG Combination Boiler in my home. Since the installer did not perform a combustion analysis upon commissioning I decided do buy a Testo 510 Digital Manometer and a Bacharach Fyrite Intech combustion analyzer to do the analysis myself. I have learned a...