Buderus, Viessman, Lochnivar, System 2000
Ford or Chevy?? I have a 20 y/o Weil that I want to replace in the next year. Considering 90% effcient that cost middle of the road. Any preferences.. My weil is going 20 years so I consider that a good and probably my 1st preference because it's proven.....last longer than the parts hooked up to it
Buderus, Viessman, Lochnivar, System 2000
We had an oil fired EK-1 System 2000 installed in September 2006 and we're extremely satisfied with it. We dropped our fuel usage from 1230 gallons per year to 790.
It is as quiet as most gas units, and in fact when it's going it makes less noise then our microwave.
Do not focus on AFUE in terms of your efficiency ratings!! They are pretty much meaningless.
What you want to know is the mileage it gets, or as it's referred to: Seasonal efficiency.
The most important thing when making your selection is that the installer knows what they're doing. Our installer, whose license plate reads 'BIASI' (a well known boiler manufacturer), installs several different brands and knows all their quirks.
Of course the other consideration was my oil company: Could they service it properly?
In any case I got 5 estimates. Our installer even agreed to come back at the 1 year mark (he guaranteed his labor for a year) to show our oil service tech the basics of doing a tune-up on this particular brand.
You will find a lot of boiler men who don't like the EK, primarily because it's steel, although there are plenty of units still in service past the 20 year mark.
In any case..........do your research and get several estimates.
Best of luck!
Hey Howard, thanks for that tip on AFUE. Those are the most mis-leading, useless set of numbers there are. Totally meaningless. BTW, my company was the first company in the New Hampshire to install system 2000's and that was way back when they were painted grey. Very good boiler indeed and we still sell a few. I am rearranging my brain however when it comes to system efficiency and though it gets way more technical than I want to get right now, it appears that high mass boilers are more efficient in the long run.
Low mass is where it's at.
The EK-1 has about 2.5 gallons internal water to heat before it makes hot water, and that's about 90 seconds from cold. The post purge of the core heat to the last zone that calls is a really smart feature.
As long as a boiler can be cold started, with no danger to seals and gaskets, it's the way to go.
I can remember how often our Blue Ray used to go on during the summer when the only thing turning the boiler on was itself calling to maintain a warm core!!! When the coil gasket started leaking we knew it was time.........
The biggest concern with EK's, I think, is if someone has really hard water. The flat plate heat exchangers can get all clogged up pretty quickly unless the core water is properly treated.
My recommomendation for the replacment is...
First: Do a real heat-loss calculation on the place, and verify it against degree-day data and fuel bills. If the rated output of your old system is oversized by 2-3x (all too typical) based on running 100% duty-cycle at design day temps, (which you should figure out by your fuel use per degree-day historical data) adjust your old boiler's rated efficiency down 10-15% and recalculate. Most software or Manual-J methods overestimate by 25-30%, so don't DARE add any additional margin yourself. If your heat-loss calc says one number, and your fuel use calc says a much lower number, go with the lower number as the output you need in the replacement boiler.
If you do that there's some chance it'll meet it's AFUE numbers, or at lest come close. Don't do it, and it almost certainly won't. For a good summary view of what being 2-3x oversized does to your annual efficiency & partial-load efficiency, check out the graphs & tables in the appendices at the end of this document (based on peer-reviewed data at Brookhaven Nat'l Labs):
(Unit #3 is almost surely a System 2000, or a system designed to operate simlarly to a System 2000)
A more condensed summary based on some of the same work lives here: http://www.bnl.gov/est/files/pdf/But...esentation.pdf
There are many good mod-cons out there- Triangle Tube & Peerless both perform well, as do many others. Find one that best matches your calculated heat loss number no bigger than 10% over, and you're good.
But you may want to tweak the system in other ways too, re-zone it to match your actual-use lifestyle, etc.
This goes well beyond the original question but I'll stick it in anyway as food for thought on the System 2000, and how you can make your system more efficient using similar high storage mass strategies.
Low/medium mass boilers coupled with (highly insulated) high mass storage is really the ticket, and the key to System 2000 performance. With the high mass storage there's no such thing as a short-cycling. Independent of load there is a significant minimum burn time, which limits the fixed losses incurred on every cycle.
Some designers of low to moderate load low-temp heating systems have done pretty well using much less sophisticated controls, adapting extremely low-mass cold-start-happy boilers aka "tankless hot water heaters", combined with well-insulated buffer tanks. They do A-OK even without the System 2K's heat-purge control & other features. (I'd really like to see how they fare in a Brookhaven type study. I'm guessing if they make their EF numbers in 10 gallon draws, they do pretty well with longer burns & fewer cycles as long as the return-water temps are reasonably low.) With radiation-returns properly plumbed to create at least some stratification in the buffers, using the tank as the hydraulic separator they can gain significant modulation efficiency under mid & high load conditions, while the high-mass keeps efficiency from falling off a cliff under the unavoidable low-load & intermittent burn conditions.
The whole notion in the mod-con world over the past decade has been that you can match the output to the load with continuous circulation, modulated flame & outdoor reset control. That almost works, but only in non-micro-zoned right-sized systems. When the outdoor temps are 20% of design-day load (a real heating day) and the system is getting a call for heat from a zone that's 10% of the whole house, you're servicing a load barely 2% of the full-on design day load (!). Mod-cons only turn down to 25%, so you're serving a load that's still under 10% of the turned-down output- it's GUARANATEED to incur a signficant cycling loss on that call, cutting into it's net efficiency.
The smallest mod-cons only crank down to 8-10kbtu, which is many times the heat loss of a 200 square foot reasonably insulated room on a 40F day (and those same tiny mod-cons are UNDER sized for running an indirect-fired hot water tank.) You can only really cut into the numbers of cycles & cycling losses only by adding mass to the system. Minimum burn times programmed into the mod-con controls may keep it falling into the efficiency abyss, but not with the same assurance or to the same degree as adding mass to the system.
40-120 gallons of buffer in the system with a reasonable amount of hysteresis to the storage temps decimates partial-load condition cycle numbers. Sure, there are standby losses with any tank, but those can be made almost arbitrarily small with more insulation. Beyond buffer standby the primary efficiency factors become the boiler's steady-state thermal efficiency, the fixed losses from flue purges, and the standby loss of the small amount of water in the heat exchanger (which is very tiny indeed in a tankless HW heater). Condensing HW heaters have thermal efficiencies similar to that of mod-cons, but even mid-efficiency tankless HW heaters will beat their low-mid-80s EF numbers in a buffered heating system configuration.
As heating loads for houses get ever lower the instantaneous loads from hot water heating with an indirect drives boiler sizing more than the actual space heating load. Sizing a mod-con with only 4/1 turn down for an indirect isn't necessarily the best or most-efficient option. While the peak load is the indirect, the bulk of the fuel use is still in space heating. Designing the full system for optimum efficiency isn't trivial. Bigger-better buffers (or buffers with internal DHW heat exchangers and heating systems designed to run at DHW temps or lower) are much under-utilized in the hydronic heating trades, particularly on small-medium sized residential.
A lot of the sophistication of mod-con controls are of-necessity wasted in the field- there's only so much the boiler itself can do when the loads are low, and the system designer makes or breaks it. System 2000 type systems designed with inherent high mass storage and low-mass boilers make it harder to screw up, but I'm sure there are still some folks out there up to the task, eh? ;-)
This white-paper summary of what buffers can do for about ANY zoned heating system is well worth reading for any residential hydronic designer, and explains a lot how the System 2000 can maintain much of it's full-fire efficiency and even beat mod-cons under partial load conditions:
You can use cast iron, mod-cons & modulating tankless HW heaters with decent sized buffers for similar gains in partial-load performance. "Right-sized" per manual-J bang-bang cast iron boiler performance usually gets killed under partial load and they often fail to meet their AFUE numbers in the real world. But even 350lbs of buffer w/10F of hysteresis can work wonders for lengthening cycles. Many cast iron beasts don't reach their steady-state efficiency with burns shorter than 10-12 minutes, and only see burns that long after overnight setbacks (even on design-day), and end up maintaining system temp with multiple burns that are but a fraction of what it takes to reach steady-state. Anything that adds a significant fraction of the time-to-steady-state burn length makes a measurable difference in system efficiency. (Even using a buffer-mass times hysteresis equal to 1/4 of the time-to-steady-state burn counts, big-time.)
I like the Pensotti DK2 boiler.
They are a low mass, triple-pass boiler. Energy Star Rated. Very efficient.
I have two oil fired DK2-3 (3 section) boilers on a lead-lag setup, that way i get the extra BTUs if i need them. Put them in last fall and saved about 30% in gallons used this winter compared to last.
I actually bought them online at a website called www.hitechheat.com and had my plumber do the install.
Saved me a little money that way.
yeah you sure do: depending on your heat input required... but you could always have two and link them together to increase output...
Last edited by flamefix; 09-06-2009 at 12:43 AM.
Gas, Oil, solar and renewable service and installation in Devon UK- Please note my advice is not based on USA regulations as I am UK resident. Therefore I will try to avoid posting where confusion may be caused or make that clear.