Boiler replacement questions

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Old 11-02-15, 05:30 PM
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Boiler replacement questions

I currently have a two family home with one oil fired boiler which I want to replace for use with my second floor unit only at this time knowing eventually when I sell the home that I will connect both floors/zones to the new mod/con combination gas boiler I plan to install. I know once I disconnect the second floor the oil boiler is going to be grossly oversized. My j-load for each floor is 25k second floor and 14k for the first floor. I am leaning towards the navien 240b as the modulation is 6:1 and will go down to 18k btus. My concern lies with the fact I have convector cabinet radiators which based on some info I found can produce 2300 btus to 3800 btus at 160 degree temp in but may fall short on heating the rooms. I understand in order to get the condensing my boiler temp should be at about 140 degrees output. I'm concerned in order to heat the rooms for the loss that I will have to run higher boiler temps thus reducing condensing and efficiency. I am also leading towards Ecm circulators. Obviously I can reduce my heat loss by insulating and air sealing more, but will this boiler work and how well? Obviously I will also save going from oil to gas. House is about 1800 sf cape with 1bath each floor and older vinyl replacement windows.
 
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Old 11-02-15, 06:01 PM
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I currently have a two family home with one oil fired boiler which I want to replace for use with my second floor unit only at this time knowing eventually when I sell the home
Two questions come to mind. How many years are "eventually" when it comes to selling? What is the total cost, of the boiler replacement?
 
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Old 11-02-15, 06:04 PM
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I estimate selling within 3 years max and install cost is about 8900
 
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Old 11-02-15, 06:29 PM
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The next question is, do you think that you will recover the $8,900, in the sale price or in energy savings, in the next 3 years? If the answer is no, then don't do it.
 
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Old 11-02-15, 07:42 PM
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Seeing as my oil bills have been running about 3k the last 2 years and the 1500$ credit and an oil boiler from 1986 it would seem to me it's a win win. I have been quoted a Laars mascot 2 ft and a viesmann vitodens 100 and the Laars would run me 12k and the viesmann 13k
 
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Old 11-02-15, 08:29 PM
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If you see savings, don't let me stop you. Keep in mind that the $12,000 estimate doesn't make the $8,900 good & your decision shouldn't be based on anything but the lowest estimate.
 
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Old 11-02-15, 08:58 PM
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Agreed. I'm just looking for a boiler with more efficiency than 85% bases on my last service. Currently the home is utilizing a trainco 94mmbtu oil burner from 1989 and the set point is 190 degrees, so I want to make sure that with my current radiation that I install something that will work with what I have and still achieve efficiencies greater than what I have now. I'm not stuck on any brand in particular or price point but I also don't want to dump that kind of money into something that I can't get my return on, either over time or with the sale of the house.
 
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Old 11-02-15, 09:15 PM
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Your savings will be great just switching to gas... Condensating boilers dont get you the payback you may expect.. Higher cost to install and more stuff to go wrong...

I would put in a standard cast iron unit sized properly..

Like a peerless for example that utilize the hydrostat controls..

Smallest they make though is 51K BTU DOE

Series MI85„

But you may be best off putting in a small burnham thats sized accordingly..

202x 41K btu DOE

http://www.usboiler.net/product/seri...er-boiler.html

https://file.ac/ZYgLWyMdFsk/Series%2...ta%20Sheet.pdf
 
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Old 11-03-15, 04:17 AM
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lawrosa
I agree that installing a normal gas boiler is a good way to go. I had a quote for a pure fire pro with gas water heater that came in at 6k, but I'm not a fan of storing hot water and I would have to vent it out the chimney which already has the oil burner vented. The install cost with the rebate on the condensing boiler is almost the same and the venting is direct.

My whole distribution piping in the basement is 1" copper on each floor/zone. I figured my additional savings would be on the modulation for dhw worst case.
 
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Old 11-03-15, 05:00 AM
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As a Broker, I've sold over a thousand homes and I can't rightly say that any Buyer placed much value on the age or efficiency of the heating plant. Given the age of the housing stock in this part of the world, 1986 is still considered "fairly new".

If you want to do it, "do it for yourself", and don't expect anyone else to notice or appreciate it. They would notice if it were absent, and they would notice if it weren't working; but that's about it. It's not one of your big pay-back investments.
 
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Old 11-03-15, 05:26 AM
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You can always install a power vented cast iron unit... Cost to install should be 1/2 of what your quoted..

But its your money. If you feel like its right for you go for it..

HWH I would do a superstor indirect...
 
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Old 02-28-16, 07:28 AM
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Name:  Boiler install small.jpg
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Size:  37.3 KBWell, my Navien NCB 240 boiler has been installed for about a month now and I had the HVAC company install a Taco Bumblebee ECM circulator and I installed an ecobee 3 wifi thermostat and so far I am pretty happy. We have had some pretty cold weather here this past month and I had to do some fine tuning by initializing the boost option due to a temperature drop when it was really cold in the negatives a couple weeks ago but it appears that the unit is condensing quite nicely with the outdoor reset installed. I have the outdoor reset limits at 7 degrees for the low and 70 degrees for the high and utilized the standard curve for finned tube baseboard. I am pretty impressed with the circulator and the fact that it shuts off all together when the ecobee hits temp. My burn times are right around 15 minutes which seem good. I bumped up the anti-fast cycling time to about 11 minutes since I was concerned my limited convector cabinets ([email protected]" high and 24-36" long) cabinets might make it short cycle. The circulator is set up with a delta t of 20 degrees and the boiler itself is using the supply temperature as the controlling factor.

I'm sure I could fine tune it more with a more accurate custom outdoor reset curve, but the directions in the manual for this aren't very clear. The supply temp is typically around 150-160. Anyone have any information that may assist in setting the curve for this?

In my original post wen I asked if this was a viable option I forgot to state that this was a two family home with one oil boiler supplying heat and hot water fro both units and that the purpose of installing this unit was for not only savings on utilizing gas but separating out the heating system.
 
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