Navien Ch210 error code e30

[Jac04]

It's not lowering the heating loop supply temp when you are using domestic hot water (DHW). When you are using hot water, the remote displays the DHW output temperature and not the heating supply temp. During DHW use, the front of the unit will display the heating loop temp, which will be well above the DHW setpoint of 120F (because it is using the heating loop to heat the incoming cold water via a water to water heat exchanger - it doesn't use the main heat exchanger to directly heat the DHW).

If you are using DHW during a call for heat, the DHW gets priority. Then when you shut off the DHW, the unit will stop firing - that's what it is programmed to do to avoid overheating. The burner will not fire again until the supply temp drops to 10-15F (I can't remember the exact difference) below the supply set point. So, it sounds like it is doing what it is supposed to do.

The CH series do not have a 'boost' function.

 

[Samat]

Thanks jac that makes me feel better. Thanks for your advice on using the outdoor sensor I think it's a great help. By the way Boston heating supply was $10 cheaper than Navien dot com on the sensor.
Thanks

 

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[Samat]

Now that I rember when I was having trouble with the overheated exhaust sensor Navien had me run two faucets at full hot and read the temps. It was 120 at the remote and 190 on the unit. They said way too much demand but who uses two faucets at full hot st the same time.

 

[Jac04]

... when I was having trouble with the overheated exhaust sensor ....

Oh yeah, I almost forgot about the original issue you were having. I assume you are running error-free now?

I have gotten into the habit of adjusting the supply temp manually each morning & evening , which is no big deal since I've relocated the remote to upstairs beside my thermostat . But now you've got me thinking about the ODR again, so I may go back to using it and see how it does. I just have to remember that it doesn't work well (for me at least) when the outside temp warms up.

 

[Samat]

Error free. You can actually scroll through your errors on the PCB in my unit. It scrolls through the last 5 errors. Newest error was low water pressure from when I flushed the heat exchanger. The others where the old old high temp errors. I wonder when I was running the unit at 180 that it didn't have to go through the cooling cycle after hot water, that's why I never noticed it.

 

[Samat]

It happened again. In the middle of a shower unit went into E30 and shut down leaving only cold water. I have installed a new high temp sensor, flushed the heat exchanger and installed an outside temp sensor. Originally set K factor at 1.6 but that was doing weird things when the temp was in the 50's. Set it up to 1.8 which raised the operating temp and seemed to work ok at higher outside temps. It was in the teens last night and the boiler was running at around 150. That's when the error kicked in. I have set the K factor back to 1.7 to see what happens. I later Checked temps with showe r running. The water temp was120 and the boiler temp was 180. The switch is designed to cut out at 149 flue temp. I put in a 180 degree board when I thought I needed higher temp and converted to CPVC exhaust. After much discussion on the forum I did the changes above. My question is if I was required to go to CPVC with the higher temp board why don't they tell you to pu t in a higher temp flue temp switch? I can install a higher temp switch from the newer NCB model or one in between. They are a industry standard thermostatic switch available in many temps. What do you guys think?

 

[Samat]

Went in and checked past codes and the E30 code has happened more than once since I made all the changes.

 

[Jac04]

I later Checked temps with showe r running. The water temp was120 and the boiler temp was 180.

That seems very unusual to me. On mine, with a high-flow shower running, DHW temp is 120F but the heating loop side rarely gets above 140F. 180F seems way too high.

I'm thinking you are having a heat transfer problem. The heat isn't getting into the water for the heating loop, so it has to go somewhere - which is out the exhaust. Is the circulator pump running? How about the 3-way valve - could it be hung up & restricting heating loop water flow? Look for anything that could be restricting flow through the heating loop.

You stated earlier "...Navien had me run two faucets at full hot and read the temps. It was 120 at the remote and 190 on the unit. They said way too much demand but who uses two faucets at full hot st the same time." This also has me thinking the same thing. Navien told you "way too much demand" because of how high the boiler side temp was (190F). They never bothered to really think about what is going on. I can run 4 faucets, 1 shower & 1 tub all at full 120F hot and never get anywhere near 190F on the heating side.

 

[Samat]

Ok just got off the phone with Navien tech. Had a guy that was very helpful. We found out that the higher temp (180) board that I put in in 2011 was set as a CH 240 so we so we set the dip switch to a CH210 setting. We ran a water demand and he said everything looked good. But to be on the safe side he gave me a part number for a higher temp limit switch which I just ordered. It made no sense to me from the beginning that when I switched to the 180 degree board and had to switch to CPVC exhaust that they didn't include a higher temp cut off switch. Should have the part in a couple of days so we will see what happens. I could always put back in the 160 degree board if this doesn't work.

 

[Jac04]

We ran a water demand and he said everything looked good.

What was it doing?

 

[Samat]

What was it doing?

Two faucets running full hot. 115 water. 193 boiler. One faucet full blast 120 water 137 boiler. When I first installed the unit I had a water volume problem with my supply line from the street. I took out all the o ring restrictions in the water supply to the navien so I am flowing a lot of water and I think that's why the unit is going so high to heat up the water. But who ever runs two hot water taps full bore? The water supply problem has since been fixed. I may put a restrictor back in and see what happens. But I think the higher temp flue switch may be the answer.

 

[Jac04]

I still think you have a DHW heat transfer problem. Even with 2 faucets running, you should be able to hit your target of 120 at a much lower boiler temperature.
I just did a test on my CH-180. 2 faucets and a high-flow shower, all on full hot with a DHW water supply pressure of about 50psi.
120F DHW and 159 boiler supply.

 

[Samat]

You think I should do a acid flush of the DHW heat exchanger? I probably will do that but we have excellent water and nothing shows any sign of calcium build up What else could it be.

 

[Samat]

Do you have the o ring restrictors in your intake?

 

[Jac04]

Yes, I have a restrictor on the DHW water supply. I don't remember which one I have in right now, but I have tried them all at some point.

If your heating loop temp is really high when in DHW mode, it could be 2 things: 1) fouled heat exchanger, or 2) low flow through the boiler side of the heat exchanger. The boiler is doing whatever it can to try to achieve the DHW setpoint of 120F, but it just can't transfer heat to the DHW quickly enough. It might just be that the DHW heat exchanger has slowly become fouled over the past 5 years and it finally got to the point where it is bad enough to trip the exhaust temp switch.

I've also heard that the 3-way motorized valve on these units is prone to failure - take a look at yours to see if there is any signs of a water leak at the valve which would cause motor issues. If the valve isn;t working properly, it could possibly cause a flow restriction through the DHW loop. If the valve isn't fully switching over, you should feel the heating side supply getting hot when you are using DHW.

 

[Samat]

JAC
I agree that the temp seems too high. I'm going to flush the DHW heat exchanger to see what happens. I think that my three way valve isn't closing all the way. Working with Navien they asked me to feel the heating loop to see if it was during the temp test for DHW to check if water was bypassing the 3 way valve. Where I grabbed it it was a little warm about 10 inches from the unit. Heat didn't go far along that loop so we assumed that the valve was sealed. Later after your post I tried it again with two faucets running and boiler at 190. This time I touched the heating loop outlet at base of the unit at the shutoff valve and it was burning hot. Can you try the same test on your unit and see how hot that valve gets. The heat does not travel all the way around the loop but the three way valve could be not closing all the way.
The 3 way valve isn't that expensive but looks to be a pain to replace but looks doable. I would appreciate you eating your unit. I did put the red flow restrictor in the unit but it didn't change a thing. Temp in boiler with restrictor got to almost 200 with the restrictor.

 

[Jac04]

OK, I'll see if I can feel the heating loop with the DHW going full blast and see what I get - it will be a little later after I get home from work.

I bought a spare 3-way valve for my unit just in case (I have a bunch of spares on hand, since they are reasonably priced but nobody local seems to stock them). On my unit, it looks like it can be changed without having to take everything apart, but it will definitely be tricky. I purchased a Makita B-51873 flexible extension so I could get to the screws without having to remove all the components around the 3-way valve. I think you could do the same. My plan would be to leave the metal bottom part of the valve in place and replace everything above that.

 

[Jac04]

OK, just checked the heating loop with the DHW on for about 5 minutes with 2 faucets on full hot. It was warm here today, so the heating loop was at ambient temp since the boiler hadn't fired on a call for heat for about 6-7 hours. With the 2 faucets going, boiler temp was 153F and DHW temp was 120F. Right where the heating loop exits the boiler, the pipe was slightly warm, I would estimate about 110F. About 10-12" away it was still ambient temperature (maybe just very slightly above ambient, but not by much).

 

[Samat]

Thanks Jac
Mine was scalding hot so I am assuming my three way valve isn't closing all the way. At 10 to 12 inches mine was probably 110. Guess I'll order the three way valve.
Thanks for your help. I post the outcome.

 

[Jac04]

I was thinking more about this...
I wonder what would happen if you closed the valves at the heating loop supply & return to the unit, then turned on the DHW. This would keep water from flowing through the heating loop. Would this force more water through the DHW heat exchanger? I'm not sure what type of pump the internal circulator pump is, so I'm not exactly sure what will happen. But, if something changes, you can be fairly sure that it is the 3-way valve. If nothing changes, well, I'm still not sure it 100% rules out the 3-way valve, but it's more info than we have right now.