High Efficiency and No Free Lunch

jerry scharf_3

Mark,

I've brought up some points, but I realized that there was something more general that I wanted to say to this.

Generating numbers for future cost is at best a difficult thing. In this case, I believe it went way beyond that. If you look at what you plugged into the fields, what degree of confidence do you have in the numbers?

There were a set of variables you needed to assign numbers to in order to calculate these. We need to look at a confidence number for each of these.

Lifetime and maintenance of units. Many of these boilers have not been in the US for 20 years, so it is difficult to predict as a group or individually what the lifetime and more importantly maintenance will be. Most people have said your numbers on both sides were too high, but I think everyone agrees that on average more complex units will have shorter lives. The confidence factor on the lifetime ratio could be fairly good. Maintenance is much harder to guage, with more things to break, one would have to add more to the complex machines side, but how much. What condifence factor would you choose? It seems low to moderate for me.

Next you made assumptions about the system efficiency difference. You chose AFUE numbers as the base, but feedback is that everyone sees wider differences than that. Even with that, confidence factor is fairly high because it can't be off more than a factor of 2, and with a little more research/discussion can be brought in fairly close. There were discussions about this, and I brought up the fact that since this is a new design you can optimize the other parts of the system for optimum system efficiency.

Then there is fuel costs. Looking over the last 10 yers, this at a historic low for the century (20th.) So neither of these seem to have high confidence. Given that both of these are compounded numbers, even moderate uncertainty at the start gets magnified over the predictive period. On the other hand, there will be a limit at which prices will force down consumption to balance. I think the confidence factor on energy would have to be low to very low.

Finally there is interest. Assuming this is part of the home loan, you lock up the rate at whatever interest rate you get. If the inflation rate were to increase during the 20 years, your net cost would drop as the future value of the money would decrease.

With all this, I would have to say that the overall confidence of the prediction would be very low. As such, you are forced to go back to the "what do I believe will happen" at the "gut" level without the spreadsheet.

One final thing before I stop beating the dead horse. You may also want to consider risk exposure as well as predicted costs. If the unit costs 3 times as much to maintain, how much money is at risk. If energy increases at 15% per year, how much money is at risk.

I'm not sure any of this helped, but I hope so.

jerry

Mark Adams

I'd like to be talked into

one of these new super high efficiency boilers like the Munchkin or Ultra for my newbuild. Problem is, I ran a cost analysis to see where the payback might be compared to a standard 83% unit. Surprisingly to me anyway, was that the gas savings on the high efficiency unit were almost exactly offset by the cost of its earlier replacement. Now, this is all very fuzzy and assumes 30 yr standard boiler life, 20 year HE boiler life with 83 AFUE and 92 AFUE respectively, 6% mortgage and 5% energy cost increases per year.

Of course it is obvious that comfort is potentially better with the modulator. But my house will be largely BB with kitchen and two baths worth of underfloor. And a towel warmer for good measure.

What say the experienced gurus? Will these newer boiler hold up?

In previous posts I got great replies on system design, constant flow, TRV's, panel rads, etc. Thanks!!

Mark

jeff_51

the new Buderus wall hung

runs as high as 98%, has a constatnly modulating burner and has been in use in Europe for 20+ yrs. Check out the Buderus web site. If you are in Mass, I don't think this one has the H stamp yet, others on this site can tell you that, but the rep told me a couple of weeks ago that it will be coming, but dodn't know when

Joe Brix

30 yr service life

I think is overly optimistic for any equipment these days unless you get a very expensive Buderus or Viessmann to start with. Did you factor in some replacement costs: I doubt burners, gas valves, etc. will last 30 years. I hope that more efficencies will be found in the future so that you would not want to be on the same old technology an additional 10 years.

Floyd_9

A couple of things....

to consider.

1. I think your 5% increase per year gas pricing is being VERY optimistic. More like 10% and that may not even cover it.

2. Comfort... at hwat temp......have you considered that you may well be as comfortable at 68* with a Mod. boiler as you would be at 70 or 72 with a bang, bang 80%er????

3. What will there be available in 10 or 15 years??? my gues is that if you lock yourself into the 30 year mind set that you will find yourself rippin' the old gas hog out way before that, simply because it will become "unaffordable" not only from a gas usage stand point but because there will be equipment out there that will be soooo much more eff. It wasn't all that long ago that we would have never dreamed of getting close to the high 90's in eff. Over 100% is not out of the realm of possiblities.... and what of other yet to be determined fuels???? I think that the periodic table has increased by what 6 maybe 8 since I left high school....what is still out there to be discovered????

4. Anything mech. is a crap shoot when it comes to the longevity projections.... I've seen things that I thought were bulletproof be a big pita and some things that I felt would be a pita last a very long time with no trouble.

Me, I'd go for the 15-20 year deal and enjoy the savings till the next lastest and greatest shows up.

Floyd

Gordy

As a consumer/ homeowner I have the same thoughts. I say if its a new system or the old boiler is shot completely go for the high efficiency. As my situation is now my standard boiler is 12 years old with alot of life hopefully. So I'm not inclined to make the switch until I have to. I think just the ability to modulate the burner in its self is a big saver.

Although if high eff. boilers are anything like the computer market, they should get cheaper and more reliable as the years progress. I still think they have along way to go. Don't think you will see any boilers lasting 30 plus years anymore either. Not a good buisness model.

One thing for sure fuel prices will not be cheaper looking forward. This country has been spoiled for a long time with low fuel prices. Time to pay the piper, and get with the program.

JMHO Gordy

Simply Rad_2

High efficiency condensing boilers

Mark
If you are going with baseboards, towel warmers and other high temp. units, high efficecy condensing are not the answer. The biggest misconcection is the efficency. YES, they can run at 98% efficient but at operating temperatures around 90-100 supply. At, higher temps the efficiency goes way down. 86% at 150 degrees. Condensing boilers are ment to condensate, which is around 130 degree return temps.
Jeffrey

Mark Adams

J Brix

Yes, I did factor in service parts. Thanks,
Mark

Mark Adams

Floyd,

Great comments all. The 5% energy cost increase is really a total guess. Over the past 10 years, the increase has averaged 7% per year, but most of that came in the past 3 years (66% of the 10 year 100% increase). If you buy oil on the futures market, you can get a barrel for delivery in 2012 for $33 last I checked. The Saudi's claim oil should not be >$30. Then there is the China. A huge apetite, nearly zero environmental costs/controls and no real interest in efficiency. Go figure. We've placed HUGE demands on NG by converting power plants and building lots of new NG-electric generation. Only bright side is if oil gets consistently past about 60 bux a barrel, it will be worth drilling/pumping again in the the US. This would help stabilize the price I think. OK, enough rambling....

Thanks,
Mark

Mark Adams

jeff

I am in NY, the "other" peoples republic.....

Mark Adams

Simpy Rad

My present design is mostly BB. Out of 2000 SF, 300 SF is rad floor, one towel warmer in each a bath and a rad panel in the mudroom to dry off gloves, hats, etc. Balance is BB. This is very near Buffalo, NY. Need I say more? I had in mind possibly going with a Dunkirk Quantum and full ODR. This way it would be near condensing for maybe 3 month of the 6 month heating season. This would also heat up quickly to make DHW in the summer. O/W, it will be an 83%'er and partial ODR. But I am still looking into other options posted by ME and SE with constant circ, more rads, etc.

Thanks,
Mark

Floyd_9

Simply Rad....

I can prove you wrong on all accounts.....
I have a mod. condenser in my basement that will condense well above 130* water temp. and I have CI baseboard in an unisulated 1920's something brick icebox that rarely runs return water temps. above 150. even at the 150 return water temps. I have a slow drip... go figure. I don't know all the reasons just the proof in the puddin'......
Also at 165* supply and 150* return temps. I get combustion eff. around 93%. The rough numbers that I get for overall eff. are not much different. Overall gas bills have also proven my findings.
Add to that the overall comfort of my "icebox" and I'll take the mod. condenser anyday.
You see I was the worst skeptic... sat right by Dan a few years back and made some comments to the WM people without taking the time or effort to try something before I ran my mouth. I later reconsidered and figured that I would take them up on their offer to try the boiler and get a refund for it being in my own house......

I never bothered to try to get the refund.......I have never had a better heat system.

You will have to try it for yourself with an open mind, before you'll ever sell one to anyone else......you can only sell what you belive in yourself.

Floyd

joel_19

ummm

Well I'm wondering if you where just calculating those numbers using efficency alone? I mean a big part of it is the modulation factor. how can you calculate that though? here's some food for thought. I just last week got a call the second one in a month actually from another happy Vitodens client. seems the gas company wanted to change his meter cause they think it's going to slow .Pretty common lately the interesting part is he had a boiler that was an 87% "revolution" back in 88 or 90'when he bought it. He states he's not surprised because his therms dropped dramatically . That shouldn't have happened if you just consider boiler eff especially since this IS a baseboard system. Modulating water temperature and boiler firing rate has abigger effect than AFUE ,take it from someone who's been studyin this stuff since I was a teenager AFUE means almost didly.

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S Ebels

Mark

The AFUE thing really doesn't tell the true story. To put it simply, the testing procedure doesn't reflect the efficiency gained by a modulating condenser. It does however, seem to accentuate the CI type boilers.

All I can say is there is a lot more to heating efficiency than what meets the eye when looking solely at AFUE. I have to say that most of my customers that have gone from 80% boilers and/or furnaces to 90% types have experienced way more than a 10% decrease in their fuel bill. In many cases I have seen documented proof that they have been running 20 to 30% based on actual fuel bills.

What exactly causes variance between projected usage and actual, based on AFUE, is beyond my meager knowledge and ability to explain. My gut tells me that matching the load exactly has a lot to do with it. Another closely related factor is that on/off cycling of a burner is vastly underestimated as a source of inefficiency. It is REALLY COOL to be working in a house and hear a Vitodens (barely) throttle up and down as the load changes. When I hear that going on and mentally compare it to a burner cycling on/off, I have no trouble "seeing" that the modulator is going to pick up efficiency whether it's condensing or not. Viessmann realized the twin problem of burner cycling and inability of a standard CI boiler to directly handle low temps years ago. That's why they developed the Vitola series of boilers before the condensing technology "came of age". It's bi-ferral HX and high water capacity allowed unlimited return temps and helped eliminate short burner cycles. It remains one of the most efficient "traditional" boilers to this day.

I can use my own home as an example. It was heated by a 150K Smith cast iron boiler when we moved in. Being the headcase that I am when it comes to heating appliances I replaced it with a Vitola fired at 144. Long story short.....With an AFUE rating difference of only 2%, my therms have consistently been in the neighborhood of 15% less month to month and year to year. Where does that extra 13% come from? I don't know. The only concrete change to the system control was the outdoor reset on the Vitoronic. All the other parameters are the same.

As far as OD reset goes...... Unless you have a boiler like the Vitola, or a condenser that will directly take low return temps, installing it is a waste of money for anything but the improvement in comfort. Your efficiency gains will take a long time to come back $$wise. (JMHO)some may disagree but that's been my experience. Both Viessmann and Buderus have long been proponents of getting the temp as low as possible even in their standard iron pieces.

I'm beginning to ramble and it's past bedtime............ Hope this helps and we can continue later.

Simply Rad_2

Condensation

Floyd
I have a Munchkin boiler in my own house. I have the ultrafin system on the main level. The reset curve is 140-180. Then I have inslab radiant on the lower level with reset 75-110 degrees. On the average the systems runs around 150-160 degrees. Now the combustion effiency of the boiler is calcualted by my Analyzer. At, 150 degrees it mesures the flue gas gas of about 160 and has a 86% efficiency while at 95 degrees the efficiency measures 97.5% with 100 degree flue gas. Just checked the boiler is runing at 162 degrees and there is maybe a drop of condesate. A drop is one thing, I like when its a constant trickle.

Now when you are talking modualating you are talking a whole new subject-system efficiency. Its hard to measure this efficiency. But, I do believe they add alot to the boilers efficiency. Then you must start to talk about constant circ. along with modualation now what is the efficiency?
This is my personal experience with my own condensating boiler with high temp heat emitters.
Jeffrey

bob_44

Key sentence

Will these newer boilers hold up? Lets see hmm about 2 to 3 hours per year to remove mouse feces and re-adjust burner @ what, $90 or $100 bucks an hour times 20 years? Maybe a new micro-processor 10 years down the road, that ought to be cheap? I've always been a gear head and a sucker for the latest hi tech stuff but when advising my customers I put reliability first. Ive been through the hydropulse,glowcore,palomapak,polybutalene years and when a product has been out for 20 years I might consider it. Then again if you can afford a Ferrari what the heck.

jerry scharf_3

my view on energy costs

Mark,

I believe you have made some fundamentally incorrect assumptions about eenrgy costs.

If you look at inflation adjusted cost of oil since 1970, we are now at/below that level. I am surprised how fast it happened, but I have seen this coming for the last several years. My chance converations with people in the field all agreed with the expectation for dramatic increases. Oil prices for much of the 1990s was at/under $20/bbl.

There was the assumption for the last 20 years that OPEC created a shortage but we could pump all the oil we ever wanted in any year. The shock was that for various reasons, OPEC actually is running at/below worldwide demand rates pumping full out.

The response to this price hike has not been to look toward conservation, but to complain and accept the higher costs. This means that the "energy hog" status we have does not appear to be ready to change. I don't see SUVs being on firesale or people talking about not using their A/C.

Our trade deficit is funding China and other countries to increase their demand for oil to an extent that it competes with us.

Do any of these situations show short term dramatic changes? Even with changes, how many years does it take to have measurable inpact on oil demand?

There are bumpy times ahead, and don't expect energy costs to stabilize any time soom. There are reasons to believe that the US may be hurt more by world energy issues than others, and it's of our own making. I'm not saying the sky is falling, but there are things that can't go on indefinitely and need to shake out.

jerry

LEAD PIPE

$$$

All I can say is that when I switched to the ultra I used 30 to 40% less fuel, depending on the month. Switching was one of the best things I have ever done!

steve gates

Why not do it for the greater good?

Mike T., Swampeast MO

I replaced my 1970s Weil-McLain CGM series (AFUE sticker long gone if it was ever there but likely about 82) with a Vitodens (AFUE 94.2).

Old boiler already used outdoor reset, TRVs on all of the radiators, constant circulation and warm weather shutdown.

Despite all of the existing "goodies" (all of which are claimed to give fuel savings), fuel consumption dropped by an absolute minimum of 38%. After some tweaking of the controls to optimize operation in shoulder seasons, reduction increased to 43.7%. That's just a touch over 12 points of difference in AFUE but MUCH greater fuel reduction in operation.

Condensing ability seems to combine with modulation to give fuel reductions that just can't be directly compared via AFUE.

p.s. Think long and hard about a hydronic towel warmer unless you're in a climate where heating is used almost continually. If not, it can be really tough to operate them properly and efficiently. Consider the oil-filled electric models. MUCH, MUCH easier to install and when loaded with towels, they really don't consume much energy.

Unknown

I strongly disagree with your OD reset comment. You can put outdoor reset on an existing boiler for what, $300 plus some wiring labor? We've seen baseboard systems increase efficiency 20% with *only* outdoor reset added to them.

Not a real long payback period there, no matter how small your load.

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jerry scharf_3

analyzer efficiency is suspect IMO

I have seen numbers off analyzers that don't match real world measurements. I believe ME has some specific numbers on this. System efficiency is what counts. Break out your gas bills and compute therms per degree day before and after. Then you get to see what it is costing you.

jerry

jerry scharf_3

need you say more?

Mark,

First, some people are talking about baseboards with thermostats and you are talking about panel rads with TRVs. These are very different animals. All heating systems are nonlinear for the BTU ouput degree increase in supply water. Baseboard is the steapest, which says you need to run them hotter in the shoulder seasons.

Second, this is a new design, you get to set the design temperatures based on the insulation and panel size. If you increase the panel size a bit, you lower the design temperature and increase the time the system will be in condensing.

Third, with TRVs, the flow slows as the load reduces, which lowers the return temperature. This again increases the total condensing capability of the system. Other than location, you have a system close to what Mike T has. If you increase the size of the rads a bit, you will have very close to the same system he has, and his numbers should be a very good estimator of what you need. If you have followed the site or look in the archives, you will see the care with which Mike collects his statistics, he sweats the details to make sure the numbers represent something real.

As others have said, it's often easier, cheaper and happier to run electric for the towel warmers.

As for equipment lifetime, I think it's time to break out the crystal ball. How long will the new gear last? How long will the new old style gear last? For lack of anything better to work from, your 2:3 ratio seems like a reasonable wild guess. Nethier will be as long as you want, and none will last as long as a maintained 30 year old system did/would. No boiler today is build with that much metal.

jerry

S Ebels

Just speaking from my own.....

Experience with standard iron boilers. Few of the customers I have spoken with have noticed a reduction in their fuel bills as a result of adding OD reset. These boilers would be your garden variety W/M's, Burnhams, Slant Fins et al. In all of the installatinos I am refering to, the boielrs are protected from condensation by either a mix valve or a bypass setup. The boiler temp is kept above the condensation point of the fuel being used. Typically 130 for oil and 140 for gas. The control is but one part of the cost, the other part being the associated piping and labor to install. I should have clarified that my reference was to retrofit situations.

That being said; I'll repeat that few have experienced any substantial amount of savings. They all however are unanimous in their comments regarding comfort levels in the house. This increase in comfort can allow a lower stat setting which in turn translates into reduced fuel costs. I guess I'm splitting hairs here but to me it's the comfort level that is generating the energy savings which then become a secondary result of the OD reset. To say that OD reset itself saves money is a bit misleading unless you are coupling it to a low temp capable boiler. When you are firing into 90-110 degree water, you can actually measure the increase in combustion efficiency vs the same appliance firing into 150-170. Try it some time.

I'll be the first to admit that this is a topic which is worthy of much greater discussion than I have just given it but I'm just in the office for lunch and I have to leave now. What are your thoughts and experiences Bob? I've probabaly been doing it wrong or something.

Unknown

well your experience is most likely more detailed than mine (we don't do a whole lot of retrofit overhauls like this). We generally use Tekmars with boiler protection features as well (standard primary-secondary piping type stuff, dedicated boiler pump, zone cut-off for boiler protection), and find that they often can fire that boiler right down to 140 or so. I can't speak for a wide range of circumstances there, however one client which did just put in an Tekmar outdoor reset controller did see that 20% drop; whether it's a result of lower thermostat settings or lower stack temperature or what, I couldn't tell you, but to me the end result is enough either way.

I have to admit I don't understand why mileage would vary as it apparenly is, and you're right this could probably be a very long discussion indeed.

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