Alpine 105 Boiler Auto Reset High Limit sensor tripping
#1
11-02-14, 08:52 PM
Alpine 105 Boiler Auto Reset High Limit sensor tripping
I had great success on the forum 2-3 weeks ago with my Trane furnace - I'm hoping for some help again from the forum experts...
My 4-year old Alpine 105 boiler is used for domestic HW and 2 radiant heat circuits. It was installed in October 4 years ago and ran the first year. In each of the following 3 years, it has failed (perhaps it's haunted?). I know today is Nov 2, but close enough.
The first year I was away and the service tech came and jumped out the LWCO - he said "it wasn't needed".
The second year the "high limit sensor" was replaced. The unit seemed okay afterward.
The last year the high limit sensor was replaced again. The unit ran for a day or two and then the problem repeated itself. The tech came back and said the sensor he installed was bad and replaced it. A manufacturer's rep came with him, and also adjusted some of the software settings.
This afternoon I kicked on one of the radiant zones and went out for the day. Came back, and the unit is in error mode "boiler safety limit open". I jumped out the float switch, no change. Took the sensor replaced last time, and connected the 2 gray wires to it (and held the sensor in my hand - not installed). The boiler ran.
My guess is that the sensor is doing it's job, and sensing something that won't allow the boiler to run. Kicking on the radiant circuit makes me think it could be a low-water or air problem (or circulator problem?). Any ideas/suggestions on how to better diagnose the problem? Any suggestions on how to get some hot water until I can fix it?
As an aside, in the last 4 years all of the internals, (incl the SG2.1 module, LED display, fan... a couple of circulators, etc.) have all been replaced. The unit has been completed rebuilt 2x already.
As always, thanks in advance for any and all suggestions.
My 4-year old Alpine 105 boiler is used for domestic HW and 2 radiant heat circuits. It was installed in October 4 years ago and ran the first year. In each of the following 3 years, it has failed (perhaps it's haunted?). I know today is Nov 2, but close enough.
The first year I was away and the service tech came and jumped out the LWCO - he said "it wasn't needed".
The second year the "high limit sensor" was replaced. The unit seemed okay afterward.
The last year the high limit sensor was replaced again. The unit ran for a day or two and then the problem repeated itself. The tech came back and said the sensor he installed was bad and replaced it. A manufacturer's rep came with him, and also adjusted some of the software settings.
This afternoon I kicked on one of the radiant zones and went out for the day. Came back, and the unit is in error mode "boiler safety limit open". I jumped out the float switch, no change. Took the sensor replaced last time, and connected the 2 gray wires to it (and held the sensor in my hand - not installed). The boiler ran.
My guess is that the sensor is doing it's job, and sensing something that won't allow the boiler to run. Kicking on the radiant circuit makes me think it could be a low-water or air problem (or circulator problem?). Any ideas/suggestions on how to better diagnose the problem? Any suggestions on how to get some hot water until I can fix it?
As an aside, in the last 4 years all of the internals, (incl the SG2.1 module, LED display, fan... a couple of circulators, etc.) have all been replaced. The unit has been completed rebuilt 2x already.
As always, thanks in advance for any and all suggestions.
#2
11-03-14, 05:21 AM
Thanks to all who have viewed my post.
This morning I pulled out my voltmeter and confirmed continuity across the two terminals of the high limit sensor that was removed last year. I performed the same check across the sensor that is still installed in the Alpine, and did not get continuity. Is it as simple as the sensor has failed, and I can swap out the one removed last year for the one currently installed?
To do this, I am assuming I can isolated the boiler, drain some water to remove the pressure, and simply remove the old sensor. A few turns of dope tape, install the new sensor, and open the feed water valve. Is there anything else I need to do? Will I need to purge the boiler? If yes, how do I do that? Any other ideas/suggestions? All help greatly appreciated. Thanks.
This morning I pulled out my voltmeter and confirmed continuity across the two terminals of the high limit sensor that was removed last year. I performed the same check across the sensor that is still installed in the Alpine, and did not get continuity. Is it as simple as the sensor has failed, and I can swap out the one removed last year for the one currently installed?
To do this, I am assuming I can isolated the boiler, drain some water to remove the pressure, and simply remove the old sensor. A few turns of dope tape, install the new sensor, and open the feed water valve. Is there anything else I need to do? Will I need to purge the boiler? If yes, how do I do that? Any other ideas/suggestions? All help greatly appreciated. Thanks.
#3
11-04-14, 07:12 PM
After this post on Sunday, I replaced the limit sensor on Monday, and the boiler ran fine for 24-36 hrs. It's now Tuesday evening and i have error mssg "soft lockout 17 - fan speed not proved" Some8ne, please help!!!
