GT INSTALLATION AND OPERATION INSTRUCTIONSPage 37
Problem | Detected Problem |
| Solution |
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ASO | This is displayed when the boiler is | 1. | Are the vinyl tubes connected between |
Indicates that the | expecting the air switch to be closed by a |
| the air switch and the ports on the inlet |
Air Switch is Open | differential pressure generated when the |
| pipe. Negative side of switch connects |
| combustion blower turns on. It can occur |
| to the port on the 1 1/2 in, 38 mm, |
| momentarily during normal operation. |
| ABS elbow. |
| A problem is indicated when ASO is | 2. | Check for blockage on the intake and |
| displayed continuously. |
| exhaust vents. |
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| 3. | If fan is running, air switch may be faulty, |
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| ensure that it’s set for 0.2 in, 5.1 mm WC. |
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| The |
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| must be set at 3 in, 76 mm WC. |
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| 4. | If fan is not running, check 120V wiring |
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| to blower, if ok remove low voltage |
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| harness from blower, if blower fails to |
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| start, replace blower, if blower does |
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| start problem may be with blower or |
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| Sentry control. |
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ASC | This is displayed when the boiler has | 1. | Is the fan running. If so check for 24V |
Indicates that the | turned the blower off and is expecting |
| between C and D terminals, see wiring |
Air Switch is Closed | the air switch to be open. It can occur |
| diagrams. If 24V is not present replace |
| momentarily during normal operation. |
| transformer. |
| A problem is indicated when ASC is | 2. | Check venting termination with |
| displayed continuously. |
| required venting described in manual. |
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Ignition Sequence | Check for 24 Volts between terminal B1 | 1. | If there is 24V, indicates faulty wiring |
not activated when | on Sentry & Ground. |
| between BI and W1 on Fenwal, or |
burner light is on |
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| faulty Fenwal. |
(Fan is on and |
| 2. | If 24V is not present proceed to next |
Fenwal not flashing) |
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| step. |
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| Check for 24 Volts between terminal F1 | 1. | If 24V exists here but not at B1, |
| on Sentry & Ground. |
| indicates faulty relay inside Sentry, |
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| contact NTI, replace control. |
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| 2. | If 24V is not present check for 24V |
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| at transformer. |
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| 3. | If 24V exists at transformer, check |
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| wiring and safety limits. If 24V not |
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| present at transformer, check wiring |
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| and replace transformer if necessary. |
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| Water Safety Limit trips (Automatic reset) | May be caused by an error in the reading | |
| Located in the supply manifold inside the | of the water temperature by the Sentry | |
| boiler cabinet. | control. Watch cycle, and ensure the | |
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| Sentry is displaying the correct water | |
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| temperature and is modulating. | |
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| This device protects the boiler from | |
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| overheating due to a lack of flow passing | |
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| through the unit when the burner is on. | |
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| FLOW MUST NEVER BE BLOCKED BY | |
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| ANY VALVES INCLUDING MIXING OR | |
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| ZONE VALVES. | |
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| Install unit as described in this manual. | |
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