Installing outdoor reset control on a Noritz combi-boiler

FredMeyer · January 8

We have a Noritz NRCB199DV combi boiler installed in 2019 by a definitely-not-factory-authorized contractor. The setup includes a 20 gal buffer tank and a single-zone Taco relay with some sort of analog hydrostat, and the single zone consists of 6 emitters - all either fin-tube or panel radiators, and not nearly enough to allow us to run the boiler at condensation temperatures, but that's a separate issue.

The contractor set up the boiler to be controlled by the indoor thermostat used by the prior furnace. I'd like to replace this with outdoor reset and want to get a sense of what I'm in for. I understand the unit should have come with the outdoor temperature sensor (Noritz part NPH-190 I believe), but because the installer didn't provide it, I'm going to buy one. I also understand that adding a control unit can be helpful, though not essential. I've been looking at the Tekmar 256 and the Taco PC700. Our setup includes the Taco pump control so not sure if it's worth staying consistent with that or not, or whether I even really want a controller separate from the features and capabilities of the boiler itself. Thoughts and suggestions happily accepted!

Pushing my luck but I'll ask a side question here. We recently had to shut off water to the house due to a cracked water main. When we turned the water back on, the boiler wouldn't ignite (neither for heat nor domestic hot water), and it was flashing error code 54. I cycled the power at the breaker, and that got rid of the flashing 54 code, but it is still not igniting. Wondering if this is a common issue with an easy fix.

EdTheHeaterMan · January 8

I believe the Combi Boiler already has the outdoor reset ODR logic in the control panel. No need to purchase a Taco or Tekmar. All you need is the sensor connected to the proper place on the boiler.

The instructions on how to operate the ODR function are on page 54 of the Noritz GHQ manual.

hot_rod · January 8

I second using the onboard reset function, no additional parts or interface, settings display on the boiler control screen

109A_5 · January 8

Seems it is a low water pressure issue. Which may be consistent with your water being off.

From the service manual;

https://noritz.com/manuals

bjohnhy · January 8

Any thermostat should be able to work. A special thermostat is not needed for this ODR function.

I wonder if air was introduced while the water was shut off. Did you try flushing the system or at least just running the circulator through the boiler to flush it out? Then reset the combi again.

GGross · January 8

By the sounds of it you have leaks. there is likely a fill valve hooked to the boiler system. when the water was turned off to the house the fill valve could no longer maintain pressure in the system, the system leaked and dropped pressure, when the water turned back on there was likely air introduced. I would try to identify and repair any leaks, or if not possible I would replace the domestic filling valve with a standalone filling station so you can control the water quality of the makeup water, and monitor the amount of water that the system is losing. excess makeup water is a leading killer of boilers and system components

hot_rod · January 8

Is there a backflow device on the boiler fill?

If not you may have lost water or pressure in the system when the main line went down.

FredMeyer · January 8

Thanks all - I'm going to do a deeper dive on the system this weekend and this is really good info.

Installing outdoor reset control on a Noritz combi-boiler

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