RSES Journal Winter 2025, RETA-RSES

Note: Installer is required to verify combustion settings as part of the installation process. CO should not exceed 200 ppm.

Natural Gas (NG)

Propane

CO 2 value

2 in. VENT 3 in. VENT

2 in. VENT 3 in. VENT

FTCW (ALL Sizes)

MAX FIRE

8.5–10.5%

9.5–11%

MIN FIRE

8–10%

9–10.5%

NG 1 type combustibility Propane type combustibility

Manifold pressure

2 in./3 in. VENT

2 in./3 in. VENT

MAX FIRE

0.130 in. WC

-0.100 in. WC

FTCW 140

and operation manuals before working on a particular product. I will stress once again, that if factory training is available, take advantage of the opportunity. Figure 1 shows a laars FT Mascot heat ing-only boiler. Figure 2 shows a Laars FT Mascot combination model, capable of providing central heating and domestic hot water. Maintenance Cautions When performing boiler maintenance, understand that maintenance on heat only and combination units require different procedures. For example, the heat-only units require annual combus tion testing, and if any differences from the last combustion test are recog nized, a full-service procedure must be performed. The tables pictured at top right list the specifications for Laars Mascot models. A combustion test must be done when commissioning a new unit and when any service is done. Combination units have a separate tank with a coil that needs to be flushed out periodically. Water quality will be an issue with domestic water. A mainte nance schedule should be made once changes in water flow or temperature are obvious. If a full-service overhaul of the unit is required, it should take a qualified techni cian two hours to complete. Flushing the Domestic Hot Water (DHW) side should take approximately 90 minutes to complete. If proper isolation valves were not supplied when a unit was initially installed, addi tional time will be required. When installing these units, it is important that proper fittings are installed on the inlet and outlet side of the central heating and Domestic Hot Water (DHW) inlet and outlet ports for future maintenance.

MIN FIRE

0.004 in. WC

0.002 in. WC

Note: Values in the range of –0.001 in. to –0.35 in. WC are indicative of proper set up. If current values are outside this range, call technical support.

NG 1 type combustibility

Propane type combustibility

Manifold pressure

2 in. VENT

3 in. VENT

2 in. VENT

3 in. VENT

FTCW 199

MAX FIRE

-0.129 in. WC -0.314 in. WC -0.169 in. WC -0.173 in. WC

MIN FIRE

-0.015 in. WC -0.015 in. WC -0.015 in. WC -0.015 in. WC

familiar with the manufacturer’s instructions and follow installa tion and service per a manufac turer's instruction. When selling any modern boilers make the client aware that unlike cast iron boilers or tank type water heaters, sched uled maintenance will be neces sary. Leave a copy of all literature that came with the equipment with the homeowner. Richard Bruno has 45 years of experience in the plumbing and heating industries. He is a licensed Master Plumber in Nassau and Suffolk Counties, NY. He has owned and operated his own company, is a licensed instructor in NY State and has held sales management and training positions with six boiler manufacturers. He is currently the

Complete servicing kit for a Laars unit described in this article. Yellow highlighting signifies gasket parts that must be replaced during a full-service overhaul, for all manufacturers' boilers.

Secretary and Assistant Educa tional Chairman of the Metro NY RSES chapter, and is heavily involved with their training program. He is the author of “Heating by Dummies” and “The Complete Guide to Residential Gas Heating.” Find both at the RSES Online Store at rses.org/store under Training: Heating.

Proceed with Knowledge There are too many different manufacturers and models to cover in one article. The only variables that technicians must always do, is first, a combustion test, which protects clients and operators. Second, technicians should be

WINTER 2025 RSES Journal 37

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