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Direct Vent vs. Power Vent vs. Tankless

Our old natural gas hot water tank vents into a chimney. The chimney above the roof is failing, I don't want to pay to have it rebuilt so I want to abandon it, the hot water tank is all that uses it.

For space reasons I don't think a direct vent tank will work (both space inside and especially a venting space outside). That leads me with power vent and tankless. We have very low natural gas bills as it is. I will have either installed, hoping to get some companies out the next few days for opinions/estimates.

My biggest concerns with power vent are the noise and it drawing in indoor air for combustion. However, I have HE gas furnace, so is this any different? Also a little concerned with longevity and efficiency of power vent. (of course are current tank is EF 0.55) Pro would be the longer run for the vent, could be located where the old one is and then vented 15 feet to a different outside location.

A tankless might be $500 to $700 more than power vent. I'm willing to spend that much more if it's worth it. My concern with tankless is reliability and maintenance, possibly not sure it could be vented directly outside from where it could be located at inside.

Thoughts and suggestions most appreciated.

Comments

  • SWEI
    SWEI Member Posts: 7,356
    Condensing water heaters (tank or tankless) cost a bit more, but many natural gas utilities have some kind of rebate program for them. The choice between tank and tankless will depend on use patterns, water hardness, and fuel costs.

    The venting also costs quite a bit less than the double wall stainless stuff and it's easier to install. You do have to handle the condensate, which can sometimes complicate things a tad.
  • Jeremy99
    Jeremy99 Member Posts: 4
    Are you suggesting a condensing would be better than either? City water, no evidence it's hard water, no rebates, Ohio.
  • Noritz (and perhaps other manufacturers) has a condensing tankless model with a flue designed to be pulled through the old B-Vent. Perhaps you can install it through the old chimney and fabricate the vent penetration at the top of the chimney.

    http://support.noritz.com/download.php?file=Literature Page/Spec Sheet/NRC663 SPEC.pdf&field=SpecSheet
    Often wrong, never in doubt.
  • SWEI
    SWEI Member Posts: 7,356
    I'm suggesting that the total installed cost of a condensing water heater can be similar to or less than that of a power vented tank or noncondensing tankless water heater -- especially as the vent length or routing complexity increases.
  • Jeremy99
    Jeremy99 Member Posts: 4
    Thanks, I will ask about condensing as well. I have 5 companies on a list to call, in addition to one that I called last week and e-mailed photos to.
  • Jeremy99
    Jeremy99 Member Posts: 4
    Thanks all for the advice. After considering three companies proposals, and not finding anyone with experience doing direct vent, we're having an AO Smith 50 gallon 40K BTU power vent (Model GPLV 50) installed this Friday.