Performing integrity checks on climate control system components

1. A method performed by a controller of a climate control system having an igniter and an igniter relay, the method comprising:

in one or more of a plurality of heating operational phases of the system, sensing current draw by the igniter and sensing voltage between terminals of a second relay of the system, the current draw by the igniter being sensed by the controller independently of the igniter relay;

for a given one of the heating operational phases in which the sensing is performed, comparing the sensed current and voltage with a current value and voltage value predetermined together for the igniter and second relay in relation to the given operational phase to indicate the presence of a condition specifically of the igniter, of the second relay, or of the igniter relay, the comparing performed using a processor; and

based on the comparing, distinguishing between a failure of one of the relays and a failure of the igniter.

2. The method of claim 1 , wherein the specific condition includes a failure of or a normal operating condition of the igniter, second relay, or igniter relay.

3. The method of claim 1 , wherein the operational phases of the system include phases of an ignition sequence.

4. The method of claim 1 , wherein the second relay is a humidifier relay or an inducer relay.

5. The method of claim 4 , further comprising detecting an open igniter relay, a shorted igniter relay, or an igniter in normal operating condition in a phase in which the igniter and the second relay are switched on.

6. The method of claim 4 , comprising identifying one of a plurality of conditions including the second relay is shorted; the igniter relay is shorted; the second relay is open; the igniter relay is open; the igniter is open; and the igniter is in normal operating condition.

7. The method of claim 4 , comprising detecting the second relay as shorted, the detecting performed in a heating operational phase in which the second relay and the igniter are not switched on.

8. The method of claim 4 , comprising detecting the igniter relay as shorted or the second relay as open, the detecting performed in a heating operational phase in which the second relay is switched on and the igniter is not switched on.

9. The method of claim 1 , performed by a furnace system controller.

10. The method of claim 1 , wherein the igniter relay and/or second relay include one or more solid-state switches.

11. A furnace system comprising:

an igniter; and

a controller including an igniter relay, and a current sensing circuit configured to sense, independently of the igniter relay, a current level through the igniter, the controller configured to sense voltage between terminals of a second relay of the controller;

the controller further configured to:

in a given one of a plurality of operational phases of the system, compare the sensed current level through the igniter and the sensed voltage between the terminals of the second relay to a current level and voltage associated together with a specific condition of the igniter, igniter relay, or second relay in the given phase, the comparing performable using a processor of the controller; and

based on a result of the comparing, distinguish between a failure of one of the relays and a failure of the igniter.

12. The furnace system of claim 11 , further comprising a humidifier and/or an inducer; and wherein the second relay includes a humidifier relay or an inducer relay.

13. The furnace system of claim 12 , wherein the specific condition is identified as one of the following: the second relay is identified as shorted; the igniter relay is identified as shorted; the second relay is identified as open; the igniter relay is identified as open; the igniter is identified as open; and the igniter is identified as in normal operating condition.

14. The furnace system of claim 12 , wherein:

the controller is configured to detect the second relay as shorted in a phase in which the second relay and igniter are not switched on.

15. The furnace system of claim 12 , wherein the controller is configured to detect a shorted igniter relay or an open second relay in a phase in which the second relay is switched on and the igniter is not switched on.

16. The furnace system of claim 12 , wherein the controller is configured to detect an open igniter relay, a shorted igniter relay, or an igniter in normal operating condition in a phase in which the second relay and the igniter are switched on.

17. The furnace system of claim 11 , wherein the igniter relay and/or second relay comprise one or more solid-state switching relays.

18. The furnace system of claim 11 , wherein the operational phases of the system include phases of an ignition sequence.

19. A controller for an HVAC or furnace system having a gas igniter and an inducer, the controller comprising:

an igniter relay for controlling the igniter, and a current sensing circuit configured to sense, independently of the igniter relay, a current level through the igniter;

the controller configured to:

sense voltage between terminals of an inducer relay for controlling the inducer;

based on the sensing performed after a call for heat and prior to a pre-purge of the system, determine whether the inducer relay is shorted;

based on the sensing performed after pre-purge begins and before igniter warm-up, determine whether the inducer relay is open and determine whether the igniter relay is shorted; and

based on the sensing performed when the igniter is warming up and before a gas valve of the system is energized, determine whether the igniter is operating normally, determine whether the igniter is open, and determine whether the igniter relay is open.

20. The controller of claim 19 , further configured to distinguish between a failure of a relay and a failure of the igniter.