Weil-McLain C-1013 - Manual (Page 4)

Is the water heater undersized for the application? (Non-Warranty)
- There are many methods of sizing various applications, i.e. ASHRAE sizing tables, or
ASPE domestic water heating design manual, re-confirm the water demand required for
the application.
- Re-confirm the flow rates of the fixtures. Was the tank sized for shower heads at 2.0 gpm,
when the actual heads are 5.0 gpm? Use a bucket and a stopwatch to determine fixture
flow rates.
- Evaluate the hot water usage pattern for a day. Is the peak demand unusually high for the
application?
- Has the demand for domestic hot water changed since the system was installed? A
bathroom remodeling project with a newly installed whirlpool tub will drastically change
the domestic water demand.
Is the boiler system properly sized? (Non-Warranty)
- Is the boiler providing the required output of BTU’s to meet the domestic water load?
Temp Rise ºF = Desired Temp.ºF - Incoming Temp.ºF
8.33 = Density of Water lbs/gal. x 1 Btu/lbs ºF
Example: A single family home with a 3.0 gpm shower fixture and a 150,000 Btu/hr output
boiler capacity. Is the boiler capacity adequate to deliver 115ºF water for an extended period?
The boiler capacity is capable of delivering 4.6 gpm continuously which is
adequate for this application.
Action Item:
- Measure the BTU input to the boiler by clocking the gas meter or finding the oil flow rate
based on nozzle size and pump pressure.
- Does the hot water system need to be wired for domestic priority? For systems in which
either the storage or BTU’s available are marginal, it is recommended to wire the domestic
water heater in a priority manner.
- Is the boiler piping to the water heater properly sized to allow the required flow rate for
maximum BTU transfer? The temperature differential of the boiler supply and return
water should be 20ºF to 30ºF.
Domestic Demand gph=
Blr Output BTU’s
(Temp. Rise F x 8.33)
Domestic Demand gph=
150,000 Btu/hr
[(115 F-50 F) x 8.33]
= 277 gph
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