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choosing a boiler

beezer Member Posts: 21
Hi guys... I'm new to this forum & looking for some advise on buying a new boiler. I'm replacing a 40y/o cast iron, natural gas fired unit with a condensing boiler... it will heat through conventional baseboards. I think I want on demand domestic hot water as well, rather than going sidearm. I am considering Veissman, Wiel//McLain, and the Ambassador Onex... these seem to be the 3 names that are common in town. I want input on reliability mostly... also interested in parts availability. I know some of this depends on location, but just looking for input on a general basis. So far my research has produced mixed results on reliability, particularly the Veissman.  Thanks!


  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    I am a homeowner, not a contractor.

    I cannot recommend one condensing boiler over another, since the only one I am familiar with is the W-M Ultra 3. I suggest, though, that if you want a useful amount of condensing, you should do two things. First is to get the smallest boiler you can get that will cover your design day so that the boiler can run in the condensing range as much of the time as possible and run it with outdoor reset so that the supply temperature will be as low as possible as much of the time as possible.

    Second is to install as much fin-tubed baseboard heat as you can in each room (and if you do not use separate zones for each room, balance the lengths to run the rooms at the same temperature). The reason for using as much baseboard as you can get is so that you can run lower temperature in the baseboard than normal. Regular baseboard is typically run at 180F supply and about 160F return, and if you do that, you will get next to no condensing. You really want return temperatures below 130F, and the lower the better consistent with getting enough heat into the rooms.

    In my case, with outdoor reset, I run supply temperatures between 110F on warm days and 135F on cold days in the (upstairs) baseboards. Downstairs, I run water between 75F and 120F in the radiant on grade slab, so it always condenses.

    My domestic hot water is from an indirect fired hot water heater off the main boiler.
  • SpeyFitter
    SpeyFitter Member Posts: 422
    Find a good contractor & ixne the tankless

    Unless you have a lot of cash laying around not doing much, I would personally opt for an indirect over a tankless for your domestic water. A stainless steel indirect tank will last you a very long time, requires very little mainteance, and when paired with a mod-con boiler, will produce water at a very solid 85-90% efficiency rate (depending on boiler temp & potable temp you select as well as the mod con). In comparison, a tankless, while many are reliable, requires annual service at the least which costs you money, has comparable efficiency to the mod con/indirect combo (depending on the model you get), and may require upsizing of your existing gas line since you'd end up with a boiler, and a tankless (tankless models pull big BTUH's), compared to just a boiler.

    As far as boilers are concerned, your best bet would be to find a contractor who can prove to you that he knows whichever boilers he bases his reputation on, well. If he not only sells, but services & regularly maintains them, and appears to have a good relationship with the manufacturer/rep of the boiler he is selling to you, as well as can produce references and potential pictures of his work, you'll be set. 

    Many consider Viessmann the cats arse, and they do build quality boilers (I've servicd a few, very nice heat exchanger, well put together), but Viessmann isn't the do all end all. For example, I'm not too keen on their lack of boilers with lower modulation figures. I was looking forward to seeing a Vitodens 100 in their new line up that modulated below 20,000 BTUH for smaller seasonal loads, smaller houses, and more moderate climates, to reduce short cycling and subsequent wear and tear on various components, but alas I guess we're either not a big enough market, or they don't care, or a bit of both possibly. Viessmann is one of the few that utlizes 316 Ti (Titanium stabilized 316 Stainless steel) for both their Vitodens 100 and 200 models heat exchangers which many regard as the most robust grades of stainless steel available on any mod-con availble today (IBC made in Vancouver is the only other manufacturer that uses 316 Ti for their heat exchangers).  Having said that, Lochinvar uses 316 L on their Knight which isn't far behind either.

    With all the above consider, I want to emphasize finding a good contractor who takes pride in what he installs. Does this contractor got one in his house?

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  • Unknown
    Good responses guys,,,

    My TT Solo 60 (on CIBB), is set for 126° on a design-day,,, so alot of condensing goes- on there.
  • tim smith
    tim smith Member Posts: 2,765
    Re: picks of boiler mfr

    I have been installing TT solo's for appx 4 yrs now. Have had very few problems with them and I feel it is one of the most reliable pieces of equipment I have installed. I recommend them with no reservations. The Viessmann is a nice piece of equipment but a little to proprietary for my liking. Good luck, Tim
  • beezer
    beezer Member Posts: 21
    choosing a boiler

    TT's are only available to me by special order... I did, and still will

    consider the brand due to good reviews. That choice comes with potential

    problems, however, such as parts availability. It was my intention to

    do the install myself no matter which brand. I also intend to do much of

    the maintenance as well. I know many will advise against this,,,

    however, my mechanical background is quite good, and I am no stranger to

    complicated tasks (I do not consider these systems to be particularly

    complicated). The initial setup may have to be done by a tech because of

    test equipment.... on the other hand, I would buy the test equipment

    myself if not totally outrageous.... especially considering that setups

    may need to be repeated at maintenance intervals.

    I can see the rational behind going sidearm. Anybody want to counter?

    I am considering the Vitodens 200... but the 100 has a bunch of bad

    reviews from techs that apparently no longer install them due to early

    failures & difficulty in obtaining parts. Any input?

    The Wiel McClain is the other popular unit in my local (Alaska). I hear

    the down side is it's more complicated multi pump setup, and the

    controls can have problems. I like the W/M stuff (I have installed

    several systems over the years in other houses), am concerned that the

    controls are no longer Honeywell (I'm told)

    Thanks & keep it coming..
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    I am a homeowner, not a contractor.

    I have a W-M Ultra-3 boiler in my house. It is my opinion that the plumbing of the unit is not all that complicated. The installation manual specifies primary-secondary piping, so you will have one more circulator than you otherwise might. If you think that is complicated, that is your decision, but having watched the contractor's employees install my system, I would say that the plumbing related to the primary-secondary piping was only 15 to 30 minutes. I have glanced at installation manuals for a few other mod|con boilers and they too seem to require primary-secondary piping to ensure adequate flow through the heat exchanger.

    My unit happens to be zoned with circulators, but you could use zone valves instead and need less circulators, but if you do, I would suggest a delta-P circulator for the secondary circuit to deal with the zone valves opening and closing. My system has two heating zones and one domestic indirect hot water zone, so it has 4 circulators. I could do with one less were I to use zone valves instead of circulators.

    I do not know who makes the control board, but it is quite good as far as I can tell. All the displays are in English, not alpha-numeric codes. It takes three thermostat inputs, and each can have its own reset curve. I use this as my downstairs is radiant slab on grade that I run with 75 to 120F water. My upstairs is baseboard (lots of it), that I run from 110F to 135F, and the domestic hot water that I run at 160F (output is 125 F).

    I know using an aluminum combustion-chamber heat-exchanger is controversial, and I cannot comment on that from practical experience. The W-M uses one, but mine has gone through only one winter and it shows no sign of imminent failure. Which proves nothing.

    Servicing it yourself may be a bit expensive because it requires a digital combustion analyzer, pH measuring tool, and torque wrench to replace the cover on the heat exchanger. If you are in the profession, I am sure such tools are justified, but for a single-residence, I doubt it -- especially the combustion analyzer. From what I read, the sensors last only about 2 years, no matter how little you use them. You might wish to read their installation manual to see if you are up to doing the work.
  • CMadatMe
    CMadatMe Member Posts: 3,086

    What do the tech mean by failures? The only issue Viessmann had in the past was a stupid little 20 cent o'ring that they recalled because they felt it didn't meet their standards and would fail over time.

    The new Vitodens line of boilers is top notch. The current Vitodens 100 is a basic simple mod/con with outdoor reset and DHW priority capability, firing rates upto 118,000 btu's and very competatively priced.

    The current Vitodens 200 with the lamda pro combustion technology and multiple venting capabilities is in my opinion the best of the best. The ability to run multiple heating curves in a plug and play control without having to out source controls is a plus and allows for greater flexability dependent on the job.

    I do have to agree with those that say the best boiler is the boiler that the contractor you choose is most comfortable with. The proper installation is the most important part of the job.

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