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Condensing or non-condensing boiler?

Felix48
Felix48 Member Posts: 1
We are going to be doing a fairly extensive remodel on our 60's ranch house (doing it mostly ourselves) and with it we will be upgrading our 26 year old water heater with a on demand unit, and our 37 year old boiler (both natural gas). We are going to be installing staple up radiant heat for the first floor and using some of the baseboards from the first floor to the basement we are finishing. The radiant heat will be split into 2 zones and the basement on its own zone.

Doing as much digging as I possibly can, I am not sure what type of boiler to go with. I know both will/can work for both applications. We live in central Wisconsin btw, so it does get cold here. Our basement does pretty well, doesn't get really cold, it does have a single baseboard down there about 8 -10 feet long. We will be framing and insulating the walls as well.

I am thinking that doing a condensing boiler and using lower temp baseboards would work? Opinions?

Comments

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,725
    DYI and Modulating Condensing Gas boilers don't go together. Hell, there are too many Professionals that can't get it right on those confound new-fangled things.

    If you are going with DYI because your location does not have a good Pro that knows the ins and outs of Condensing boilers, then i would go with something simple. a Forced Draft boiler that can chimney vent (with a proper liner) or sidewall vent with Stainless steel venting material.

    That said, if you want to get the 90+% efficiency boiler then you need to get a good Pro

    ...or go to several trade classes on the boiler you select, purchase the proper combustion analyzer, and ' oh yea, get about 8 to 10 years experience on hydronic piping design.

    But seriously, It is a good thing that you are here. There are several resources here to help you decide. You can ask questions and get answers on a variety of situations. Hell, there are people who will give you a thumbs up or thumbs down on your design choices, piping layouts, and equipment selection.

    I would go with a condensing boiler, but I have been doing this for 45 years and know a little about this stuff. I might have installed one or two before I retired. You have to know your limitations and decide on the best option for you. What happens if it breaks down in the middle of a cold snap? Who is available to fix it?

    Wait for tomorrow to see the rest of the comments.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • MaxMercy
    MaxMercy Member Posts: 507

    DYI and Modulating Condensing Gas boilers don't go together. Hell, there are too many Professionals that can't get it right on those confound new-fangled things.

    "A man's got to know his limitations".. ~ Det Harry Callahan.

    That's the reason I didn't choose a mod/con when it came to replacing the boiler in my house. I know what I know and, more importantly, I know what I don't.

    But my question for the professionals is, for all the added complexity and service issues of a condensing boiler, how much more efficient in *actual* fuel used (not AFUE efficiency ratings) per heating season is a mod/con *properly designed and installed* as opposed to a good three pass or even a pin boiler?
  • psb75
    psb75 Member Posts: 828
    The "modulating" feature is a real fuel-saving benefit. The "condensing" aspect is "frosting on the efficiency cake." The boiler will ONLY condense if the rest of the heating system is designed correctly for the application.
    The concepts work well...if they are understood, and applied correctly.
  • clammy
    clammy Member Posts: 3,104
    Bottom line even w proper installation ,set up and maintenance a wall hung will never out last a cast iron boiler . Cast maybe 30 years if not more at the very best a mod con w yearly maintenance maybe 15 tops 20 and I think that a stretch no matter which manufactures they will never last as long as cast . On the other side sized properly and used for low temp up to lower mid temp is where it will shine . My own home is some staple up and panel radiators max temp about 135 at 10 oat . Everything is sizes for low temp .It s getting up in age close to 13 or 14 years old and I haven’t had any error codes or product failure and yes my gas bill is low always averaging in colder months no more then 120 bucks , it s a small home also . Am I planning to replace soon of course I m a little unsure of what will be next but it will be another mod con hopefully w a 10 to 1 turndown and modulation on the low end of 8 mbtu would be great . In closing do as much research as possible and weigh out your roi between cast and mod con . There s a lot a mod con can do w ease that a cast iron boiler will require return water temp protection from extend low return water temps something that mod cons can handle and doesn’t worry about . It can get equally expensive either way cast boiler will require return protection and mixing for low temp output plus what ever chimney updates u may need like a chimney liner while all that’s gone w a mod con except there’s the maintenance costs w a mod con ? Really do some math low temp system are very comfortable when designed correctly and everything is taken into account when not there a head ache and never meet the customers expectation unfortunately . Also low temp system usually over all cost more on the convector end because to increasing size to cover the lower input temp . One smaller note to remember w low temp systems don’t expect to use temperature set backs these type of systems can take hours to reach temp from a set back unless it has a boost feature but not much help when the boiler max temps are low just something to keep in mind .take a look at panel radiators they perform better then baseboard at low temps Peace and good luck w your project clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
    psb75SuperTech
  • Jamie Hall
    Jamie Hall Member Posts: 23,176
    I think I'd agree with @EdTheHeaterMan here. Yes, you do get more efficiency -- at least some of the time -- with a condensing boiler. But... as he says, they aren't all that easy to set up properly and keep that way. Not saying that a really good DIY person couldn't do it, they could -- and probably better than some of the professionals could. On the other hand, with much of the heat from a radiant floor, return temperatures can be low enough much of the time to really use the condensing feature.

    The real question is -- how careful and thorough do you want to be in learning -- yourself -- how to set up and control your new boiler. If you technically reasonably savvy, and want to take the time, a mod/con would work well. Given the extra capital cost, however, you may or may not save any money with onte.

    Before you start thinking about what boiler, though, work the procedure as a professional would.

    Start with a Manual J heat loss for the house. Slant/Fin has a very good calculator here: https://www.slantfin.com/slantfin-heat-loss-calculator/ which, granted, is partly advertising for their products (it will happily tell you how much baseboard you need in each room -- maybe no bad thing?) but which is easy to use and works well.

    Then figure out your baseboard and the radiant floor. Be a little wary of the radiant floor, and make sure that it can really provide the heat the spaces need.

    Then size the boiler to that load, and set about designing the system. There's a lot of help here on the Wall (check on https://heatinghelp.com/systems-help-center/category/hot-water), and Caleffi (www.caleffi.com) has a lot of information.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EdTheHeaterMan
  • TAG
    TAG Member Posts: 755
    Make sure you do a proper heat load on the building .... that also includes each room individually. You have to make sure you will get the needed BTU's from the retrofit radiant floor to heat each room.

    I had the debate a few years ago when I was redoing a large stone victorian. After much back and forth we ended up using two conventional Buderus Cast Iron boilers with the Logmatic controls. The house has natural gas and while not cheap to heat -- the payback on the more expensive Buderus 142's (wall) was many many years out. But more important -- I liked the simplicity of the CI boilers and I have used them in many projects some 25+ years old with very little done to them.

    The problem today is the old cast iron boilers from the German makes that can run at lower temps are going away.

    One of my first projects was an early 50's brick extended cape -- it's now my office. We retrofitted radiant (plates) on the main floor and used panel radiators in the lower and upper levels sized a bit larger to use ODR ... we also used panels in two rooms at the corners where we were not going to get enough from the floor. It's really important to understand the load and output. Same with baseboard ... it will work but you have to understand what you will get out of the old baseboard at various temps.

    I will say the the panel radiators are very nice -- easy to control with thero heads on each
    psb75
  • ethicalpaul
    ethicalpaul Member Posts: 5,695
    > Hell, there are too many Professionals that can't get it right on those confound new-fangled things.

    I'm not sure this is a great argument against DIY
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
    EdTheHeaterMan
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,725

    > Hell, there are too many Professionals that can't get it right on those confound new-fangled things.

    I'm not sure this is a great argument against DIY

    I'm not against DIY, I fix my own electric, and I'm not an electrician. I'm pointing out that the more complicated the system is, the more Pros there are that decide to call that equipment "Junk" rather than learn about it.

    That said, if the DIY guy wants to tackle a project, he has to know his limitations. Many Professional tradesmen decide to exclude certain equipment from the scope of their business.

    Prime example, the General Electric down fire boiler from the 1940s When General Electric suspended factory maintenance and support for that product in the 1960s, many oil heat repairmen excluded them from the service contract they offered.

    FP Young Company in Philadelphia became the largest independent fuel oil dealer in part, by offering service contracts on GE boilers. There was a very small (1 column by 3 ") display ad in the OIL BURNER section of the yellow pages with the GE logo and a phone number.

    They had in house training with an operating GE boiler on-site to train techs on the proper operation and maintenance of the thing all the other burner repairmen call "Junk".

    Sold a lot of oil to those GE owners.

    So in conclusion, Know your limitations but before you commit to the equipment of choice, learn as much as you can on how the thing works. You (The DIY) may be the only source for repair and maintenance down the line.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    ethicalpaul
  • TAG
    TAG Member Posts: 755
    ED -- that's so funny. I had two of them in my place in Chestnut Hill PA ... assume it's the same Young on Green Lane. Mine must have been from the very early 50's .....