efficiency reality

CC.Rob_13

I'm totally on board with this. Great question.

I just did a "heat budget" for my house based on measurements of boiler runtime, outdoor temperature, supply temperature, radiation output at varying water temperatures, heat loss, etc. I can close it to within 2000-4000 BTU/hr. In other words, I can take the gas input, the boiler output, and other parameters to come up with how much heat goes in, and how much comes out, within 2000-4000 BTU/hr. That's about 10-20% of the total heat input depending on the outdoor temperature. (Unresolved losses/inefficiencies, uncertainties in data collected, etc. are probably the difference.)

The system is a 88% AFUE cast-iron boiler with p/s and VSI, running nearly full (80-140F) reset using a tekmar control.

I'm missing out on about 5-10% efficiency because the system isn't condensing. It's reliable, and will be around for the long term.

Hmm....

Darrell_7

Real world efficiency...long term

For kicks and grins, and because I really want to know what you think, compare these two scenarios.

Scenario #1. Nameless High Efficiency Mod/Con boiler with 5:1 turndown ratio feeding btu's into a moderately sized house through a properly sized and controlled piping and delivery scheme. We can assume 95% maximum combustion efficiency in full condensing mode, and lots less than that at 100% of load. Higher out of the box component cost, higher maintenance cost, shorter maintenance cycle, shorter life cycle. Less emmissions. Federal or State progams and grants for the install/upgrade. Parts are expensive and hard to get on demand. it takees a fortune to stock a truck, forcing specialization to a few brands.

Scenario #2. Two, (or more), sealed combustion Cast iron boilers sized at 50% of load, (effectively a 2:1 turn down ratio?), properly controlled with off-board tekmar or similar controls, feeding btu's into a primary/secondary piping scheme and properly designed delivery system. We can assume at lest 85% combustion efficiency whether at 50% or 100% of load. Lower out of the box component cost, (two can be placed for marginally more than the single mod/con), longevity of cast iron, simplicity of controls, availablity of parts, longer equipment life, lower maintenance costs, the safety margin of redundantcy.

Which is really the more efficient when we consider more parameters than simply the combustion efficiency? Manufacturing replacements has to count for something. What is the real-life reduction of "green house gases" between the two scenarios? The cash economics, post install, are pretty obviously on the side of simple and sturdy. What is the projected economics when amortized over the expected life span of the two scenarios? If the full meal deal, mod/con, 96% plus is such a good deal, why do we have to mandate it through the various inspection, upgade grant schemes, mortgage points, available today?

This area is putting in the very high efficiency boilers like crazy through a program financed through the State and pushed by local inspectors and home efficiency wizards. Are we gonna be sorry in five years that we ripped out perfectly good 80% CI boilers?

I'm not interested in getting crucified for asking the questions that need to be asked...I am very interested in your opinion and factual information.

k_2

re

If you have a normal well insulated house, you cannot get a small enough CI boiler to achieve that 2:1 ratio. Especially with oil.

Also one has to argue the 'perfectly good' part.

My father replaced a ~35 yo CI gas boiler and separate HW with a Buderus mod con, figures about 30 percent less gas[calc, not WAG]. Now he would have saved no matter, and at least the water heater had to go, so given that labor is the big expense, and a change is going to be made, does it not make sense to get the best efficiency, given uncertainty on fuel prices?

Perry_5

Lets add some reality to your scenerio

The 5:1 turn down system only effectively works at 3:1 turn down after 6 months.

The basic facts are.... that while 3:1 turndown is relatively easy to do, 4:1 is a stretch (but can be done); and anything higher than that cannot be effectively done with any kind of efficiency unless you start adding separately valved in combustion air supplies and perhaps multiple burners.

Lots of people have tried, lots of stuff has hit the market; but I'm not aware of anything that effectively does it long term without a multiple burner or air control system. Even at the power plant stage - with multiple burners and all kinds of control over air and combustion gas flow - 5:1 turn down is all that is normally achievable although some of the newest plants can do a 6:1.

It has everything to do with the fixed size of the boiler and burners for maximum capacity.

------------------

2 smaller boilers can in fact be more efficient than a single boiler. Many industrial plants with variable steam loads actually install a series of smaller boilers so they can keep the overall system efficiency high (and have great reliability).

I also agree with your concept on installation/repair and reliability in general. Your question is very similar to the question I presented in the "practical Mod/con" thread. Just from a different angle.


Perry

Darrell_7

Does it make sense is the question. 35 year old CI boiler would have been in the 70% combustion efficiency range...the stand alone water heater much less. In fact the water heater was probably the bulk of the heating bill and simply replacing it with an indirect waterheater and keeping the old boiler would have lowered the fuel bill by a third in most cases in my experience and he'd be making money in a year and still have a very reliable, sturdy and simple boiler.

I agree, the change up for the boiler makes sense while you're doing the project...but change up to what? Maybe changing up to a new 85% CI boiler makes more sense economically if the higher efficiency is actually going to cost more to operate.

What would be the real world difference to the environment between the two choices?

Brad White_203

\"The 5:1 turn down system only effectively works at 3:1\"

"The 5:1 turn down system only effectively works at 3:1 turn down after 6 months."

OK, I'll bite. Where does one get this and how is it backed up?

If you have a 100 MBH heat loss you certainly will have a 20 MBH heat loss at some time. If the boiler is properly sized, are you saying that my low level turn-down somehow rises to 33 MBH by some fluke of system decay?

I specify all sorts of commercial condensing boilers and while the norm (or rather, lowest denominator) is 3:1, there are those that can and do 20:1.

A agree though, as a practical matter, with multiple boilers in battery, the number times turndown ratio, even if 3:1, is plenty, especially when one has a 10-20 million BTUH input plant spread over five to ten boilers.

1bourbon

the difference?

What would be the difference? Big question, and the answer, naturally, is that it depends.

Assume a stainless or aluminum modcon. Are the components made of recycled material or virgin (i.e., mined and processed -- ever seen a bauxite mine up close? Most of the big ones are in Australia, and the stuff gets shipped all over the world).

Same with the CI boiler. Recycled CI, or virgin? Which of these has less environmental impact? Which has lower total environmental cost of maintenance, including what it takes the service tech to drive there, service and depart on whatever maintenance schedule is required? Think about the potential savings and reduced carbon footprint if you only really needed to service a CI boiler every other year and could do it with limited expendables.

If you really want to go nuts, figure out which requires more specialized tools, which themselves need to be fabricated, shipped, etc., in typically lower quantities than more common tools.

Slightly less nutty but probably no less important is what kind of chemicals you need to maintain the modcon system so it doesn't die a premature death. All this business about water-side chemistry is not trivial. Not singling out a specific company, but all that Rhomar and other stuff has an environmental cost, too. From production to delivery, to installation to disposal.

Controls. Say the modcon has an internal proprietary control and the CI has an external (but no less 'proprietary') tekmar. Which has the more environmentally friendly production process, has lower MTBF (mean time between failures), etc.

And of course there's probably a lot more to it not covered here.

But one very important issue is the ultimately declining availability of the fossil fuels and non-renewables needed to make and maintain all this stuff. Consider a limiting example: you have run out of 'stuff' and are running out of fuel. With what you have left, you can build a modcon with controls or a set of solar panels with controls. Which do you choose?

bob_46

Senario

Youse guys are forgeting the government. If you happen to live in Pitkin county CO you have to install 90+ by code. Do you think the local planning and zoning is going to work through a sensible analysis like Darrell? As with most things the last 10% of perfection costs big bucks. Why are we so concerned with such a small incremental increase in home heating and yet ignore electric generation and the auto which are both less than 50%. Our government thinks that if you plug a car into the grid it's 100%. Yeah, you never have to put gas in it. Thermodynamics be damned. bob

Unknown

Plug your car in

You gotta love that. If the Gobermint only could read the statistics that our power plants get electric to your house plug at about a 35% efficiency. Go Green. What a salesjob.

Darrell_7

Again with the question...and trying to stay on topic...

What is the real economic difference between a properly sized, installed and maintained 85% Cast Iron Boiler and a properly sized, installed and maintained 96% Mod/Con Boiler amortized over ten years? Twenty years?


What is the real environmental difference between a properly sized, installed and maintained 85% Cast Iron Boiler and a properly sized, installed and maintained 96% Mod/Con Boiler amortized over ten years? Twenty years?

I really want to be educated on this topic so I can in turn educate my customers and influence their thinking properly. I'm not being impertinent. To date I am being asked to believe that the yellow sticker on the side of the boiler trumps all other data...and I'm just not sure it is that simple.

Perry_5

Brad: the problem with high turndown equipment is...

The problem with high turn down ratios with fixed size air supply and exhaust piping is that you cannot do it efficiently - and I am not aware of anyone who has figured out how to do it reliably even if you are willing to sacrifice the efficiency.

So yes, you can put a variable gas valve and a variable speed fan - and yes some burner designs will handle a large turn down ratio without failing. But efficiency goes out the window at the lower firing levels (a small fire in a large volume is not efficient).

Now if you can have multiple air supply ducts - and valve them off and on, and a few other neat tricks - you can improve on the efficiency. But reliability of all that extra stuff sneaks in.

Many companies have developed and marketed high turn down equipment over the last 30 years. It usually doesn't last long. Even at the central baseload power plant level - where we can spend tens to hundreds of millions of dollars on such a concept... we have not yet figured out how to make it work effectively. The key is that regardless of how small we put in burners - a small fire in a large boiler is inherently inefficient; and the cost of the inefficiency is too large for us.

That is why you see ganged boilers. Far more efficient - and the improved efficiency pays for the added cost of installing, operating, and maintaining multiple smaller boilers.

Also, the reason I stated that 5:1 turndown equipment becomes 3:1 is because when parts start wearing that is what happens. Burners and gas valves typically maintain their higher capacity and loose the ability to run at the lower firing rates. So you can keep the boiler as it ages. Just not the turndown ratio.

Perry

CC.Rob_13

run some numbers

A place to start....

Assume the modcon costs $x more than the CI for the boiler itself. Because the CI boiler will have p/s and ODR, assume the install labor and additional material cost is the same.

Assume the modcon requires annual maintenance. Y dollars, including full teardown, cleaning, combustion test, waterside chemistry test and adjustment.

Assume the CI boiler requires maintenance every other year. Z dollars, including full teardown, cleaning, combustion test.

Assume the same fuel costs. Now figure out the building heat loss. Assume both boilers will provide the same BTU/hr per year to replace the lost heat. Figure out how much time during the year (e.g., in hours) the modcon will condense and achieve its 10% more efficiency. Reduce fuel use by that amount.

Make some assumptions about major part replacement and costs over the 20 years.

Add it all up.

1bourbon

numbers to play with

Against my better judgment, here are some numbers. I'm about to leave for two days so can't defend these numbers, which are not based on professional experience because I'm not in the industry and therefore might be wildly wrong.

The fixed costs should be self-explanatory. The annual maintenance assumes the MC gets annual service, and the CI gets service every other year (thus half of an annual price).

The fuel costs and maintenance costs are assumed to go up 5% per year. The both boilers are assumed to last 20 years, and there are no, or at least equal, "catastrophic" parts replacement costs (e.g., over 20 years they might each lose a control board, the cost of which is not included here).

Assumed a building design heat loss of 33k BTU/hr. Used 33k for Dec/Jan/Feb. Assumed heat loss of 16.5k BTU/hr for Sep/Oct/Nov and Mar/Apr/May.

Assumed that the MC would not condense for 25% of the heating season, and that during non-condensing periods the efficiency was 85%.

The 20 year total cost of ownership is shown at the bottom. Looks like a wash. Of course, the assumptions above must hold, and there are a LOT of them.

I understand and respect the "don't talk prices here" dictum for this site. These are not prices. This is a totally theoretical -- and possibly quite incomplete or incorrect -- exercise. A point of discussion, nothing more.

mark ransley

Energy prices will continue to rise as supplies drop and demand grows. The price of energy you base a payback on today will grow reducing payback. Of course we could have a depression, or oil could be 300$ next week if Irans reactors are bombed and Iran blockades the straights.I hate paying the utility co so I opt to upgrade. But as you say its not simple.

k_2

re

One question that comes to mind is where the savings in the mod con come from. The modulating or the condensing? Would seem that you gain less than 10 percent from the condensing section, and then only when condensing.

Would seem to point to a modulating CI boiler...........

Perry_5

Would work as long as

The key is to maintain the combustion gas temperatuer above the condensing point.

You can in fact modulate any Iron or Steel boiler up to a point on this.

If you can vary the flow through the boiler you gain a lot more margin. So a system with a variable speed pump - tied to the combustion rate would be perfect.

On larger industrial systems this is common.

Given the state of electronic controls and the availability of variable speed pumps I am not sure why this has not started to enter the general home market. I know it would not work on all systems.

I do note that the Vitodens 200 actually has this feature - even though it is a mod/con boiler.


Perry

Darrell_7

On the basic residential cast iron boiler that would require sealed combustion and forced induction with a negative regualtor gas valve...very common items...pricer than forced draft and positive regulator gas valves but not prohibitively and fairly reliable. This proposed boiler would have to be piped primary/secondary or ito a tempering tank in order to limit the boiler limiting and keep it in its modulation range without condensing. Also very doable with controls available today. The benefit of sturdy cast iron and fairly common, reliable and affordable controlling. Maybe a good compromise to overcome the expected ahort service life of a stainless boiler, but still more maintenance than a simple cast iron boiler. There are so many optons available for us today, and so many modifications that ought to be tried that it is difficult to make a definitive absolute statement like, "everybody ought to be putting ss/mod/con boilers 'cus they're the most efficient and best thing in the world."

Unknown

Modified Cold Start?

One thing I have tried recently with an old 80% cast iron water boiler is a modified cold start control system. To the basic cold start boiler, I have installed an additional reverse acting aquastat to allow a post purge of the hot water contained in the boiler until it reaches a preset low limit. So when the thermostat is satisfied, the gas valve closes, but the circulator continues to run until the residual heat is removed. I am presently using a low limit setting of 110F for the reverse aquastat, and it seems to be working out well. In addition there is the benefit of increased circulation time which provides better uniformity of temperatures without actually running constant circulation.

With a high mass system ( cast iron boiler and rads) this system operates similarly to an ODR system. Run time and resultant water temperature is dependent on heat loss so the system always provides the minimum water temp necessary to meet requirements.

From what I have been reading here, this type of operation seems similar to that of the System 2000 which does a post purge of the heat in the boiler? In any case, it seems like a simple and inexpensive modification to increase the efficiency and comfort of an existing cast iron boiler

Unknown

How nit picky.

How nit picky do you need to be.

Do we go down to the level of the manufactures employee's energy use at home to factor in the impact.

Well company A has green employee's and company B uses coal to heat their homes.

OMG.

Darrell_7

On the "green side"

We are being told that we need to convert to supposed "greener" equipment with all haste in order to be more efficient and "save the planet from certain destruction." It would appear that, possibly, the newer equipment that gets the "greener blessing" is not all that green when we look at more than the yellow label.

On the "money side"

We are being told that to rip out and install higher efficiency heating equipment will return money to our pockets...some claims are more "robust" than others. When we look at more than the yellow label it becomes apparent that the monetary return is not so great as one might be told...if at all. In fact, considering the apparent shorter service life of the Ultra-High Efficiency equipment, it may cost considerably more to put in higher efficient equipment.

Yes, we can go to extremes looking for monsters under the bed...but, some of those monsters need to be exposed.

It is possible that when a customer asks us professionals to increase their efficiency and economics, that a more reasoned approach to the situation is in order...but, that requires honest information, anecdotal information and homework on our part. All of those are available here on the Wall...which is why I started the thread.

I'm afraid we'll wind up with egg on our face in five to ten years by jumping too quickly to R+R equipment.

Unknown

scale of economy

On the other hand if the market were 95% Ultra-High Efficiency equipment the cast iron would cost more.

I think that in the long run the Ultra-High Efficiency equipment will prevail.

The cost of fuel savings is compounded like a 401K. It is hard to figure the real cost in the long run.

High efficency equipment will cut down fuel usage and will have an effect on the overall price of fuel if enough are installed. More efficent pumps will cut back on electic use wich will lower use and have an effect on power cost and generation. Will one pump or one boiler make the difference? Not one, but all the one's will add up to millions. That will.

Going Green is another issue.

Darrell_7

Yes, the scale of economy as regarding combustion efficiency, multiplied over many systems can be significant.

But, the same scale, considered in reverse is what I'm investigating here. The higher cost of operating/replacing/maintaining the Ultra-High Efficiency equipment while perhaps only incremantal, when multiplied over years or many systems is significant...maybe.

"Green equipment" does not necessarily equate to "green ecology" or "green wallet syndrome".

Paul Cooke

Geat Discussion

Thanks for starting this thread, Darrell.

Although hot water heat is my choice for almost any structure, I think that somewhere in the not so near future we will only be designing superinsulated buildings with heat pumps and HRV"s.

It will probably be unnecessary to use boilers, either CI or mod con. It will be a sad day indeed.

I also think we will likely replace doors and windows on existing homes, peel off siding, re-insulate, add exterior foam insulation, and reside. Adding additional attic and floor insulation is next.

All this is already happening here where I live to many of the homes I have worked on. Lots of young "green" builders doing their thing.

Paul Cooke

Geat Discussion

Thanks for starting this thread, Darrell.

Although hot water heat is my choice for almost any structure, I think that somewhere in the not so near future we will only be designing superinsulated buildings with heat pumps and HRV"s.

It will probably be unnecessary to use boilers, either CI or mod con. It will be a sad day indeed.

I also think we will likely replace doors and windows on existing homes, peel off siding, re-insulate, add exterior foam insulation, and reside. Adding additional attic and floor insulation is next.

All this is already happening here where I live to many of the homes I have worked on. Lots of young "green" builders doing their thing.

Darrell_7

I disagree. There will be a huge market in the existing homes for maintenance and upgrades that this discussion directly addresses. How many of the men on this Wall maintain homes and systems approaching 100 years old? At some point super efficient has to cross swords with practical and affordable whether we want to admit it or not.

There are huge areas of this country where the "alternative" heat sources just are not effective let alone cost effective. The same discussion needs to happen in that venue...just what return do we get for our buck? Or do we get a return at all?

I do agree...there are many, many contractors cashing checks for doing "green upgrades" that perhaps don't make any real difference other than reallocation of funding. You can't simply tighten up a home and walk away...there are ventilation issues, operation issues, maintenance issues, that were never a problem with simpler systems. These all come with a cost...and often with unintended consquences like mold, carbon monoxide, sick-house syndrome, allergies and the results of poor or no maintenance.

Unknown

considered.

I see your point. But the ecomomy of scale will change over the years. Yes the blower for a Mod/Con might cost $300+ dollars today but in the future due to higher production volumes they might only cost $100. We tend to make assumptions on todays variables and they might not always be correct.

What was said about power vented boilers years ago? Cost of inducers. Cost of boiler. Computer controls. Same thing today with Ultra-High Efficiency equipment.

This is the most exciting time to be in the heating industry. There is so much flux and so many new inovations coming our way so fast that we are struggling to comprehend all the implications.

In 10 to 15 years the replacement for the Ultra-High Efficiency equipment of today will most likely be of something completely different. Might not be gas electric or oil. What we learn from today will help us progress into tomorrow.

I find that when I compare the cost of replacing a cast iron boiler for my customers it is almost a wash.

Mod/Con boiler cost more. Venting cost less(PVC vs SS or Chimney liner). Low water cut-off needed for CI, Mod/Con included in controls. Outdoor reset cost for cast iron, included in Mod/Con. Circulator for mod/con cost more or need more(price will drop as the bigger circulators are stocked and sold in volume). Boiler protection needed for CI(Labor & Materials), not for Mod/con. Need helper to bust up old CI and drag out of basement. Less effort to bring boiler to job w/ mod/con. Now add in rebate and tax credit fuel saving. Price of install is not that far apart.

Unknown

Customers.

No offense to customers intended:
When you start trying to educate most customers about efficiency, modulation, condensing equipment, outdoor reset, their eyes glaze over and they hear blah, blah, blah, blah, $9,000.00 blah, blah, blah, $8000.00 blah, blah.

Not all. I just give them quote A, B, C, D. Here is the AFUE (another discussion) and expected energy savings for each. These are the rebates for each. Here is the warranty information for each. If you have any other questions please call.

That is why as an industry we need to have these discussions. So that we as the installers and sellers can understand the implications and recomend the best course. It is ultimatly up to the consumer to decide. We can only give him the options.

Having done this many times I still have not put a cast iron boiler in for a hot water application since 2000.

How? Just with the basics and good service.

TimS

I have a different point of view.

I don,t sell based on efficiency . Too many variables . I do sell comfort ,reliabilty , better installs for residential the pay back from efficiency is several years at best factor in any service any money saved from efficiency is a mere bonus really not much of a selling point that fancy mod/con is really eye candy.
On commercial the efficiency pay back can be rather quick in just a couple years but still sell first comfort , best install and reliability.
Also you can sell better warranty like 5yr parts and labor.
Do more service work you get to learn from everyone else's mistakes and improve your own installs.
The customers who want comfort are buying exactly that, for example an indirect water heater =comfort in unlimited hot water or a regular 40 gal nat draft big difference in cost.

jp_2

operating Reality

that 85% eff is steady state operation, you will see that around your 50% and 100% operation modes only.

what about the more typical 15-35% and 65-85% load operating modes where the boiler will be on and off where the mod/com will be running steady?

Darrell_7

I am talking about existing equipment refurbishment or replacement in this particular post...

Well...if we go really simple, as in natural drafted open burner natural gas, then the first start in a heating cycle is the least efficient until the core temperature comes up above the 140 mark or so. After that, properly adjusted limits will keep the burner cycling on and off in a fairly efficient parameter. In a simple boiler there is no waiting for control lag, blowers, prepurge, post purge, and etc. The t-stat calls for heat and it gets delivered shortly. If this type of boiler is piped primary/secondary or into a tempering tank then the limit cycle can be lengthened out effectively increasing the efficiency of the unit and system. Yes, there is stack loss, which most manufactures have addressed, with frustrating results, with motorized draft dampers. Several options are available to the efficiency conscious contractor such as ODR, (admittedly limited parameters), burner cycle limiting, (Beckett heatmanager), two stage gas valves, control schemes like constant or extended circulation, modulated circulation with variable speed circs, etc. all of which can readily be applied to existing systems with realizable savings and, in fact, can be planned for staged upgrades over time and budget realities. Notice that I did not include setback t-stats...they don't save any money...they are a convienience to automatically adjust temperature without user interface. I take them out by the bucket full.

The next step up is going to have direct venting which, in most cases will require either forced draft or forced induction, which introduces control lag for blowers, pre-purge, post purge and flame proving. Most manufactures are still using the standard 20 degree limit, which calls at 20 degrees below setpoint, (kinda), and then goes into the burner control sequence allowing the core temp to fall many more degrees before the burner actually starts to heat, especially with the more recent low capacity boilers. Again, properly sized primary/secondary piping or a tempering tank will lengthen the time that the boiler stays out of limits and effectively increase its efficiency. All of the above tricks can be applied to this type of boiler as well for way less than a total replacement with a mod/con boiler. They still have the stability of CI and relatively simple and available controls.

The next step up will be some form of mod/con or ultra-high efficiency gimmick(?) that introduces more control lag unless the burner can modulate down far enough to stay out of the limits. In order to take advantage of full modulation and condensing along with full outdoor reset the whole house generally has to be redone with whatever form of heat emitters that are called for sized to be able to effectively deliver sufficient heat at reduced temperatures. If the contractor simply replaces a less efficient boiler with a mod/con you'll have to be pretty quick to catch it spending much time condensing. Modulating is another story, and the boiler will spend much time at less than 100% assuming that the heat delivery emitters will work at reduced temperatures. Most of the systems that I have followed contractors on are for comfort calls...the install is good but the owner feels cold because the room IS cold while waiting for the brain to decide to increase the temperature of the system fluid, especially if the system has to pick up after a deep setback or recovering from a warm day that suddenly looses twenty or thirty degrees. The contractor didn't change anything but the boiler. The baseboard is still the same, probably dirty...there goes efficiency, the zones are still the same and are now at war with each other fighting over the btu's at lowest common denominator. The only fix then is to change the parameters of the brain and the boiler typically never goes into condensing after that and modualtes much less. So much for 96%.

Yes, the contractor could have spent time educating his customer...but, I guarantee that the average customer does not want to have a system that he has to understand, let alone know how to tweak from season to season...unless of course he is Perry! (Sorry, I couldn't resist! I enjoy Perry!).

I guess I'm thinking that it might be better money, both now and long term, economically and environmentally, to maybe change the control strategy, or add ODR, change the near boiler piping, clean the darn thing, (now there's an idea...I can raise the combustion efficiency of the avaerage simple boiler 5-10% simply by cleaning it and adjusting the gas valve), clean the baseboard or radiators, (the years of cat hair and dust directly effect the efficiency of any heat plant), or any number of way less expensive and equally as efficiency stimulating ideas rather than rip the thing out in favor of something very expensive and potentially temperamental that we may be bsck to replace in 5 years.

Unknown

I agree

What you say makes a lot of sense. I can't see ripping out a well functioning cast iron boiler just to replace it with a modcon without consideration of the system as a whole. If simple control system modifications and proper maintenance can achieve a significant increase in comfort and efficiency, then this option should be given careful consideration.

There are many solid, reliable, older systems out there which could be substantially improved by inexpensive control modifications. The customer should be informed of these possibilities as well as the option of total replacement

Darrell_7

With over eight years of field experience behind you, I'd like to know what boilers you are putting in and what service issues you regularly encounter. As a serviceman that would very useful information indeed.

Unknown

HTP

There was not much to choose from 8 years ago. I started using the Munchkin. I followed the directions to the letter. I set them up when installed. Had the blower issues. Had some outdoor sensor issues. I have one of the VWH water heaters installed as well.

I get great service from my local rep and supply house. Customers have been happy. Couple of them had the gas company change the meter shortly after install. Gas company thought the meter was broke.

I service a few of them every year. I call to see if other want to service as per mfg directions but most do not. They are the type to call when broke.

When you look at the market just about everyone is using the same blower, heat exchanger, gas valve. The box, price and controls differ.

I have never had a problem with warranty issues. The few blowers i had changed they took care of no problem. The few outdoor sensors no problem.

I like other mfg products but the price point is not there from my local supply houses. I am open to all mfg. All are good products. I do not like the AL heat exchangers but that is just me.

I used to use all Burnham CI boilers. I was hoping the Opus would be a hit but when i priced one for a job I dropped the phone. Glad I did now. No word on that line, it appears to never have taken off.

I was excited when Burnham came out with Mod/Con it was AL but i was willing to try it. Then i price one. Went with the Munchkin again. Got excited when they came out with SS Mod/Con. Then found out it was not wall hung. Priced it anyway, installed Munchkin.

Did the same for other Mfg. boilers and keep putting in Munchkin. It seems like other Mfg let HTP do the R&D.

When it comes down to it, I don't think there are any junk boilers out there. It comes down to the install and choosing the right equipment for the right job.

Lot of folks might not agree. They have the right. I keep my customers happy and that is all that matters to me.

Unknown

price grows

when the price of energy goes up the payback increases.

Darrell_7

Thankyou, I appreciate the beating you may get for your position! Not much Munchkin going on around here, but, as a serviceman I would agree that the install makes a great deal of difference to the overall performance of whatever brand boiler you install. And now that so many of them are using the same heat exchanger it kinda narrows down the field work.

I started this thread to try to get at some of the real world experriences out there...thankyou for participating.

joel_19

darrell

Your thinking hard about this but with some outmoded ideas. You talk about contractors tightening up houses and creating mold and IAQ issues. That is because they are doing it the wrong way. There is no reason a house can't be as tight as a refridgerator and have perfectly good IAQ IF done properly. That old fear left over from some bad stuff from the 70's scares people from making the upgrades they should. Imagine the fuel we could save if we simple reduced the typical houses energy use by 30% in N.E, with all our old housing stock this would be really easy to do. Even many new houses here are incredibly loose. This is not a WAG. I have a blower door and have tested many brand new super leaky houses.

Many leaky houses have WORSE IAQ than tight houses. Can't explain here it's really in depth.

Where we are i haven't done atmospheric gas in years. We require a lined chimney to do regular gas. Add that on top of standard boiler cost. Now take modcon and subtract the rebate your going to get. Now the difference is only a few thousand dollars,assuming that like us you are changeing all the near boiler piping either way.

This is a no brainer for any home owner. They pay THOUSANDS more for a certain car or upgraded car model that they keep for just a few years. I've never had anyone save less than 30% compared to their CI beasty and the emmisions is much much lower on the model I sell.

Going with your argument no one would ever by a hybrid car or BMW or Lexus etc. We'd all drive a small truck (cheap,crude,rearwhl drive, easy to fix,virtually indestructable,)

Also why would any house be bigger than 700sqft. Why are there any resteraunts more exspensive than Mcd's. Why does Rolex exsist?How come we don't all drink wine from a box?Who needs to spend thousands to fly someplace warm for vacation?Why did people ditch their perfectly good T.v's for big flat screens???Why does any one need an Ipod or Iphone when you can get a cell for 39 bucks? Better yet why does anyone need a cell at all?.We don't need any of those things yet we buy them every day.

Even with Modcons our industry is woefully outdated tech wise and backwards. What you really should be asking is how come the new mod con I'm putting in isn't Blue Tooth enabled and integrated with the solar system,the houses ventalation,IAQ system with all parameters instantly accsesable on the customers Iphone? Why can't their gas and electrical ussage be tracked in real time updated and displayed on any device (computer,phone,etc)of the customers choosing including emmisions reduction just like the dash board of their Prius does?

If a 22k car can do it then surely their $500-600k starter house should be able to shouldn't it? We shouldn't be trying to figure out ways to stretch the lifespan of old outdated outmoded equipment that has been the bane of HVAC for years.

Our boiler line will soon be able to communicate directly to our office from the customers house (for a monthly monitoring fee of course!) This technology can't come soon enough!!

k_2

re

Mcd's maybe, but wine from a BOX!!! NOOOOOOOOOOOOOOO!!!

k_2

re Perry

As far as the efficiency on turndown is concerned, as long as it is tuned at the high output end, does it matter?

If is 90 percent at 100k BTU it wastes 10k BTU

85 percent at 60k it wastes 9k

80 at 40 K it wastes 8k BTU

75 at 30 k it wastes 7.5k btu

If you could turn it down to 10kBTU[which would seem pointless] it would waste less than running at full bore even if it were 10 percent efficient....

Unknown

what line.

Is the communication package part of the boiler control or user installed?

Unknown

I've bee beat before.

I am used to it. I got beat for years using PEX. Now everyone in my area is switching. I have had a few ask for advice on the switch. What is my R&D worth?

I try to stay ahead of the curve. I do a lot of research and try to make a well educated decision on my choices. Some are good and some are bad. In 10yrs when the market is going to be Mod/Con I will be using something few have heard of.

Perry_5

It doesn't exactly work that way

Boiler efficiency is dependent on many things; and I probably cannot list them all of the top of my head. Suffice to say that shape of the boiler, volume of the firing box, burner design, surface area of the effective HX area, size of the air inlet ducting, and exhaust gas ducting are all factors. The boiler designers can play with these factors and shift how the efficiency curve will be shaped for a given boiler (and at what cost).

There is a design range where a mod/con is very efficient. For example it is not uncommon to see a mod/con efficiency curve that is perhaps 85% at 100% firing rate and high water temperatures (no longer in the condensing mode in the HX) and 95% at 33% firing rate. They actually get more efficient as the firing rate decreases.... to a point.

Non-condensing boilers typcically have a fairly dramatic efficiency drop off as the firing rate is reduced. They can design a boiler that minimizes that for a bit - but by the time you get to 50% firing on a single burner you are going to be in real efficiency trouble.

The key question is at what point does the efficiency of a boiler start dropping at a high rate of speed. It may be simpler to explain it from the perspective on how boiler efficiency starts from zero.

There actually is a point where the efficiency is 0% (heat in to usable heat transferred to the working fluid - water or steam). That is the point where the firing rate is so low that all combustion heat does is heat up the boiler itself to the point that it just radiates heat away into the room or up the stack. There is no effective heating taking place. Constant pilot lights are a typical example of this.

So - as the firing rate increases from near zero where there is zero boiler efficiency, the efficiency of the boiler increases through 25%, 50%, etc until it is in the design efficiency firing range.

The key point is that no matter the boiler... having too small of a flame in it is inherently inefficient.

Also, in order for a burner to handle the full firing rate - you also have just limited the minimum firing rate that it can actually work well at as you cannot efficiently support combustion in that burner at low fire rates.

The key way around this is to have multiple burners - or even multiple boilers (or boiler sections). Aerco advertises commercial sized boiler with up to 23:1 turndown ratio that operates at high efficiencies:

http://www.aerco.com/products/modulex.shtml

But look how they achieve it: They have essentially 150,000 modules - complete with their own burner handling section. The boiler with the 23:1 turndown has 7 sections (and is about a million BTH). That works out to each boiler section having a turndown of about 3.3:1. This is quite doable (4:1 is often considered the practical efficiency limit for a single burner).

I am often baffled on how no one in the commercial world has achieved high turndown ratios and high efficiencies without multiple burners - yet some home boiler companies claim they can do it.

I am working from memory here - and I don't recall which home boilers claim high turndown rates. However, several years ago I looked at the documentation on one of them and I do not recall seeing an efficiency curve for the boiler; just a AFUE claim.

I do note that Viessmann publishes the efficiency curves for the Vitodens 200 in its technical data manual (and even for different circulating water temperatures). The Vitodens 200 6-24 has a turndown ratio of about 3.7:1. Of course, they do not publish what happens below the minimum design firing rate.

I understand that the Vitodens 100 - with the same boiler HX but a cheaper simpler burner has a turndown ratio of about 3:1. More basic burner = less practical achievable turndown ratio.

If anyone can tell me which home boilers are claiming better than a 4:1 on one burner - I'll look at the tech data and see if there is an efficiency curve for the low firing rates (or any efficiency curve for the boiler published at all).

At some point - it is more economical to cycle the boiler on and off than to let it run inefficiently.

Hope that helps,

Perry