Navien condensing line runs only when recirc is off

Navienguy

I have a Navien NR 180 NG and just recently there is a constant flow from the condensation line only when the timer has the external recirculation system is off. When it is on the flow stops. Is there a connection between the recirc sytem and the condensing line? What would you say is the problem. I called Navien and they were no help.
Thanks for any help.
Jeff

Jamie Hall

Should be no connection. Sounds like there is a sneaky leak somewhere...

Navienguy

Jamie,
Thanks for the response. I am hoping someone will chime in with a suggestion as to where the leak might be. It is strange that when the timer has the recirc running there is no running water- only at night when the recirc is off.
Jeff

EBEBRATT-Ed

@Navienguy

Don't know if I am understanding the question

BUT

If the unit is running and the recirc is on the boiler temp will probably be higher (warm recirc mixing with cold inlet water)

If the unit is running with no recirc the water temp may be lower and you get in the condensing range.

Just an idea

Whats your water temp??

Zman

Is there a chance you have some check valves that are closing when the circ is off? This might allow the water pressure to build in one isolated section as the unit heats. This could then expose a leak in the HX that does not leak under normal system pressure?
That is the direction my mind takes me...

Navienguy

Thank you both for the replies. Let me re-state the problem. At night when the recirc is not on and there is no demand for hot water, There is a constant running of water through the recirulation hose out to the floor drain. It never stops. During the time when the recirc system is active there is no running water. One cure for the problem so as not to waste water is to leave the recirc system on 24/7.
There may be a check valve that is not functioning but I have no idea which ones could create this situation. I really appreciate all your responses.
Jeff

Jamie Hall

Wait a moment. In your first post, you mention a constant flow from the condensate line. In the post just above you mention a constant flow from a "recirculation hose".

The former appears more likely -- I have no idea why there should be an open recirculation hose of any kind -- but either one implies that somehow, for some reason, water from your domestic water system is leaking out of the Navien.

First, note that if it were actually condensate, it would appear only when the burner in the heater was running, and for a few moments after the burner shut off (unless you have a condensate pump -- but that would not be related to the recirculation0. You don't mention such a relationship. Therefore, the only other source of water is your domestic water supply, and the only way that can appear as a constant flow is for there to be a leak or the pressure relief valve is open under those conditions.

The pressure relief valve should be on the hot water supply.

Since the problem occurs when the recirculation is not on, I'm tempted to wonder if you are looking at the pressure relief valve outlet, and then to wonder if perhaps the system is getting hotter than normal at that time -- and then to wonder if there is a check valve somewhere on your piping before the water reaches the heater. And then to wonder if there is one, if you have an expansion tank on the hot water lines and if it is properly charged...

Although that should be just an intermittent flow from the pressure relief, not a constant flow.

Perhaps a more complete description of your water system -- any check valves, expansion tanks, and this heater and how they are all hooked together -- and perhaps a photo of the unit, indicating where the constant flow is, would help.

Navienguy

Jamie,
You are right that I mis-spoke in the previous post. I meant to say that the flow is from the condensation hose to the floor drain. It's not an external leak. The water is flowing exactly where it is supposed to except it never stops. You are also right that the flow is only when the circulation system off (after 11PM and before 6AM) If I shut the water supply to the unit using the valve underneath, the flow stops. This makes me think that water is leaking from the cold water supply directly to the condensation outlet somehow. Does that make sense?
Jeff

EBEBRATT-Ed

@Navienguy

I would call the people that installed it. What your describing make no sense. Is there something else tied into the condensate line?

If the unit is off and there is no demand there should be no condensate to drain.

If it was a heat exchanger leaking it would leak 24/7