I installed a Navien NCB-180 as the boiler for my radiant floor heat system in a pole barn apartment. This is the first winter it will operate so I will be tweaking things as we go. I am already concerned about how often the internal pump is cycling. I have not timed it but the pump seems to start up every 10-15 min. The burner will kick on for less than a min, heat the water in the boiler to nearly 10 degrees above the set temp, then kick off. The pump will continue to run for the over run setting time then shut off. This process will continue to repeat itself. Meanwhile, the floor circulating pumps are not running very often at all since heat for the apartment is not being called for. Is this normal?
Navien NCB-180 cycling
- Thread starter doozer
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DIYorBust
Active Member
Try purging the loop. It's possible air is preventing water from moving through the piping.
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I am more suspicious of what is causing the internal pump to operate so frequently. Some sort of setting? Pressure seems to be steady, the temp of the supply/return water in the unit only falls about 5 degrees below the set point, and I cannot find any other setting that would cause the pump to operate when floor heat is not being called for. Navien will not talk to anyone who is not a licensed installer. One other item that may have an affect is that I am currently not using the domestic hot water side of the unit. It is plumbed in, but I have been more concerned about heating before we switch off the traditional water heater tank and use the tankless side of the navien.
Bannerman
Well-Known Member
Your tankless unit uses a separate water/water heat exchanger for DHW. Water from the space heating heat exchanger will be circulated through the DHW heat exchanger to supply the DHW temp. Even as there currently may not be any water utilized from the DHW circuit, the pump is likely being periodically activated to heat the DHW heat exchanger.
Check also the Pump Freeze Protection Temperature setting as specified on page 59 of the Installation Manual. As the setting adjustment range is between 43-50℉, perhaps the setting is currently too high and is activating the pump when the space heating return temp remains lower than the set temperature for more than 10 seconds.
Check also the Pump Freeze Protection Temperature setting as specified on page 59 of the Installation Manual. As the setting adjustment range is between 43-50℉, perhaps the setting is currently too high and is activating the pump when the space heating return temp remains lower than the set temperature for more than 10 seconds.
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Fitter30
Well-Known Member
All those settings are in install & operating manual starting at page 53. What controls the system?
https://www.google.com/url?q=https:...FjAAegQIChAB&usg=AOvVaw0Vv5pIdlSHry7OjNAussgy
https://www.google.com/url?q=https:...FjAAegQIChAB&usg=AOvVaw0Vv5pIdlSHry7OjNAussgy
I had set the dip switch (#7 I think) to the wrong position. So it was set to "continuous space heating" I wrongly believed this setting would cause the unit to operate only when it sensed water flow caused by the secondary circulating pumps. Though it did fire when the circulating pumps were turned on by the thermostat, the primary (internal) pump was trying to provide continuous heated water all the time. So when this happened and the secondary pumps were not cycling water, it was shutting the burner off then resetting because the high temp setting was being reached.
I initially had my thermostat wired into a relay and then from the relay into the secondary circulator pumps. I had no wiring connected to the navien. I have since ran my thermostat wire directly to my navien. I still need to do some reading on the wiring side to figure out the correct way to connect the relay to the navien. I currently just piggybacked some jumpers to the relay to activate both the navien and my circulator pump at the same time. This is fine for the single zone but will not work for two zones operating on two thermostats. Again, more reading/learning. Thanks for the replies.
By the way bannerman, I was thinking the same as you before I turned to posting here. I watched the temps on the info screen and none of them were ever the same when the unit would start up nor did they ever reach a cold enough temp to start the freeze protection. I was certain that would be the issue. Thanks for the suggestions
I initially had my thermostat wired into a relay and then from the relay into the secondary circulator pumps. I had no wiring connected to the navien. I have since ran my thermostat wire directly to my navien. I still need to do some reading on the wiring side to figure out the correct way to connect the relay to the navien. I currently just piggybacked some jumpers to the relay to activate both the navien and my circulator pump at the same time. This is fine for the single zone but will not work for two zones operating on two thermostats. Again, more reading/learning. Thanks for the replies.
By the way bannerman, I was thinking the same as you before I turned to posting here. I watched the temps on the info screen and none of them were ever the same when the unit would start up nor did they ever reach a cold enough temp to start the freeze protection. I was certain that would be the issue. Thanks for the suggestions
Fitter30
Well-Known Member
Check out this taco panel it will control your two zones , boiler and dwh. Download the install manual.
https://www.supplyhouse.com/Taco-SR...MI26vQjaqM7QIVz8DACh19nwAoEAQYASABEgK1CPD_BwE
https://www.supplyhouse.com/Taco-SR...MI26vQjaqM7QIVz8DACh19nwAoEAQYASABEgK1CPD_BwE
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