braindrain22
New Member
Hi everyone,
Aside from the internal circulating pump failing in September, the unit has been running without issue since its install 5 years ago.
Everything was in order during my annual service 3 weeks ago by a Navien certified plumber.
Starting 2 days ago, I noticed the thermostat calling for heat for an hour--which was very odd. The boiler can typically get the temp up in about 5-10 minutes, never an hour (outside temp wasn't much lower than 30 which is pretty typical here in New England).
When I went down to unit I noticed the boiler firing for about 1 minute until hitting the temp setting (140) then ending the fire until the temp dropped back down to about 115, then firing again in the same pattern.
The temp of the supply was definitely 140, right until it hit the T in the Navien manifold, at which time the hot water blended with the circulating water and was cooled. Return temp was very cool, maybe 100 deg F.
In the morning the house temp was 5 degrees below thermostat setting (63 deg F, set at 68 deg F). So the unit was calling all night, and sending warm water to rads, just never hot.
Randomly later that morning the unit began firing as normal (nice long 10 minute fire with appropriately warmed return water temps).
The problem went away for about a day, then returned again. This time I shut the unit down completely. Following the full shutdown it worked fine for a day, then fell into the short cycling pattern intermittently.
I imagine a sensor is beginning to fail somewhere, just not sure where or which. Since it's the beginning of heating season here, lead time for a tech is a couple weeks. Perhaps this could be a setting update (during the last service the tech did mention turning the unit down to use about 80% capacity).
Anyone see anything like this with a Navien?
edit, the unit has no errors; domestic h/w works fine.
Aside from the internal circulating pump failing in September, the unit has been running without issue since its install 5 years ago.
Everything was in order during my annual service 3 weeks ago by a Navien certified plumber.
Starting 2 days ago, I noticed the thermostat calling for heat for an hour--which was very odd. The boiler can typically get the temp up in about 5-10 minutes, never an hour (outside temp wasn't much lower than 30 which is pretty typical here in New England).
When I went down to unit I noticed the boiler firing for about 1 minute until hitting the temp setting (140) then ending the fire until the temp dropped back down to about 115, then firing again in the same pattern.
The temp of the supply was definitely 140, right until it hit the T in the Navien manifold, at which time the hot water blended with the circulating water and was cooled. Return temp was very cool, maybe 100 deg F.
In the morning the house temp was 5 degrees below thermostat setting (63 deg F, set at 68 deg F). So the unit was calling all night, and sending warm water to rads, just never hot.
Randomly later that morning the unit began firing as normal (nice long 10 minute fire with appropriately warmed return water temps).
The problem went away for about a day, then returned again. This time I shut the unit down completely. Following the full shutdown it worked fine for a day, then fell into the short cycling pattern intermittently.
I imagine a sensor is beginning to fail somewhere, just not sure where or which. Since it's the beginning of heating season here, lead time for a tech is a couple weeks. Perhaps this could be a setting update (during the last service the tech did mention turning the unit down to use about 80% capacity).
Anyone see anything like this with a Navien?
edit, the unit has no errors; domestic h/w works fine.
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