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need help switching for oil to gas

stevedave Member Posts: 1
I am trying to figure out is the best decision.  I am switching from oil to gas, and had a contractor come in suggested a weilMclain GV90 stay with the water heater that i have now which is from 2009.  I also have another contractor saying that the new way to go is the Navian Combi unit CH210 ASME which would mean i need to remove that water boiler.  Space is not a issue and both are around the same price to do all the work that needs to be done.  Which is a better option? do i just replace the heater or go with a new system.  The warranty is much different on both but does that make a huge difference I am a new homeowner and want to get the best bang for my buck but want to get a quality product.


  • Paul48
    Paul48 Member Posts: 4,470
    Million $?

    What were the results of the heat loss done on the home? If one wasn't done, I'd use neither contractor. The money wasted year after year,is your money. You could put the most expensive boiler in the world, in a home, and if not sized correctly and installed correctly, it would be out-performed by a cheap,piece of junk, done correctly.
  • HomeOwner1
    HomeOwner1 Member Posts: 134
    We were faced with a similar decision

    We had an oversized oil boiler with the hot water built in previously.

    Also, we got different opinions from just about every contractor that came in.

    The WM with an indirect option was out of our budget.

    It then came down to a 83% Cast Iron boiler with separate 50 gallon water heater or a Navien for the same budget.

    We chose the Navien CH-240 and are very happy.

    We have a 3500 sq ft home with 3 baths in Cherry Hill New Jersey. The Navien service center happens to be just down the road from our house as well, so having parts availability and support is good for our location, which helps.

    The efficiency ratings on combi units is said to be a bit misleading, since on heating side can operate more efficiently then the other.

    Assuming you have a traditional tank water heater, it may already be 50% through its serviceable life anyway depending on the model. Heck, why not have all new at once?

    If you choose to go the Navien route, make sure you opt for the outdoor sensor. Also, get an installer that has attention to detail and knows how to install this unit correctly. Our installer even admitted he messed up a few things on his first few installations on these units. They have to be installed correctly and can be a bit less forgiving from what he indicated.

    The unitis very efficient and our new heating bill is less than a quarter of what we were paying for our old 86% way oversized oil boiler. The savings for your situation would most likely depend on whether yours is correctly sized or not. Gas alone is roughly 50% the price of oil, so at least you should get that much logic would dictate.

    The older Naviens were not so great when they were first introduced from what we were told. The ASME Stainless commercial version is the only one offered now and they did away with the troublesome early models. We were also told to stay away from the 180 version by contractors that installed many of these so far.

    We followed the good advice people gave on this site and had a heat loss analysis done on our home. This helped eliminate many bad options quoted to us. Many of the installers we dealt with estimated units that were too large for our home, which we were told would impact the efficiency immensely with short operation heating cycles.

    We are happy with our unit and proper installation. The unit has proven many installers wrong that said it could not possibly work for our home or that combis could never handle the hot water demands on our home. This forum and experienced installer tips were helpful in making an informed decision.

    Good Luck.

    By the way, as a tradition on this forum now, you will see a whole bunch of folks chime in on how they hate Navien.
  • heatpro02920
    heatpro02920 Member Posts: 991
    We will need to know your heat loss

    how many sq ft is the house, I wouldn't go with a navian because you want to get it sized for the heat load as close as possible and the navi is 200K btu's so unless you have a 5000+ sq foot house I would go with something that fits..

    What is your existing water heater, how does your budget look? Where are you in the country?
  • CMadatMe
    CMadatMe Member Posts: 3,085
    Better Get a Heat Loss

    The onboard pump supplied with the unit can only push 5gpm across it's heat exchanger. It does not move 210,000 Btu/hr for heating. That is the unit btu/hr output for domestic hot water.

    Also make sure you calculate your DHW demand in gallons per minute before choosing a unit. Homeowner1 learned that and is very happy with his choice.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • HomeOwner1
    HomeOwner1 Member Posts: 134
    Heatopro: That does not make sense to me?

    How is that thing running so efficient in my place if that were really true? I only have 3500 sq ft and my gas bills are really low. Just based on our gas consumption alone, it appears to be running efficient and correctly for our home?

    Our installer indicated that the unit is set to modulate down to the required fire rate down to 17kbtu. From what we were told, the combi units will never have a matching rated BTU based on the difference between hot water demands and heating needs.

    Isn't this true for all combi units out there?
  • HomeOwner1
    HomeOwner1 Member Posts: 134
    I second that!

    You gave us good advice measuring our needed gallons per minute and getting an official heat loss done. There is definitely wisdom in not having a unit that sized incorrectly. We had a 150,000 BTU cast iron unit prior that was much too large.

    For us, the combi unit was first verified to meet our hot water needs then verified to align with the heating needs. The out door temperature sensor is said to play a big part in efficiency. We were about to pull the trigger on the Triangle Tube then realized it was not going to meet our hot water needs. I believe it was you on this forum that explained the real life between brochure on that unit with the initial 50 gallons at only107 degrees or so, which was then verified with the manufacturer. Good thing.

    As well, the Navien is about half the price of the Triangle Tubes but does not yet have the long-standing brand reputation yet.

    We got the Navien set to 130 degrees on hot water, which does the trick for us.

    By the way, for heat loss, it is not the simple method of 12kbtu for 500 sqft. They actually measure each room, factor in insulation, windows, exterior walls, factor in your region's design temp and add up heat loss per room to get the answer. The really good guys use a door blower test and can tell you where you have home sealing opportunities. We had some contractors try to convince us the square footage calculation alone was adequate enough.

    In the end what we realized was, there are many correct answers, hence many correct choices. It then comes down to the unit quality, reputation, installer comfort and budget factors.

    We are glad we took a time to research before pulling the trigger.
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,195
    Homeowner you are correct

    The boiler will ramp up for domestic hot water production and turn down to simmer for the lighter heat loads. This solves the domestic load vs. heat load debate for boiler sizing.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
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