Navien NCB-240E possible purchase

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DR-DEATH

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My lochinvar sensor reads high too.

At 29 degrees my starting water temp is about 120 or so. I would go down until it struggles to maintain temp and then go back up about 5 deg at a time

Gotcha. I'll play around with it and see. It's exciting to see it work as advertised as far as short cycling goes!
 

NY_Rob

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Below is the reset curve I'm using currently.
29F outdoor temp gives me about 123F supply water temp.
...it's a work in progress.
 
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DR-DEATH

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Below is the reset curve I'm using currently.
29F outdoor temp gives me about 123F supply water temp.
...it's a work in progress.

What are your exact settings for max temp and low temp. If I understand correctly i have to choose a max temp and min temp and that automatically makes the curve? So is your max supply water temp 135 and low temp 65? Basically I'm not sure what to set in the settings to get your same curve.
 
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Leon82

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yes, they are just 2 points on the curve, and the line is drawn thru them

it will continue to rise as it gets colder until you hit the max ch heating set point
 

NY_Rob

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On that curve:
Max water temp: 135F
Min water temp: 110F
Max outdoor temp: 65F
Min outdoor temp: -4F

The 135F is based on staying in condensing rage while still being able to deliver enough BTU's to offset my 27K BTU heatloss at 15F Design Day temp. The 110F is based on the boiler's minimum output of 8K BTU's and my shortest zone's 43' of fin-tube.
 
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NY_Rob

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As Leon said... start with higher water temps and work your way down.
My SWT started at 145F, then 140F, then 138F, last Sat I set it down to 135F... and it's still satisfying my demands at 34F outside.
 

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On that curve:
Max water temp: 135F
Min water temp: 110F
Max outdoor temp: 65F
Min outdoor temp: -4F

The 135F is based on staying in condensing rage while still being able to deliver enough BTU's to offset my 27K BTU heatloss at 15F Design Day temp. The 110F is based on the boiler's minimum output of 8K BTU's and my shortest zone's 43' of fin-tube.

I understand setting the max water temp because that's how we can control the condensing part etc. would 110f min low water temp be the same temp I use? My smallest zone is 14 feet but rarely gets ran and can be ran with other zones. What does the min outdoor temp do?
 

Leon82

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Fintube may not heat well under 110.

They are just points on a Cartesian graph to determined the curve. You can use your design day temp or 0 degrees. Once you dial the curve in it will be fine
 

NY_Rob

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You really need to do a heatloss analysis for your home. Once you have that you will know how many BTU's you need at Dedign Day temp.. and you build your chart around that fugure/temp.
If you don't know your DD heatloss - you're just guessing.
 

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Gotcha I have enough time to mess around with it. I was reviewing the install manual again and under backflow preventor area it states if local codes require a backflow preventor an expansion tank must be installed on the cold side. We have to have a backflow preventor here but my expansion tank is on the hot side. Under warranty it specifically states home owners responsibility requires:
If the cold water supply line has a backflow preventer, then an expansion tank should be installed to allow for water expansion.

How bad is not having it on the cold side other than voiding warranty (which needs to be fixed)

Can it cause performance issues or safety concerns or damage the boiler?

I also noticed under the condensation part of the manual it has a diagram that lists a vent right out of the boiler and then the condensation line that came with the boiler. My installer did not use the condensation line that came with the boiler. Attached is a photo. Any thoughts on that on importance?
 

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Leon82

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The back flow preventer is there to prevent an explosion if the water main were to break and suck your system dry. When the water was repaired it would rush into a red hot boiler which had been running dry.

The modconds have sensors which would shut it down in that case .

The back flow preventer prevents the system from pushing excess pressure back into the water line. Your tank will still work but could cause problems under certain conditions.
 

NY_Rob

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I also noticed under the condensation part of the manual it has a diagram that lists a vent right out of the boiler and then the condensation line that came with the boiler. My installer did not use the condensation line that came with the boiler. Attached is a photo. Any thoughts on that on importance?
That oem coupler includes a vent that is a vacuum breaker... it may be there to prevent condensate in the drain tube pulling fluid out of the boilers condensate trap leaving the trap dry and providing a way for CO to escape into the boiler room?

Also, the condensate trap must be serviced at least once a year- you have to remove it from the underside of the boiler- that's why they include flex hose and a spring clamp not permanent PVC connections.
 
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NY_Rob

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I was reviewing the install manual again and under backflow preventor area it states if local codes require a backflow preventor an expansion tank must be installed on the cold side. We have to have a backflow preventor here but my expansion tank is on the hot side.
You're probably referring to the section regarding a domestic hot water tank used w/a backflow preventer.
Some municipalities now require a backflow preventer on the water main entering the house. If you had one- and you heat your domestic hot water to 140F that would build dangerous pressure in your domestic water system- so you use an expansion tank specifically made for domestic water pressurized to 70+ PSI on the cold side of the DHW tank and that adsorbs the pressure buildup.

Even though your boiler expansion tank isn't ideally located- it will function, and your boiler fill backflow preventer is installed correctly.
 

Leon82

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It will be hard to clean the trap.

Did they install the neutralizer? The condensent is very acidic and can eat thru some piping
 

DR-DEATH

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You're probably referring to the section regarding a domestic hot water tank used w/a backflow preventer.
Some municipalities now require a backflow preventer on the water main entering the house. If you had one- and you heat your domestic hot water to 140F that would build dangerous pressure in your domestic water system- so you use an expansion tank specifically made for domestic water pressurized to 70+ PSI on the cold side of the DHW tank and that adsorbs the pressure buildup.

Even though your boiler expansion tank isn't ideally located- it will function, and your boiler fill backflow preventer is installed correctly.

That info was just under backflow preventor and didn't mention anything about dhw. I'm ok with where the expansion tank is if the warranty is intact. I'll have to get clarification from HTP as we aren't using it for dhw. Attached is a photo of the part of the manual im looking at. (Bottom part)

Rob, can you post an up close picture of your vent for the condensate line? I'm assuming they didn't use it due to the gas pipe being right under it. Doesn't seem like it would fit the vent with their tube without bending it/creasing it. The plumber said the pump being vertical was fine due to 20psi or more but taco just responded to my support inquiry stating that model has to be horizontal and if we used an 007 it could be vertical with 20psi.

Leon, both my rinnai and HTP do not have a neutralizer due to it pumping into laundry drain and the soap neutralizes it.

I'll have to call them back and have them fix the pump as it voids pump warranty and I hope they still have the original drain that came with the HTP.
 

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Leon82

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Taco freedom flanges are 40 bucks and swivel so the pump could be indexed wherever it needed. It also has the isolation valves.
 

NY_Rob

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Rob, can you post an up close picture of your vent for the condensate line? I'm assuming they didn't use it due to the gas pipe being right under it. Doesn't seem like it would fit the vent with their tube without bending it/creasing it.
I ran the OEM flex line out then inside a section of down pitched 1" PVC to prevent sagging....
 
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NY_Rob

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^ correct, the trap is inside the boiler case.
It's a bit of a pain to service, it almost seems like it was an afterthought.
 
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