navien and odr?

jonny88

Hi,customer wanted Navien Combi ch 240. We installed boiler as per manufacturers specs,primary/secondary,sch80 on exhaust,etc.

So the boiler has been running for a couple of weeks now and customer is very happy which is great.I asked a heating consultant I know to come and calibrate the boiler and test for efficiency.

By the way there is two heating zones with a taco switching relay and room thermostats.

Boiler was running at 83% eff.it condensed a little on fire up but after a few minutes it stopped condensing.So we installed ODR.Now boiler wont fire.

We call tech support.It appears you cant use the odr if you are using two zones .We are told that the remote control that comes with boiler has to be used as the room thermostat and then the odr will work as long as you have only one zone.

I went to a Navien class and this was never mentioned,we were actually told to put the remote inside boiler away from the homeowner.

I am not here to knock Navien,I would just like to know if anyone has had a similar experience or is there a way to correct the problem because right now I do not have a condensing boiler.

Thanks.

CMadatMe

Makes No Sense

There is a TT connection at the boiler. It's nothing more then a switch to tell the boiler I need heat or I don't need heat. Should have no bearing what so ever with outdoor reset.

I would think you'd just set the programming to 24hr clock for heating, set your K-Factor, stick it in the cabinet, end switch from zone control to 'TT" on the unit and away you go.



http://www.navienamerica.com/__DATA/ProductDocument/2013/4/3/[2]_Navien%20CH-ASME%20Installation%20Manual_20130404.pdf.

TonyS

I was disappointed also

I did not realize this fact until after the install. Hopefully they correct this in the next version coming soon.

jonny88

odr

I know it doesnt make sense Chris.From what I am gathering from Navien (you get a different answer from tech support every time you call)the only way odr will work is by using the remote control as room stat,and this will only work on one zone.You can use odr but only on a single zone system.I am not knocking the product for what it costs it is great.I would just love to see it condensing a bit more.I am trying to get a rep to come to my job and correct the situation,obviously it is very possible I am doing something wrong.

HomeOwner1

Runs ODR with separate zones just fine

We have separate stats and the outdoor temp sensor and things work great.

jonny88

odr

i dont understand why a tech support manager said it wont work on more than one zone if not using the remote.What temps is your boiler running at and did you measure the efficiency of the boiler.Without the odr the boiler i installed runs great it just goes to 180 etc.I have a navien rep coming this week so hopefully he can figure it out.I must say they do have a good support team behind them.

Gordan

I don't know this boiler

But it seems that you can make this zone just fine even if it doesn't support both a heat demand input and the indoor feedback unit, just as long as you place the indoor feedback unit in your "most difficult" zone. This will then be the only thing that drives your system demand, and thermostats in other zones will only open zone valves for their zone without any feedback to the system. This is the same way TRVs are usually employed - since they don't have any end switches on them. :-)

HDE

Use the remote

Sounds to me like you unplugged the Navien remote?



A DIP switch disables the navien remote as the room stat allowing a different input such as end switches or a aftermarket thermostat to be connected to R &W on the term strip. However the Navien remote must stay installed and plugged in as its the means of setting and controlling the ODR. If the remote is not plugged in to board, how do you expect to select and set the outdoor reset curve? This is done on the remote in place of a supply or return water temp setting.

Most installations leave it mounted close to the boiler. It will now be the means of dialing the domestic water temp, overriding the board settings.

It's quite simple to do and use.

jonny88

remote

I have in the past used this boiler with odr.This is why im boggled.Remote is plugged in.Boiler was runnig for 2 weeks.Went to install odr.boiler wont fire.we are told from navien,remote must be used as room stat in order for odr to work.one remote equals one zone.i used circs on this install and not zone valves.as i said i have rep coming this week so hopefully they can address the issue.Thanks for your input.

HomeOwner1

How mine is setup

We have the dip switches set to use external thermostats on ours. Have control unit mounted right beside our boiler and always keep on. Installed the thermo-resister outside and plugged into two wire cable for unit. Set the K-Curve based on the formula Navien customer support provided, which is not in the manual for some strange reason. Was pretty straightforward. Entire process took about 15-20 minutes for us.



On a side note, there are different resistances available on the sensors. Did you get the correct resistance sensor?



Do you have the dip switches set correctly?



As soon as the sensor was plugged in, the unit did its thing. If I can do it, anyone can.



Good luck with yours.

jonny88

warmweather shut down

A senior tech from California emailed and said you must use remote control as room stat when using odr.I did what you did homeowner and all is well,unit runs like a champ.Only problem is you cant raise wwsd past 65 degrees to test.Unit is in 3 months and havent had a call back yet,Thanks

HDE

Just now?

That's what I posted back on April 27th





But it's not the indoor stat, just a means of setting the curve, as long as DIP switch 3 of 8 is up (on). A external input on R & W is then the call for heat.

.

crhaag

Navien NCB 240 zone control

Hi everyone. I'm not a heating professional, just a home owner. I have an NCB 240 unit that has been running all winter without a thermostat. It runs a radiant floor system. I have been adjusting the temperature of the supply loop to manage our home temp.



I just installed a thermostat to control a pump on the supply side. The thermostat works and turns the pump on, and I turned dip switch 7 to the off position like the manual says to do when using zone control, but the unit never seems to fire up.



Am I missing something else that you need to do with zone control?

HDE_2

Check your manual for wiring diagram

Once you switch from constant operation to a input required you need a signal from the zone panel to enable the heat wired to the TT terminals of the NCB

jonny88

I stand corrected

I now have 5 Naviens out there running on odr and condensing.So far no complaints,

scott markle_2

Odd

I have a couple of Navien combi units installed. I was a bit surprised to see a condensing boiler sold without ODR in the box. After doing a training on these boilers I can see that they are kind of dumbing things down for the American market, they seem to want to keep it simple and make this boiler an easy swap for a conventional boiler. I will say that the menu structure on the remote is not terribly elegant but the advice that it should be hidden from the end user (given in the training) I find a bit condescending. It certainly depends on the client but I generally work for intelegent tech savy people who I feel deserve the opertunity to understand how to operate thier boiler at it best efficiency.



To clarify a few things in the post. The remote is not an indoor "sensor" it is just an on/off thermostat. The boiler pump and burner are activated when the set point falls below target, if an outdoor sensor is installed supply is determined by the k-factor and outdoor temperature, if not supply is determined by the dip switch settings (it's fixed).



One notable think missing -The boiler has to be pumped P/S but there is no relay for the secondary pump. So if you want to do a single zone system running on the remote you will have to figure out how to turn the secondary pump on and off. My solution was to use an ECM pump that uses about 20 watts and run it continuously durring the heating season, it gets manually unplugged and plugged into a timer durring the summer (1 min. Day for exercise)



I'm a big believer in a tight reset curve (k-factor). I also feel that when you turn down the heat you should be turning down the reset curve as opposed to turning the boiler on and off. So I have instructed my clients (vetted for this ) to set the remote thermostat to 80 (constant demand) and slowly tweek the k-factor to find the setting that keeps the house comfortable. When they are away they set a lower k-factor as opposed to turning down the thermostat , I have also explaind that when they want the house to warm up quickly they can set the k- factor avove it's required setting to get hotter water flowing. Not for everybody and takes some patience to explain since it's so different from how most people are used to operating a heating system, but it works nice and the heating bills have gone down dramatically. Since these systems were originally multi zone I put a TRV's on the upstairs zone (directly in the baseboard). Most zoning is about balancing not the ability to heat one zone and not another, so I think the TRV is a fine substitute in most cases, it also helps with cycling which can be a real problem if a small zone is calling solo and you have a 105 target temperature. Bottom line is this boiler is priced very competitively but you have to kind of hack it's operating system to make it run like a European system.



Are you sure you can leave the remote connected, not use it's thermostat and still get the boiler temp to run on ODR with the TT ? , I was also under the impression this was not an option

Jean-David Beyer

they seem to want to keep it simple

"I was a bit surprised to see a condensing boiler sold without ODR in the

box. After doing a training on these boilers I can see that they are

kind of dumbing things down for the American market, they seem to want

to keep it simple and make this boiler an easy swap for a conventional

boiler."



I guess they do want to keep it simple, but they do not keep it simple enough.

When my mod-con was installed, the lead technician did not want to install the outdoor sensor, because it did not make any difference. Since it comes in the box with the boiler, I insisted that it be hooked up.



I had read the entire installation manual. So I was quite surprised that he used all factory defaults for the setup. I have an indirect across the supply and return of the boiler, and two heating zones that require different reset curves. The controller readily accommodates this, but he did not know how, so I told him. He also had no idea how to set the reset curves, even though it is explained in the manual, and there are no funny codes or anything: everything in plain English.



I figured out why he said outdoor reset did not make a difference. They tried to sell me an oversized boiler (they did not calculate the heat loss), and if I had taken their advice, the boiler would have come off the minimum firing rate only when the outdoor temperature was considerably below the actual design temperature.



So my boiler was not dumbed down enough for that technician, who also had no combustion analyzer. He did not need one because they are preset at the factory (or so he said).



Some contractors should not be selling mod-con boilers because they are too dumb to install or service one.

HomeOwner1

Thought it was strange they did not include it too

Yes, before ours was installed, I read through the entire manual myself as well. Based on the advice of another installer up in Mass who had installed many of these, he recommended we got familiar with all of the dip switches, how to hook up the thermostats, get to the hidden settings and figure out my outdoor reset curve number to input into the controller. Good thing we did, because same story here, Being familiar ahead of time we got the unit up and running quicker.



We also did a heat loss on our home to ensure we would fit in the envelope of this unit, but very few installers were willing to do so. When questioning many installers, it was curious about how many had no software to do so, and just used a simple square footage general rule of thumb. You may get away with that for a modulating unit many times, but for the cast iron traditional boilers they were recommending mostly, it would have been grossly over-sized. We even told the guys giving quotes up front we thought the old unit was way too big due to short cycling observations.



Is that normal in this industry that most installers don't size units for a home and just go bigger or the same size as what was there?



Another curious thing was that most of the guys giving quotes just wanted to install a replacement cast iron boiler and not a lighter newer modulation condensing unit. Why would an installer prefer to lug down a 900 lb boiler down into a basement versus a 100 lb wall hung unit? That confused me. Why continue to break your back if you don't need to?



Well, so far so good with our Navien. We have the CH-240 but I think there is a newer one out now. So maybe they do things differently now with the outdoor sensor on that new unit. Have to check yourself on that one. A few of our neighbors now have one as well.