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Replace an unreliable mod/con with another?

PollyQ
PollyQ Member Posts: 1
Part A
I am going to replace my mod/con gas boiler (94% AFUE) because it has had three failures in 12 years (company name begins with B). For each failure, I was out of the country for an extended period in winter. Twice the exhaust blower had to be replaced (different problems), with a corresponding delay waiting for parts to be overnighted. If it were not for these failures, I would say that I am pleased with the comfort and operation of the boiler. Compared to the previous oil-fired, 40 year old original, the comfort and operation is great! I now have internet connected thermostats so I can monitor for possible heating failures.
Conditions: 1950’s, well-built home in upstate New York, upgraded insulation and windows; baseboard emitters, most rooms have excess output for heating requirements so low circ temps work ok, 4 thermostat zones and two radiant floor heat zones without thermostats (They work really, really well. Explanation by request.); boiler provides indirect hot water to a 40 gal tank; outdoor reset not used but water temp is actively managed when I am home or set to 135f when I am away.
I am also not sure if a mod/con boiler is the best choice. I am willing to pay extra for the high efficiency version and I need to stay with a low temperature, side wall vent. I want the efficiency AND reliability.
Should I consider a non-condensing boiler in hopes of improved reliability? I have seen just as many failures for other non-mod/con installations. Did I buy a race car that should have been expected to be babied? I am considering a replacement from a company that starts with V. The manufacturer is better represented locally (parts off the shelf). But an annual servicing will run ~$500. Would this be swapping a Ferrari for a Porsche when a Ford would do just as well?
My background is in physics and engineering and it can skew my thinking because I love to understand and be involved in the nuances of physical processes. Certain joys come with a cost. I know.
Thoughts?
Part B
Here is a (unrelated) question. Observing the exhaust from my boiler in operation. There is always a cloud of condensate in the air at the vent. Does that mean that there is uncaptured heat since the moisture has not condensed in the heat exchanger? Or does the cloud represent the captured heat-bearing condensate?

Comments

  • mattmia2
    mattmia2 Member Posts: 2,873
    edited March 24
    Another option, depending on what your loads look like, might be to use 2 very small modcon boilers so you have redundancy and can provide at least emergency heat. Pipe them as primary-secondary to the same house loop and they can run individually or together. i suspect one can heat the whole house most of the time and you would only need both to heat dhw at peak demands and for the coldest days of the year.

    This is probably more of a viable option for less expensive modcons but you have to make sure they have the controllability to do things like keep the output low and steady vs racing up to get a certain supply water temp then shutting off. That might mean built in controls or a separate controller and a 0-10v control input.
  • STEVEusaPA
    STEVEusaPA Member Posts: 4,926
    Maybe research and choose a different contractor who is more familiar with mod/cons and their maintenance and service. Let them pick the boiler, one they know for reliability and easy parts availability.
    If you're out of the country frequently, you should at least have a way to monitor the system. Should it lock out or have a problem, you can get someone over there before there's a freeze up.
    You should be using outdoor reset with a mod/con, otherwise you're rarely taking full advantage of efficiency and savings.
    steve
    HVACNUT
  • JUGHNE
    JUGHNE Member Posts: 8,265
    Often blower problems are related to rebreathing of exhaust gases.
    If you post some pictures of the exhaust and inlet piping someone may give advice.
    Some close and then back up to see the outside of the house as to inside corners and roof overhangs.

    Your oil burner was the "Ford", although you can get a new gas burning "Ford" but will need a chimney thru the roof, (probably reline existing).
    And you will drop 10% efficiency.....crunch those numbers with the annual $500 visit.
    You might need service only every 2-3 years for the Ford.

    That extra 10% is the condensing of exhaust gases to liquid. It requires a phase change to milk that 10% out of those gases.
    Most of that liquid should be draining out of the boiler condensate piping.
    What you see is residual vapors carrying with some water vapor...product of CH4 combustion. The exhaust pipe should drain/slope back towards the boiler to avoid most of the liquid.
  • Steamhead
    Steamhead Member Posts: 14,425
    This is why we don't recommend mod-cons. Traditional gas boilers have gotten a lot better in the past decade or so, so the difference in efficiency is much less than it was. And, this type of boiler can usually be fixed using standard parts, eliminating long delays for OEM stuff.

    The fact that you're often out of the country would seem to indicate that reliability and ease of repair should be your primary considerations.

    Mod-con manufacturers need to do what oil-burner manufacturers did in the early-to-mid 20th century: Standardize parts across brands so all brands are easier to service. I'm not holding my breath............
    All Steamed Up, Inc.
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
    bucksnortHVACNUTPC7060SuperTech
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 2,094
    edited March 24
    If your V brand is Velocity (formerly Crown) I would highly recommend that boiler. On the non-condensing boilers, Velocity/Crown has a habit of using standard off-the-shelf parts (like Honeywell Tradeline series) making it easy to get parts. Some of the repair service providers who advertise "Wearhouse on wheels" may even have the needed part on the truck. I used to have a substantial stock of parts on my service vehicles. But my experience with Velocity/Crown is every few failures especially on the lower cost, cast iron, chimney vented models. They use the KISS method for building boilers.

    If the V is for Viessman, I'm not too familiar but I hear it is quality stuff.

    The non-condensing boiler has its place, and your home may be one of them.

    Yours Truly,
    Mr.Ed
    Edward Young
    Retired HVAC Contractor from So. Jersey Shore.
    Cleaned & services first oil heating system at age 16
  • Jamie Hall
    Jamie Hall Member Posts: 15,746
    You've got a joker in your deck: you want to keep the sidewall exhaust. That makes a condensing boiler almost mandatory (and yes, the cloud of steam does represent lost heat -- though probably not that much of it. The water in the exhaust gas will be at 100% relative humidity when it leaves to boiler -- at the temperature at which it leaves the boiler. When it hits the outside air, that moisture is going to condense. Pretty well can't help it. Even if it leaves the boiler at say 110 -- which would be a very low return temp -- it's going to make a jolly cloud).

    Whether the boiler can condense or not is a matter of material choice and construction by the boiler manufacturer -- as well as the ability of the rest of your heating system to consistently return cool enough water to the boiler. Modulation, by itself, actually doesn't do much for efficiency, as it's perfectly OK -- with only minor losses -- to use on/off modulation instead of analogue burner modulation. Granted, if one's system is relatively low mass you are going to want a buffer tank in there to decrease the frequency, but that's minor, as is adding mixing valves which respond to outdoor conditions, perhaps with an indoor trim.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • STEVEusaPA
    STEVEusaPA Member Posts: 4,926
    edited March 24
    The problem with Velocity/Crown, is when you do need a part from them, you can only get it from them thru a supplier-big PIA with chambers. So there will be a delay getting parts that no one stocks. Or your supplier calls in an airstrike and you get the joy of driving into to the opioid capital of the world to get a part.
    steve
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 2,094
    edited March 24

    You've got a joker in your deck:

    Flattery will get you nowhere Mr. Hall*

    Remember this gentleman wants something with as few things to go wrong as possible. Adding mechanical valves and the like to save another 1% or 2% on operating cost may be the reason for a frozen pipe to happen. I'm for the simple boiler connected to the regular baseboard zones and setting the high limit to 150° max in order to achieve a 130° minimum return temp. to reduce condensation of flue gases. There are also some fan-assisted, non-condensing boilers that can be sidewall vented with stainless steel (if the chimney vent is no longer available). Looks like the reduced temperature for the floor heat can just be connected to the 130° to 150° piping. Looks like @PollyQ has a handle on that:(They work really, really well. Explanation by request.)

    The choice is difficult I'm sure, but consider all the costs. Annual maintenance, repairs, and fuel when selecting & comparing. There are tens of thousands of old gas boilers out there that have been chugging along without maintenance for over 5 years (and longer) with gobs of rust and dust covering the atmospheric burners. They will perform just fine for another 5 years without anyone even thinking about them. That is the dependability PollyQ is looking for. Of course, Polly Q will have the necessary maintenance completed... At least I hope so... Just using those unmaintained systems as an example.

    Respectfully Submitted,
    Mr.Ed

    * see how I made it look like Jamie was talking about me! It's all about me here. LOL




    Edward Young
    Retired HVAC Contractor from So. Jersey Shore.
    Cleaned & services first oil heating system at age 16
    MaxMercy
  • MaxMercy
    MaxMercy Member Posts: 164
    When I decided to replace my 28 year old boiler proactively (running fine) three years ago, I did a lot of research into mod/cons and talked to several people I know in the trade.

    There were two issues: one is that my home is a hydro-air with an air handler for each zone (floor), and there might be a loss of efficiency due to running temp requirements of the air handlers, or so I was told.

    The second is that the opinion of pros as to how much fuel I would save with a mod/con over a good pin or triple pass cast iron boiler might be 5% if everything was running well. I had to reconcile the *potential* fuel savings with the more expensive maintenance the mod/con would need, the much higher cost and less local availability of repair parts, and most importantly, the short life of a mod/con.

    I installed my packaged boiler basically reproducing what was there with all new piping, expansion tank, and valves, electronics, etc. and was maybe into it for $3K (parts cost, so this shouldn't be against the rules I don't think. If so, I'll edit...). Compare that to a significant difference if I had a mod/con installed professionally (I wouldn't attempt that) plus the other cost factors and half-life of a traditional cast iron boiler, and it was a no-brainer. Even if I had the cast iron boiler installed professionally, it still made much more sense to me to go with a cast iron boiler. Traditional boilers are also far simpler and easy to troubleshoot.

    I don't know if my new boiler will go 28 years like my builder spec steel boiler did, but it should.

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 8,857
    All Mod Cons should have yearly service, if you want them to last that is. And by last I mean maybe 15 years. And with changing technology a Mod Con is obsolete after 15 years. Look at all the Munchkin owners on this site, they can't get parts for their old boiler so they become throw away's

    And the cost of parts is one thing, what do you do when you have a long wait for parts? Need some form of supplemental heat.

    When you add up the pros and cons I cant see it for a convential heating system.

    If it's all low temperature..................................maybe

    Nothing worse than going on a no heat call and telling the customer you can't do anything and that the supply house doesn't have the parts
    MaxMercy
  • HVACNUT
    HVACNUT Member Posts: 3,909
    If you absolutely need sidewall venting, then your in a different category right off the bat. An atmospheric boiler won't do it but there are options. There are plenty of induced draft boilers out there. A cast iron 3 pass boiler with a power burner? I know you can direct vent (not power vent) some in oil applications. Not sure about gas.
    The System 2000 Frontier Gas can also be sidewall vented. 
    Annual maintenance by an experienced, thorough tech is important no matter what you choose. 
  • mattmia2
    mattmia2 Member Posts: 2,873
    Of course power venters tend to fall in the same reliability category as modcons...
    EdTheHeaterMan
  • Zman
    Zman Member Posts: 6,539
    I am thinking you should post the names of the boiler you have and are considering as well as the area of the country you are in.
    I like mod-cons and think the increased efficiency is worth a little extra maintenance.
    Would you buy a Toyota over a Subaru if someone told you that Toyota will last longer if you prefer to never bring your car in for service? For some reason many people don't see heating appliances the same way...
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • SuperTech
    SuperTech Member Posts: 1,634
    You must have a lot of baseboards in your house to be able to heat with 135 degree water. Why no outdoor reset? 
    I don't think a mod con is the best option for a home with the majority of the heating is baseboards. An Energy Kinetics EK-1 with a Carlin EZ gas burner can be sidewall vented and will have an AFUE rating over 85 percent.  It will be much more reliable than any mod con and is easier to service using readily available parts. 
    I've found that the majority of homeowners value reliability over efficiency.  Efficiency is great until someone has to wait several days on the coldest or hottest day of the year for a model/brand specific part for their fancy mod con or mini split that isn't readily available locally.  
    szwedjbucksnort
  • MaxMercy
    MaxMercy Member Posts: 164
    edited March 25
    Zman said:

    I like mod-cons and think the increased efficiency is worth a little extra maintenance.
    Would you buy a Toyota over a Subaru if someone told you that Toyota will last longer if you prefer to never bring your car in for service? For some reason many people don't see heating appliances the same way...

    It's not just the maintenance - it's the cost going in, the cost of repairs, the cost of replacing it again after 15 years if one is lucky.

    When I looked at mod/cons, I figured that I would save $100 a year over an 86% cast iron boiler in my application. The downside is that the mod/con is far more sophisticated a beast that will cost me more in maintenance, more in parts and labor when it breaks, and I will have to replace it again in 12 -15 years.

    My wife's co-worker had a Buderus shut down in January. Three local companies couldn't figure out why. I finally found someone through my contacts that was sure he could fix it, but my wife's friend just bit the bullet and replaced their 10 year old boiler with a new system.

    https://forum.heatinghelp.com/discussion/182503/buderus-gb142-no-heat-update-error-codes#latest

    SuperTech
  • Steamhead
    Steamhead Member Posts: 14,425
    MaxMercy said:

    My wife's co-worker had a Buderus shut down in January. Three local companies couldn't figure out why. I finally found someone through my contacts that was sure he could fix it, but my wife's friend just bit the bullet and replaced their 10 year old boiler with a new system.

    https://forum.heatinghelp.com/discussion/182503/buderus-gb142-no-heat-update-error-codes#latest

    I recall reading somewhere that in Europe, you have real trouble finding parts for mod-cons after about five years or so. So the usual practice is to replace the whole unit if it breaks down after that time. Wouldn't surprise me if they're starting to do that here.

    Another reason to not recommend mod-cons.
    All Steamed Up, Inc.
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
    MaxMercySuperTech
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 8,857
    The first time you need a blower motor assembly and the supply house doesn't have one and it cost's $500 or more for the part let alone the labor and inconvience and your freezing you will think twice about a Mod Con.

    People are replacing them and their only 10-15 years old. A throw away like a refrigerator or washing machine
    MaxMercySuperTech
  • bucksnort
    bucksnort Member Posts: 109
    edited March 25

    The first time you need a blower motor assembly and the supply house doesn't have one and it cost's $500 or more for the part let alone the labor and inconvience and your freezing you will think twice about a Mod Con.

    People are replacing them and their only 10-15 years old. A throw away like a refrigerator or washing machine

    I replaced a frig last June that lasted 3 years when it crapped the bed. My "new" power vent boiler will replace a 1987 PV CI boiler. I looked at Mods and wanted to be green and save the world. I decided a $60 a year savings in fuel didn't offset the $300-500 yearly maintenance costs plus the half life they flat out tell you to expect.
    I follow a youtuber guy that goes around fixing units he pushes (Navigen). Skip the yearly maintenance and the unit is junk after 5 years or less. He recently discovered why these units are crapping early. They have a poor exhaust seal that causes the unit to breath it's own farts.
    It must be rough being a shill for the manufacture and publicly pointing out a design defect that effects thousands of these units to die early.
    EdTheHeaterMan
  • mattmia2
    mattmia2 Member Posts: 2,873
    If you know why the unit will fail of you don't maintain something then you can keep ahead of it. This was most of the big 3's reliability issue, they would find something minor that would fail and destroy something major, they would find a fix for it, but they wouldn't tell the customer about the fix so people stopped buying their product.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 8,857
    Heating system maintenance is non existent in most peoples minds. They have money for vacations and cars but don't think about heat until it fails.

    My niece is a perfect example.

    She bought a house 2 years ago with a 31 year old condensing furnace and split system. Told her before she bought the place to get some money off for new equipment. She didn't and instead bid up on the price because she wanted the place.

    The stuff runs good and is in good shape, I checked the HX.

    But last week she had no heat and i changed the high limit control

    all she did was complain about a $16 part
    EdTheHeaterManSuperTech
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 2,094

    Heating system maintenance is non existent in most peoples minds. They have money for vacations and cars but don't think about heat until it fails.

    My niece is a perfect example.

    She bought a house 2 years ago with a 31 year old condensing furnace and split system. Told her before she bought the place to get some money off for new equipment. She didn't and instead bid up on the price because she wanted the place.

    The stuff runs good and is in good shape, I checked the HX.

    But last week she had no heat and i changed the high limit control

    all she did was complain about a $16 part

    As it should be! How dare you charge your favorite niece for fixing her heater!
    BTDT

    Mr.Ed
    Edward Young
    Retired HVAC Contractor from So. Jersey Shore.
    Cleaned & services first oil heating system at age 16
  • Zman
    Zman Member Posts: 6,539
    The savings are a bigger consideration with low temp emitters. I have in-floor heat on propane. The boiler runs at a max SWT of 130 on design day. I started saving 25% over non condensing when I installed it 13 years ago. It is still running strong with very few issues. I save about $600 a year.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    flat_twinSuperTech
  • mattmia2
    mattmia2 Member Posts: 2,873
    Zman said:

    The savings are a bigger consideration with low temp emitters. I have in-floor heat on propane. The boiler runs at a max SWT of 130 on design day. I started saving 25% over non condensing when I installed it 13 years ago. It is still running strong with very few issues. I save about $600 a year.

    Propane is also much more expensive than natural gas in most markets.
    Zman
  • SuperTech
    SuperTech Member Posts: 1,634
    Zman said:
    The savings are a bigger consideration with low temp emitters. I have in-floor heat on propane. The boiler runs at a max SWT of 130 on design day. I started saving 25% over non condensing when I installed it 13 years ago. It is still running strong with very few issues. I save about $600 a year.
    Thats an appropriate application of the product.  The thing that drives me crazy is that I see a lot of companies pushing the mod cons as replacements for good working cast iron boilers that heat fin tube baseboards. They sell them on the mod cons and their "efficiency" because they don't want to deal with installing a heavy cast iron boiler.  They don't educate the customer about how efficient it is when heating water to 180 degrees, the service issues and the fact that they don't last nearly as long as a cast iron boiler.  All they care about is making a sale. Its really a disservice to the customer.  

    ZmanbucksnortPC7060
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 8,857
    @EdTheHeaterMan

    LOL, HAHA. I didn't charge her a thing except for the $16 for the part. She said she didn't have any cash on her. She is going to send me a check. Will see.

    I have done work for her sister. She won't let you out of the house unless she pays you
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 2,094
    @EBEBRATT-Ed, I'm sure that she would rather owe it to you than cheat you out of it.

    One of my favorite "almost famous quotes"
    Edward Young
    Retired HVAC Contractor from So. Jersey Shore.
    Cleaned & services first oil heating system at age 16
  • Skyline
    Skyline Member Posts: 90
    MaxMercy said:

    When I decided to replace my 28 year old boiler proactively (running fine) three years ago, I did a lot of research into mod/cons and talked to several people I know in the trade.

    The second is that the opinion of pros as to how much fuel I would save with a mod/con over a good pin or triple pass cast iron boiler might be 5% if everything was running well. I had to reconcile the *potential* fuel savings with the more expensive maintenance the mod/con would need, the much higher cost and less local availability of repair parts, and most importantly, the short life of a mod/con.

    I wish I did a lot of research in to replacing my 20 years old non-condensing combi-boiler. In retrospect, staying with the non-condensing combi-boiler technology would had saved me some pretty good penny both in installation and maintence cost.

    While the fuel saving is real with mod/con combi-boilers, it's nowhere nearby to the level advertised. At least not for my house with CI radiators and baseboard:



    Especially, if you take it into account the increased electricity utilization, that takes away roughly 40% of savings in natural gas utilization. For some reason, the electricity utilization is not accounted for calculating the EFUE value; in my view, it should be.

    Nor do anyone tells you up front, that to achive the 95-98% EFUE rating the RWT needs to be 80, or less Fahrenheit. Crank up the RWT to 115-120 degree Fahrenheit, the EFUE rating drops like brick to the mid to high 80%. In another word, the high efficiency boiler runs at marginally higher efficiency rating, than the none-condensing boiler.

    None of the installers warned me about, that to actually achive the maximum AFUE rating, I should change the radiators to large conductive heating surfaces such as radiant floors, walls and ceilings. I learned this after the new boiler had been installed.

    Despite all of this, I still like the Viessmann boiler for number of reasons. On the otherhand, this is my first and last mod/con boiler, at least in my current "this old house". I did fall for the high efficiency mod/con boiler once, I'll be damned if I do it again...

  • clammy
    clammy Member Posts: 2,647
    I have to agree on all points ,most never did maintainace on there cast iron boiler so there never doing it on some thing that is required yearly w mod cons . I try to keep it simple and unless it’s all radiant or low temp they get cast iron and a liner plain and simple . I see all crap jobs in hi end house and just smile fix em get them running leave w suggestions of service and that’s the end till it codes off again . Most of the time there never installed correctly or set up no combustion testing no condensate neutralizer just 2 pipes and 2 tees and that simple . I recently looked at one and when it goes who know what can be done for a replacement installed in a crawl space and the rest of the basement is completely finished and there’s no mod con that will be shoe horned into the crawl space ,big issue but as usual the big company who installed just gets out of service by being overly expensive and doing nothing and in my eyes not doing a dam thing at 12 years old and never been cleaned or set up w combustion analyzer wow only a large company could get away w it and have the balls to say it the way it’s done .its a testament to the equipment but that does not make it right . I feel in the future it won’t matter which mod con u put in after 10 to 15 years w proper maintainace they will like ancient Mayan history gone ,plus after 10 years who knows what parts will be available . As for proper install and maintenance including water testing ,combustion testing and set up makes any thing other then hang and pipe and go a costly proposition in any case which puts those who do all the right things right out of the potential customers budget being every body just price checks you outta business . As for the whole green thing why not start w not living a renewable throw away lifestyle which is extremely common and be a little more frugal w energy use and everything in general . If you really want the lastest and greatest then be prepared to put the money where the mouth is and pay for the annual service and also be prepared to replace in 10 to 15 years , hell they change there cars every 3 on lease so where that being green ? I think the lack of maintance on hvac equipment is beyond common being we live in a throw away economy so why service clean and repair when’s u can make more money installing new and replace again in a few years works for the global economy . Every body wins plus u get to cut out and toss those expensive press fittings and press in some more . Peace and good luck clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
    bucksnort
  • hot_rod
    hot_rod Member Posts: 14,755
    Are you saying with the building upgrades you can heat on design day with 135 SWT? So 80% if the heating season you could heat with lower SWT?
    If so a modulating condensing boiler seems like the best match. Not sure you want to turn a new cast boiler at 130- 135? If so add some return protection,
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
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