Residential Direct Vent Natural Gas water heater install

Discussion in 'Water Heater Forum, Tanks' started by cgs878, Aug 1, 2012.

  1. cgs878

    cgs878 New Member

    Messages:
    4
    Location:
    Bellmore NY
    Hello all,

    I am converting my house to natural gas and need a new gas-fired water heater for my basement location, where the old boiler & burner were (good riddance to oil). I have two issues that I need some advice on.


    First, I spoke with the plumbers whom are on my house job, and they suggested that I buy a Bradford White with Direct Vent 50-gallon capacity, which is (according to them) the proper size for my situation. I went online to the Bradford White website and found 2 that meet their requirements:

    1- Model DS1-50S6FBN ("Residential Direct Vent Energy Saver Gas Water Heater" - 50 gallon, 42000 BTU)
    2- Model DH1-504T6FBN ("Residential High Input Direct Vent Energy Saver Gas Water Heater" - 48 gallon, 50000 BTU)

    I also went to Lowes.com and found a model listed as being made by Direct Vent (probably a GE or Rheem 'generic' rebrand): Item #: 205229 ; Model #: DVG62-50T42-NV

    The price for the Lowes.com model is about $812. The price for the Bradford White models is between $1400 and $1600 (as seen on PexSupply.com, might be lower from a local plumbing supply company). Both have a 6 year warranty. Both seem to be similar / equivalent models with similar/equivalent ratings for EF and hot water recovery times.

    So, my general question (from a layperson's perspective) is... is the Bradford White 'name brand' really worth double the cost of the Direct Vent 'generic' branded one?? I don't really care what's in my basement as long as it's reliable, makes hot water consistently, works even when the power goes out, and doesn't leak once installed properly. I will be having a professional plumber install the hot water heater, so there will be no DIY errors on my part.


    Second, I am removing the old boiler + oil burner, which leaves me with a hole in the wall to the chimney. Can I have the plumbers put the hot water heater's vent into this hole for purposes of venting? If so, do I need them to install a wire mesh barrier so that crap from the chimney insides does not fall into the water heater vent pipe?


    Thanks for reading... I know that it was a bit long-winded. I look forward to an answer so that I may make an intelligent choice on both issues.


    Regards,
    - Chris S.
  2. Dana

    Dana In the trades

    Messages:
    3,028
    Location:
    01609
    If you are installing a gas-fired boiler in place of the oil-burner, FORGET about a standalone hot water heater, and use an indirect-fired HW heater running as a zone off the boiler instead. It'll supply far more hot water at much higher efficiency and usually last longer than any standalone tank (except possibly a condensing tank hot water heater, at more than 2x the cost of an indirect.)

    Under no circumstances should you vent a sub-50,000 BTU hot water heater into a chimney unless you run the appropriate sized liner all the way to the top. [edited to add] Venting hot water heaters into oversized flues results in condensation in the flue and erosion & failure of the flue liner. With atmospheric drafted units there's a real risk of backdrafting too, but not with a power-vent.
    Last edited: Aug 1, 2012
  3. cgs878

    cgs878 New Member

    Messages:
    4
    Location:
    Bellmore NY
    Thanks Dana.

    I don't think that I have a choice in the type of hot water heater because the contractor installed a Lennox forced-air heating system (furnace?) in the attic alongside the air conditioning condenser as part of a package deal forced-air heating/cooling system. I doubt that I should be putting 50 gallons of water over my master bedroom, and I do not have a boiler in the basement anymore.

    I'll make sure that the plumbers do not use the chimney / flue for venting. I guess they're going to be drilling a rather large hole in my exterior wall!


    Regards,

    - Chris S.
  4. Dana

    Dana In the trades

    Messages:
    3,028
    Location:
    01609
    With a hot air furnace there's no way to run an indirect, so

    You may want to consider going with a sealed-combustion/direct vent condensing hot water heater like the Vertex, especially if there are any state/local/utility subsidies. The installation expense of the 76,000BTU-burner version isn't going to be more than a non-condensing power-vented tank. Yes it's 2x the cost of the DVG62-50T42-NV but with any kind of subsidy it may end up slightly cheaper than the DH1-504T6FBN or DS1-50S6FBN, and deliver more first-hour gallons, using only ~2/3 the water heating fuel.

    Be sure to brick-up the unused flue openings in the old chimney, as it will be a major driver of air infiltration 24/365 if left open, or even leaky- you really want it to be air-tight.

    I'm not crazy about attic-mounted HVAC in a Long Island climate unless it's a sealed-insulated attic with air handlers/ducts etc all entirely within the insulation & pressure envelope. Otherwise duct leaks drive air infiltration, reducing system efficiency, and the conducted losses/gains of the ducts also add up. If it's all living above attic floor insulation, at the very least the ducts and air handlers need to be sealed on every seam with duct mastic (or FSK tape, where appropriate), and insulated to at least R8. And every place the ducts penetrate into conditioned space it needs to be air-sealed with the appropriate expanding foam or caulk, etc. I'm sure getting off the $4/gallon 80% efficiency oil and into buck-a-therm 90% efficiency gas will be a huge heating cost savings, but that's not to say it isn't still cost effective to ensure a tight duct system and tight house.
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