Boiler help

Discussion in 'Boiler Forum' started by Steve Lanham, Jul 18, 2013.

  1. Steve Lanham

    Steve Lanham New Member

    Messages:
    17
    Location:
    Maryland
    To the point. . Replacing a oil boiler to gas. Considering the Pioneer with indirect . The pioneer versa combo or the Columbia Power vent I think it's CSVB. Has anyone had experience with the pioneer boilers. The warranty is 12 years where as with the Columbia the warranty is life time...I live in Baltimore , 1800 sq ft 1932 medium insulated. Burnt about 500 gal a year...two contractors both suggested 150k for boiler size,, any suggestion is appreciated. Thanks !!
  2. Tom Sawyer

    Tom Sawyer In the Trades

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    Unless you live in an Un-insulated mansion I suspect that 150k is about twice as much boiler as you need. Not a Columbia or pioneer fan either. Look into Biase, buderus, lochnivar, something that is a two or preferably three pass boiler.
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Location:
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    It would be a leaky old barn conversion that needed 150K btu...Find someone to actually do a manual-J heat load analysis on the house, room by room, you may have to pay for this, but it will save you lots of money in the long run, and you'll be more comfortable with a longer lasting system. When it's too big, it short cycles...cycles are the killer, not running all the time. Ever had a light bulb fail while it was already on, verses when you turn it on? Almost never. Slightly different issues with motors and burners, but things get stressed each time you cycle it...a right-sized boiler is as good as you can get on this, and it's highly unlikely that 150K is right. Lots of threads here discussing the same issues, some before buying, some after and trying to fix it.
  4. Dana

    Dana In the trades

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    150K is an INSANE oversizing factor for your true heat load! With an indirect you could probably get along just fine with a 35K boiler!

    The 99% outside design temp for Baltimore is about +15F. Assuming a typical heating/cooling balance point of 65F (typical for non-superinsulated houses) that's 50 heating degrees below the balance point.

    A typical heating season in Baltimore is about 4600 HDD base-65F

    500 gallons over a 4700 HDD is (500/4700=) 0.106 gallons per heating degree day.

    A gallon of heating oil has about 138,000BTU, and assuming a steady state combustion efficiency of your oil burner is about 85% (could be, but it's probably lower), that's delivering (0.85 x 138,000= ) 117,300 BTU/ gallon. So per degree-day thats (0.106 x 117,300=) 12,434 BTU per HDD being delivered to the heating system.

    With 24 hours in a day, that's (12,434 / 24=) 518 BTU per degree-hour. So with 50 heating degrees at the 99% outside design temp you're looking at a heat load of about (518 x 50=) 25,900 BTU/hr.

    And that's probably an overestimate, since the odds of your oil boiler actually delivering 85% isn't high, and we haven't accounted for distribution losses on the system or hot water heating (assuming you're heating hot water with oil.) Odds are pretty good your true heat load is around 22-24KBTU/hr, and there are probably cost effective ways (even with cheap natural gas) to reduce it.

    Even a tiny 2-plate 35KBTU-in ~80% efficiency cast iron boiler delivers (0.80 x 35,000=) 28,000BTU/hr, which gives you ~10% margin even if your oil boiler was really running 85% AFUE (not likely) and is probably closer to 30% margin on your space heating load. That's also about the output of a standalone gas hot water heater, and if you zone the indirect as "priority" and size it for your biggest tub-fill you'll have equivalent or better performance of a standalone gas heater.

    The HTP Pioneer is a nice unit, but it's probably way overkill. If you go that route, the smallest of the bunch (PHR100-55) with the 35-100K burner would be an OK match, and is enough burner to deliver the "endless shower" experience. It would never modulate on space heating loads, since it's min-fire output is more than your heat load on the coldest day of the year, but since it's inherently self-buffering you'd be free to microzone the hell out of the place without risk of short-cycling.

    Got a link to the Columbia units you were looking at?

    It's probably cheaper to hit the same performance point with the AO Smith Vertex (the smaller 76K burner version) or smallest Polaris hot water heater and a plate-type heat exchanger for the heating system loop.

    Whether you'd be able to run the system at condensing temps and still deliver the ~20-25K of heat on design day is an open question- depends on the amount & type of radiation you have. If your system has big old-fashioned cast iron radiators, and was installed before the house was insulated odds are pretty good you'd never need more than 135F out of the boiler, and would likely get at least 90% average efficiency out of it. If you need 150F or more out of it odds are you'd be better off with a 2-3 plate mid-efficiency cast iron boiler with internal smart controls & outdoor reset, which should deliver an honest 85% when tweaked in, and a separate indirect. It just depends.

    What sort of radiation (total amount & sizes) and how many zones?

    [edited to add]

    Do you have a mid or late-winter oil bill with a "K-factor" stamped on it? The K-factor number is heating degree-days per gallon, and using the K-factor on a late winter fill-up would be a more accurate way to measure the true heat load. The nameplate BTUs in/out on the existing boiler would also be useful for making that calculation.

    Some years are colder or warmer than others, and I know the 500 gallons probably isn't a very precise number either, but most 2x4 framed homes with retrofit insulation and storm windows (or middle-of-the road double-pane replacement) will come in between 12-15 BTU per square foot of conditioned space @ +15F outdoor temps, and almost never over 20 BTU/ft unless it has major air leakage (which can usually be fixed for cheap.) If you have any single-pane windows it's worth installing tight low-E (not cheaper clear-glass) storm windows, which which usually pay back in 5 years or less- faster than the lower-cost clear-glass windows, and make the place a lot more comfortable, both winter & summer.
    Last edited: Jul 18, 2013
  5. Steve Lanham

    Steve Lanham New Member

    Messages:
    17
    Location:
    Maryland
    Great forum!! Thanks to all...I've read some of the other threads about sizing. I find some of the figures confusing. I have big cast radiators measuring 682 sq. feet. That was counting the tubes and sections. Not sure what the K factor is. My old oil boiler was a converted coal monster. Someone said it was about 70% efficient. I have gas right next to the boiler feeding 2ea. 50 gal HWH. Changing to 1, i guess 50 gal. indirect. I do have insulation in the walls and old storm windows. Its the blown in type insulation. Columbia boiler recommended the Pioneer because of my chimney. At least 3,000 to reline and could end up being more. Columbia recommended the installer too. Seems like he knows his stuff. He still was thinking 150k because of the indirect....The Pioneer boiler is about 4,000...indirect HWH 1,500...Mechanic wants 10,000 about to do the job..Thats everything.... Plus I have to get rid on the old asbestus boiler for another 1,000. Getting very pricey...PS...2 ea. 50 gas HWH= 2 family house..One
    zone...
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,324
    Location:
    New England
    Unless you're running a spa and need hot water in large quantities constantly, it's stupid to size the boiler for the indirect plus the space heating...you install the indirect as a priority zone, and while it is reheating the water, it stops heating the house. You almost would never know that happened - worst case, the house cools off a degree while that happens, then recovers. A typical WH only has around a 40K or so burner and those aren't very efficient, so maybe 32K going into the tank. About the smallest boiler you'd likely install is a 60K at maybe 95%, or 57K, nearly twice as big - they recover quickly, plus, you often don't drain the whole thing. You might want a 60g indirect, but it would depend on how many bathrooms and simultaneous uses there's likely to be. Read up on waste water heat recovery units (lots of discussions here), and if those hot water uses are for showers, you'd likely never run out if you installed one or more depending on layout and typical use. THey only work on things like showers, but they minimize the hot water you use by making the cold warmer to the shower so you don't need as much hot.

    Get a modcon boiler or other closed combustion boiler, and you vent it out the sidewall...don't need the flue anymore and can seal it up, or tear it out. Not having that there is one less air leak, and often a big one. Most closed combustions boilers use PVC plastic piping as the air inlet and outlet - cheap. Usable because the boiler extracts so much of the heat, the exhaust is cool enough for the plastic pipe.
    Last edited: Jul 18, 2013
  7. Dana

    Dana In the trades

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    What Jim said- a smallest-in-class mod-con + 50 gallon indirect would typically run on the order of $10K installed as a retrofit, and sizing the boiler output for massive domestic hot water is just ludricrous, unless you actually HAVE a need for that much hot water. Scrap the chimney- seal it up, and only go with power vented, since it's clearly oversized for any right-sized combustion appliances.

    A 2-3 plate mid-efficiency cast iron beast (even a power vented sealed combustion version) + indirect would usually be under $10k. The ~70K-in Peerless DE-03 or Burnahm PVG3NI-BS would be on the big side, and still ~$2K for the boiler itself. The New Yorker PVCG30NI-T2 is a 62K-in, running under $2K. I'm not sure who if anybody is still making a 2-plate power vented cast iron, but ~50K would definitely be better sized for your heat load, and still enough to deliver the hot water, provided you up-size the indirect (50 gallons isn't going to cut it for a 2-family.)

    The Triangle Tube Solo-60 or Peerless PF-50 and similar mod-cons run about $3K for the boiler, and have low-fire output sufficiently small to modulate for at least of the the winter at your heat load, and give you a true mid-90s performance when the reset curve is dialed in (provided you don't micro-zone the hell out of the place with only low-mass fin-tube baseboard for heat emitters and short-cycle it into lower efficiency and an early grave.) If you keep the system configured as a single zone system it'll do fine. Don't get pulled into the temptation to up-size the boiler for better hot water performance unless you really do the math on it. If you need more hot water since it's a 2-family, upsize the indirect, not the boiler. Any ~50KBTU/hr mod-con has nearly 2x the burner output of a typical 50 gallon tank, but if you have both sides filling a bathtub or showering simultaneously for more than 10 minutes you'll need more than 50 gallons of storage.

    What type of radiators/baseboards, sizes, lengths, etc?
  8. Steve Lanham

    Steve Lanham New Member

    Messages:
    17
    Location:
    Maryland
    My radiators are 682 sq. ft. I measured the sections and tubes as instructed.12ea. radiators...At this point I,m willing to spend the extra cash for a mod con with a 60 gal. indirect single zone. Reading different articles and it seems lots of people have different ideas about the best boilers. I would like to have something efficient but with the duribilty of my old Winchester oil boiler. Also who can give me an accurate " J " reading. Does the Co. thats doing the change over offer that service or are there specailty Co. that do it. I,ve spaced around but have'nt nailed that down. So in a nut shell...1800 sq. ft. 1932 well built cedar shake original with aluminum siding over that. Wood lathe plaster walls. Blown in insulation. Older storm windows first floor. New replacement windows on second floor. Finished basement with electric heat thats not used to often. Finished attic that is also electric heat and also not used often. PS...glad i found this sight. Info feels genuine !
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,324
    Location:
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    There are some on-line apps that take a wag at a proper manual-j calculation, but the better applications are costly, so you don't want to buy a copy. With the accurate oil usage, the K-factor, and the heating degree day info, you can figure a typical heat load. Dana did part of it for you, but to be more accurate, you need the K-factor (essentially the actual energy content of the oil delivered if I understand it properly). Mate that with the heating degree day info for your zip code, and you'll be close. The HDD info is free to download.
  10. Steve Lanham

    Steve Lanham New Member

    Messages:
    17
    Location:
    Maryland
    In reference to my K factor...On Dec 5th 2012 we had 47 gal. of oil delivered which topped off the tank. On Jan 12th 2013 we had 131 gal of fuel delivered to top it off. The oil Co. told me our K factor was 7.01. Does this sound right ? I kind of feel like I,m leaving the work to others. But if someone can use this info to help size my boiler I would be grateful. In the mean time I'll read what I can and try to come to my own conclusion. Thanks !!
  11. Steve Lanham

    Steve Lanham New Member

    Messages:
    17
    Location:
    Maryland
    After further investigation....I am now considering the Alpine 80. Still looking at indirects...Would like one with a stainless steel tank..60 gal. i'm guessing. It's a two family house but the kids are gone which leaves four adults who generally don't abuse the HW. ... The Alpine 80 modulates from 16 to 80 kbtu which should be fine for my aproximate 24,000 btu hr. heat load...I'm new at this so I hope I'm stating things somewhat correct. I have'nt looked over the prices yet but so far I feel I'm going in the right direction...Always open for ideas. Thanks !!
  12. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,324
    Location:
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    The quality of the install is critical along with proper selection of components. I have a Buderus for a couple of reasons: it was recommended to me, and the US headquarters is about 15-miles away. So far, about 4-years or so, it's been trouble-free. SuperStor has a decent warranty, but there are others. http://www.htproducts.com/superstor-ultra-waterheater.html
  13. BadgerBoilerMN

    BadgerBoilerMN Master Hot Water Mpls,MN

    Messages:
    303
    Location:
    Minneapolis
    We design hydronic heating systems for professionals and homeowners all over N.America. We always start with a proper Manual 'J' 8 heat load. For retrofit installations, particularly conversions oil to gas or steam to water boilers we consider the radiation for design temperature and potential output but it does not factor into any calculation unless a steam boiler will be replaced with steam.

    When converting an oil boiler to gas the overall heat load and any small or micro-zone may be of interest but the block load is the thing.

    Here in Minneapolis we do a considerable business replacing old gravity and atmospheric boilers with condensing boilers of every kind. If you are happy with your current tank-type water heater and you don't plan to add a large tub, the same size indirect will usually satisfy.

    As for brand, warranty doesn't matter. It is the selection of size, features and proper application, control programming and start-up that really matter. The HTP VersaHydro is a useful tool and quite exclusive in terms of design so not everyone will be qualified to install or service it. Ask if the potential installer has any in the field.

    More common condensing boilers use indirects for DWH with a few combi-units like Navien, Triangle Tube and Bosch, which are essentially low-mass, condensing boilers with built-in tank-less water heaters. Good for certain applications.

    All will need regular annual maintenance performed by qualified service technicians. Rare.
  14. Steve Lanham

    Steve Lanham New Member

    Messages:
    17
    Location:
    Maryland
    Hey Badgerboiler...What you said about qualified service techs...Rare... and some of the issues I've read about on the net with customers not happy with the install and having trouble finding someone who can fix their problem is making me second guess the high eff. mod con...Buy a lemon of a car and you trade it in...have the wrong boiler installed or one that no one knows how to work on your stuck...I'm now pondering staying with non condensing cast iron boiler. With my aproximate heat load of 24,000 btu I'll have to find a boiler that can handle that small of a load..I even think 24k is a over shoot. I'll continue to shop, if anyone has a suggestion it would be appreciated.
  15. Tom Sawyer

    Tom Sawyer In the Trades

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    Location:
    Maine
    http://www.qhtinc.com/

    Check out the Firebird boiler. It is a condensing oil boiler but it does not need to condense to still give you very decent efficiencies and performance
  16. Steve Lanham

    Steve Lanham New Member

    Messages:
    17
    Location:
    Maryland
    Thanks Tom but I am changing over to gas. I hope someone has a few suggestions. I'm going to contact some local HVAC Co. and see what they come up with. I work with some competent plumbers but I think I should go with a HVAC shop to do the install for warranty reasons and it would be easier to hold them accountable. More $ that way but I'd have piece of mind. After reading some post on this sight as well as others I have a much better insight on what to look for. I just can't figure out why Columbia Boiler recommended someone who suggested putting in a 150,000 BTU boiler for my 1800 sq. ft. house. I'm going to contact him again and make sure I heard him right. Thanks !!
  17. gennady

    gennady New Member

    look at lochinvar wall hang boilers. they also have cadet boiler line, but i would prefer WHN series firetube boilers. their low fire11k.
    http://www.lochinvar.com/_linefiles/WHN-02.pdf
    i personally prefer viessmann vitodens boiler. if you will find installer for viessmann boiler, go for it,
  18. Tom Sawyer

    Tom Sawyer In the Trades

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    Location:
    Maine
    Non condensing gas, try the Biase with a carlin EZ gas burner.

    Radiators are good but your piping may not be. Ther is a good chance that hooking any sort of mod con to the system may be a bit of a disaster which is probably why you were quoted such a big boiler. Properly done, all of your radiators should be re-piped using much smaller supply and return piping. I like to pipe each radiator individually to zone manifolds and or use thermostatic radiator valves on each. So, unless you have the money to totally re-do the system I suspect that you might want to look into a decent cast iron, 2 or 3 pass boiler with a power gas burner. The Biase will get you in the low 90's efficiency wise which if you do a cost vs savings is probably going to make more sense.
    Last edited: Jul 21, 2013
  19. Dana

    Dana In the trades

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    A K factor of 7 is credible. The simple-arithmetic assuming an outside design temp of +15F and a steady state combustion efficiency of 85% looks like this.

    7 heating degree day /gallon is the same as (24 x 7= ) 168 degree hours / (0.85 x 138,000 BTU), 117,300/168= 698 BTU per degree-hour.

    With a balance point of 65F and a 99% design temp of +15F you are at (65-15=) 50 heating degrees, for a heat load of 50F x 698= 34,900 BTU/hr.

    That's a bit on the high side for an 1800' house, there may be some low hanging fruit left on the building envelope, but any 50K boiler (condensing or otherwise) can handle your loads. If the true steady state efficiency of the boiler is only 70% (could be, hard to say without measuring it), the heat load is more like (70/85) x 34,900= 28,740 BTU/hr.

    That works out to about 16 BTU/ft of conditioned space- still a bit on the high side, but not a total energy pig. (Do you have foundation insulation? Have you ever performed blower-door directed air sealing done on the place?)

    Assuming the heat load is closer to the 28,740 number (probably is), with 682' of radiator you're looking at (28,740 / 682 =) 42 BTU per square foot of radiator. Most radiators are good for about 170 BTU/ft @ 180F AWT, and drop fairly linearly with temp to about 0 @ 70F AWT. So you get about 170/( 180F- 70F)= ~ 1.5 BTU of output for every degree over 70F. That implies the water temp out of the boiler you'd need at the 99% condition is about 70F + (42/1.5)= 100F, which would be well within the condensing range of a condensing boiler, and with the right boiler & system design, when dialed in you'd average above 95% efficiency. If the heat load is the higher 34,900 BTU/hr number that's still only about 51 BTU ft of radiation, and your water temp requirement @ +15F outside would be around 105F, still well within condensing range, and achieving over 95% likely with a decent design.
  20. gennady

    gennady New Member

    There is no need to repipe system. Just do primary secondary loop with outdoor reset.Also system must be properly cleaned and water must be conditioned. Also, you get quoted big boiler because probably nobody calculated how much heat your house loses on the coldest day of the year.
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