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  1. #1

    Question

    Hi,

    I live in the mountains of western Maryland and have a 1903 Al covered 3 story house ~4500 sq ft plus full basement and attic but the boiler is only for the first 2 floors. The boiler is a National - U.S. Radiator (who went out of business in 1955) input of 155,000 BTU, output of 125,000 BTU. The boiler vents alone into a 50 ft brick chimney on the outside wall of the house. The flue pipe is about 10 inches in diameter. The house is on radiator heat with one thermostat on the first floor that controls the two floors of living space. Even though the house is very big, our ANNUAL gas bills, indicate 1100 ccf, mainly because the majority of the time the house is empty and sitting at 50 but years ago when people were home most of the day it runs around 3000 ccf. The largest gas consumption over the past three years was in a January and used ~700 ccf of gas.

    According to the guys who measured, they say it's sized right on the money. First guy was a co-worker's brother who owned a HVAC company, now he's retired in Florida. Passed on that opportunity then, now the flooding damaged the gas control valve so might as well replace my monster boiler. New guy is great, but tends to have a "hands off" approach. He seems torn between the Munchkin 140M and a Weil-Mclain Ultra. Prices, installation ease and major options are about the same, according to him. Personally he leans a little toward the Ultra because of the outside temp sensor, inclusion of a wall hanger and long parts/labor warranty but people on this site seem to like the Munchkin. Though when I pressed he did say he installed three times more Munchkins then Ultra's.

    Please talk specifics:
    Al boiler?
    Taco pump?
    Why Munchkin?
    (I can handle it, BTW I'm not a fan of 316L SS -weak and not very corrosion resistant)

    P.S. Please hurry, it was 35 outside this morning, about 55 indoors. He said if I know by Friday he can have either here by Monday - what a guy!

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,922
    I prefer the ultra.
    15 year hx warranty, has its own outdoor reset controls.

    Remembers its last burner cycle, and adjusts its firing rate to higher or lower based on its last run time.

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  3. #3
    Join Date
    Jun 2002
    Location
    Colorado
    Posts
    59
    Old house, loose construction...I figure 40 btu's per sq ft for those. Say 180K output.

    A 125K (output) boiler for 4500 sq ft is allowing 28 btu's per sq ft, Which would be marginal in a brand new tightly constructed house considering a full basement too.

    This is rule of thumb thinking without doing a heatloss calc. Also dunno what winter design temp is in MD. I;m in CO and it's zero here.

    Baseboard radiators give off 580 btu's per linear ft. Add em up and see what you get.

    I like ultra's. Good stuff if its set up right.

  4. #4
    Join Date
    Aug 2002
    Location
    manitowoc wisconsin
    Posts
    4,943
    one thought:munchkin is stainless steel,the ultra is aluminum.If you install the vision package on the munchkin the outdoor sensor & outdoor reset is available too.This guy might not be certified as a vision dealer.
    Take your time & do it right!

  5. #5

    Strange, no Munchkin supporters?

    So people (beenthere) prefer the ultra for the warranty, outdoor thermocouple and the PhD (precision hydronic data) technology. What about durability? Honeywell valves? Taco pumps? I don’t expect my replacement to last another 50+ years but I’m impressed with the cast iron one I’ve got, which will be moving next door to suppliment a neighbor’s coal system while he’s unable to shovel.

    I believe the output is right on, remember the first two floors are heated by this system (third floor has electric baseboard). 1600 sq ft x two floors x 40 btu = 128K ( I think that’s the current output). The new HVAC guy measured all the cast iron radiators, counted fins and columns. Said he had a secret calculation to determine the size and the old one was right on. Strange thing was some radiators with 33” high and others were 31”, thought they’d all be the same.

    I asked him about an outdoor thermocouple for the Munchkin, he said he’d check into it and get back to me today. I’ll check his business card and report his certifications but I do remember it saying things about commercial refrigeration and heating.

    Any advantage to wall hanging? (Space is not an issue.)

    Other side of basement has a dirt floor, would dampness cause issues with spark ignition?

    Thanks for all the replies!

    Getting colder every day....

  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,922
    The advantage of wall mount is space.
    Taco circs are the most common, and are very reliable.
    The honeywell gas valves are holding up good.

    I don't know about your hvac guys secret method of determining the rating of rads, but we get out the Burnham book and use their ratings, oooops, maybe thats his secret.
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  7. #7
    Join Date
    Sep 2002
    Posts
    3,708
    I too have a hard time not going with highmass boiler..just
    for the simple reason they will be there another 50 years.

    As other have said munchkin or any condensing boiler is or
    will be a perfect match to your castiron rads.
    But that is only if you can keep the returns temp lower enough on the coldest day of the year.Which is doubtful.

    So the question would be to you have mild winter or brutal
    winter where the boiler is wide open all winter.If that the
    case I see very little benerfit in a condensing boiler.

    Before someone goes off and says huh? Just think of the
    emitter its a high mass emitter.It require 180 to 190 and
    sometimes 200 when it a long cold winter.

    Thats condensing boiler is no longer condensing.

    Also I would be asking for a strainer to go along with that
    low mass boiler.Very tight water passage we are talking here.












  8. #8
    Join Date
    Feb 2003
    Posts
    1,996
    Modulation might not be your biggest benefit but you might be able to condense in the spring and fall if you can run the rads at a cooler temp according to the reset curve.
    Maybe a non modulating/condensing boiler like the Dunkirk Quantum series might be a better fit for you with rads. It claims condensing goes on even with 160° return water thanks to it's secondary heat exchanger. It doesn't look like any high efficency condensing boiler gives you more then 15 years warrenty on the heat exchanger. I guess you're keeping the 3rd floor electric? Basement staying unfinished with a dirt floor? No heat needed in the future?

  9. #9
    Join Date
    Nov 2003
    Location
    vermont
    Posts
    48
    I got one question "do you wona be replacing your boiler in 15-20 years" or so is the warranty on most low mass high efficiency boilers 12-15 years. I'm not knocking munchkin or weils ultra but does anybody remember "heatmaker". hey they were a great boiler when they work, but prone to plugging up and they have more safety switches to to break. Besides what is 5 or 6 percent efficiency chump change. Your savings don't come from burner efficiency but from system efficiency meaning running your boiler as low as practical to heat your house. get yourself a good castiron boiler and add a good outdoor re-set control and start saving money.

  10. #10
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,922
    A modulating boiler will still decrease its firing rate at the colder temps and save you money, as the return water increases in temp. Weather or not enough to justify its cost, i can't see your house from here to know that.

    What ever boiler you decide on, one thing is most important, its put in right, and they know how to sevice it. Use a good contractor.
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  11. #11
    Join Date
    Jan 2002
    Posts
    1,196
    I'm a big fan of any boiler that does not use indoor air for combustion by design.

    Munchkin is a good choice not only for that reason but the fact that it matches the firing rate to the load on it. Whether it condenses all the time or not is a bonus. Venting the combustion byproducts with PVC means that minimum heat is being lost, again, condensing or not. Even being a draft induced direct vent boiler, you have to lean very closely to hear the thing run.

    Water quality is important for any boiler, but in the case of the Ultra, even more so, and if glycol is used, critical, with the Ultra's aluminum block.

    Get a heat loss done on the structure. Counting and measuring rad's is nice for reference, but not the way to size hot water boilers, guessing by square foot is inaccurate.

    [Edited by hydronicsman on 10-07-2004 at 07:29 PM]

  12. #12
    Join Date
    Sep 2002
    Posts
    3,708
    You say tomato..I say tomato.Hello hydro hows ya doing?

  13. #13
    (simpleman) What about Thermal shock from a low return temp? It's my understanding the optimum return temp is around 165, shouldn't either of these modulating models be able to adjust so the return water temperature is ideal?

    What conditions does the condensing boiler become of great benefit? High/Low return temp? Outside (exhaust) temp? I remember doing a calculation in P-Chem that showed little benefit in condensing water vapor to liquid water, a theoretical increase of 10%. But with the raising price of natural gas I thought a 5% increase of efficiency might be worth a 20% increase of cost. The math didn't really add up as an advantage but I thought the higher end models might have other benefits (like getting rid of the "smart valve" on something like the Burnham RV5). Can the RV5 take an outside re-set?

    The 3rd floor is relatively separate and I have no plans to place heat off the boiler, as long as the bathroom doesn't freeze up there I'm happy. Perhaps in the far future I'll use the gas lines above it in the attic, from gas lights to do something.

    No plans to ever finish the basement, <6 foot ceilings with huge cast iron pipes hanging down to bump your head. Nearly knocked myself out once.

    Good call on water quality! Our water is soft (not softened) but the old iron pipes cause my toilet water tower valve to stick open from little bits of rust, every few weeks. I'll definitely want a strainer, any recommendations?

    At first I asked about Dunkirk Quantum but didn't get much feedback so I decided to let the installer recommend something "equivalent" like the Munchkin. I still like this HVAC guy even thought his specialty is commercial coolers/freezers but also does industrial, commercial and residential heating.

    What's the advantage of using outdoor air for combustion? Density? I thought slightly pre-warmed would be better?

    Thanks again everybody!

    [Edited by md_moutain_man on 10-07-2004 at 10:29 PM]

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