My first post here!
I have a Navien tankless boiler and have noticed a small leak originating from the Pressure Release Valve.
When I tap on the expansion tank it sounds fairly full.
With the exception of tasks that require a certified professional (such as gas installation), I like to perform as much maintenance on my own in order to get better understanding of how things function (metallurgical engineer by training).
I'd like to tackle this project on my own but wanted to confirm the procedure:
1. Shut off power to the boiler
2. Close the water inlet to the boiler
3. Close the water outlet from the boiler to the radiators
4. Drain the water remaining in the system -- essentially what remains in the pipes between the inflow and outflow shut-off
5. Remove the failed expansion tank (I understand it may be quite heavy)
6. Install a new expansion tank (using teflon thread tape)
And now here's where I'm unsure -- should I be:
1. Turning on the boiler
2. Opening the inflow to the boiler and then
3. Opening the outflow
Will this introduce air into the system that I need to bleed out from radiators?
Also, I believe the pressure relief valve looks okay, but I'm thinking since I'm going to all this trouble I may as well just replace it as well.
What are everyone's thoughts on all of the above?
I've attached photos of my system.