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Designs, materials, weights and performance ratings are approximate and subject to change without notice. Visit
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Coil Anti-Scaling Prevention Feature
The ABH controller contains sophisticated software that enables it to monitor the rate of temperature rise through the heat
exchanger. By doing this, it greatly reduces the possibility of heat exchanger failure due to scaling or fouling. A set of parameters are
programmed in at the factory, to provide a design temperature rise (∆T) setting on each size unit that is fixed. The Anti-Scale is based
on an increase over the design ∆T through the heat exchanger. This Anti-Scale is determined using the inlet and outlet sensors, even
if a tank thermistor is being used. If the Anti-Scale setting is reached, the unit will display H11, shut down and not re-fire until it has
cooled. The first 3 times this happens, there will be a reduction of the maximum firing rate. The fault will be accompanied by either an
A, B, or C suffix, indicating a maximum firing rate of 80%, 50%, or 30% respectively. The control will go into hard Lockout after the C
suffix is achieved, and have to be manually reset. Once the heat exchanger has been acid cleaned, contact the factory for instructions
on resetting the unit for full rated BTU input.
Typical causes for repeated H11 indications at start up are air trapped in the heat exchanger (be sure air vent cap is loose) or
contaminates lodging in the piping or heat exchanger during installation, both of these causes can generally be cleared by isolating
the hot water system and flushing water at full city pressure through the drain valve or relief valve on the heater outlet.
The procedure to access the parameters is as follows: while in STANDBY mode, in SETUP page, or in HISTORY page, press DOWN
and BACK keys at the same time for about 5 seconds.
The passwords are as follows:
Level 0= USER (No password needed)
Level 1= INSTALLER
EAZ1LVL
Time Schedule page:
Example of a Multiple Choice Parameter:
Password Protection page:
View/Edit page:
Maintenance - continued