Recommendation On a Propane Tankless Water Heater

Discussion in 'Tankless Water Heater Forum' started by jackr, Oct 5, 2013.

  1. jackr

    jackr New Member

    Messages:
    6
    Location:
    New York
    OK you guys steered me well on my Toto toilet & I thought I'd hit you up again on this. I realize that opinions are like.... but I have some specific questions too.

    I have a small house with one bathroom for 2 people with an electric heater. I am on a well (30-50lbs) although the water is a little hard we don't need a softener. I don't want to over or under buy. Maybe ~$600?

    My propane appliances now are the furnace and a living room stove on a 1/2" line.
    I also have an electric clothes washer & dryer & dishwasher.

    What types of units use the pvc vents like my furnace?
    Can I tie into my furnace vents?
    Is my water pressure a problem?

    Thanks!!!
    Jack
    Last edited: Oct 5, 2013
  2. lipton80205

    lipton80205 New Member

    Messages:
    5
    Location:
    Denver
    Hey Jack,

    Check the manufactures specs for using PVC. For example: You can use PVC venting on the Rheem Prestige line. However Rinnai's Ulta series you can not use PVC.

    Since your furnace uses PVC for venting, I am about 99.9% certain you can NOT common vent with your furnace and a condensing water heater. Both have a positive pressure vent. One of the pros will chime into verify this.

    What's the temperature of the incoming water? You will want to look at the temperature rise charts to select the right size model to fit your needs.
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,321
    Location:
    New England
    Closed combustion devices have sensors that look at the gas pressure between the intake and the exhaust, and if they aren't correct, they shut the burner down. There's no way a closed combustion system can share a flue with another burner, at least none that I know of.
  4. guy48065

    guy48065 Member

    Messages:
    117
    Location:
    SE and north MI
    To use PVC venting you're going to be shopping for a condensing heater. It's the only kind where temps are low enough for plastic vent. None of the Rinnai units use PVC so you can strike that brand from your short list. There are models from Rheem, Noritz, Navien, Takagi, Bosch, AO Smith, Paloma. Some of these are re-branded units from other asian mfrs. None are near $600 unless you find one on **** or Craigslist that "fell off a truck".
  5. Dana

    Dana In the trades

    Messages:
    3,028
    Location:
    01609
    I'm wondering what the reasons for going to a propane fired tankless are?

    Is it capacity?

    Space savings?

    Operating cost?

    The answers to those questions can steer the recommendations several ways.

    To answer at least some of the questions:

    Only condensing tankless units can use PVC. All condensing units are forced-draft.

    NO you can't tie the output into the vents of any other forced-draft or atmospheric drafted appliance (like a condensing propane furnace.)

    Water pressure between 30-50 lbs is not an issue. Water pressure under 15psi or over 80 psi might be, depending on model.
  6. jackr

    jackr New Member

    Messages:
    6
    Location:
    New York
    Thanks guys ! OK my water temp is ~40-50 winter. Also I noticed after checking various brands that it looks like I need 3/4" propane supply, I have 1/2" now. I still would like a condensing unit sized for a small home with 2 people & 1 bath. What would be the right size & maybe a model for me?
    Thanks
    Jack
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