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Confused about converting to Gas

I am going to convert from oil to gas. I know that I will have a fair amount of savings by simply switching. But I am not sure if I will get my ROI if I go all the way to a mod/con boiler. I think my chimney needs a liner so I am looking at Direct Vent atmospheric boilers with indirect water heater. Any problems with direct venting these provided I follow the installation instructions?


  • JStarJStar Member Posts: 2,668

    What size system? Was a heat loss done?

    Barring some odd reason....go mod/con.
    - Joe Starosielec
    [email protected]
  • Paul48Paul48 Member Posts: 4,256
    From A Convert

    I was on a budget plan with the oil company. It use to be 10 months a year, equal payments. Because of the high oil prices, the company had graciously extended it to 12 months, at $423 a month. I changed to gas last fall. Last months bill, which will be my highest, was $370. I'll come out of the winter not owing a penny.
  • bob eckbob eck Member Posts: 564
    Oil to gas

    Get your self a good heating contractor. Get them to do a heat loss so you get the right size boiler. Get a price both ways with a mod/con with outdoor reset control and something like a Burnham ESC cast iron boiler with outdoor reset control and both with a indirect water heater. This is my fourth heating season with a Triangle Tube PE110 high efficiency condensing boiler with built in indirect water heater. With today's high cost for fuel oil and the lower cost for natural gas my heating cost have been cut by more than 50% and I added a gas cooking stove and added some cast iron radiators and got rid of electric cooking stove and electric baseboard in one room and also lowered my electric bill. Today's low price for natural gas will not last forever it will be going up soon and I would put in the most efficient gas boiler for the long run not just what you would be saving at today's nat gas prices but what you can save in five or ten years down the road. Get a good contractor that has been factory trained and has many installations under their belt. There are many great high efficiency condensing boilers on the market today but unless they are installed the right way you will not get the maximum efficiency out of the system as you should. Stay warm and comfortable in the winter and still save money.
  • heatpro02920heatpro02920 Member Posts: 991
    edited March 2013
    First order of business is...

    getting a heat loss done,

     sounds like you want to do the system yourself?

    If so there are some programs online that will let you do your own heat loss.

    Now once you know our BTU Load, its easy....   If you have a small load I wouldn't go mod/con, rather go with a Weil McLain cgi boiler, direct vented {more efficient than a chimney}, install an ODR with it and delta t circs....  For your DHW install a tankless water heater, I like the Rinnai Condensing units the best, ru98i or ru80i depending on you use....

    Now if you go mod con, I still like the Rinnai for DHW {some will disagree} and I like the Triangle Tube prestige solo boilers for the mod con itself, again install it with delta t circs, and use the ODR....

    If you are installing it yourself its harder to get the rebates and warraties can be a problem, but if you know how to follow a wireing schematic and solder tubing, its not impossible... 

    If you are not doing it yourself than find a good contractor and go with what they advise you to do, since they will be servicing it not you or me...

    Now for ROI, hat depends on your heatloss and your current system, get us that info and we can ball park her pretty close....  When installing a mod con smaller heat loads dont make sense because they cost much more and they tend to not last as long and have higher maint costs....   Honestly installed and sized correctly, an 85% boiler with an ODR vs a modcon will only save you around 10% {and as soon as something isnt perfect like warm retrun temps and short runtimes, you can throw that 10% out because I have seen mod cons running much lower than a std unit...}  Definitely takes some planning and know how to get a mod con rite...  
  • Heat loss

    Thanks for the posts. Sorry for the delay. I had two heating companies come to give me a quote, but that did not share with me the heat loss numbers. I found an app from slant fin for the ipad and ran those numbers last night. The heat loss was about 42k btus. I am not going to do the job myself, but I want to understand what I am buying. This is what I understand so far. I have used on average 720 gallons of oil per year for the last 5, @ 3.70 per gal that is $2664 per year. My local gas company calculator says that I will save about $1350 per year. If I use their calculated cost of gas I would use per month and start comparing systems from there, I am not sure I will get to my ROI before the warranty runs out on the condensing boilers.

    Here are some details regarding my house.

    23 year old Weil Mclain boiler p-468-w1

    2000 sq ft Colonial with two zones

    Recessed fin tube radiators in most rooms, but baseboard and toe kick in my kitchen.

    2.5 bathrooms, one with a tub and the other with a shower stall. 2.5 gpm shower heads in both.

    I have been quoted the following systems

    UTICA MGB-100 with indirect water tank 50 gal(but I won't the model that allows for direct vent)

    UTICA UB90-100 with indirect water tank

    Buderus GA124/30 with indirect water tank

    Bosch Greenstar Combi 4 GPM dhw

    Bosch Greenstar 131 with indirect water tank

    Triangle Tube Prestige Trimax Excellence 110

    I am concerned about the Bosch with only a 12 year warranty, Utica UB90s 15 year warranty. I hear about the high maintenance costs to keep these systems running properly. Is it true? Will any extra saving I get from the higher AFUE be spent on maintenance? Then on top of if I will have to change the system out 10-13 years sooner than the atmospheric boiler.

    Sorry for the long reply, but I am pretty confused. It seems that the more I ask the more confused I get.
  • Paul48Paul48 Member Posts: 4,256

    Keep in mind, the savings they calculate are just costs per therm, and don't reflect additional savings from efficiency upgrades.
  • Efficiency Upgrades

    What would be an example of an efficiency upgrade between the Utica MGB-100(atmospheric) and the UB90-100(condensing)? Both need indirect hot water tanks.
  • Efficiency Upgrades

    What would be an example of an efficiency upgrade between the Utica MGB-100(atmospheric) and the UB90-100(condensing)? Both need indirect hot water tanks.
  • Paul48Paul48 Member Posts: 4,256

    I was refering to your savings vs. oil, and the decision making process of standard vs. condensing, based on that.
  • SWEISWEI Member Posts: 7,356
    42k heat loss

    Would lead me towards a TT PTS 60 or a GA124/17.  A larger indirect might be in order.
  • SteamheadSteamhead Member Posts: 11,379
    If your chimney needs a liner

    then have one installed. Direct vent is more mechanically and electronically complex than a chimney, and will likely require more service. Add to that the fact that a lot of direct-vent parts are unique to each make and model, so they're not likely to be stocked at the local level.

    Chimneys are simple. They have no moving parts. Simple is good.
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
  • Paul48Paul48 Member Posts: 4,256
    I Think

    The GA 124 is discontinued, and if so, I'd have some concerns about buying one. Namely, parts availability beyond 10 years?
  • Paul48Paul48 Member Posts: 4,256

    Munchkin Contender? With a proper install, the price is hard to beat.
  • SWEISWEI Member Posts: 7,356
    edited March 2013

    just responding to the listed candidates, all of which were massively oversized.

    Lochinvar WHN 055 offers higher turndown than the PTS 60.

    Contender doesn't include ODR as I recall.  I believe the Cadet does, though I've yet to actually see one.  I'm going to call them in the morning and see what I can learn.
  • Paul48Paul48 Member Posts: 4,256

    I know....I just wanted to put that out there. There is probably stock still available. I'd be hesitant though.
  • heatpro02920heatpro02920 Member Posts: 991
    edited March 2013
    I don't like any

    of your options so far, lol...

    I would go CGs3 {I know earlier I said CGi, I always do that, we used to use CGi, now we use CGs, WM and their damn model letters}...

    That cgs 3 will let you direct vent {I know it adds mechanical parts but it takes away too, like draft damper, chimney upkeep, the need for a liner, and it adds efficiency, I have seen around 10% difference, no air infiltration, IMPO its the way to go} The CGs3 is 85.3% eff out of the box.... My testo usually says 85.8+ after installation...

    Have a contractor give you a price on the CGs3 direct vented with the hydrostat ODR control, 2 taco bumble bee circulators, and a Rinnai Ru80i tankless water heater...

    Also another note there are gas boilers with internal tankless water heaters, Weil McLain actually makes one, its a CGt I believe {but don't quote me on it}, I have installed a few they work very well, no complaints yet...

    Don't be afraid of direct vent, I know its not as simple as a chimney like steamhead stated but it has some pretty good advantages over a chimney drafted systems... Mainly initial costs and energy efficiency but thats the entire reason for switching from gas...
  • JStarJStar Member Posts: 2,668

    You can get 85.5% efficiency with a wet-based, chimney vented boiler.
    - Joe Starosielec
    [email protected]
  • 10 % difference

    When you say "85% boiler with an ODR vs a modcon will only save you around 10%" and "mod cons running much lower than a std unit...}", do you mean that if the mod con is not configured correctly it might run worse than a standard unit?
  • Heat Loss numbers

    So I called one of the contractors who provided a quote. I asked what heat loss numbers they used to choose the system they quoted. All he told me was that he used the temperature of 70 and 0 to calculate heat load, then offered a discount on the standard boiler systems. I went back to the slant fin app and change the temps to match what he gave me. Instead of 42K, I know came up with 51K. He also told me he used 8k to factor in the indirect hot water tank. Combining those numbers, I come up with around 60K BTUs. What is a comfortable cushion to properly size a boiler? I assume I don't want to find a boiler that puts out that exact amount. BTW, do I look at the "DOE Heating Capacity BTU/Hr" or "the Net IBR BTU/Hr" numbers?

This discussion has been closed.


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