Help with adjusting Navien Boiler / Outdoor Reset

k_k

hey all - I found this forum and my time spent indiana jones'ing through posts here have been very helpful thus far. The wife and I just bought a house in southern NH and I'm doing my best to ramp up on our boiler and heating here - which for a newly installed (2019) system was a bit of a mess when we got here. This is a bit of a long post, so I included the system details and specific questions I have at the top. There's a whole bunch of context below, if you're bored.

We recently bought a 2750sqft home, about 1700sqft on the main floor with three zones of radiant in-floor heat under engineered hardwood and about 1000sqft of finished basement with ~35ft of baseboard.

The system is a Navien NHB-80 with a Caleffi ZVR106 zone controller for the valves on the 4 space heating zones and a 40gal indirect water heater (Heat-Flo HF40). I'll attach a photo of the entire system.

TL;DR - Here's a few questions on things I'd like to improve:
1. I have mixed emitters (radiant floor and base board) and attempting to use outdoor reset targeting low mass radiant (80-140f). While it seems like the baseboard can currently keep the thermostat at setpoint, I'm pretty sure the boiler is running constantly and ~115f seems too low for baseboard based off my reading, is this a problem, or just let it ride? I thought I read that a mod con running consistently was a good thing?
2. else, do I need a custom range to support the mixed emitters here? I could target the ODR curve based on baseboards and use the mixing valves to lower the temp to the radiant zones, but would that lead back to the temperature differential error?
3. If I don't adjust the outdoor reset, should I just open up the mixing valves on the radiant zones and let the boiler control the water temp to those zones?
4. I ordered a pump to descale the heat exchanger - I don't think anyone has ever done regular maintenance to this thing - anything else I should prioritize?

Context:
Wife and I grew up in new england, but have lived out in san diego for the past 15 years before moving back - all our previous homes have been in SD... heating systems were not really a san diego problem, per se. So, as a home owner, this is pretty new to me.

When we moved in the wife quickly noticed that water would get cold during her shower (usually after the kids have showered or dishwasher was running concurrently, etc). So, I went to take a look. The Navien was flashing a red wrench, but not showing a specific error code (that I could find). After all my reading, I now know it was also short cycling like crazy. It was also making a whining noise when firing at full.

I'm quite capable, but this was a brand new system to me, we're in the middle of winter and I didn't want to have to explain to the wife why we had no heat because I thought I was a hvac contractor and broke it. so I called around. Four different hvac companies told me they aren't taking new customers - but, I finally got someone scheduled to come out.

The person came out, replaced both circulator pumps which he said were gummed up with sediment. He also found the error, e271 Temperature differential limit - but seemed to have no clue how to fix it. I had him call Navien support and between the tech support rep and this guy, they seemed to determine "yeah, that's just gonna happen" (!!?).

In the end, the tech found that the DHW was not set as priority on the zone controller and flipped the dip switch. He left after five hours and I was billed almost a grand for replacing two pumps and this guy just monkeying on a system he clearly didn't understand - I was left with the navien still flashing a red wrench, short cycling like crazy - but at least hot water was more consistent?

Over the next couple days, I read through the entire operation manual of the navien and zone controller and did a bunch of forum digging. I realized that due to how the zone controller was wired, the boiler thought everything was space heating and had no notion of the DHW. The outdoor temperature sensor is installed (while, oddly, I can't find it outside, its hidden somewhere) and reading the outdoor temperature correctly, but no outdoor reset was configured. The way it was wired, it couldn't really be used, else it'd never fire hot enough for the indirect.

Seems like the e271 error code was because the boiler was set to fire at 180f for everything and then mixing valves were used on each space heating zone to limit the temperature. I also saw the return side circulator pump was set to high, I lowered it to medium and the whining noise under load went away. I don't know if the boiler was never configured properly, or maybe the settings were reset at some point.

I ran a new wire from the Zone 1 E/S terminal on the zone controller to the DHW TT on the NHB-80, went in and configured the outdoor reset on the space heating side and made sure that system and boiler pumps would still run during DHW heating. This means the zone controller still actuates the valve for the indirect water heater, but now the boiler knows to fire up to 180 for DHW, but can properly use the ODR curve for the space heating.

I also found the hot water tank was set to store at 110 degrees and the mixing valve above was wide open... I swapped that to store at 140 and used the mixing valve to protect against scalding above.

Magically, no more red wrench. No more short cycling and I can hear the drip of condensate into the condensate pump - it seems to be condensing like a champ.

The last part of the equation, mentioned in questions above is how to best deal with an outdoor reset setting when I have mixed emitter types between zones. Target for the highest temp emitter type and mix down on the radiant?

EBEBRATT-Ed

I will let others comment on the ODR setting etc. Sounds like you did a good job digging through this. Big time shortage of qualified technicians.

Naviens are having issues with exhaust gas flue gaskets etc so watch for that there are u tube videos on that

Looks like the installer did a reasonably good install, too bad they didn't get the set up right

psb75

Agreed. It wasn't set up right at the installation. The install looks like it was well done. It sounds like you have a good enough understanding of the Navien at this point from reading the manual that you could call their tech support and have them help you with the settings. Can you set the curve for a low-ish baseboard temp. and mix down for the floor zones?

hot_rod

Is it heating comfortably?  Odd piping, typically you have a circulator on the mix outlet of each thermostatic moving valve. I’m surprised a single pump can flow all mix valves and loops?

For a mix valve to work efficiently you pump away from the mix port so it pulls from both hot and cold side. 

Daveinscranton

If you are warm, and it doesn’t short cycle, you may be close to done.

If you absolutely want higher temperature water for the baseboard emitters, you could determine the resistance of the outdoor reset that gives 140 degree water.  And then switch that resistance in instead of the outdoor reset when the baseboard calls for heat. Single pole or double pole double throw relay would do it.  You could set up the logic, simple, with relays and it might not take much, to turn off the low temperature radiant when the baseboard calls for heat.  

I have been dialing in a Triangle Tube Instinct.  Great boiler by the way. Ultimately, I used a linear taper 25k potentiometer in series with a 27k fixed resistance in lieu of outdoor reset  to get the temperature range I wanted.  Very fast way of setting max water temperature.  I graphed the resistance vs temperature curve of the outdoor reset with an ohm meter at room temperature, outdoor temperature that day, my refrigerator and my freezer.

My new Triangle Tube Instinct comes with 2 thermostat inputs, each with its own assignable and adjustable heating curve and max temperature.  May come in handy as I have pex in slab floors and a loop of 1” copper in the basement on a separate zone.  Just rearranged my piping and zones along with the boiler replacement.  Fresh on my mind.  Still optimizing my settings.

Keep good notes.  You will forget in a year.  My guess is that it would take an experienced tech with mod cons to set up exactly what you want. May be already there 7 layers deep in the menus.  The approach I have taken has been of help in my application.  And no pro would put up with my antics.  To their credit, Triangle Tube was amused. And encouraging.  In the next couple of days I will try out the outdoor reset.

Best wishes

Daveinscranton

Another way to do this is a separate pump, bronze or stainless steel, and use domestic hot water as your heat source for baseboard.  The domestic hot water tank would be your “boiler”  for the baseboard.  Lots of dissolved oxygen so everything would have to be copper, bronze, or stainless steel.  Wire it and pipe it correctly and it should work fine.  Not terribly elegant.  

k_k

@psb75

psb75 said:

you could call their tech support and have them help you with the settings.

My impression was if you are the homeowner and not a licensed technician, they pretty much tell you to kick rocks and hire someone - is that not the case? I don't/wouldn't blame them for liability purposes, but not super helpful.

psb75 said:

Can you set the curve for a low-ish baseboard temp. and mix down for the floor zones?

Yeah, I think I can just do a custom range that splits the difference and/or leans toward the desired baseboard temps and mix down for radiant, I'll experiment with that.

@hot_rod

hot_rod said:

I’m surprised a single pump can flow all mix valves and loops

I guess I'm not confident that it can. Specifically, I noticed while DHW has been better, its still not great. This morning I checked the supply and return lines for the indirect while it had demand - the boiler was reading 178*, supply line on the indirect was 148*, return was a few degrees lower.

I checked the supply at the top of the manifold where it exits the boiler it was 174* while the boiler read 176* (didn't expect painters tape on copper and an infrared to be perfectly accurate, so this seemed close enough). Lastly, I checked just after where the supply tees at the bottom of the manifold and it was 150*. So, it seems like I'm losing ~24* just exiting the manifold.

I'd assume this would be circulation issue? Specifically is the Taco 007e (supply) over powering the Grundfos (return) and pulling cooler water from the return side?

I do have a pump showing up in a day or two so I can flush and descale the boiler. When the Grundfos is set to High, the boiler makes an unpleasant whining noise when it fires above 170*. Is it possible that, ideally, the Grundfos should be on high but the HXC is just gummed up with sediment, causing the whining noise at high load?

Daveinscranton

To get any real efficiency out of a mod/con, near as I can tell, the return temperatures need to be low.  Really low.  Lower the better.  You want the condensing to occur in the boiler.  If it condenses in the stack, in an unheated space, you will get condensing but it will be the illusion of efficiency, rather than efficiency.  (Maybe plenty of condensate water, but not doing you any good).   I sort this stuff out with a bucket and hose, keeping an eye on flue temperatures and return temperatures and burn cycle length.

When this technology works well, it is elegant.  The problem is that it is easy to have the illusion of technological elegance.  And the maintenance, which is absolutely required.  And the complicated computer part.  Which is heat sensitive as far as circuit board and component longevity.  …. And get zero savings compared to cast iron boilers.  But with triple the headaches.

I have looked at this 7 ways from Sunday.  For me, it makes sense.  My guess is that few mod cons are saving money and resources.  Most folks only know if the house is warm or cold.

hot_rod

Don’t discount the modulation function it can and often does lessen or eliminate short cycling which can put the hurt on as my boiler. The excessive cycling is tough on all the components under the hood.

o2g

What part of nh

psb75

He said "southern" NH in original post.

o2g

S nh goes from Vermont to the Atlantic if the guy wants help all I asked is his location

you advising this guy call navien tech support and work on this unit is foolish

there are too many issues that need rectification before this unit can even get to programming

k_k

@o2g It’s NH seacoast, about 15min from Portsmouth 

k_k

Quick update - I finally had the pump show up, so was able to run vinegar through the boiler to descale it. Also did the other maintenance while I was at it.

There was a pretty gnarly amount of sediment / mud in the filter and HX. Getting this clean fixed my temperature issues leaving the manifold on the supply side.

Given the state of this filter, I’d assume I need to do a full purge / flush of the system to get this sediment out?

Also, I don’t have a dirt separator, I’d assume having one installed would be a good idea?

JosephTonozzi

I agree with Hot Rod on the mixing valves only working with a pump downstream on the mixed supply . But I also see your indirect water heater is just piped off of the heat main supply and return . So unless you had a relay turning off the other zone valves there would be no way to prioritize the DHW on the boiler . I’m starring at your photos and can’t really figure out what they did besides they may have done a nice job doing the wrong thing . If your Navian is a water heater type and not a NHB then everything is all wonders . It looks like it has a screen like the ones for domestic hot water have . But anyway mixing valves don’t do magic and work without pumps for heating , unless they are working with domestic waters flow like on a water heater Good Luck with your system!
.

JosephTonozzi

Daveinscranton I replace a lot of old cast iron boilers some that I may have put in in the last 45 years . They were efficient in the way they worked so long with out much need for any maintenance. But a lot were oversized which a mod con can compensate for . And a lot of them were also puking out carbon monoxide from bad combustion air or a bad burn . I like how the mod cons can just hang on the wall and have sealed combustion for safety ,and adjusted properly for a nice clean burn .And if they are leaking co if you have the sealed case like a TT boiler or a IBC SL &XL the CO is only messing up your boiler and topknot the people in the house .And they make a nice clean mechanical room floor that people can pile their junk by and not worry about it starting on fire . I don’t see to many people driving old flat heads around anymore. And the new cars yep you have to maintain them . JOE from CO