Will 5-Section Boiler Be Too Big for 2300 Sq Ft Home? Buderus G115 /5


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Old 01-22-14, 07:43 AM
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Question Will 5-Section Boiler Be Too Big for 2300 Sq Ft Home? Buderus G115 /5

My 28 year old Weil-Mclain P-366HE boiler is shot...seals gone and leaking. We heat with wood pellet & use GeoSpring hybrid electric hot water heater in our 2-story 2300 sq foot colonial in CT built in 1986. We still need a backup source and we may not always heat will pellet so it is time to replace the boiler. Not wanting to spend much and being a do-it-yourselfer, I have my eye on a used Buderus G115 /5 section oil-fired unit for the replacement. It came out of a home similar to mine with 2 zones plus an indirect water heater and is about 5-years old for $600.

From what I am reading a larger 5-section may be too big and inefficient and could lead to short-cycling on & off frequently. I believe the 5-section is rated at 120k BTU p/hr. I think I know the answer... do the heat loss calculator to right-size a boiler. I downloaded the Slant Fin program and started it but don't think I am going to spend hours doing it. I think I will pay $75 for a professional to do it.

So, based on experiences from those reading this thread... do you suspect a 5-section boiler will be overkill in my case and should I stay with a 3 or 4-section? My top pick is Buderus but realize there are other good products out there. Thank you for your replies...
 
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Old 01-22-14, 08:27 AM
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You need about 60K btu boiler... Yes do a heat loss to verify...

I like slant fin...Or burnham...

IMO Buderus are over priced....
 

Last edited by lawrosa; 01-22-14 at 10:35 AM.
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Old 01-22-14, 08:33 AM
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Yes its overkill. The slant fin calculator wont take long to do. Shouldn't take more than an hour.
 
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Old 01-22-14, 09:45 AM
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I believe the 5-section is rated at 120k BTU p/hr
Sounds low for a 5 section...

Agree with the others that it's too big.

If you need to stick with oil, my choice would be the Burnham MPO... the smallest one.

MPO-IQ115 - Burnham MPO-IQ115 - MPO-IQ Series 85,000 BTU Output Oil Fired High Efficiency 3-Pass Boiler
 
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Old 01-22-14, 11:34 AM
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Good comments, keep them coming!

I do need to stick with oil - NG not available and propane too expensive. On my last service my boiler tech recommended the Burnham MPO actually which I will consider. I like the idea of an outdoor reset no matter which I go with. The used G115 /5 section is rated at 120k max and 104k net Btu/hr with 1 GPH oil firing rate and has 12.9 gal water content. I can see how it would take more to maintain that over a 3-section 8.7 gal. The old Weil 3 section that crapped out is rated at 109k max.
 
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Old 01-22-14, 12:12 PM
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120k max and 104k net Btu/hr with 1 GPH oil firing rate
If oil has 140K BTU per gallon, and firing rate is 1 GPH then the INPUT is 140K... maybe you are looking at the DOE or the IBR ratings?

To me, the biggest single plus to the MPO is the ease of cleaning... by far the easiest boiler to clean that I've come across, and that's important because there's better chance that the boiler actually GETS cleaned.

But mine is saving me about 15% on fuel also, partly because it's a 3 pass which is a few points more efficient, but probably mostly because my old boiler was so over-sized.
 
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Old 01-22-14, 12:23 PM
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Here is the slant fin version of the MPO..

I like the concentric vent option myself that lets it vent side wall... Plus I am partial to slant fin....

http://www.slantfin.com/images/stori..._ec1020_10.pdf
 
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Old 01-22-14, 01:03 PM
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I am quoting the tech info from Boderus install manual 03/2004, for a 5-section G115/34.
 
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Old 01-22-14, 01:18 PM
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Right... INPUT is 140K - OUTPUT is 120K - IBR rating is 104K
 
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Old 01-24-14, 05:41 PM
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I've decided to pass on the 5-section and go with a 3-section, 3-pass, cast iron type and leaning towards Buderus. If I don't find a nice used one I'll buy new online and install it myself and hire a consultant for the design and startup if I have to.
 
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Old 01-24-14, 05:43 PM
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leaning towards Buderus.
How come? Just curious your reasoning..........

What are you 'pickin' if I may ask? just more curiosity.
 
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Old 01-24-14, 08:27 PM
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I would try to stay away from buying boilers online if you could. Its best to get one from a supply house. May cost more upfront but if you ever need to deal with warranty problems its MUCH easier. Some manufacturers wont even stand by their warranty if you buy online.
 
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Old 01-25-14, 07:08 AM
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Some Reasons

Buderus, Biasi, Solera are on the list, all seem to be similar design. Why Buderus? I like the name/reputation, I like German engineering, the easy of cleaning and the owner of my plumbing and heating service company has one. I need a boiler that will withstand being shutoff for periods of time if I am solely burning pellets and turned back on when I am not, like the in-between seasons.

I will call local supply company and see what they can do. The online supply house (that rhymes with rex) seems to have many happy customers with a good return policy.
 
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Old 01-25-14, 07:37 AM
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will withstand being shutoff for periods of time if I am solely burning pellets and turned back on when I am not, like the in-between seasons.
A caution to this strategy is advised... when using an 'alternate' heat source, the extremities of the home can get pretty cold and this leads to frozen pipes, so it's advisable to run glycol in the heating system.

The online supply house (that rhymes with rex)
That's where my MPO came from... good deal, fast delivery... and fact is that the 'online presence' is a 'broker' in many cases, working with more 'local' distributors. You find that out when the delivery is made by looking at the labeling on the shipping cartons.
 
 

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