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IS a Mod/Con or a GV90+ a better choice for me?

oski73
oski73 Member Posts: 2
I am a homeowner, not a heating pro. Ihave decided to replace a 30+ year old natural gas boiler and direct fired DHW heater, primarily due to availability of $3900 in rebates from local utilities (Eversource & GasNetworks) here in Massachusetts. I don’t expect the current boiler to last forever. I want to take advantage of the rebates while they are available.

House is 2500 sq ft, with 140 feet of standard Slant Fin baseboard heaters in two 70 foot loops. Current boiler is rated 150,000 BTU input and 120,000 output. Boiler has no difficulty keeping the house warm on coldest days.
Current DHW is 40 gal direct fired, 40,000 BTU.

I have proposals from multiple contractors for 95% mod/con boilers from a range of manufacturers (Bosch, Buderus, Burnham, Triangle Tube, Viessmann, more if I want them). Each of these includes an indirect DHW heater. All proposals are recommending a mod/com with approx. 80,000 BTU capacity.

The complexity of state-of-the art mod/con boilers gives me some concern regarding operational uptime, as well as HX lifetime (certainly compared to the current boiler, which has been bullet-proof).

Sensing my hesitancy, two of the contractors have also proposed a Weil McLain GV90+ as an alternative that meets the 90+% efficiency target and qualifies for the $3500 boiler rebate. This option appeals to me primarily because of the C/I boiler in the GV90+, and the reduced system complexity –vs- the mod/cons. The longer warranty of the GV90+ appeals as well.

I am also concerned that higher annual maintenance and repair costs of the mod/con will significantly cut into the potential fuel savings. Annual heating bill is $1500, and I expect to save $500 fuel per year.

I am a homeowner, not a heating professional. I could use some advice from the professionals on the selection of mod/con or GV90+.

Thanks for any insights you can provide.

Comments

  • RobG
    RobG Member Posts: 1,850
    The first question is, how did the contractors come up with 80,000 BTU's? Was a heatloss of the home performed? As to the question of what boiler to use, that is really between you an the contractor. What kind of boilers is he certified and comfortable working on? Are parts readily available locally? Most boilers today are reliable for the most part and service life is very good on most.
  • FranklinD
    FranklinD Member Posts: 399
    Fellow homeowner here.

    I went through that process last year. I also considered the GV90, but in terms of complexity, it's very similar to a modcon. I think it actually has more 'guts' inside overall than a Triangle Tube. It has circulators built in (which concerned me... Are they standard or specialty items?) and just as complicated controls.

    If you have baseboard and it needs to run at a higher overall temperature to satisfy heating needs, you probably won't see very high overall efficiency out of a modcon...they like low return water temps (like radiant in floor heat or big cast iron radiators).

    A well-done heat loss calculation is needed and will give you an idea of water temps at given outdoor temps. Don't trust the sizing of a boiler based on guessing or an installers "experience".

    I ended up choosing a Burnham ESC4, which is rated at 68000 btu output. Turns out I could've dropped another size quite easily.

    I like the boiler, but as others here have pointed out, once you purchase even a cast iron boiler with a modern control board (to run an indirect etc), you're basically at the same reliability point as a modcon anyway.

    In hindsight, if I had been able to come up with the extra $, I definitely would've gone with a Triangle Tube for my house (I have cast iron radiators and for 75% of the season, my water temps never exceed 120* -- perfect for a modcon).

    As stated above, heat loss is key. Too much boiler capacity is a bad thing. And yes, local support is also a big factor. That's why I turned down Buderus, Viessman, Slant Fin, and Bosch...absolutely zero support in my area.

    Good luck!
    Ford Master Technician, "Tinkerer of Terror"
    Police & Fire Equipment Lead Mechanic, NW WI
    Lover of Old Homes & Gravity Hot Water Systems
  • SWEI
    SWEI Member Posts: 7,356
    Just to summarize:

    Unless that house is completely uninsulated and leaks like a sieve, you're going to want a smaller boiler. You want the mod/con, since your system will probably be able to heat the house on the coldest day using something like 140°F water.

    I would choose a Triangle PTS60 or a Viessmann 200-W B2HA 19, depending on which contractor seemed the best qualified and likely to support me.

    How big are your DHW needs? If they're modest, a Viessmann 222-F B2TA 19 would take half the space (and require perhaps 25% less install labor) than a separate indirect and boiler.
  • Rich_49
    Rich_49 Member Posts: 2,559
    A complete survey of the installed radiation and the temps required at design on a room per room basis are a good step toward you making an informed decision . As Swei said above , sounds like you certainly may only require mdo con liking water temps which would give condensing temps for most of the season along with those higher efficiency numbers .

    As far as the WM GV 90+ . Stay away from it , repackaged WM nonsense that does not work much better this time around . You'd be better off with the true mod con . With a 3,500.00 rebate at stake the boiler is damn near free anyway .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
    jonny88Steve Minnich
  • Steve Minnich
    Steve Minnich Member Posts: 2,642
    I wanted to say what Rich said, but Rich says what he says so much better than I do.

    What Rich said.
    Author - Hard Knocks: My Life Inside Boiler Rooms
    PHC News Columnist
    Minnich Hydronic Consulting & Design, LLC
    https://heatinghelp.com/find-a-contractor/detail/minnich-hydronic-consulting-and-design
  • Jason_13
    Jason_13 Member Posts: 297
    I would use the Burnham Alpine or K2. The K2 offers a Fastpipe which is a LLH that would simplify the installation. Also offers as a combi for DHW. The big savings here would be to use the new zone control for either boiler
    . This allows you to program in the btu's of each zone and limits the firing rate per zone. As more zones demand heat it just keeps adding up the btu zone requirement.
    The boiler can still modulate down if needed. The boiler fires and goes imedietly into a 2 minutes low fire hold. Than determines where to fire to dependent on setpoint and return water temp. You could have a few zones calling which do not exceed the minimum input and the boiler will stay at minimum.
    They also show the cycle rate per zone so after operating for months or a year you could see where it may be possible to reduce the rpm's the that zone and add some more fuel savings after the sale.
  • rick in Alaska
    rick in Alaska Member Posts: 1,160
    I have put in a few wm GV 90+ and have had no problems. What is it that I am missing? They seem pretty established and bulletproof, but a this is new gas country to us, I have not had a lot of experience with them.
    So, what should I look for?
    Rick
  • Tom_133
    Tom_133 Member Posts: 720
    I hardly ever disagree with the knowledge base on this board, but I really love GV's. I am still working on units that are 20 years old and they need a pump here and there. The other plus to them is that they are simple and basically any boiler tech out there has worked on them and can usually diagnose the problem with them. Another great part about them is that they have 007 pumps so easy to find and swap and the rest of the parts are relatively inexpensive. Also, the boiler can hold some water helping with short cycling. I could go on, but no need I like the GV's, and I think the GV+'s are very good. Though I do struggle when it comes to application as to what boiler to use when it's a high temp baseboard application. I like reliability but I like fuel savings as well.
    Tom
    Montpelier Vt
  • rick in Alaska
    rick in Alaska Member Posts: 1,160
    My thoughts as well. Old school cast iron reliability, water buffer in block, and over 90%.
    Rick
  • Rich_49
    Rich_49 Member Posts: 2,559
    My thoughts are that not many boilers short cycle where you are operating Rick . LOL.
    Wire to water efficiency is terrible on that boiler , too much going on to make a simple boiler appear to be what it is not .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • rick in Alaska
    rick in Alaska Member Posts: 1,160
    Actually, almost all jobs I have to work on suffer from short cycling. Where I live at is considered the banana belt of Alaska, and is usually mild. Typical winter low is 15. But, we also have insulation here, and lots of it. Which it seems most of your older homes back there don't have. My walls are double walls and insulated to about R32. I would say the average home around here only needs about 25-30,000 btu. I can't remember my own , but am heating 2400 feet with radiant and I think it was something like 32k. Definitely hard to find boilers small enough. We finally have gas in here now, so am able to use mod cons that are at least closer. Still hard to convince someone to put in a whn055 with domestic water off it. Even that is usually too big though.
    Rick
  • Shane_2
    Shane_2 Member Posts: 138
    Just to throw in another opinion.

    I use Weil-McLain pretty regularly. 3/4 of my suppliers carry them. I have used them for steam(EG) and for hot water(CGa). I would never recommend the Ultra, the WM97, or the GV series. Have seen way too many problems.

    I happen to be a fan of Triangle Tube. Believe you would be much better off with a true Mod Con, especially with the rebates available to you.
    Rich_49
  • oski73
    oski73 Member Posts: 2
    Thanks to everyone who contributed ideas and recommendations based on your expertise. Greatly appreciated.

    The key thing I learned from your posts was the value of a thorough heat loss analysis. I have eight proposals, but not a single heat loss analysis in the group---and quite a range of explanations for not doing the detailed calculations. Based on this, I will do the analysis myself.

    I have found two tools to use---one from Slant Fin and one from Taco. Any recommendation as to which of these to use? Is there a better alternative than these two?

    At this point, I’m leaning towards the GV90+, since it offers a better warranty and a lower purchase cost. For me, these factors outweigh the add’l fuel savings of the mod/con.
  • Rich_49
    Rich_49 Member Posts: 2,559
    edited July 2015
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
    jonny88
  • FranklinD
    FranklinD Member Posts: 399
    Oski - I had the same thoughts and reached the same conclusion as you when I replaced mine a year ago. And I'll be honest, I've been kicking myself in the behind ever since. I should've gone with a WM ECO or a Triangle Tube. It would've paid for the extra cost in one season in my case.

    In terms of longevity, that would be something I would've had to wait and see on. In my opinion (from the research I did), the GV isn't any less complex internally than most mod/con boilers. That's why I eventually passed on it.

    The Burnham ESC I ended up with is nice, but I discovered the built-in outdoor reset capability (with a plugin card) is really intended for hi-temp baseboard use. If you run under 150* supply water, it really won't help.

    Whatever you decide, and it IS your decision, do that heat loss calc. I used the Slant Fin app and it came out on the high side, saying 68000 btu/hr (at -21*) when in reality it's more like 45-48000. But it's also an old house with who knows what in the walls for insulation, and there have been all sorts of improvements done willy-nilly over the years -- made some of the variables tough to account for.

    I can't believe, that out of 8 companies, none did a heat loss. Then again, the company I hired DID do a heat loss -- They just didn't know their b-hole from a hole in the ground when it came to near boiler piping or how to look at that weird rectangular paper book-thing that came with the boiler.

    From one homeowner to another, best of luck...it's a jungle out there. You're well on your way, though, since you've found the best place in the world to educate yourself.
    Ford Master Technician, "Tinkerer of Terror"
    Police & Fire Equipment Lead Mechanic, NW WI
    Lover of Old Homes & Gravity Hot Water Systems
  • phoenix15
    phoenix15 Member Posts: 4
    Hi Oski

    I am in an identical situation to you! Also located in MA, my home is a bit smaller than yours (1300 sq ft) but also have baseboard in two 50ft loops.

    Multiple contractors looked at the job and not one has performed a heat loss. Everyone has been quoting the mod-cons or combis, as well as a typical 300-400$ yearly maintence cost. I'm pretty concerned with all I hear about the mod-cons not being a good match for baseboard, shortcycling, etc. Even the Burnham Alpine brochure says their ES2 models are a 'more viable option' for baseboard heat.

    I'm also leaning strongly towards the GV90+ because: 1) Qualifies for the MassSaves rebate. 2) Can be direct vented- saving the cost of a stainless chimney liner 3) Traditional cast iron style that I'm assuming will require less lifecycle maintainence.

    Most of the negative comments on the GV90+ I've read haven't really elaborated as to why they dislike the unit.. just alot of 'stay away', 'junk', etc.

    The ES2/ESC Burnhams look like a good option, though do not qualify for the big MA rebate.

    I've read through the owners and install manual and the GV90+ the controls/maintenance don't seem all that complicated to me.. less so than the mod-cons I've looked into. I know the previous poster came to a different conclusion and would be interested to hear more.

    I think for myself personally, any extra savings I'd get from a mod-con would be lost on required maintenance.

    Anyway just wanted to let you know there is someone with the exact situation, going through a very similar throught process. Let us know how you make out.

  • Rich_49
    Rich_49 Member Posts: 2,559
    Here's a mod con that won't require much maintenance . Will qualify for any program there is , is made in Mass and requires no exotic piping . Still have the room by room heat loss calcs done and measure the installed baseboard to determine required water temps at design and above so you can set the reset curve correctly and use the coolest water possible to adequately heat the space .
    Since it has 55 gallons of mass don't have to worry about the short cycle issue nor the stack losses and jacket losses of a cast iron boiler .
    Now you have a real good solution without 2 pumps and a boiler bypass and lots of other nonsense . You will keep all the money in mass and support a company that listens to what the market needs and have yourself the best boiler available for your application .

    http://www.htproducts.com/pioneer.html
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • phoenix15
    phoenix15 Member Posts: 4
    The Pioneer looks like a great choice, and was recommended by one of the contractors. Unfortunately, it's a somewhat tall unit- and with the recommended clearance, 77" is required for install. Alot of homes in the area (mine included) do not have the sufficient headroom.
  • Rich_49
    Rich_49 Member Posts: 2,559
    edited July 2015
    Pioneer is only 53" tall . You possibly looked at the manual which is shared and mistook the Pioneer for Versa Flame . I assure you the Pioneer will readily fit into 60" height space .

    http://www.htproducts.com/pioneerspecifications.html

    http://www.htproducts.com/versaflamespecifications.html
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • phoenix15
    phoenix15 Member Posts: 4
    Yes the Pioneer is definitely 53" tall, but the install manual calls for a minimum of 24" clearance above- hence the 77" required for install. Not sure if installing in a smaller space would void warranty, etc?
  • Rich_49
    Rich_49 Member Posts: 2,559
    No warranty issue due to clearances . No anode rods to change , only T & P valve on top , supply & return connections and air vent .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • phoenix15
    phoenix15 Member Posts: 4
    I guess the concerning thing is why list it in the install manual if it shouldn't be followed? Just seems to open the door to where if problems do arise an arbiter may reasonably say the work was done outside the recommendations of the manufacturer.

    Not having ever seen one of these, I'm not saying it can't be done properly. I personally would feel a lot better with that unit if it didn't have that minimum overhead clearance listed.. Too bad because it looks like a great fit.
  • Tom_133
    Tom_133 Member Posts: 720
    Though I really like the GV and have had no issues, I also very much like the HTP that Rich is suggesting, it won't short cycle, it will do all that it claims. The price though is a hard sell with many, especially the older new englanders who at 80+ years of age would still rather chop and stack wood!!!!
    Tom
    Montpelier Vt
  • billyboy
    billyboy Member Posts: 152
    oski73 said:


    I have proposals from multiple contractors for 95% mod/con boilers from a range of manufacturers

    The complexity of state-of-the art mod/con boilers gives me some concern regarding operational uptime, as well as HX lifetime (certainly compared to the current boiler, which has been bullet-proof).

    reduced system complexity –vs- the mod/cons.

    I am also concerned that higher annual maintenance and repair costs of the mod/con will significantly cut into the potential fuel savings.

    Installers much prefer Modcons to C.I.

    Whats not to like:
    Modcons are much lighter to cary in & easier to install than C.I.
    Higher up front cost = more profit,
    More maintenance = more profit,
    Parts cost more = more profit,
    More susceptible to lightning = more profit,
    And will need replaced 2-4 times as often = more profit

    Hatterasguycnmdesign
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