NTI vs. Viesmann

upnorthduck

Hello. I am hoping to get some advice from the experts here. This forum is a great resource!

I am a homeowner in Northern Lower Michigan along the shores of Lake Michigan (about an hour SW of Traverse City). We have a 3,500 sq ft home with a large number of windows and am also on a high ridge overlooking the lake so we get wind as well.  

We recently got natural gas in our area and I am planning on replacing our 24-year-old propane boiler. The current setup has a Slant/Fin Victory V-150 boiler and an Amitrol 72G boilermate. The system has 5 zones including the one for the boilermate. The setup works very well for our house, including hot water, but is aging and nearing the end of its lifecycle. Plus, we are looking for a new boiler to be much more efficient and economical. Propane prices have increased dramatically over the past several years.  

I had two trusted HVAC contractors bid on the job. We are keeping the boilermate and just replacing the boiler and valves. The boilermate was previously replaced and is only 10 years old.  

The bids came back within a few hundred dollars of each other.  

One contractor specified a Viesmann Vitodens-100-W 96% modulating boiler.  

One contractor specified an NTI FTVN 199. 

Both seem like they are quality manufacturers and get good reviews.  Which would you recommend and why?

Thank you for any guidance or experience you can provide.

hot_rod

Michigan is certainly a strong Viessmann state, good dealer support. The NTI is a fine boiler also.

Most important is the installer understands the specifics of the boiler you chose, to get it piped and dialed in properly.

199 sounds large for that size home. A heatload would be a good first step. What type of heat emitters?

Radiant floor heat for examples, figure 25 btu/ sq ft as a comfortable output, so an 87,000 boiler output would cover that. Even with a fairly high load of 30 btu/ sq ft with radiators or fin tube, you are at a 105K boiler requirement.,

upnorthduck

We have baseboard heat.  Slant/Fin circa 1998.  

hot_rod

upnorthduck said:

We have baseboard heat.  Slant/Fin circa 1998.  

Another way to calculate boiler size is measure how many feet of SlantFin you have. Just
the sections with actual fin, no dummy board. Probably #30 or similar size and output?

Multiply times 550 (btu/ linear foot). See output chart, below average water temperature of 170- 175, boiler running 180°

Assume you have 150 feet of total fin. 550btu/ft. X 150'= 82,000btu per hour is all you can put into the building running an average water temperature of 170- 175° Regardless of how large the boiler is, the heat emitters and average water temperature dictate what can be moved into the building.

So really no reason to have a boiler larger than maybe 100,000 input.

Get your tape measure out

Probably 80% or more of the heating season you will not need full output, so with a reset control, (boiler cruise control) included on most mod con boilers, and modulating boiler, the boiler will attempt to match its output with the ever changing building load. Some days the boiler may be running 140° and heating just fine.

In addition the system will run with less on/ off cycles, less noise, better comfort, higher fuel efficiency.

There are systems running with well adjusted boiler controls that just modulate all season long, rarely turning off, just ramp up and down to the building load. Constant circulation.

offdutytech

I'm in the SE Michigan area and we install Viessman. When I was looking at what modcon to rep it was between two choices for us. Viessman and Lochinvar. When installed properly sized and installed correctly both I felt were good choices. Ultimately for us Viessman had a few tech features that we liked with a seamless app that customers could have on their phone to view the system and help troubleshoot remotely via their app. In addition the support network for us was good. My wholesale cost is slightly more, but that easily was justified by the features and support for us ( legacy parts, etc)  Lochinvar is also popular downstate because there is a distribution hub close, but we felt we got a slightly better value with Viessman based on features. 
At any rate ensure your contractor does a load calc and sizes for heating load and domestic water output for your tank. If i'm not mistaken you should be close to the B120HE or B150HE based on you loads. The NTI 199 seems high unless they were trying to sell you a combi. Personally not a combi fan.