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Navien NCB210 Heating Help

zanesilkzanesilk Member Posts: 27
edited December 1 in THE MAIN WALL
Hello all I am running into some problems with my new install.

I finished my install today and fired it up at 9AM, it took 6 hours to reach 70 degrees from 56 starting temp. Does not seem normal to me. Single Zone, 1400sqft 65 Feet of Baseboard, Temp set to 180, 20 degree delta. What is the deal here ? Unit is at 31 PSI pressure which does not seem normal to me on top of the i have a manual gauge on the manifold supply tee and that reads 20. What gives ? I have purged the unit and i am pretty sure its not an air problem. I have a 1/25HP circulator on the supply side, could it be that it is too weak to overcome the primary loop pump ? All baseboard piping feels very hot. Here is the install picture for piping purposes, its been completed since. -I am hoping i'm missing something here ?
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Comments

  • SuperJSuperJ Member Posts: 557
    edited November 30
    If the base board is hot and the boiler at set point. Then the amount of baseboard is probably the limiting factor for the recovery rate (not the boiler). Your boiler has enough capacity for about 180' of baseboard (@180f in multiple loop of course).

    65ft of baseboard at 180degF is about 40,000 btu/hr. That's almost 30btu/ft2 which should be enough assuming basic insulation and air sealing.

    What is the temperature of the water coming back from the loop before it gets to the boiler tee? This may be different than the boiler entering water temperature.
    Also, what is the temperature going out to the loop (not the boiler SWT it might be different too).

    Read this:
    https://heatinghelp.com/systems-help-center/loop-system-hot-water-heating-q-and-a/

    If you're using 3/4 baseboard you're right on the max for a single loop. Since you won't be able to efficiently pump enough water into a 3/4" to feed more than about 65' at a reasonable temperature drop.
  • GordyGordy Member Posts: 9,347
    As pointed out the limiting factor is the emitter. You stated baseboard is hot. I wouldn’t get to worked up.

    Your recovery is over 2.3 degrees per hour. What’s the outdoor temp?
  • zanesilkzanesilk Member Posts: 27
    Outdoor temp was 39 degrees at the time of startup. Around 40-41 when I reached 70.
    So I cannot add more baseboard on the same loop?

    I measured the inlet and outlet temps via IR gun in the steel manifolds typically 15-20 degree drop form supply to return.

    Any idea why there is such high operating pressure 31 psi.
  • GordyGordy Member Posts: 9,347
    Gauge accuracy. 31 psi would pop the relief valve.
  • zanesilkzanesilk Member Posts: 27
    The unit is telling me 31. My mechanical gauge on the PRV provision on supply side tells me 20... which one is correct ?
  • zanesilkzanesilk Member Posts: 27
    I’m getting worked up because my 40 year old gas unit that let go a month ago was able to being the temperature of the house up MUCH faster. I don’t see this being normal.
  • GordyGordy Member Posts: 9,347
    edited November 30
    Okay. You need to take actual temp measurements at emitters.
    Using an ir gun you also need to use painters tape on the surface you are measuring for accurate readings.

    Supply return out at the farthest point in system.
    Supply return at the P/S t’s

    Boiler supply/return.

    Was the navien doing domestic hot water during space heating in that time frame?
    Are baseboard fins clean?
    Are they blocked?
    What was high limit setting on old boiler? 190? 200?

    The navien , and mod/cons in general are a different animal than the old ci boiler you had.

    Also was your old boiler piped primary/secondary?
  • GordyGordy Member Posts: 9,347
    edited November 30
    zanesilk said:

    The unit is telling me 31. My mechanical gauge on the PRV provision on supply side tells me 20... which one is correct ?

    If the location of the psi gauge you are reading low is on the suction side of the circulator it will read lower due to the delta p of the circulator. If the other one is on the outlet of the circulator it will read higher. System psi setting should be when pumps are off, and system water ambient.

    Edit: also the xtank pressure should be set “isolated” from system.
  • zanesilkzanesilk Member Posts: 27
    Thank you Gordy I will take measurements tonight.
  • zanesilkzanesilk Member Posts: 27
    Anybody see any piping issues that could contribute to this problem?
  • GordyGordy Member Posts: 9,347
    Are all dip switch settings properly set?
  • GordyGordy Member Posts: 9,347
    You only have one zone? Second circ for another zone?
  • zanesilkzanesilk Member Posts: 27
    Second circ for future basement zone. Dip switches have not been touched ... any specific one I should be paying attention to?
  • GordyGordy Member Posts: 9,347
    Check your I/O manual for proper settings.
  • zanesilkzanesilk Member Posts: 27
    Gordy sorry for not answering but old boiler was just piped in regular fashion no primary secondary loop. High limit 190 but does not reach it.
  • SuperJSuperJ Member Posts: 557
    edited November 30
    Are the secondary pumps pumping away for sure? It's hard to tell from the picture. It kinda looks like the pumps might be pumping downwards which would be a problem for sure.
  • zanesilkzanesilk Member Posts: 27
    Yep! Arrow points up SuperJ can circulator sizing be an issue ?
  • SuperJSuperJ Member Posts: 557
    edited November 30
    zanesilk said:

    Yep! Arrow points up SuperJ can circulator sizing be an issue ?

    If you're seeing a 20deg delta from the start to the end of the baseboard, then it's likely seeing adequate flow. Are you sure the secondary flow is the same direction as with your previous boiler? The length of baseboard in each room was usually selected to compensate for the reduced temperature from the start to finish.

    Did you open the pressure relief when filling the system to purge the boiler, and purge the pump?

  • zanesilkzanesilk Member Posts: 27
    Direction was kept the same. Just for my ow knowledge would more flow increase delta or reduce it ?
  • zanesilkzanesilk Member Posts: 27
    I did not open the PRV! what effects would this have ?
  • zanesilkzanesilk Member Posts: 27
    I’m purging the following way;

    Close return manifold valve
    Hook up washer hose to washer connection and introduce water into unit via port on supply side manifold provision.
    With 3 way valve on return manifold closed o am opening the drain provision on 3 way valve and shooting water outside house. Close it up and plug unit In.


    Am I missing something ?
  • SuperJSuperJ Member Posts: 557
    You want to force open the PRV to release any trapped air from the heat exchanger. Odds are it's probably purged on it's own but go ahead and burp it (and the pump). The manual goes over this process.
    https://www.navieninc.com/downloads/ncb-e-manuals-installation-manual-en

    Also, looks like you have PVC venting, which means that the boiler should be setup to throttle if your return water exceeds 149F. Page 49 in the manual linked to above.

    Dip switches should be set for supply water control.

    I would recommend setting up the outdoor reset and installing an outdoor temp sensor.

    Note that some of the dipswitches control some critical settings for safety, so you should understand what you are doing if you touch them.

    The boiler can tell you the return and supply temperatures on the screen, but you'll have to measure your zone supply and return. They will be different because the primary and secondary loops usually have different flow rates which will cause some blending of either the boiler inlet (if primary flow > secondary), or blending of secondary supply (if secondary > primary).
  • DZoroDZoro Member Posts: 934
    56* to 70* with base board properly sized to "maintain" your home. I'd say it performed just fine. Remember the system is designed to maintain comfortable/constant heat.
    What you just asked it to do is not normal for its designed application.
    Set up the boilers odr, combustion analysis, gas pressures, and keep good maintenance on the system
    Pressure is high, maybe reduce it to 15psi and it should hold pretty close to that.
    D
  • SuperJSuperJ Member Posts: 557
    edited December 1
    Agree with @DZoro the measure of a good heating system is not how quickly you can recover 15deg of setback. To me it's about efficiently maintaining comfort throughout the home, which usually means sizing the system so that it will take substantial run time to maintain the temperature setpoint. Longer run times often equate to more comfort and even temperatures throughout the home.

    Until you get the outdoor setpoint reset working, I would reduce your supply setpoint to something between 160f and 170f to make sure it isn't bouncing off the high return water temp limit to protect your flue. Or set the dipswitches to run off return water temperature and make the setpoint lower than 145F.

    You won't see full efficiency at the these high temperatures, so now that it's at set point try and reduce the setpoint to the minimum that maintains the space. You're only going to get 85-90% efficiency right now.
  • GordyGordy Member Posts: 9,347
    edited December 1
    The OP points out the old boiler recovered faster. Was it the same conditions?

    This also gives you a good idea of recovery times. If you intend on using a setback schedule.
  • zanesilkzanesilk Member Posts: 27
    Ok thanks all I will get the outdoor reset working , bleed one more time for good measure and adjust my temps . Currently it’s 70 here. I tried measuring emitter temps to no luck , tape trick is not working :(
  • GordyGordy Member Posts: 9,347
    You want to measure the pipe (not the cover) carrying the fluid. You also need to get close to the target with the IR gun. Also while system is calling for heat.
  • zanesilkzanesilk Member Posts: 27
    @Gordy yep ... tried it won’t work tells me it’s 80 degrees meanwhile pipe is scorching hot .
  • mikeg2015mikeg2015 Member Posts: 1,041
    Something I did see mentioned, I might have missed. A Combi is best used in high mass heating systems. After a DHW call, there’s a delay before it switches the internal 3 way valve back for heating. So you lose even more capacity. There is a parameter you can set to change the delay time. In baseboard, the emitters can cool off while waiting and worse, if someone takes a long shower, the whole house can cool off. Cast iron and radiant floor can take over an hour ot change temperature so it’s not an issue. But it’s still a cost effective, pace saving alternative to two appliances. Just be aware of that limitation.

    I think default is a 5 minute delay. So if you are doing laundry or taking a shower, dishes, there is no heat for 5 minutes after you finish. Even just washing your hands for 20 seconds, and you wait 5 minutes for heat.
  • zanesilkzanesilk Member Posts: 27
    @mikeg2015 thank you sir, So with my PVC exhaust dip switch 8 should be set on the off position ... but it mentions it won’t work without exhaust thermostat ???
  • zanesilkzanesilk Member Posts: 27
    Iowered thermostat to 66 degrees last night this morning at 8:40 I called for 68... it’s been 1.5 hours and it’s still only at 67. I just tried manually calling for 180 water temp at it will not go over 167... will the outdoor reset solve this and get me to 180
  • mikeg2015mikeg2015 Member Posts: 1,041
    I haven’t messed with that setting before, only know it’s there. I suspect they recommend a temp limit switch to interrupt the call for heat to protect the pipe. Wouldn’t be needed with stainless steel, but might with Polypro.

    We never install these in high return temp situations. Might actually need to reduce the primary pump and secondary pump to get return water temps lower, then no need to turn off the switch. Shouldn’t be changed if vented in PVC.

    Emitter output will be higher with 174F water and a 25F delta T @ 6gpm, than with 160F water with a 15F Delta T @ 9gpm (both would be 149F max return water temps (unit is only about 88% efficient at those return water temps) but you’ll get 6000BTU’s more heat with the lower flow rate, higher temp.

    Emitter output and supply temp is roughly linear relationship. FLow rate is not. Double the flow rate and you get a small increase in heating output in most cases.



  • SuperJSuperJ Member Posts: 557
    edited December 1
    zanesilk said:

    Iowered thermostat to 66 degrees last night this morning at 8:40 I called for 68... it’s been 1.5 hours and it’s still only at 67. I just tried manually calling for 180 water temp at it will not go over 167... will the outdoor reset solve this and get me to 180

    Your boiler won't let the return water temp go over 149f regardless of the set point. This likely what's limiting your supply since the boiler should have ample heating capacity for the amount of baseboard you have attached. The exhaust flue gas temperature is directly related to the return water temperature, and PVC venting cannot handle high temperatures.

    If you want 180F supply temperatures with a 20deg delta you have to change the exhaust venting to a higher temp capable material. and then set the dip switches appropiately.
  • GordyGordy Member Posts: 9,347
    edited December 1
    I would suggest you get intimate with the I/O manual. Specifically dip switch settings, and their safety limitations. It spells out the parameters for venting materials quite clearly.


    Also parameter functions to get the most out of that combi to fit your needs.
  • GordyGordy Member Posts: 9,347
    I am curious what size the old boiler was. With that being said compare it to the space heating output of this combi.
  • GordyGordy Member Posts: 9,347
    The OP still has not stated if DHW calls were during these recovery periods. As I said this combi is a different animal compared to the old CI boiler.

    You will never get 180 supply with out changing venting to CPVC, or Polypropylene. It can’t do domestic hot water, and space heating simultaneously, it’s one, or the other.

    It’s DOE output is 95k.....
  • zanesilkzanesilk Member Posts: 27
    @Gordy No DHW calls whatsoever during recovery. Just installed outdoor reset switch. Old unit was a peerless 80,000 BTU. So I am assuming switching to cpvc will let me force higher temps ? At this point it has been 2.5 hours and it’s STILL not to 68... something is just not right here
  • SuperJSuperJ Member Posts: 557
    Can you do some detailed photos of the system?
    Wiring, jumpers, pump closeups, etc.
    Maybe something will jump out.

    In the meantime can you reduce the SWT set point to 160f? It might seem counterintuitive, but it should be plenty this time of the year, and keep you from bouncing off the safeties. If you hit a safety there might be a minimum off time.

    To get a good IR measurement, you need to be close, and you need a surface that is measurable (tape helps), and also know the laser doesn't do the measuring it just helps you point it. The actual measurement area is basically a cone that gets bigger with distance. If you point it at the tape on the copper pipe and move it around just note the highest temperature it registers.
  • GordyGordy Member Posts: 9,347
    It appears that way since you recovered 14 degrees in 6 hours before. Unless outdoor temps are lower than before, this time.

    All emitters are hot?
    All emitters are clean?
    No gurgling anywhere out in the system?
    If max temp is 167 supply, and 149 return at boiler, because of venting material.
    We need some temps out in the system emitters. Preferably before, and after the closely spaced t’s, and out in the system farthest point.

    This will give some idea of the amount of mixing going on at the closely spaced t’s.
  • zanesilkzanesilk Member Posts: 27
    I just got temps on system emitters ... i put switch 8 in on position just to trick it quick to see if i can get 180 (entire exhaust length is 4 feet and only 1 90 degree elbow. I am monitoring PVC temp. This is for testing purpose only don't crucify me lol. It did however raise house temp to 68- (it wasn't able to reach 68 today with 30 outside temp)

    Anyways emitter temps:

    Supply:176
    Return:160

    Secondary Tee Supply 178
    Secondary Tee Return 163

    Primary Loop (From Unit) Supply 177
    Primary Loop (From Unit) Supply 168

    Total Loop Length measured today 144 Feet of Piping.






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