outdoor reset savings report
#1
12-15-06, 09:55 AM
outdoor reset savings report
Old system: 2+x oversized CI boiler, bang-bang, 180F (2003 Burnham Series2 206) no controls
New system: right-sized CI boiler (Burnham Revolution) with tekmar 260
Building: 2100sf, fin-tube throughout
Fuel use down by 23% (normalized for degree days). This under light loads for past 6 weeks.
There are a few other competing factors, but in general, pretty neat.
New system: right-sized CI boiler (Burnham Revolution) with tekmar 260
Building: 2100sf, fin-tube throughout
Fuel use down by 23% (normalized for degree days). This under light loads for past 6 weeks.
There are a few other competing factors, but in general, pretty neat.
Last edited by xiphias; 12-15-06 at 11:29 AM.
23% savings
#3
12-15-06, 06:15 PM
I think it will get a bit better (but not hugely) if and when the heavier loads of winter start.
At this rate and at current fuel prices, the control will have paid for itself in one heating season.
At this rate and at current fuel prices, the control will have paid for itself in one heating season.
#4
12-15-06, 09:39 PM
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I try to convince people to go with a control that gives continuous circulation with a modulating water temp. Unfortunately I don't have a crystal ball that tells how much they will save, and most people want to know before they spend the $$$. Buderus makes some great controls and boilers.
#5
12-16-06, 05:15 AM
One of the reasons I like this comparison is that the "old" boiler was only three years old. It was not an aged, oil- or gas-sucking monster running at 65% AFUE. It was a modern, well-maintained, standard cast-iron boiler. The replacement is also a single-stage cast iron boiler, albeit with internal primary-secondary piping/pumping. So the difference is really in being properly sized, piping that allows full outdoor reset, and having a good control package. The new one is about 7-8% more efficient by AFUE, but even after subtracting that out it's still 15%.
The additional cost of doing it right (sizing, piping, and controls) would pay for itself in about two heating seasons.
Unfortunately, under my circumstances (the 3-year-old boiler installed by an incompetent, with a bunch of code violations including combustion air that was a health hazard) the total costs of doing this twice in four years were obscene. More evidence that doing your homework and paying a bit more up front can save aggravation and money.
The additional cost of doing it right (sizing, piping, and controls) would pay for itself in about two heating seasons.
Unfortunately, under my circumstances (the 3-year-old boiler installed by an incompetent, with a bunch of code violations including combustion air that was a health hazard) the total costs of doing this twice in four years were obscene. More evidence that doing your homework and paying a bit more up front can save aggravation and money.
#6
12-16-06, 05:22 AM
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Originally Posted by xiphias
One of the reasons I like this comparison is that the "old" boiler was only three years old. It was not an aged, oil- or gas-sucking monster running at 65% AFUE. It was a modern, well-maintained, standard cast-iron boiler.
Pete
#7
12-22-06, 08:11 PM
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Originally Posted by xiphias
More evidence that doing your homework and paying a bit more up front can save aggravation and money.
#9
12-23-06, 05:15 AM
Who: yes, everything from outside through the concrete foundation. Vent is 3" AL29-4C stainless. Intake is 3" PVC.
HVAC: The payback time on an install as you suggest was several decades. I'm very into energy efficiency and the environment but don't have the cash for "environmental virtue" at this scale. I ran the numbers and believe me I thought about it. Retrofitting the house for radiant would be a big deal and without major improvements to the envelope, the supply water temps for things like staple up plates were pretty high anyway. The Buderus GB was on my short list. I ultimately didn't choose it for a number of reasons, but even on a blank slate I would have gone with something else. I am concerned about the longevity of cast aluminum heat exchangers in general, and in conversations with some professionals, also learned that there might be issues with salt-laden intake air. I'm in a coastal location downwind of a large body of salt water (an arm of the Atlantic) and we have significant salty air that really does a number on aluminum. Not beachfront but within a mile.
If I was really into spending a fortune and tearing the house apart to get efficient, I'd go radiant and put a bunch of Thermomax or similar panels on the roof. We have an ideal roof orientation with a clear view. Put a 600-1000 gal storage tank in the basement and need very little boiler. Integrate with the DHW, etc. etc. Add a windmill and I'd pretty nearly be off-grid. Nice to dream about....
HVAC: The payback time on an install as you suggest was several decades. I'm very into energy efficiency and the environment but don't have the cash for "environmental virtue" at this scale. I ran the numbers and believe me I thought about it. Retrofitting the house for radiant would be a big deal and without major improvements to the envelope, the supply water temps for things like staple up plates were pretty high anyway. The Buderus GB was on my short list. I ultimately didn't choose it for a number of reasons, but even on a blank slate I would have gone with something else. I am concerned about the longevity of cast aluminum heat exchangers in general, and in conversations with some professionals, also learned that there might be issues with salt-laden intake air. I'm in a coastal location downwind of a large body of salt water (an arm of the Atlantic) and we have significant salty air that really does a number on aluminum. Not beachfront but within a mile.
If I was really into spending a fortune and tearing the house apart to get efficient, I'd go radiant and put a bunch of Thermomax or similar panels on the roof. We have an ideal roof orientation with a clear view. Put a 600-1000 gal storage tank in the basement and need very little boiler. Integrate with the DHW, etc. etc. Add a windmill and I'd pretty nearly be off-grid. Nice to dream about....
Last edited by xiphias; 12-23-06 at 07:22 AM.
