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Thread: old house with oil/steam heat - help

  1. #16
    Retired Defense Industry Engineer jadnashua's Avatar
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    The higher the temperature of the heating medium, the more likely it is to waste energy in a typical residential heating situation. The delta between heat on/heat off means you have to put in a lot more to restore the operating temp, and the higher the delta, the more likely it is to waste energy. The bigger the differential, the faster it can disperse the heat to the outside, too. Things are more efficient when the delta is lower. Steam takes a lot of energy to go from liquid at 212 to steam at 212 - it does have LOTS of potential energy which is both a benefit and a problem. Keeping things liquid is lots better for the typical home verses using steam.
    Jim DeBruycker
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    Quote Originally Posted by jadnashua View Post
    The higher the temperature of the heating medium, the more likely it is to waste energy in a typical residential heating situation. The delta between heat on/heat off means you have to put in a lot more to restore the operating temp, and the higher the delta, the more likely it is to waste energy. The bigger the differential, the faster it can disperse the heat to the outside, too. Things are more efficient when the delta is lower. Steam takes a lot of energy to go from liquid at 212 to steam at 212 - it does have LOTS of potential energy which is both a benefit and a problem. Keeping things liquid is lots better for the typical home verses using steam.
    In injection loops for radiant heat you might find 70F delta t with delivery temperature of water 180F. It is done to reduce GPM , pumping costs and installation costs. In hydronic applications the larger delta T supply return ( non radiant ) desired, to reduce pumping costs, installation costs and so on. In Europe in hydronic non radiant applications installers are shooting for 60F Della T. If you are talking about indoor outdoor temperatures difference, who said that on steam indoor temperature is higher than on forced hot water system? Indoor temperature stays set by customer

  3. #18
    Retired Defense Industry Engineer jadnashua's Avatar
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    By it's nature, steam is at least 212-degrees, often higher. While the room temp may be the same, there are MUCH bigger deltas involved. More of the room is comfortable when the radiant input matches the losses, and that is only done reasonably with lower temperatures MOST of the year. 180-degree supply temps are not required for most residential heating situations except maybe on the coldest day of the decade. And, even then, probably not if there's enough radiation surface area. Pumping in a typical residential situation is not a big load...it is potentially in a larger commercial/industrial situation where you need to move large amounts of heat long distances - steam can be a great and maybe the only solution if you want a central heating plant. Mostly irrelevant in a typical residential situation.
    Jim DeBruycker
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    Btu is btu. What gets lost trough envelope of building gets replenished by radiator output. When balance loss/gain is reached temperature in the room gets stable. Your reference to lower radiator temperature on forced hot water system probably is outdoor reset, on steam I use indoor reset. High and medium temperature radiators use mostly convection heat rejection, radiant heat rejection is less of the factor. Also even steam has 212 F at atmospheric pressure, it does not mean whole radiator is 212F all the time. Maybe first section will be 212F the rest of sections might be much less.
    Last edited by gennady; 08-24-2013 at 07:02 PM.

  5. #20
    Retired Defense Industry Engineer jadnashua's Avatar
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    And, if you had children around, would you prefer a radiator that had a section that was 212+ degrees, or something that was maybe 120-degrees. Which one would you like to sit next to? Water verses steam also likely means you can actually use more of the room, and not get boiled. If you're putting in 212+ steam, and your load is low, like most of the season, how often does it need to cycle verses running more constantly at a much lower temperature. Commercial steam? Maybe a good solution, residential, not.
    Jim DeBruycker
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  6. #21
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    Quote Originally Posted by jadnashua View Post
    And, if you had children around, would you prefer a radiator that had a section that was 212+ degrees, or something that was maybe 120-degrees. Which one would you like to sit next to? Water verses steam also likely means you can actually use more of the room, and not get boiled. If you're putting in 212+ steam, and your load is low, like most of the season, how often does it need to cycle verses running more constantly at a much lower temperature. Commercial steam? Maybe a good solution, residential, not.
    Why you discriminating against elderly people and cats? They can be burnt by hot radiator too. And what about a cup of tea? What if children are around cup of tea of 200F. They can get burnt too.
    Steam is around for a quite a few years and i still have to hear about children burnt by hot radiator.
    Regarding short cycling of the boilers, it has nothing to do with media, more with sizing of the boiler, and i had seen same amount of short cycling hot water boilers as steam ones. Of course modulating boilers work better, but they always over sized, zoned and installed without primary secondary piping. Few contractors know how to install and set up them.
    Half of my business comes from fixing other people installations, and I see terrible nightmarish installations all the time.
    My point is that properly installed and set up steam system is on par with properly set up and installed high efficiency hot water system. How i know? I had done this.
    Last edited by gennady; 08-25-2013 at 09:13 AM.

  7. #22
    Master Hot Water Mpls,MN BadgerBoilerMN's Avatar
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    Primary/secondary was "invented" to keep old-fashioned fuel eating boilers hot enough to make sure the condensing occurred in the open atmosphere instead of the boiler, flue or chimney. Most hot water heating technicians are still doing this today, just as some are still shoeing horses. But like riding horses to work, retrofitting suitable hydronic systems with old worn out technology can only be attributed to ignorance or greed. Since there is nothing in it for the homeowner but a cheaper fix and in many cases the contractor charges more to do it wrong, being an "expert" in steam heat and all. There is no merit in P/S in and of itself. If your system flow requirements meet your boiler flow requirements you need one pump, assuring minimum flow through the low-mass heat exchanger and the lowest, unmixed, return temperature available in all operating conditions. Perfect systems and boiler efficiency in one.

    I have signed copies of DH books and Ziggy's etc. I can read and write, hold a Master's license in steam, hot water in Minneapolis/St.Paul and know that a 400F stack temperature can only be called "efficient" relative to the extreme inefficiency of adding enough energy to change phase in water. I will take the 100 stack temperature of the condensing boiler every day and still use the built-in outdoor reset to squeeze every drop of usable heat from the fuel.

    The people who advocate cast iron and those who sell the trim to dress up the pigs, try to make this argument continually, but without effect since they can't honestly nor reasonably explain where the other 300F of energy goes. If it the heat isn't recovered in the boiler it is lost to the atmosphere. Period.

    We are talking about residential hot water/steam conversions here. Naturally process, one-pipe and systems short of radiation must be replaced with all the latest technology, which will in fact lower the fuel bills, but this is rare in my experience. More often a condensing boiler can be installed and pay for itself in less than a decade. No such assertions can be made for steam systems.

    Give me a Brownstone and I'll give you a properly sized condensing boiler with indirect water heater and cut the fuel bill by half.

    As for the government. It doesn't take that much to get ahead of a bureaucrat but sure embarrassing when you get behind.

    "And over sizing of the radiators are things of the past."

    That was my point of course. When cast iron radiators were king, the radiators were generally and typically over-sized, thus able to heat space at much lower design temperatures using the same EDR as the old system. With modest home improvement, e.g. storm windows and insulation, many old cast iron radiators can heat hundred year old houses with temperatures well below steam and well within sustained flue gas condensation (the bane of all old-fashioned heating systems originally designed for coal consumption). An old cast iron radiator is a terrible thing to waste and often a perfect match for condensing boiler technology without the inherent maintenance associated with steam heating. We use TRVs with both but they will not assure efficiency of any kind unless sized, balanced and maintained by experienced techs. Nice little niche.

  8. #23
    In the trades Dana's Avatar
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    The distribution losses of steam system due to large diameter plumbing and high temperatures can be gia-normous. If fully contained within a tight conditioned space this can be of small consequence, but that's not always the case. The size and expense of pipe insulation sufficient to manage/reduce those losses isn't trivial either.

    But it can be cheaper than installing a mod-con and low-temp radiation. The heat loads on old uninsulated brownstones can be large, and the ease of installing sufficient low-temp radiation (or retrofit insulation to the building) difficult. I can believe there will be instances where the differences in raw combustion efficiency are small enough that the pumping cost at NYC type electricity rates (~2x the national average) would make the operational cost comparable to a not-so-low temperature mod-con setup, but like I say, it's probably more the exception than the rule. The raw combustion efficiency of steam is one limitation, typically high distribution loss/low system efficiency issue is another, and the exceptions shouldn't be confused with the rule. The notion that optimized steam and optimized mod-con systems somehow offer equivalent-efficiency or equivalent operating costs is simply false for nearly all single family homes, and most multi-family homes, and very unlikely in elizabeth40's home.

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    Quote Originally Posted by BadgerBoilerMN View Post
    Primary/secondary was "invented" to keep old-fashioned fuel eating boilers hot enough to make sure the condensing occurred in the open atmosphere instead of the boiler, flue or chimney. Most hot water heating technicians are still doing this today, just as some are still shoeing horses. .…......…............

    I have signed copies of DH books and Ziggy's etc. I can read and write,
    Maybe you need this book signed by Dan Hologan


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    I attached photo of afterword page.

    Interesting reading, isn't it?


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    BTW, last time I saw Dan, he thanked me for contribution to his site.



    And this page is from viessman vitodens boiler installation manual. This boiler is so new, it will appear on US market only in a week. And yet these old timers from Germany want this boiler piped primary secondary trough hydrolic separator. Shame on them?

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    Last edited by gennady; 08-26-2013 at 04:59 PM.

  10. #25
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    Quote Originally Posted by Dana View Post
    The distribution losses of steam system due to large diameter plumbing and high temperatures can be gia-normous. If fully contained within a tight conditioned space this can be of small consequence, but that's not always the case. The size and expense of pipe insulation sufficient to manage/reduce those losses isn't trivial either.

    But it can be cheaper than installing a mod-con and low-temp radiation. The heat loads on old uninsulated brownstones can be large, and the ease of installing sufficient low-temp radiation (or retrofit insulation to the building) difficult. I can believe there will be instances where the differences in raw combustion efficiency are small enough that the pumping cost at NYC type electricity rates (~2x the national average) would make the operational cost comparable to a not-so-low temperature mod-con setup, but like I say, it's probably more the exception than the rule. The raw combustion efficiency of steam is one limitation, typically high distribution loss/low system efficiency issue is another, and the exceptions shouldn't be confused with the rule. The notion that optimized steam and optimized mod-con systems somehow offer equivalent-efficiency or equivalent operating costs is simply false for nearly all single family homes, and most multi-family homes, and very unlikely in elizabeth40's home.
    Well insulated steam pipes losing as little heat as well insulated hot water piping. It does not matter what diameter piping there, it matters how well piping insulation done in unconditioned spaces. And we do it well. Heat losses of uninsulated brownstones are high, but does heat loss depends on heat transfer medium or just on wind, infiltrations, outdoor temp, indoor temp and R of envelope? Heat loss is a heat loss. All you have to do is compensate it to keep indoor temp steady. And the manner in which this compensation is done plays huge factor in system efficiency. I find boiler efficiency a factor in system efficiency, but not a main factor. Just my 2 cents.
    Last edited by gennady; 08-26-2013 at 08:01 PM. Reason: Grammar

  11. #26
    In the trades Dana's Avatar
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    "Well insulated steam pipes losing as little heat as well insulated hot water piping."

    Both the surface area and the delta-T on the fat steam pipes is much larger than in the skinny pumped water- diameter definitely matters- you can't cheat the basic physics & geometry.

    "It does not matter what diameter piping there, it matters how well piping insulation done in unconditioned spaces."

    In less-insulated buildings the heat loss from the distribution doesn't always accrue to places where it's needed or wanted, but yes, keeping it all inside of a fully conditioned space minimizes the impact of those losses. I've seen balloon framed 3-story houses where the steam pipes were run in the exterior wall cavities. A 190F delta-T on less than an inch of retrofit cellulose is pretty lossy (glares like a blinding streak in the infra-red imaging.) If that's the way her house was done, she should probably be moving on, but not with mechanicals her contractors were pushing.

    If her steam distribution is done somewhat better than that it's still speculative whether optimizing the steam system is a better use of funds for elizabeth40 than some other system with other building upgrades. To keep the steam she would be on the hook for a new boiler at a minimum, and I can think of plenty of ways that house that vintage could be thermally optimized. But the oversized mid-efficiency gas hot air furnace + heat pump system advise seems like a pretty gross hack that would likely cost more up front than a new steam boiler and provide lower heating-season comfort than re-commisioned steam with a shiny new boiler & tuned venting etc. .

    Retrofitting the low-temp radiation required for a mod-con seems unlikely to be financially rational (unless it was ridiculously oversized 2-pipe steam that could be converted) and if air conditioning were the goal well placed & sized ductless would probably be preferable to a 2-stage ducted hack. Lowering the heat load with building upgrades is likely to be more cost-effective and higher impact than trading in the steam for a low-temp mod-con, unless a lot of retrofit work has already been done to the house, and the low-temp radiation were already in place.

  12. #27
    Master Hot Water Mpls,MN BadgerBoilerMN's Avatar
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    WE rarely install any boiler with P/S except for those manufacturers that mandate it, such as Buderus, Weil McLain and Slant-Fin and the reason we will not use these boilers on steam or gravity hydronic systems and yes, over-radiation. The first use of P/S was to keep atmospheric boilers hot enough to maintain minimum stack temperatures. I wish it still was.

    As Dana points out, with upgrades to the thermal envelope the radiation by definition is over-sized since the lower the load the lower the AWT required. Steam radiators are almost always big enough to facilitate ready conversion and unlike a steam boiler the outdoor reset built in to all residential condensing boilers will allow the boiler to operate below design water temperature in all but outdoor design conditions.

    We design new hydronic systems every week and always over-size our radiation to accommodate the condensing technology. I thing over-sizing radiators is a thing of the future. Steam a thing of the past.

    As for system vs. boiler efficiency I have to agree. Of course first we have to agree that installing two pumps on one single zone boiler is wasting labor and 20 years of operating cost at 100-200 watts/hr and kills system efficiency before you get started. Then we could talk about thermal, combustion and AFUEs...not the same thing.

    Viessmann does not mandate P/S and one of the reasons they are one of our favorites on steam and gravity conversions. They do like to sell hydrolic separators, something trade magazines and those who write for them are sensitive to.

    There is no logical argument for doubling electrical operated costs and the chance of a nuisance no-heat by adding a redundant circulator to any single zone hydronic system. The only thing this will accomplish, beyond the obvious wasted labor, material and operating cost, is to inevitably raise the return water temperature to the boiler. This is not progress where condensing boilers are concerned.

    But it does make their installation a little more idiot-proof. Having build condensing boilers I can understand their logic, but still am not convinced that is serves you or your customers.

    We will commission a 150mbtu IBC this week; six-zones, DHW priority, old cast iron radiators, sub-floor radiant, radiant ceiling, cast iron baseboard...one pump. Imagine...
    Last edited by BadgerBoilerMN; 08-29-2013 at 05:53 AM.

  13. #28
    Master Hot Water Mpls,MN BadgerBoilerMN's Avatar
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    Quote Originally Posted by gennady View Post
    In injection loops for radiant heat you might find 70F delta t with delivery temperature of water 180F. It is done to reduce GPM , pumping costs and installation costs. In hydronic applications the larger delta T supply return ( non radiant ) desired, to reduce pumping costs, installation costs and so on. In Europe in hydronic non radiant applications installers are shooting for 60F Della T. If you are talking about indoor outdoor temperatures difference, who said that on steam indoor temperature is higher than on forced hot water system? Indoor temperature stays set by customer
    Injection is rarely justified in residential application. The reason? Higher installation cost, operating costs etc. It is a crutch for those handicapped by old-fashioned, inherently inefficient cast iron boilers. The "Europeans" wouldn't have it. In England only condensing boilers are allowed.

    The higher the water temperature delivered to the radiation, the higher the heat load. Yes, the heat load since temperature differential between indoor air and outdoor air during design conditions is but one factor of heat loss 200F radiators next to double hung window from the horse-and-buggy days will drive more heat out of the building than the same radiator at 100F operating on ODR. Even if (rare) the radiator ever needed to be operated at 200F supply water temperature it would amount to a few days and easily done with some of the condensing boilers available in the market today. The rest of the season lower water temperatures would prevail and operating costs go down accordingly.

  14. #29
    In the Trades Tom Sawyer's Avatar
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    Think........VFD pumping

    One of the big problems with steam boiler is that you need head space above the water level. without the head space the boiler makes steam so fast that the water level drops faster than the condensate can return causing overfilling of the boiler along with surging and steam hammer. So most installers get around the issue by installing oversized equipment and down firing the burner. We have a lot of steam systems in my area. I grew up on steam, have an unfounded fondness for steam but its time has come for residential heating. Then again, a lot of times salesmen will tell folks that if they tear the old steam system out and install a new boiler and radiation of some sort (even converting the radiators) the customer will save a ton of money and honestly, probably not. Sure, the new system will cost less to operate but when you back that out against a 10 to 20 thousand installation cost, it takes a whole lot of years to pay that back. In fact it takes so many years that by the time its all paid for the equipment is outdated again. Its like chasing your tail. I don't blow smoke up the customers back side. I try to sell the conversion based on comfort, less maintainence, safety (steam can and occasionally does blow up) and reliability. Also too note is that most steam systems are getting on close to 75 years in age and that old steel piping is going to start leaking.
    [B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]

  15. #30
    In the trades Dana's Avatar
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    I haven't chased a lot of steam systems, but I've yet to see an old steam with serious leakage issues (which was one of elizabeth40's concerns.) Is it really all that common?

    The only leakage issue I've seen was corrosion on the Hartford loop of a friend's circa 1920 1-pipe steam system- not exactly disasterously expensive to repair. The original boiler got swapped out in the past 5 years with an 82% AFUE Burham- fuel use improved ~15% with the swap out. Tweaking the venting got another ~15% but there's probably more to be had in simple & cheap tweaks. This house has no wall insulation, and the heat distribution plumbing uses the balloon framing as chase- it's a real efficiency nightmare. Were it my own home I would not have swapped in a new steam boiler, but she was stuck with an inspector-condemned boiler and cash-strapped, with insurance covering most of the cost of the swap.

    I convinced my in-laws to get rid of a few ~90 year old 1-pipe steam systems in one of their multi-family rental properties though- originally coal boilers converted to oil then gas-burner pieces of scrap iron junk, with 2" distribution piping (also in exterior wall cavities, but with retrofit cellulose), replaced with 2 & 3 plate mid-efficiency cast iron and sufficient baseboard for 140F AWT operation, zoned by floor. Fuel use dropped by about 2/3. The steam systems were still functional, but a liability. A Maine Coon Cat could have crawled through the passages of the heat exchangers of those boilers with room to spare, and between the likely ~45% combustion efficiency and the huge distribution losses there was no argument for re-re-re-commissioning the systems.

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