For Installations On The Commonwealth Of Massachusetts; Field Testing Of High Limit Switches - Viessmann Vitocrossal 300 Series Service Instructions Manual

Vitocrossal 300 CU3A 26 to 199 Service
Important Regulatory and Installation Requirements
For installations on the Commonwealth of Massachusetts, the following modifications to NFPA-54 chapter 10 apply:
Excerpt from 248 CMR 5-08:
2(a) For all side-wall horizontally vented gas fueled equipment installed in every dwelling, building or structure used in
whole or in part for residential purposes, including those owned or operated by the Commonwealth and where the side-
wall exhaust vent termination is less than (7) feet above finished grade in the area of the venting, including but not limited
to decks and porches, the following requirements shall be satisfied:
1. INSTALLATION OF CARBON MONOXIDE DETECTORS. At the time of installation of the side-wall horizontal vented gas
fueled equipment, the installing plumber or gas fitter shall observe that a hard wired carbon monoxide detector with an
alarm and battery back-up is installed on the floor level where the gas equipment is to be installed. In addition, the
installing plumber or gas fitter shall observe that a battery operated or hard wired carbon monoxide detector with an
alarm is installed on each additional level of the dwelling, building or structure served by the side-wall horizontal vented
gas fueled equipment. It shall be the responsibility of the property owner to secure the services of qualified licensed
professional for the installation of hard-wired carbon monoxide detectors.
a. In the event that the side-wall horizontally vented gas fueled equipment is installed in a crawl space or an attic, the
hard-wired carbon monoxide detector with alarm and battery back-up may be installed on the next adjacent floor level.
b. In the event that the requirements of this subdivision can not be met at the time of completion of installation, the
owner shall have a period of thirty (30) days to comply with the above requirements; provided, however, that during
said thirty (30) day period, a battery operated carbon monoxide detector with an alarm shall be installed.
2. APPROVED CARBON MONOXIDE DETECTORS. Each carbon monoxide detector as required in accordance with
the above provisions shall comply with NFPA 720 and be ANSI/UL 2034 listed and IAS certified.
3. SIGNAGE. A metal or plastic identification plate shall be permanently mounted to the exterior of the building at a
minimum height of eight (8) feet above grade directly in line with the exhaust vent terminal for the horizontally vented
gas fueled heating appliance or equipment. The sign shall read, in print size no less than one-half (1/2) inch in size,
"GAS VENT DIRECTLY BELOW. KEEP CLEAR OF ALL OBSTRUCTIONS".
4. INSPECTION. The state or local gas inspector of the side-wall horizontally vented gas fueled equipment shall not
approve the installation unless, upon inspection, the inspector observes carbon monoxide detectors and signage
installed in accordance with the provisions of 248 CMR 5.08(2)(a) 1 through 4.
(b) EXEMPTIONS: The following equipment is exempt from 248 CMR 5.08(2)(a) 1 through 4:
1. The equipment listed in Chapter 10 entitled "Equipment Not Required To Be Vented" in the most current edition
of NFPA 54 as adopted by the Board; and
2. Product Approved side-wall horizontally vented gas fueled equipment installed in a room or structure separate
from the dwelling, building or structure used in whole or in part for residential purposes.
CSD-1 Field Testing of High Limit Switches for
VIESSMANN IS NOT RESPONSIBLE FOR ANY DAMAGES THAT THE FOLLOWING TEST PROCEDURE MAY RESULT
IN BY OVERHEATING THE SYSTEM.
The fixed high limit, when tripped, produces a fault that will require manual reset of the boiler control.
Fixed High Limit fault simulation:
- Run the boiler to high fire via relays test.
- Throttle the boiler valve to a point where the burner will run with as little flow as possible.
- When the burner shuts down on the electronic limit, close the ball valve to stop the flow.
- The boiler temperature should continue a steady increase to trip the fixed high limit.
- Once the fixed high limit is tripped, slowly open the boiler valve to safely cool the boiler down.
Vitocrossal 300 CU3A
boilers – where required by law.
General Information
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