Navien NCB 180-E Installation Not Matching Manufacturer Guidance

Walt_10

I had a Navien NCB-180E Combi Boiler installed several years ago. Recently problems have developed with overheating combustion chamber, Error Code 001, and shutdown/reboot. In subsequent repair visit, the professional installer replaced the circulator pump in the unit as indicated by Navien customer support. The problem resolved temporarily but after less than 12 hours, overheated with same error code 001 and reboot. I now can only use the hydronic heat side of the combi unit, due to overheating when using domestic hot water. In researching the installation, I noticed the installer (a professional HVAC business) did not follow the installation instructions to use a primary manifold or create a recirculating loop in the domestic heat side of the unit. Now dealing with expensive repair and trying to determine if installation could be responsible for the malfunction and need to repair and replace parts.

Jamie Hall

It seems rather unlikely that a problem on the heating side would cause a problem on the domestic hot water side. There may be a problem with lack of circulation or flow on the domestic hot water side, however.

Walt_10

Thanks for the input. This model incorporates a three-way valve that is important in Navien combi-unit for heating and domestic hot water. This is the motor that diverts hot water when it is being called for Domestic Hot water or when zone (secondary loop) heat is being called for. So it appears there is a nexus for one side to affect the other? On one occasion two weeks ago, while I was monitoring the domestic water operations, the primary supply read well over both set temps for heat (140) and for water (120). I believe it was 190 (seconds later it shut down...Error 001 due to exceeding combustion max temp of 203. The interesting observation was that the supply side distribution became super heated as if hot thaat 200 degree water was bleeding in. Likely through the 3-way valve?

Ironman

No, if it’s going over-temperature, you most likely have a circulation issue. Bad circulator, air bound, possibly a dirty heat exchanger.

Ironman

Some some pics of the boiler and it’s near piping would help.

Walt_10

Thanks for the reply and input. The original unit circulation pump was running when HVAC was onsite with Navien on the cellphone. Tech indicated he could hear pump running but Navien advised pump replacement, which occurred on follow-up visit since tech did not have part on the service vehicle. The new Navien pump did not resolve the problem. NCB-180 will run for minutes or several hours as a combi-unit before overheating to max combustion chamber temperature of 203 degrees F. Attached are 2 pics showing E001 (I also looked in manual and saw that errors start at E003 but several youtube videos depict E001 and resolutions), and high temp of 199-200 before displaying error code. The last photo shows the HVAC contractor installation with no Navien manifold or recommended primary loop (tee between supply and return).

Walt_10

Primary (boiler) and Secondary (zone) installation instruction from Navien NCB manual.

hot_rod

It sounds like either the boiler side of the HX is plugged, of the 3 way valve is not modulating properly of something inside restricting flow

Walt_10

Regarding the recirculating loop in the domestic heat side of the unit that is currently not present, I've read that the connection should be no longer than 4x the diameter of the supply - return plumbing. Since these are 1 inch, separation should be 4 inches or less. The only way I can see to accomplish is to install the T in location shown in the picture below (black line). If I use the red line location the distance is 7 inches.