SOLVED- Navien CH-210, no heat to radiators, domestic works fine

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artworkanonymous

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Hello all,

I have a Navien CH-210 water heater. It continuously leaks water from the air bleed valve on the primary heat exchange outlet, with the water then exiting through the condensate outlet. This leak tends to subside when the unit is shut off and allowed to sit for a while. Currently, the hot water circuits for the radiators aren't heating up as expected. Only the outlet pipe and a section about 2 feet from the unit are getting hot. The domestic hot water is functioning correctly, but when it's running, the water coming from the primary heat exchange outlet becomes very hot. In addition, I've already replaced the heat exchanger and an air separator. I've also examined the recently replaced flow sensor, Ive triple checked the install (the missing o ring problem I have read about) , and it seems to be correctly in place. What could be causing these issues?

Video here:

Only discovered this problem today. I will call Navien tomorrow but have had mixed results with them since I am the homeowner and not a professional.

Thanks in advance,
 

artworkanonymous

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Thanks Fitter30!

I tried to make a short update but it ended up being 3 minutes. Video attached.

The first thing I reference "Im pretty sure you cant find that..." is the air bleed valve.

essentially, that bleed valve came with the new heat exchanger, however, that doesnt seem to be a problem any longer?! All I did was unplug it for a few hours. I dont know what changed...

I am still having issues getting heat to the radiators. You can hear my conjecture in this video.

Off to chop more firewood...

 

artworkanonymous

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I added a valve in the high spot just to the left of the zone one pump so I could bleed air from that section. That isn't the problem.

Turning on the thermostat does activate the boiler but the heat never travels out to the zones, it just maintains a high water temp very close to the unit. :(

I will call Navien tomorrow.
 

Fitter30

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One story house 10-12 lbs with system pumps off 100° or cooler. Expansion tank pressure same as system pressure. Measures with a 50 lb tire gauge air pressure adjust with hand pump. There is a air bleed on top of the the air scoop is the cap loose? Air scoop have u removed the cap and pressed the schrader stem to see if there's air? 1" taco air scoop wants 18" of straight pipe entering side. Have u inspected the heating side strainer page 36. When u opens the air bleed at heat exchanger didn't seem like there wasn't enough pressure in system. Could put a gauge on that hose to compare readings.
 
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artworkanonymous

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One story house 10-12 lbs with system pumps off 100° or cooler. Expansion tank pressure same as system pressure. Measures with a 50 lb tire gauge air pressure adjust with hand pump. There is a air bleed on top of the the air scoop is the cap loose? Air scoop have u removed the cap and pressed the schrader stem to see if there's air? 1" taco air scoop wants 18" of straight pipe entering side. Have u inspected the heating side strainer page 36. When u opens the air bleed at heat exchanger didn't seem like there wasn't enough pressure in system. Could put a gauge on that hose to compare readings.

expansion tank is same as system pressure at ~27lbs.

air bleed cap not loose, pressed schrader stem and water came out.

heating strainer (page 36) is clean.

Maybe i could measure that pressure at air bleed but would need extra kit, but there is no pressure error on machine, and it knows when i depressurize it cause it drops to zero and takes a minute to build back pressure when i pressurize it.
 

Breplum

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I think you have an air lock. We like to use tees with FIP branch and hose bibb to allow purging etc..
Webstone makes fancy versions. We also put isolation valves on both sides of pumps to make swap-outs a piece of cake.
 

Fitter30

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Max water pressure heating is 30 lbs. Don't need if there is a relief valve piped in it would blow when boiler would get up to temp. 27 lbs is 62.4' 2.31 ' per lb.Take some pics of the pumps and piping i can tell in the video exactly how their piped.Can u hear the pump running? If not hold a screwdriver tip on it and your ear on the handle.
 

artworkanonymous

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Currently, the only observable problem is no heat when zone pumps are running. I have summarized where I am at with this repair in this video. I have high confidence that it is the internal circulation pump. I will update the forum and make a summary video for youtube repair people once I figure this out.

 

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artworkanonymous

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I think you have an air lock. We like to use tees with FIP branch and hose bibb to allow purging etc..
Webstone makes fancy versions. We also put isolation valves on both sides of pumps to make swap-outs a piece of cake.
Thank you for your comment

Airlock is a good tip, I hooked up hoses to those upright valves, and let water run through the system both directions. I did hear some air escape but it seemed minimal. Im not clear if this would purge the air, but it hasn't been a problem in the ten years of operation. Isolation valves would have been fantastic, and I wish I would have just used pex for the whole thing. At the time of the install, I couldn't afford any more kit than you see here on this install. When this unit gets beyond repair I will redo the system proper.
 
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artworkanonymous

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Max water pressure heating is 30 lbs. Don't need if there is a relief valve piped in it would blow when boiler would get up to temp. 27 lbs is 62.4' 2.31 ' per lb.Take some pics of the pumps and piping i can tell in the video exactly how their piped.Can u hear the pump running? If not hold a screwdriver tip on it and your ear on the handle.
Hopefully the pictures help. I have tested power on the zone pumps. there is power when activated by taco, and I can feel them running with your screwdriver trick. I found this in the service manual. I ordered a new internal circulation pump. Wish me luck.
 

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Fitter30

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Look at diagram post 12. Verses yours. The water will flow to top pump easier than bottom pump. Notice where ex tank and air separator is located. Just because a system might work piped wrong doesn't mean it's right.
 

artworkanonymous

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SOLVED

New circulation pump was not necessary. If you peel the sticker off the pump, you can see a brass flathead that you can unscrew and peek inside the pump. It was working fine.

The thing that wasn't working, was the 3 way valve. It must have sat too long over summer and froze open to the domestic side only.

Video description here:


It is officially working even though its evidently piped wrong. :(

Thanks forum!
Hopefully this helps someone else.
 
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