Any Boiler Techs on here?

[Hnthrdr]

So boiler went out at the family cabin, had a plumber come up and I was bummed when he said we couldn’t have cast iron/ steel (something about inadequate venting, we had double walled 4” but said 5” was necessary) installed a condensating boiler (navien combi units). Had it installed and it keeps throwing pressure codes. It’s a long shot, but wondering if anyone has experience with navien combi units. Would love to chat, was told we could shut the water to the place off and the boiler would run, what we used to do, but wondering if the condensation is causing the problem ie calling for more water supply and none to be had with the shut down water. Anyhow would love to hear from a boiler tech or anyone with one of these navien units, so far had it for about 2 months and I am not impressed :/

 

[StuckoYota99]

What error codes are you getting?

These newer navien probably have a water pressure sensor in them that wants to see a minimum water pressure on the heating side. 14 psi for example.
So therefore you cannot shut the water supply valve off and run the boiler.
The condensation comes from the boiler combustion process not the water in the system.