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Best system for domestic hot water

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chapchap70_2
chapchap70_2 Member Posts: 147
About how your boiler was running before;

"This time I called an independent heating contractor who spent an hour fussing with the system and established that whenever the boiler temperature got above the lo set point the circulator would shut off. Then the temp would go up to the high set point without the circulator coming on. When it hit the high point the burner would shut down and the boiler temp would drop. When it got to the lo set point the circulator would come back on."

At first, it seems that you would have no heat at all because the circulator would hardly come on, (properly working aquastats would turn on the burner at low limit so the boiler would not be below low limit for long enough for you to get heat) then you state the circulator came on after the boiler water temperature dropped to its low limit setting. It is not clear to me what happened (it doesn't really matter now that it is fixed) but I'm curious; did the contractor just change the settings on the aquastat or was there a wiring problem?

I'm sorry about your situation and the purpose of my original post was to get you to think before you jumped into buying equipment that wouldn't gain you enough energy savings to pay for itself.

The findings from the book were averages. Your energy savings depend mostly on how efficient your boiler is if you use a tankless coil or indirect. I do not see the difference being more than 5% either way between the two using the same boiler. A tankless coil in a boiler would be less efficient to heat water in North Carolina than where you are in upstate New York. As to why the info from the book is different from what you've been reading, it is possible that the info is outdated. If the average boiler has become more efficient, it would change the results. I've read in other places since my last post including the Energy Kinetics website, and it seems that the common perception is that the tankless coil is a little less energy efficient in creating hot water than the indirect. If you are leaning toward a direct fired water heater, keep in mind that some boiler manufacturers recommend that their boilers not be turned off during summer months to prolong its life. I do not know if this is the case with your particular boiler.

As to a new system, the findings in the book make sense to me about purging the heat out of the boiler after every cycle. If there is no heat in the boiler, there are no off cycle heat losses. Off cycle losses are not taken into account in the AFUE ratings but are factored into the Energy Factor of direct fired water heaters. I think if boilers were rated in a similar fashion as water heaters, the Energy Factor would be somewhat less than the average direct fired water heater rating of 60% because many boilers have less insulation than water heaters and the water temperatures of boilers are higher. The higher the water content of the boiler, the higher the off cycle losses are. (The heat escapes up the chimney.)

If you are wondering why many boilers have so little insulation, you would have to ask the manufacturers but consider the following:

If a boiler has a lot of insulation, the heat in the boiler room or basement (which does not count against the AFUE) would be kept in the boiler. When the burner is running, that extra heat would raise the stack temperature which decreases steady state efficiency which decreases the all important AFUE rating.

Comments

  • Anthony Ferrer
    Anthony Ferrer Member Posts: 13
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    Best system for domestic hot water?

    It seems that if I ask 5 people how best to create domestic hot water I get 7 answers. Be that as it may, I currenly have a Burnham America V-15 oil fired boiler that's creating domesic hot water with an internal coil. What everyone agrees on is that this is the least efficient way to create hot water. What I'm now trying to figure out is which way to jump for a better hot water system. The house (an 1850's converted carriage house) when we are done renovating will have a kitchen with 2 sinks, a pot filling faucet, and a dishwasher. There will be 3 bathrooms; one guest bath with a single vanity and a shower stall, one master bath with two vanities, a shower and a 4x6 whirlpool, the existing bathroom with one vanity and a tubshower, and a washing machine. Currently there is only my wife and myself. Around the time we finish the renovation there will probably be a little one in the equation. At that time the grandmothers will probably be in the guest room a bit more frequently.
    The suggestions I have gotten are an indirect tank (either a 60 gallon or an 80 gallon), an electric tankless, a direct fired oil hot water heater, a LP tankless, and ferrying hot water from the fireplace (okay, we'll ignore dad's suggestions). As I try to research the options it is very much like comparing apples to kumquats. Everything I read says that each of the options are better than the coil on my boiler, but not how them compare to each other. So, for the situation that I'm describing, what would you recommend? And what's the best way to compare them on a level playing field?

    Thanks,

    Anthony
  • Joe Brix
    Joe Brix Member Posts: 626
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    Since you heat with oil

    I assume you live on the east coast, which usually does not mean cheap electric rates. A decent size electric tankless needs about 100 amps of power, probably half of your residential 200 amp service. You got that much extra power unused?

    The LP tankless units are OK, You have to have a bigger high end model to do a whole house.

    If your current boiler didn't have the extra BTU's I might say get one, but I still believe in having the reserve capacity of a tank. Since your boiler has a tankless coil now I'm sure it was oversized and has the extra BTU's to spare already.

    How does the boiler look? Is it worth putting an indirect on an old boiler? Have you improved the house with new windows and insulation? Might be a good time to have a smaller properly sized boiler put in at the same time.
  • Anthony Ferrer
    Anthony Ferrer Member Posts: 13
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    East Coast, yes...

    Peekskill, NY. Yes, the boiler is apparently oversized. No, we haven't upgraded the windows and insulation, but it's on the list. I'm going to work my way around the house putting weatherstripping kits on the windows (which have storms). We also plan to remove the existing insulation from the attic and replace it, probably with blown in cellulouse. Replacing the boiler is on the list, but probably not for another 5 years or so. We just replaced the old Sunray burner with a Riello 40 which we hope will reduce our oil consumption significantly ($800month in oil bills has been a bit crippling).

    Mostly I'm trying to get a hot shower without having to take out a second mortgage to pay for it.

    Thanks,

    Anthony
  • Joe Brix
    Joe Brix Member Posts: 626
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    You probably have

    large cast iron radiators? You could invest in an indirect and boiler controls to give you outdoor reset. You could then reuse them when you get a new downsized boiler in a few years. Get a control like a Tekmar 260 (www.tekmarcontrols.com). You probably don't need priority on the indirect now since you have an oversized boiler, but it will help give yo plenty of hot water later when you get a smaller boiler.
  • Anthony Ferrer
    Anthony Ferrer Member Posts: 13
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    where does the outdoor reset go?

    I took a look at the tekmar website and the 260. Not quite sure where it figures into the system. I'm researching creating zones with a Taco ZVC and Taco zone valves on each loop. Would the 260 wire to the aquastat? Or replace it?

    Thanks,

    Anthony
  • Joe Brix
    Joe Brix Member Posts: 626
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    A 260

    would control power to the circulators (boiler and indirect) and wire between the aquastat of the indirect and your house thermostats. It then takes ownership of the "TT" contacts on your boiler's aquastat to call for the boiler to fire. Your boiler aquastat remains, acting ast the high limit safety. It also has an outdoor temp sensor and a sensor that should go into the boilers supply piping so it can read the outdoor and boiler temp. It will then only fire the boiler to a temp better matched to the outdoor temp. Colder it gets outside, the higher it fires the boiler to.
  • chapchap70_2
    chapchap70_2 Member Posts: 147
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    Not everyone agrees

    "I currenly have a Burnham America V-15 oil fired boiler that's creating domesic hot water with an internal coil. What everyone agrees on is that this is the least efficient way to create hot water."

    Not true.

    According to the book, Advanced Oil Heat "A Guide To Improved Efficiency" by the Petroleum Marketers Association of America, the least efficient way to heat domestic water on average is with a direct fired water heater. In my opinion, these should only be used in combination with warm air furnaces. (if the person insists on not going hydro-air)

    The next least efficient according to this book is the indirect followed closely by the tankless coil.

    Of course water heating efficiency depends on the efficiency of the boiler. If you have an oversized boiler in which you are using the internal tankless coil, your efficiency will not improve if you get an indirect using the same boiler. The tankless coil is very efficient during the heating season because the boiler is running a lot anyway but very inefficient during the summer months.

    I believe the best way to address your hot water needs is with the purchase of an efficient, properly sized boiler that also addresses domestic water. If you are going to wait to get your boiler, I wouldn't spend money on your domestic water needs unless your tankless coil cannot supply you with enough hot water. In this case, if (and this is a big if) you can get the old tankless coil out, replace it with another one. This should work until you get your new boiler.

    By the way, the most efficient way according to this book to heat domestic water with oil is with a low mass boiler that uses a plate coil heat exchanger with a well insulated storage tank. It describes the boiler purging the heat to the last heating zone that called or to the storage tank.
  • Joe Brix
    Joe Brix Member Posts: 626
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    That book

    sounds like it was writen by Energy Kinetics, a boiler that doesn't work well with an indirect and sells a flate plate HX and booster tank. Kind of a biased answer if you ask me.
  • Anthony Ferrer
    Anthony Ferrer Member Posts: 13
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    That information contradicts everything I've read so far. I think I would have a bit of hesitation trusting information from The Petroleum Marketers Association of America. It's sort of like taking health advice from the Tobacco Marketers Association. Particularly since my oil company assured me that my heating system was running at its optimum settings. Sure, optimum for them.

    Anthony
  • chapchap70_2
    chapchap70_2 Member Posts: 147
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    About the book

    The primary author listed for this book was John Batey who at the time the book was written (1995) was President of Energy Research Center, Inc.

    Funding for the book was provided by Brookhaven National Lab and the U.S. Department of Energy.

    The conclusions arrived by this book were the result of testing at BNL.

    To lie about the test results so oil dealers can make more money because their customers burn more oil would be short sited and stupid.
  • Joe Grosso
    Joe Grosso Member Posts: 307
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    Boy I hope you do not feel this way about everyone you deal with in life.No I do not think your oil company is looking to screw you.Being a owner of a oil company I do look out for my customers and if I help them save on their overall usage of fuel I have done a great job.
  • Anthony Ferrer
    Anthony Ferrer Member Posts: 13
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    I may be a little bitter right now

    Actually I tend to think the best of most people and I trusted the oil company, which is why I'm so steamed. I called them before we bought the house and they assured me that the heating system had been regularly maintained and was in excellent condition. I asked if we should consider replacing the boiler and they said that the new boilers are not really any more efficient than the old ones and we should look to the insulation to save money. Then, when we were facing $800mo oil bills I called to talk to them. They sent someone over who cleaned the system and said that everything was fine. A couple of weeks later I called again and expressed concern that the burner seemed to be running a lot without the circulator coming on. They sent a repairman out who replaced the aquastat and said it wasn't hitting its high limit. A couple of weeks later we had an energy consultant come in who said that there didn't seem to be anything right about our heating system. This time I called an independent heating contractor who spent an hour fussing with the system and established that whenever the boiler temperature got above the lo set point the circulator would shut off. Then the temp would go up to the high set point without the circulator coming on. When it hit the high point the burner would shut down and the boiler temp would drop. When it got to the lo set point the circulator would come back on. When the burner was on it was stuttering and surging, so the boiler never achieved a steady state. Two different service men from the oil company (one of them, it turns out, the owner)looked at the system and pronounced it to be in good shape. We replaced the burner and the aquastat and I can tell, just by hearing when it cycles, that the system is running probably less than half the time it did before.

    Now I prefer to think that my (former) oil company was negligent and not deliberately rippping us off, but does that make them any less culpable? Friends of ours with comparably sized homes in our area have gone through 400- 500 gallons of oil this heating season. We've been going through 300 gallons a month. I'm giving myself a couple of weeks to calm down and see what our oil usage is before I decide if I should speak to my attorney about it.

    I'm sure that you take good care of your customers and realize that saving them money will make them loyal to you. I'm also sure you realize that not everyone does business the way you do. Hopefully this explains my previous comments and why I'm a tad mistrustful at the moment. Right now I think I'm happier paying for outside service and buying my oil elsewhere. My apologies if I offended.
  • Joe Brix
    Joe Brix Member Posts: 626
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    What boiler

    recommends that it should run 365 days a year if just being used for heat? If a tankless coil was OK on efficency, how come Buderus, Viessmann, or Energy Kinetics don't offer them? Your insulation comment also doesn't make sense. If an insulated boiler retained more heat, then they could fire the boiler at a lower rate, producing even better AFUE's.
  • Ron Schroeder
    Ron Schroeder Member Posts: 998
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    "That book sounds like it was writen by Energy Kinetics, a boiler that doesn't work well with an indirect and sells a flate plate HX and booster tank."

    Hi Joe,

    I know that the Energy Kinetics is usually sold with a flat plate heat exchanger and a storage tank, but why wouldn't it work well with an indirect?

    Ron



  • Anthony Ferrer
    Anthony Ferrer Member Posts: 13
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    I should have taken better notes

    To tell you the truth, I'm not sure I got the exact sequence of what the circulator was doing. What I do know is that when it ran seemd to have very little to do with when the burner ran, and the radiators didn't get very hot. So we did get heat, but not a lot of it. It was enough to keep the house warm, so we didn't really notice the problem. This is our first winter in the house, as well as it being our first house, so all of this has been a new experience. What's also interesting is that we just got our electric bill. It's within the past month that I've been experimenting with different hilo settings as well as the change in the aquastat and the burner. Our electric bill is down by $70! I can't think of anything else that we've changed, so I'm wondering if the circulator could possibly have been running enough to have drawn that much power. It seems unlikely, but my wife isn't turning the lights off any more than usual. Hmmm... come to think of it, we just replace the dishwasher, too. I wonder if that could have anything to do with it?
  • chapchap70_2
    chapchap70_2 Member Posts: 147
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    I would guess a lot of it is the dishwasher

    Maybe someone can check my math but I think it would cost just over $200.00 per year to run one 007 circulator continuously for the whole year at 16 cents per KWH.
  • Joe Brix
    Joe Brix Member Posts: 626
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    I have the same question

    The flat plate has always seem to be a point of failure for some. Have heard about it requiring cleaning. I know the boiler is pricey to start with, but sales guys I spoke to alwys push the booster. I think the supply/return on the EK is only 1" and they'd rather cycle the DHW through the flate plate frequently to avoid cooling off the boiler from my guess.
  • PJO_5
    PJO_5 Member Posts: 199
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    How about...

    A reverse indirect for that oversized boiler? This would give you a buffer tank for longer cycles and tons of hot water.

    Also, if it is still oversized with the new burner, see if your (current) contractor can down-size the nozzle without going into condensing mode.

    Also, what about solar? Is it decent in your area? If you are going to do some re-contruction in your house, consider a GFX heat exchanger to pre-heat your domestic hot water.

    All of the above options are viable solutions...with the one excerption if you don't have much solar in your area.

    Hope this helps. Take Care, PJO
  • chapchap70_2
    chapchap70_2 Member Posts: 147
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    oops

    I remembered after posting yesterday that you had an old burner and I reviewed your post that you had an old Sunray burner. That new Riello might be saving you a good portion of that $70.00. I deserve a slap in the head for the above post.

    Joe,
    I'll try to answer your questions the best I can in a while but right now, it is my son's turn with the computer.
  • chapchap70_2
    chapchap70_2 Member Posts: 147
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    Various

    "What boiler recommends that it should run 365 days a year if just being used for heat?"

    I won't give a brand because it is hear say from other techs. The type is the cast iron boiler with rubber gaskets between the sections. My understanding is it is better to keep the gaskets warm so they don't deteriorate which would cause the boiler to leak. So spend the money to burn extra oil or buy a new boiler prematurely. Maybe someone can confirm or deny this? The Crown boiler manual states that if you take their boiler out of service, clean it first because the soot would harden which makes it extremely hard to clean and causes the cast iron to corrode.



    "If a tankless coil was OK on efficency, how come Buderus, Viessmann, or Energy Kinetics don't offer them?"

    The answer to this might have nothing to do with efficiency but with the life of the indirect compared with the tankless coil. I think the tankless coil generally has a shorter life because film and crud in the domestic water adheres to the inside of the coil causing less heat transfer and lower flow rates and eventual failure. With the indirect, the hotter boiler water flows through the coil which essentially elliminates this problem. I understand that reverse indirects which are basically coils inside a small well insulated tank instead of the boiler are making a comeback.

    I don't know the Buderus or the Viessmann boilers water design but where would you put a tankless coil on an Energy Kinetics boiler? Also, it would take over two minutes with an EK to get hot water out of a tap because the boiler sits cold until there is a heat or hot water call which is why their system works better with an indirect or a storage tank with the heat exchanger. An added benefit with the plate heat exchange outside the tank is that if one fails, you do not have to replace both like you would if an indirect coil OR the tank fails.



    "Your insulation comment also doesn't make sense. If an insulated boiler retained more heat, then they could fire the boiler at a lower rate, producing even better AFUE's."

    If the fuel input of a heating appliance is reduced, what happens to the BTU per hour rating of said appliance?

    An oil boiler combustion area is designed for optimum efficiency and cleanest flame at a particular firing rate and nozzle. If the firing rate is reduced in that boiler, the air currents change so some of the oil droplets do not come back into the flame which produces a smokey fire. To compensate for this the percent of excess air has to be higher than in a combustion area designed specifically for that firing rate and nozzle. The result is a lower flame temperature--lower AFUE.

    AFUE ratings assume a boiler is properly sized. Some boilers are never properly sized for their required heating load and the others are only properly sized maybe 5% of the year. Purging the heat out of a boiler seems to negate the effect of oversizing. This has no effect on stated efficiency ratings. The reason I like the EK concept is they seemed to have designed a system that uses less fuel while others seem to design their boilers to get a high AFUE rating.





    "That book sounds like it was writen by Energy Kinetics, a boiler that doesn't work well with an indirect and sells a flate plate HX and booster tank."

    The EK manual states that the heat exchanger and storage tank works best for their system but how do you know their boiler doesn't work well with an indirect? Consider this post from Oil Tech Talk. I don't think the original storage tank was piped properly from what he says.

    Robby Perkins
    Dedicated Professional


    Joined: 08 Jul 2004
    Posts: 26


    PostPosted: Tue Apr 12, 2005 8:46 pm Post subject: E-K's tank Reply with quote
    We replaced their tank and heat exchanger for a dissatisfied customer. His complaint was that he ran out of hot water rather quickly and always had. The cold water entering his tank went through a dispersion tube directly in line with the hot water outlet ??????????? this resulted in about 3min of usable hot water.

    We installed an indirect with a check pump/ tied it in with his controller and piping (pay attention) and he now fills the big tub in no time, can't seem to run it out!




    "Also, what about solar? Is it decent in your area? If you are going to do some re-contruction in your house, consider a GFX heat exchanger to pre-heat your domestic hot water."

    I know next to nothing about solar but since you brought it up, maybe it is possible to have a dual purpose indirect water heater with the EK boiler as the back up. Superstor makes this kind of indirect that has two heat exchangers. Since the EK starts cold and ends cold, any demand that the solar exchanger doesn't handle, the boiler would provide and very little energy would be wasted. Theoretically, it is possible for this boiler to not run all summer with the solar set up and I don't see a problem with that.



This discussion has been closed.