Navien Combi boiler flush question

[gt5oh]

Hello, I am preparing to do a flush of my Navien NCB-240E combi boiler. I have it connected to a hydro air handler on the space heating closed loop side but for now I am only going to flush the domestic hot water side.

In all of the YouTube videos I've watched the manifold systems have service ports/valves that allow for easy flushing. Typically two valves, one to open/close water to the unit and one to allow water to enter the service port. I noticed my system has service ports but I only have one handle to control water flow.

My question is, if I turn the copper cold water valve to the off position will that allow cold water to come out of the service port? I don't understand the type of valve being used, if its a 2 way or 3 way valve? I assume if I turn it horizontal that it will stop the water from the main and then allow water to enter via the service port, is that correct?

Also, why do I have 2 cold water in lines? One is a copper line that runs to the valve, and the other is a pex line. Both are cold water in lines.

 

[breplum]

The domestic water bypass valves are three way, so closing allows recirculation of descale solution via the hose bibb ports.
You have three critical issues with this installation:

1. Neutralizer is only supposed to be installed horizontally (nobody read the instructions ???) No neutralizer is needed if the condensate goes to outdoors dirt.
2. the pressure relief valve must be piped to the outdoors via gravity
3. the boiler make-up water, which is the other cold water supply, must have reduced pressure, typically a preset low pressure regulator like Watts 1156F series.

 

[gt5oh]

The domestic water bypass valves are three way, so closing allows recirculation of descale solution via the hose bibb ports.
You have three critical issues with this installation:

1. Neutralizer is only supposed to be installed horizontally (nobody read the instructions ???) No neutralizer is needed if the condensate goes to outdoors dirt.
2. the pressure relief valve must be piped to the outdoors via gravity
3. the boiler make-up water, which is the other cold water supply, must have reduced pressure, typically a preset low pressure regulator like Watts 1156F series.

Thanks for your reply. I assume to service the unit I must connect the hoses to the service valve first. Then turn the handle so that I close the cold water in and hot water out which will force the water to flow through the service valves, correct?

1. Not sure why the neutralizer was added as I have the system set to go to a pump which then sends the water to my sump pump pit. Perhaps they added the neutralizer to minimize the condensate to the sump pump so that it does not kick on as often?

2. Can you explain this more? Are you talking about the pressure relief valve on the space heating closed loop side or the domestic hot water side? This unit is in a basement so how should I fix this issue?

3. I knew something was off with the cold water inlet for the boiler make up water. They simply connected it via a pex line with a on/off valve but no backflow preventer nor regulator. However doesn't the internal of the unit have an auto-feeding water connection and motorized feeding valve? Why would I need an external regulator as well?

 

[TomFOhio]

What are you using to flush the system out?

 

[breplum]

I'm pressed for time rtm but quickly, the sump pump and piping, if entirely 100% plastic is ok with acidic water, but normal sump pumps are not.

I'm not going to argue about normally required -FOR A REASON- proper practices. Talk to Navien if you want to chat about improper installation practices. Backflow prevention is to protect the vital public water supply!!!!!
There are not a lot of great solutions to a stupid installation with no place for relief valves to drain...
sump pit with battery backup i suppose

 

[gt5oh]

What are you using to flush the system out?

Just distilled vinegar.

 

[gt5oh]

I'm pressed for time rtm but quickly, the sump pump and piping, if entirely 100% plastic is ok with acidic water, but normal sump pumps are not.

I'm not going to argue about normally required -FOR A REASON- proper practices. Talk to Navien if you want to chat about improper installation practices. Backflow prevention is to protect the vital public water supply!!!!!
There are not a lot of great solutions to a stupid installation with no place for relief valves to drain...
sump pit with battery backup i suppose

Understood. I also think the pressure relief valve should be vertical and not horizontal right? See attached image.

As far as the lower pressure regulator, doesn't the system only take in make up water as needed? See attached image.

Any thoughts?

 

[breplum]

Your pressure relief valve, as installed onto the bypass kit is perfectly fine and correct...nothing to worry about orientation there.

I must stand corrected on the neutralizer orientation, I see on p.27 they show that vertical orientation is allowed if the outlet is higher than the inlet, but you have to pipe it completely differently than your installation.



We are not concerned with whether or not you have a low water cutoff. That is a local code issue.

I understand what your are asking re, limited make up water.
I do know that normally, space heating systems that use water use specifically low 15 to 30 psi "Make -up Water".
Call Navien and ask would be my suggestion. Installation instructions are not clear to me on this unit.

 

[Twowaxhack]

From Naviens literature they want they relief valve standing up.

Maybe they’re thinking it will not fill with crud if it’s standing upright.

Just for kicks, read me the pressure rating on that relief valve.

 

[gt5oh]

Here are some other pictures. Let me know what else is wrong or you think I should fix please, thanks all.

 

[Twowaxhack]

I’d like to know why Navien specified the relief position. I’ve speculated but I might call them for an explanation. I suspect you could get 3 answers if you called them 3 times. That’s just my honest opinion.

 

[Ole Dodge]

Reading this opens door for me to ask advice on condensate drain. I have a high efficiency gas furnace. When it was installed many years ago in unheated attic a float activated pump was put in drain pan. Well the first time temp was below freezing, you know what happened. So, my solution was to pipe condensate between brick veneer and wall to near ground level exit. Then the next problem was drain freezing and condensate backing up and overflowing the pan. Temporary solution (turning to not so temporary), was to build small enclosure with light bulb to prevent freezing. I’ve had to endure my wife’s dissatisfaction (along with visitors) wanting to know where’s that little light at the bottom of wall coming from? I wanted to vent my Navien outside also, but know the same problem will arise. Please tell me if there is a way to drain outside during freezing weather.
Thanks for this forum. It’s really a blessing to have access to professional advice!

 

[Twowaxhack]

Reading this opens door for me to ask advice on condensate drain. I have a high efficiency gas furnace. When it was installed many years ago in unheated attic a float activated pump was put in drain pan. Well the first time temp was below freezing, you know what happened. So, my solution was to pipe condensate between brick veneer and wall to near ground level exit. Then the next problem was drain freezing and condensate backing up and overflowing the pan. Temporary solution (turning to not so temporary), was to build small enclosure with light bulb to prevent freezing. I’ve had to endure my wife’s dissatisfaction (along with visitors) wanting to know where’s that little light at the bottom of wall coming from? I wanted to vent my Navien outside also, but know the same problem will arise. Please tell me if there is a way to drain outside during freezing weather.
Thanks for this forum. It’s really a blessing to have access to professional advice!

Use heat tape instead of a lightbulb. Or they make ceramic heat lamps that screw into a lightbulb socket and only produce heat, no light.