How Does Energy Kinetics not lose efficiency to short cycling?

95percent

I was checking out Energy Kinetics' website. They've got some really cool technology. But what I can't figure out is how they don't lose a ton of efficiency to short cycling. They claim the highest "real" efficiency, even a bit better than Viessmann and Buderus. With baseboard hot water and a low mass oil boiler, where's all that heat going to go? How do they not lose everything they gained with the low-mass design, outdoor air, insulated boiler, thermal post-purge, etc, etc, back to short cycling? Or cause premature burner wear and failure?

It seems like the perfect oil boiler if there is such a thing... if they configured it with an insulated buffer tank by default or had a modulating burner. Why aren't there modulating burners out there? Gas and pellet boilers do it, wouldn't oil get the same efficiency and comfort benefits?

On the flip side, if EK can avoid losses from short cycling, what is their secret? Why does everyone else care so much about boiler sizing and short cycling if the losses can be avoided?

EBEBRATT-Ed

Size the boiler correctly and do not oversize it. Most equipment is oversized, that's the problem. Have enough radiation, buffer tank etc to keep the boiler from short cycling.

Doubt you will ever see a modulating oil burner in that small a size. You can get low-high fire (two position) burners but they probably don't even start until probably 1,000,000 btu. Full modulation is seldom seen below 2,000,000.

contaminated oil, small nozzles and cost prevent modulation in in small sizes

bob eck

Energy Kinetics claims their oil boiler will save 40% on your oil bill.
They compair there boiler with storage tank (cold start boiler) to conventional cast iron oil boiler with a domestic coil in the boiler. This type of boiler is 180 degrees 24/7/365 just to make domestic hot water.
When you use a cast iron oil boiler with an indirect water heater what is the difference that a System 2000 boiler will save?
What about using an Trio or Buderus cast iron three pass horizontal oil boiler with indirect water heater. The Trio and Buderus oil boiler is also an cold start oil boiler and to get domestic hot water you need to add an indirect water heater.
Using an System 2000 or Trio or Buderus oil boiler with an indirect water heater will use less oil than any oil boiler with a domestic coil in it to make domestic hot water.
Size the oil boiler for the heating load of the home. Use outdoor reset controls. Remember the boiler is designed for the coldest days of the year and that might only be 10% - 20% of the heating season so about 80% of the heating season your boiler is oversized. The lower the water temp you use to run through your heating system the less oil you will use all heating season.

lchmb

Bob I can't speak for them (Energy Kinetics) but I will say, i've never had a complaint on their savings. Whether I replace a cold start low mass or warm run coil boiler I have always saved. That and the noise reduction...sorry I'll be adding one to my house soon. I'll leave it to better to explain the operation of the system 2. I understand it's operation and can work on them all day long but im not an engineer so cant get all smart language..;)

SuperTech

I can't speak for EK, but I will say I have heard some very high praise from the lucky homeowners that have their products. I can also attest to the fact that they are a pleasure to service compared to most other oil fired boilers. I've never seen one "short cycle".
Customer service is top notch too.

Speak with someone who has one. EK boilers are great.

EBEBRATT-Ed

We will see about this Babington burner

Anyone else here old enough to remember "BLUE RAY" boilers and furnaces?? Back in the 70s Used a modified Carlin burner to burn with a blue flame.

It was going to be the greatest burner, boiler and furnace ever made.

Worked great.................................................in a lab

Didn't work in the field, they all got replaced. They even came out with a "yellow flame" kit to convert it back to a standard burner

And it was tested and tested and tested by Brookhaven Labs.

Time will tell

I can wait

SuperTech

Haha! I've heard the nightmare stories about those!
I've seen quite a few EK boilers almost as old as I am, and I'm pushing 40. Still chooching. That's good enough for me to believe that they are stout. It looks like the advancement in manager technology has only gotten better since the days of the "classic manager".

AnthraciteEnergetics

40% is a huge claim and needs real hard data and test protocols to back it up.

Heat only has 4 places to go:

Into the system
Into the boiler room (jacket loss)
Heating combustion air
Up the flue/vent

Short cycles lose energy if there is a purge cycle, where cold combustion air blows through the boiler and carries heat out the vent before/after each firing.

Atmospheric gas burners use a lot of excess air, meaning more combustion air and vent loss.

Thermal mass of the boiler is inconsequential unless it has little insulation or is being used for DHW in summer. Buffer tanks add mass and more heat loss to the boiler room, but can be better insulated than a boiler.

Boiler touting low standby jacket loss is meaningless in an uninhabited basement with a 5 zone brass orchestra of uninsulated pipes like I often see hooked to EK boilers.

Roger

Thank you for your question, 95percent and comments from all.

The Department of Energy’s Brookhaven National Laboratory did a very comprehensive study on heat and hot water boiler efficiency which shows annual performance is primarily determined by two factors, steady-state thermal or peak efficiency (very similar to AFUE), and idle loss (energy wasted when the boiler is off). The results show the substantial savings Energy Kinetics low mass boiler with thermal purge achieves over all other boilers in the study including tankless coil boilers, boilers with indirect tanks, and even modulating condensing gas boilers. The savings are even greater with our 90+ Resolute boiler and the Accel CS which were introduced after the study was published. A link to the results and the actual report can be found in the footnotes here:
http://energykinetics.com/afue/

In summary, because of the integrated design of the well insulated low mass boiler, hot water tank, and integrated thermal purge control, our boilers run at near steady-state efficiency from very small loads through full output loads - this is really the key to achieving the best efficiency. Basically, our boilers run efficiently for all loads; High mass boilers in general, poorly insulated boilers, and boilers that maintain temperature, and boilers that finish hot simply don’t do this nearly as well.

Thermal purge means the boiler starts cold, and more importantly, finishes cold. This means that the energy that went into heating the boiler and the piping when the thermostat was calling is transferred into the conditioned space after the burner shuts off; it is not wasted in the boiler room or up the chimney during the off cycle. (For clarification, this is not a burner post purge which forces air through the boiler and wastes energy.). Since the burner will only fire with an active thermostat call, the boiler will not maintain temperature in an idle state. Short cycling loss is really a “rule of thumb” which is applicable during an idle or an off cycle state (think of “maintaining temperature” with no heat call), or during extremely long calls with virtually no load. Fortunately, very few homes have extremely small amounts of radiation that are incapable of satisfying a thermostat call, so thermal purge virtually eliminates “rule of thumb“ short cycling losses.

The report referenced above also reveals that Energy Kinetics boiler annual efficiency is much closer to its thermal efficiency than is achieved with the modulating burners on condensing boilers. The primary source of efficiency gains from modulating condensing boilers occurs because they are often low mass (less energy wasted at the end of the thermostat call), and because modulation allows them to finish at a lower operating temperature (again less energy wasted at the end of the thermostat call). The thermal efficiency may increase somewhat due to lower stack temperature, but a quick inspection of a combustion efficiency chart shows that a stack temperature that is 50° lower only increases efficiency by about 1 1/2%. If the boiler operating temperature is between 120°F and 100° F, then condensing can occur, resulting in about 1% to 4% greater steady state efficiency from the latent heat of condensation.

Sorry, no voodoo or secret sauce, just common sense and well applied thermodynamics - with a nearly 40 year history and solid lab and field results to back it up.

Best,
Roger
President, Energy Kinetics

Erin Holohan Haskell

Thanks, Roger!

Roger

Thank you for your additional questions, 95percent.

This is somewhat technical, but I think you'll find it to be common sense.

The overall efficiency is a combination of the thermal purge control, well insulated low mass boiler, and integrated and thermally purge-able hot water tank. Take any piece out and the efficiency will be reduced. During an active heat call, we put more heat into the conditioned space, saving energy that would have to go into the boiler itself if it were high mass. Energy Kinetics boilers have virtually no oversizing efficiency loss (or losses from short cycling).

Here's another way to look at it:
As you can see in the BNL report, our boilers run at near steady state efficiency from about 2% through 100% loads (see Figure A3-2, Appendix 3, page 3). Short cycling has virtually no impact on Energy Kinetics efficiency until the loads are less than 2% of the full output. When does short cycling happen for any appreciable amount of time at under 2% of the output? Only when a very small zone is under-radiated and can't satisfy a thermostat (or for common boilers that maintain temperature at 0% output). Short cycling is not a concern for our design.

Compare that to a typical cast iron boiler with indirect, and the efficiency starts to fall off around 50% of load (see Figure A2-2, Appendix 2, page 3). A well insulated 3-pass boiler with a blue flame burner and burner damper starts to fall off around 20%. The difference between our high efficiency even at a 2% load vs losses at 20% and 50% is because we're low mass and we can use heat that is left in the boiler instead of letting it dissipate.

Why is low mass combined with thermal purge so important? Because there is virtually no heat left wasted in the boiler, the off cycle losses virtually disappear. It's much better than relying on insulation and burner dampers to "hold the heat," and it doesn't matter how long the off cycle is - there's no heat to wasted and no heavy boiler to heat up, ever.

As an additional point, when boilers waste enough heat to warm the boiler room, you have to remember that if there's a draft regulator (which we don't use), much of that heat is sucked up the chimney through the draft regulator.

To address the question about modulation and efficiency, the two factors we originally mentioned from the BNL study, steady state thermal efficiency and idle loss, have to change to improve energy savings. At a modulated lower firing rate, the stack temperature will be lower than a higher fixed rate, increasing thermal efficiency by 1% to 4% in general. To reduce idle loss, the boiler has to shut off at a lower temperature (its end state matters, not how it got there i.e. through modulation or fixed rate).

I'm not interested in making a high mass boiler - it's simply less responsive (unless it's temperature is maintained which wastes energy), and you spend money heating the boiler itself instead of the conditioned space or hot water. With low mass, you still have to heat the boiler, but it's a lot less and it's usable with thermal purge.

Roger

Roger

90percent, it sounds like some of the confusion could be resolved by observing how boilers run in the field. If you heard or think Energy Kinetics boilers short cycle and that makes them less efficient, that is not correct (not to mention a bit disturbing that someone would make that claim).

On most boilers, the burner runs until the supply reaches the operating limit (supply water temperature), and this may not have anything to do with the heating load.

Short cycling is solved on Energy Kinetics systems with thermal purge because they run based on the heating load in the system (determined by return water temperature). The burner runs when there is an adequate load.

If the return temperature is below the operating limit, it means the boiler can add more heat to the zone. If the return temperature reaches operating limit (170°F return for example), the system is up to temperature (maybe 180°F to 190°F in the supply) and there is no need to run the burner. The circulator continues to run and the zone continues to heat - that heat is not mysteriously lost. If the return temperature drops (by 15°F for example), the boiler now has a load to satisfy - it needs to heat the mass in the system (boiler, copper tubing, fins, water, etc.) and pick up the temperature in the system. This takes some time, prevents short cycling, and does not reduce efficiency.

When the thermostat is satisfied, the heat left in the boiler and piping is purged to the conditioned space, recovering the energy the burner put into the system, improving the distribution efficiency, and preventing off cycle (idle) losses that have a huge impact on boiler efficiency. In the meantime, the chimney is still hot and drafting, but soon afterwards, the boiler finishes "cold" and there is no heat left to be wasted regardless of chimney draft.

On cast iron boilers, the chimney draft continues and it is sustained at a higher level because these boilers finish hot, especially models that make hot water. Some cast iron boilers are well insulated and some have burner dampers to slow the heat loss, and that certainly helps, but heat can still easily flow out the wide open 4", 5", or 6" flue connection. Further, hot water tanks typically call for heat 3 to 5 times a day, running the boiler up to 180°F each cycle (because indirect tank coils can't transfer the full output of the boiler); higher temperatures cool off more rapidly so heat energy is dissipated faster. On Energy Kinetics boilers, the plate heat exchanger can transfer the entire boiler output for most of the hot water call duration. The heat remaining at the end of the burner run is purged to the tank and useful, not slowly dissipated and wasted.

Regarding your prior question on boiler mass, System 2000 only has 2 1/2 gallons of water (not 7 gallons), so here's another point to consider: For an 85% efficient 400 lb boiler containing about 14 gallons of water, it takes over 20,000 BTUs to heat the boiler itself from room temperature to 180°F. That's over 1/2 a quart of #2 fuel oil. That may take several hours to cool off, but that's a lot of energy required to heat it back up. Wouldn't you rather keep that in your oil tank?

STEVEusaPA

I'd like to chime in...probably make it worse.
@95percent, are all your questions answered? Roger was kind enough to explain this to you a number of times in a number of ways.
Roger & EK have an amazing, outside-the-box-thinking that they brought to their boiler technology. You ask why the others don't do it? Someone has to be first. And as you see the evolution of controls for boilers, they are heading in that direction.

I don't know Roger, but met him in Hershey last year and chatted for about 15 minutes. Very smart, very nice guy. Real knowledge and passion about his product.
I'd imagine his reasons to come on here reflect that as well and to address anyone trying to bad mouth his product, now that you put it out there (here) he has the right to dispel any questions and present the facts.
Roger, Hot Rod, Wilo and Taco, just to name a few, their reps and owners come on this site regularly and swiftly, and get personally involved with any disputes about their products, and provide amazing information.
Dan (and now Erin of course!) have put together a great place for people to come together to help, educate and learn. I doubt anywhere, any website, any type of business, provides that service, and us readers and HVAC professionals benefit greatly from the discussions and information.

So, I think you have all the info you need, to do whatever you want with it, so please go on your merry way and stop posting about things you just don't understand. And if now you do understand, great.
Either way, let it gooooooooooo.

Canucker

I don't know @STEVEusaPA , Don't you think @Roger should be the one to decide when he's answered all of the questions? I learned a lot from the exchange, I'm glad he took the time to answer. I might be missing what you're seeing but @95percent questions are better than someone who thinks they know it all and have nothing left to learn.

STEVEusaPA

Oh I think the questions were great for someone who wants to know, I learned a lot too, and of course it's up to Roger to decide-he doesn't need my help. But it's not just about a few questions (in my opinion).
My point was, it seems odd someone comes in as a new poster, and wants to debate his theoretical knowledge and what he learned on the internet vs. someone who has the real-world facts and empirical evidence of their own battle tested product.
Reminds me of a former Wallie (maybe he came back), removed a few times, who liked to argue to the point of being rude, with anyone who disagreed with him because he had to win and have the last word. I don't like bullies, or blowhards.
I felt (again, my own opinion) that we were heading down that road, and quite frankly I don't like to see someone I respect having to constantly respond to nonsense. Once again, the questions were fine, the disagreeing after getting the responses are my point.
Not my place to decide who what where at all on this site, but I am allowed to give my opinion, the same as if we're all sitting around having a few-until I'm warned, banned or censored by the operators of this site-if that's their wish.
Anyone can feel free for anyone to PM me, as I don't want to de-rail the thread anymore.
And also, the OP could've called EK, and talked to the man himself or one of his engineers, asked the questions and received the answers. EK is that good with customer service.

Rogers excellent explanation is now online for the world to benefit (a lot of this is on their website, btw).

SuperTech

I have to admit, after re-reading that exchange the OP did set it up nicely for the finer points of the EK boilers to be discussed. I enjoy it as a technician who prefers these boilers.

A recent experience where I had to call and e-mail a company before I was able to get assistance with a warranty issue made me appreciate how readily available support is from EK and others.

HVACNUT

My EK Regional Territory Manager, John Hachman, ALWAYS answers his phone. He's traveled far to bring a part out to a job, that very day! Just recently, after hours mind you, he met me half way to give me a warranty replacement gas valve. The customer was delighted, as was I, at the "above and beyond" support.
The only problem I have with EK is they're almost too easy to install and service. The big wrenches stay in the truck.
I've got a Resolute coming my way soon, and I can't wait to see my Beckett Rocket receiver think somethings wrong because the indicator takes twice as long to drop a notch.

SuperTech

@HVACNUT how do you like the Rocket? I was considering getting one. My tank is a pain to access to check the gauge.

Roger

Thank you all for your comments, questions, input, and certainly for such kind words about our family of employees and our products.

Dan, Erin, and the everyone in the HeatingHelp community have done a remarkable job at developing a forum where we all can pose questions, exchange ideas (and sometimes opinions), and have the opportunity to help each other out in a responsive and positive way. I’m glad to help out where I can!

Best,
Roger

HVACNUT

@SuperTech, I love it. I removed my basement 275 and installed a Roth outside. My only complaint is sometimes condensation builds up on the transmitter, and it does clear itself, but it beats going out to check a float gauge.

Roger

95percent, just a few clarifications from your last post.

With a plate heat exchanger, we can draw cold or make-up water off the bottom of the tank, heat it, and pump it into the top of the storage tank. This means the tank is heated from the top down, adding hot water where it is drawn off to the fixtures for rapid recovery and response. It also means that when the tank thermostat is satisfied, there is a reservoir of cold water at the bottom of the tank that almost perfectly balances with the heat remaining in the boiler. This is key to purging on the hot water zone.

With an indirect tank with a coil, the water is heated by convection (gravity) around the coil, which is slower than the heat exchanger's forced circulation. As the tank heats, the water temperature and boiler temperature difference is reduced and the heat transfer slows. When the tank thermostat is satisfied, if the water is heated to 140°F, the lowest you could possibly purge the boiler would be 140°F; because the coils are not perfect, it is often higher. This is a reduced, not eliminated, energy savings benefit from thermal purge.

For this reason, in a typical home, we see somewhere around 5% to 10% greater annual savings with a tank using a plate heat exchanger compared to a tank with a coil (greater savings with smaller heat loss homes because hot water is a larger portion of the annual energy use). The savings difference would be even greater if the boiler were higher mass. As you mentioned, there are good reasons to use an indirect tank. We do recommend and have very good success with Scale Stoppers or equivalent for any hard water applications (indirect with coil or plate heat exchanger).

Another clarification is the "cold start" question. I believe I touched on this earlier, although the hotter the boiler, the more rapid the heat loss (a larger temperature difference compared to the room). Just as a cup of coffee will cool off much faster outside in the winter than in the summer, larger temperature differences increase heat transfer rates.

Roger

Roger

Yes, thank you for bringing up that point.
Energy Kinetics boilers can recover much more energy with a tank with a plate heat exchanger than an indirect tank with a coil. This happens 3 to 5 times a day in a home with typical hot water use. This is another one of the reasons why our 87 AFUE oil boiler has a higher hot water efficiency and a higher annual efficiency than the 95 AFUE modulating condensing boiler in the Department of Energy laboratory study.
Roger

SuperTech

It's incredible how effective the flat plate heat exchanger is at heating up the storage tank. Last time I replaced a storage tank the EK-1 was able to satisfy the call for DHW in a couple of minutes. I have never had a customer complain of lack of domestic hot water with the EK boilers, even when using the stackable set up with the smaller storage tank. Scale stopper installation and back flushing the FPHX regularly are a must.

Big Ed_4

I always recommended the rocket for COD home owners , you know why too...They always go by time rather then temperature ..

The Famous Blue Ray ... The problem with them was it was made cheaply ... There was an insulated ring I called the donut that the flame whipped around , the supports that held it dead center would burn and warp and pull it off center . Then they would Rumble. "Seems normal to me Lady"

It seemed to last in the furnace longer then the boiler ... First residential hot water boiler I seen with a LWCO ... Needed a special CC nozzle If I remember correctly ...

HVACNUT

> @Big Ed said:
>
> It seemed to last in the furnace longer then the boiler ... First residential hot water boiler I seen with a LWCO ... Needed a special CC nozzle If I remember correctly ...

Yup, 70* CC Monarch with a Carlin 99 or 100, forget which. Temp sensor wired in series with the cad cell. Heavy buggers for a steel boiler.

JohnHachmann

Thank You to HVACNUT for the kind words. All of Energy Kinetics' Territory Managers do their best to assist our dealers whenever / wherever possible. It is always my pleasure to help you guys! Call me (or call the office) anytime you need our help. on another note, "Thank You" to all the technicians, oil drivers, customer service reps. and the sales reps. who spent countless hours away from their families during the extreme weather conditions that we experienced this winter. You guys (and gals) are amazing and you deserve a round of applause, Good Job!!!