New natural gas heating system

[BugHunter]

They were playing with combustion analyzers to lessen the noise, never really went away especially when it is cold outside.

If you're curious, remove it and open it before it goes away. I'm betting the fan cage is damaged and running out of round, and that's what is making the noise. Mine wouldn't run more than a few hours that way before everything would quit. The screeching was unreal. It just melted the fan and case together. They have safeties (barometric sensors) that can tell if it's working, and if it isn't, exhaust gas is left inside the house which is a no-no. So it shuts down.

 

[clifish]

mine only makes the noise on firing then it goes away, it has never shut the unit down due to it.......as far as I know...lol

 

[clifish]

So got another quote for a Navian heat system and a 40 gal indirect water heater $23,780 ouch.

Went back to the first gut about it being oversized and he responded

Why the NCB-250/150H Works Perfectly.

• Maximum Load Matches: Your 125' baseboards can safely emit up to 72,500 BTU/hr on the coldest day of the year. This falls comfortably below the boiler's maximum space heating limit of 150,000 BTU/hr.
• Minimum Modulation Fits: The boiler’s minimum firing rate is 14,000 BTU/hr. Your baseboards only need to be active for about 24 feet (out of your 125 feet total) to safely absorb that minimum heat.
• No Short-Cycling: Because your total radiation capacity (72,500 BTU/hr) is much higher than the boiler's lowest floor (14,000 BTU/hr), the boiler can easily modulate up and down to match your home's exact heat loss without rapidly turning on and off.
• Hot Water Demand: The 250/150H model is sized to deliver up to 4.5 gallons per minute of domestic hot water. This is perfect for running your 2 bathrooms simultaneously without anyone getting a cold shock in the shower.

Final Summary
The Navien NCB-250/150H is perfectly compatible with 125 feet of baseboard. It will modulate smoothly, prevent short-cycling, and easily satisfy the heating and hot water needs of your 4-bed, 2-bath 2,156 sq feet home.

Any thoughts on this?

 

[BugHunter]

So got another quote for a Navian heat system and a 40 gal indirect water heater $23,780 ouch.

Went back to the first gut about it being oversized and he responded

Why the NCB-250/150H Works Perfectly.

• Maximum Load Matches: Your 125' baseboards can safely emit up to 72,500 BTU/hr on the coldest day of the year. This falls comfortably below the boiler's maximum space heating limit of 150,000 BTU/hr.
• Minimum Modulation Fits: The boiler’s minimum firing rate is 14,000 BTU/hr. Your baseboards only need to be active for about 24 feet (out of your 125 feet total) to safely absorb that minimum heat.
• No Short-Cycling: Because your total radiation capacity (72,500 BTU/hr) is much higher than the boiler's lowest floor (14,000 BTU/hr), the boiler can easily modulate up and down to match your home's exact heat loss without rapidly turning on and off.
• Hot Water Demand: The 250/150H model is sized to deliver up to 4.5 gallons per minute of domestic hot water. This is perfect for running your 2 bathrooms simultaneously without anyone getting a cold shock in the shower.

Final Summary
The Navien NCB-250/150H is perfectly compatible with 125 feet of baseboard. It will modulate smoothly, prevent short-cycling, and easily satisfy the heating and hot water needs of your 4-bed, 2-bath 2,156 sq feet home.

Any thoughts on this?

Yea, the guy who wrote that is an idiot...
Here's your chart.

There's the load info from the bills. The gas bill = the lie detector. Unless someone froze in the house, those numbers are enough to heat it in the worst of all conditions we've know. The far right column is the 140% safety margin over the heating load.

Boilers and furnaces are designed to run continuously. They are not designed for turning on and off 100s of times a day. Boilers are a "little" more forgiving in this regard, but not 400% forgiving. As those demand numbers fall, the system becomes less and less efficient, and has to turn on and off an incredible amount of times, which eats parts. That's bad...

• Maximum Load Matches: Your 125' baseboards can safely emit up to 72,500 BTU/hr on the coldest day of the year. This falls comfortably below the boiler's maximum space heating limit of 150,000 BTU/hr.

This has nothing to do with "Comfortably below". It's TOO BIG. We're aware of what it has capacity to provide, it just can't provide that IN THIS HOUSE. Moreover, it will never be asked to provide that, or anything close to it.

What it really says is no matter what ever happens, there's no way this unit will ever run at anything more than an idle. I only have the numbers for the months you gave me, and I threw in a guess on the Oct days. Those 'warmer' months are where this thing is going to beg for mercy. It is intended to modulate the output so that the burners never turn off. They have the ability to alter the output water temp to match the heating load and they do this with an intelligent controller. Ideally, it will never shut off, and will sense that the water is warm enough to keep the house at a constant temp (not raising and lowering constantly). These have an outdoor sensor that is used along with historical data it stores to tell it how much the home needs to not cycle the unit. Takes a little 'learning' time, but after that it's pretty bulletproof at maintaining a constant temp, which means better comfort.

I already said how this heating and cooling during short cycles is what is killing your inducer fans. It's easy enough to google that I'm not making that up.

• Minimum Modulation Fits: The boiler’s minimum firing rate is 14,000 BTU/hr. Your baseboards only need to be active for about 24 feet (out of your 125 feet total) to safely absorb that minimum heat.

Oct and Nov are below anything that unit can provide. Now what? Ah, yes, even at the 1:10 modulated setting it still can't go low enough. Now, invariably at some point it'll be warm enough that they need to cycle. But that should not be in Dec-Mar...

• No Short-Cycling: Because your total radiation capacity (72,500 BTU/hr) is much higher than the boiler's lowest floor (14,000 BTU/hr), the boiler can easily modulate up and down to match your home's exact heat loss without rapidly turning on and off.

Huh? This guy can't be serious. Short cycling happens when the heating appliance is larger than the heat delivery system (baseboards or ducts) will deliver. This is made worse when the entire system is larger than the house demand. You've got both, in spades. The company makes 2 smaller models, both of which are WAY big enough for your house. What are the reasons for not using one of them?

You've got the house and the baseboards perfect now. The only thing remaining is to size the boiler to match. They're not doing that. This is a recipe for exactly what you have now, a unit that will be dead in no time, or at least a maintenance pain in the ___ .

As to the hot water, I would not do an indirect water heater. That's yet another annoying can of worms. Separate tankless water heater? Yes. Combi? Fine. Indirect? Not so much. I can think of reasons to do one, but in a residential setting, I don't like it.

 

[clifish]

Yea, the guy who wrote that is an idiot...
Here's your chart.

View attachment 736316

There's the load info from the bills. The gas bill = the lie detector. Unless someone froze in the house, those numbers are enough to heat it in the worst of all conditions we've know. The far right column is the 140% safety margin over the heating load.

Boilers and furnaces are designed to run continuously. They are not designed for turning on and off 100s of times a day. Boilers are a "little" more forgiving in this regard, but not 400% forgiving. As those demand numbers fall, the system becomes less and less efficient, and has to turn on and off an incredible amount of times, which eats parts. That's bad...

• Maximum Load Matches: Your 125' baseboards can safely emit up to 72,500 BTU/hr on the coldest day of the year. This falls comfortably below the boiler's maximum space heating limit of 150,000 BTU/hr.

This has nothing to do with "Comfortably below". It's TOO BIG. We're aware of what it has capacity to provide, it just can't provide that IN THIS HOUSE. Moreover, it will never be asked to provide that, or anything close to it.

What it really says is no matter what ever happens, there's no way this unit will ever run at anything more than an idle. I only have the numbers for the months you gave me, and I threw in a guess on the Oct days. Those 'warmer' months are where this thing is going to beg for mercy. It is intended to modulate the output so that the burners never turn off. They have the ability to alter the output water temp to match the heating load and they do this with an intelligent controller. Ideally, it will never shut off, and will sense that the water is warm enough to keep the house at a constant temp (not raising and lowering constantly). These have an outdoor sensor that is used along with historical data it stores to tell it how much the home needs to not cycle the unit. Takes a little 'learning' time, but after that it's pretty bulletproof at maintaining a constant temp, which means better comfort.

I already said how this heating and cooling during short cycles is what is killing your inducer fans. It's easy enough to google that I'm not making that up.

• Minimum Modulation Fits: The boiler’s minimum firing rate is 14,000 BTU/hr. Your baseboards only need to be active for about 24 feet (out of your 125 feet total) to safely absorb that minimum heat.

Oct and Nov are below anything that unit can provide. Now what? Ah, yes, even at the 1:10 modulated setting it still can't go low enough. Now, invariably at some point it'll be warm enough that they need to cycle. But that should not be in Dec-Mar...

• No Short-Cycling: Because your total radiation capacity (72,500 BTU/hr) is much higher than the boiler's lowest floor (14,000 BTU/hr), the boiler can easily modulate up and down to match your home's exact heat loss without rapidly turning on and off.

Huh? This guy can't be serious. Short cycling happens when the heating appliance is larger than the heat delivery system (baseboards or ducts) will deliver. This is made worse when the entire system is larger than the house demand. You've got both, in spades. The company makes 2 smaller models, both of which are WAY big enough for your house. What are the reasons for not using one of them?

You've got the house and the baseboards perfect now. The only thing remaining is to size the boiler to match. They're not doing that. This is a recipe for exactly what you have now, a unit that will be dead in no time, or at least a maintenance pain in the ___ .

As to the hot water, I would not do an indirect water heater. That's yet another annoying can of worms. Separate tankless water heater? Yes. Combi? Fine. Indirect? Not so much. I can think of reasons to do one, but in a residential setting, I don't like it.

Hahaha, I sent him your response and he ran it through AI, needless to say we are stepping down to the unit YOU recommended...you have been awesome! this is what his AI said...and he owns the company.....I did delete the comment that he is an idiot....lol

From AI....

=============


Clifford is 100% correct, and his PA contacts are giving you excellent advice. You should absolutely go to the next size down (the Navien NCB-190/060H).
His email identifies the exact trap of "combi-boiler sizing" that many installers fall into.

Why Clifford is Right (The Core Issue)
Installers often size a combi-boiler based on the domestic hot water (DHW) demand (showers) rather than the space heating demand.

• The NCB-250/150H has a massive 150,000 BTU heating capacity. As Clifford correctly noted, your 125 feet of baseboard can only physically emit 72,500 BTUs.
• This means the 250 model is more than double the size of your entire radiator network. It will never run efficiently; it will sit at an "idle," short-cycle constantly in shoulder months (October, November, April), and prematurely burn out parts—exactly like your current Alpine unit.

Why the Next Size Down (NCB-190/060H) is the Correct Choice
The NCB-190/060H is a much tighter, safer match for your home:

• Max Heating Capacity: 60,000 BTU/hr. This beautifully matches your 72,500 BTU baseboard capacity. It allows the boiler to actually run long, efficient cycles.
• Lower Minimum Modulation: It can drop down to 10,000 BTU/hr (instead of 14,000 BTU/hr). This lower floor means it can stay running continuously on milder spring and autumn days without short-cycling.

The Only Trade-Off: Hot Water GPM
The only reason an installer pushes for the larger 250 unit is to guarantee endless hot water for two showers running at the exact same time in the dead of winter.

• The NCB-250/150H provides 4.5 Gallons Per Minute (GPM) of hot water.
• The NCB-190/060H provides 3.4 Gallons Per Minute (GPM) of hot water.

A standard modern showerhead uses 1.5 to 2.0 GPM. At 3.4 GPM, the smaller 190 unit can easily handle one heavy shower + appliances, or two low-flow showers simultaneously. If your household can handle a minor restriction on running two simultaneous, heavy-flow showers in the dead of winter, the smaller unit is vastly superior for the longevity and health of your heating system.

Final Recommendation
Do not buy the NCB-250/150H. Tell your installer you want to drop down to the Navien NCB-190/060H. It fixes the short-cycling issue that killed your Alpine boiler, matches your 125-foot baseboard load perfectly, and will save you thousands in future repair bills. Clifford's "lie detector" gas bill data proves your house simply does not need a 150,000 BTU heating beast.

 

[BugHunter]

Now that is too funny! Lol. And just so ya know, I didn't use any AI, I typed all that mess! And I wouldn't ever trust AI, even when it does agree with me.

I'm not sure the AI is correct on that domestic water spec. My water heater here (intended to service all 7 baths) is a 200,000 BTU unit with a spec of 13.x gallons per minute at 120 or 130F. (can't recall which, I have it set to 130). That has the 4" PVC supply and exhaust air, so a bit more diameter than your combi unit was calling for, and I'm not sure why. My boiler uses 2", and my furnace uses 2" which necks up to 3" only because of the distance it runs to make it outside. I thought the BTU's /Distance determined that diameter, but I could be mistaken. Mine is a commercial WH unit. Not sure if that matters. Either way, I can't imagine the combi unit you looked at can't handle those two showers with ease. Full disclosure, I've never "owned" a combi boiler. There's probably a little nuance between them and separate boiler/water heater units. But I can't imagine they don't work more or less the same.

If you have old shower heads that really waste water, and it isn't capable of running two showers and the heat together, swap out the shower heads, or just stagger the showers. How often are both running simultaneously now anyway? Ever?

 

[Nodak21]

This has been an interesting read, and I appreciate the time and knowledge that bug hunter spent. He is totally right.