Navien CH-240 is this normal?

**nadaplumber** · 03-13-2012, 12:52 PM

First post so excuse my ignorance : )
Here's my setup.......
Navien CH-240, remote controller, outdoor temp sensor, external thermostat on main floor of home, cast iron radiators

I had the Navien installed in late December last year and it ran fine until just yesterday. Now, no heat though I do have not water. Yesterday a contractor turned the heat off to work on a bathroom radiator. When I got home I noticed the unit was back on but not producing heat. When I looked at it there was an error code indicating low input water pressure. I noticed the input was shut. I turned the Navien off then slowly turned the valve on; it did have to fill a bit. Turned the Navien on, no more error code. After that I did not check it again, nor did I make sure the heat was working as it was pretty warm here yesterday. This morning I turned the thermostat up a bit as it had cooled off. I heard the circulation pump come on. After a little while I noticed it was not getting warmer. I checked, the Navien was not running; only the circulation pump was running. I have reset the Navien several times; I turned the remote controller off/on, the Navien itself off/on and pulled the power plug out of the wall - while it was off of course. I also turned the thermostat off/on. Still no heat. Is this thing working normally?? You'd think that when you turn the thermostat up you get heat. Is the outdoor temp sensor somehow overriding the thermostat? Thx for any replies.

**nadaplumber** · 03-13-2012, 01:08 PM

BTW, I also cannot set the supply temp. When I follow the instructions in the user manual the display appears to want me to set the K-Factor even though the space heating supply icon is flashing. I cannot get the K-factor icon to flash at all. Only the supply icon will flash; the display shows "2.0". That is K-factor stuff, yes? Tapping the button again does not change which icon flashes. There are three icons in the lower part of the screen. Space heating supply temp, Thermostat and K factor. These are on continuously. Thx.

**Dana** · 03-13-2012, 01:18 PM

The problem isn't likely to be the Navien. I'd put money on the contractor not properly purging air from the heating loop after breaking open the system, and you have a vapor-lock interfering with flow on the heating loop. The circulator pump may be running, and you may be getting some flow, intermittent flow, or none. But bleeding/purging the air out of all the radiators would be the critical first-step, and it may take more than 1-2 tries. Hopefully there's an air-scoop in the system that gets rid of the rest over time, after you've manually purged it sufficiently enough to restore at least enough flow that it can heat the place.

What is the pressure on the heating system?

**nadaplumber** · 03-14-2012, 07:46 AM

Thx, Dana. The pressure when the unit is not running is in the middle 9.X range, when running it is over 10. I had been purging the radiators of air as I had done when the unit was initially installed. I've done this three times already and as you have pointed out I may need to do this even more. The good news here is that this morning the heat came on so except for the niggling issues of using the remote controller I may be OK.

Here's something I did discover late yesterday. Pushing the buttons on the remote controller when it is OFF produces cryptic (to me) stuff to appear on the display. Must be infoirmation or readings for the pros to use; there is nothing in the installation or user manuals about it.

**Dana** · 03-14-2012, 12:13 PM

Are you sure it's not displaying something in Han-gul (Korean script) !?! :-)

The system pressure is a bit on the low side if it's only 9-10psi, 12 would be better, since that reliably inhibits oxygen diffusion through most (but not all) pipes. Chronically low pressure can lead to excess corrosion on iron impeller pumps, etc. Unless you have a 4 story house or something you'll never need more than that. The expansion tank should pretty much keep the pressure the same no matter what the system temp is, but the 1psi delta between 9-10 when the pump is running vs. not is nothing to sweat about.

**zl700** · 03-18-2012, 02:27 PM

The Navien CH has a built-in electronic feeder. Street pressure must be connected to the 1/2" thread connection on the bottom and left turned on. Many contractors make the mistake of putting a boiler feed pressure reducing valve factory set at 12lbs. This is a problem since the CH fill pressure switch is downstream of the circulator outlet which raises static pressure to about 18 PSI.
12# + 6 PSI = about 18 PSI shut off.

Then not running it will be between 12-15 PSI, and running 18-22 PSI on average.

Sounds like the CH doesn't have enough pressure due installation error.

Also the K factor is outdoor reset. You can disable that and switch back to water temp operation mode by unplugging connection on board on LH side. Tapping heat button will allow you to change temp with dial as per manual.

**Surfing Plumber** · 07-11-2012, 02:06 PM

Navien is a low end product, installed many and had to return to job sites many times...Waste of my time and my customers' money...I would not recommend Navien at all... Please look elsewhere, such as Noritz for your tankless needs

http://www.complaintsboard.com/compl...t-c617997.html