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Advice needed on replacement hot water tank

tm3tm3 Member Posts: 7
i would really appreciate some advice on what to do about replacement of my hot water tank, a 20 year old natural gas direct vent PenField Hydroclean 40 gallon.

i have two tanks in my home (2 adults, no children), with the PenField considered kind of a "low demand" tank as it provides hot water for the kitchen and two bathrooms: sinks, dishwasher, and maybe 10-15 times a year showers for guests.  the other tank is 7 years old and provides hot water for daily showers, bathroom, and washing machine.

due to the low hot water demand and size of the existing line to the PenField, i don't think that tankless makes much sense.  however the problem that i have run into is i am having trouble finding anyone that can install a replacement tank the same size to fit the existing direct vent configuration.  i would like to avoid putting a new vent through the wall at a higher height to accommodate the dimensions of available new tanks.

my research so far suggests that one of the hybrid heat pump electric tanks might be the best option.  with my low demand situation it seems like the tank could run on heat pump mode all the time, which should make the annual cost close to that of a natural gas tank.

am i on the right track with a heat pump tank?  other suggestions?   thanks


  • kcoppkcopp Member Posts: 2,744
    In my opinion....

    a tankless makes a great deal of sense. You have nat gas. You already vent to the outside and your demand can fluctuate. Tankless only heats what you use. No standby losses. Lifetime of an tankles is 15-20 yrs.

    The hybrid has standby losses. Can be pretty loud (its a compressor)  Takes up a lot more room than a tankless. Requires much more electricity to operate in demand load times. Lifespan is 6-10 yrs.
  • tm3tm3 Member Posts: 7
    edited July 2013

    thanks for giving your opinion!

    total cost for tankless is over 4 times the cost of the heat pump electric after rebates.  i have relatively low mineral content water thus water tanks tend to last a little longer (the one i am replacing is 20 years old, which i realize is pushing the limit).

    would you still say that the tankless is the best choice?
  • SWEISWEI Member Posts: 7,356
    edited July 2013
    Hybrid heat pump water heaters

    Check the output capacity of the heat pump -- pay attention to the design conditions and see if they actually represent yours in winter.   Most of them are rather limited and can have you running resistance heat more often than you might be led to believe.
  • kcoppkcopp Member Posts: 2,744
    Not sure where you....

    are but gas tankless water heaters here in NH have a $800.00 rebate. Not sure what model you are looking at....there are lots of options. Yes do check the output. many of the water heater do most of the heating off a standard water heater element... AND ask around to other in your area about the electrical "savings"
  • tm3tm3 Member Posts: 7
    edited July 2013
    more information

    part of the high tankless cost is for regulators so that the gas pressure can be bumped up to 2psi.

    further looking on my part indicates that there may be some tankless gas units that run off of the standard size pipe and standard pressure.  but i'm told that when the "call" for hot water goes out, they run about 3 gallons of cold before the hot starts coming.  that seems like a lot of water and a long wait for something like hand washing.

    what am i missing here re the tankless?

    thanks again!
  • Charlie from wmassCharlie from wmass Member Posts: 3,911
    one thing we do not discuss price on the board

    the hybrid does require a place to get the heat for the water. As it heats the water it cools where it is located.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • tm3tm3 Member Posts: 7
    prices removed

    sorry i have removed the pricing and just commented on relative cost.
  • kcoppkcopp Member Posts: 2,744
    Why would you....

    need to bump up your gas pressure to 2psi? They run on 6-10" water column... less than 1/2# psi..... If price is the whole concern just put in a regular electric water heater and that will be fine.
  • ZmanZman Member Posts: 3,476

    Are you sure you have exhausted the direct replacement option?

    If you post more info and some measurements, someone on here can probably help.

    The reason they are suggesting a 2# system is that you have an undersized gas line. If you increase it 2# then reduce it back down, you can do a tankless.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • tm3tm3 Member Posts: 7
    drop in replacement?

    sure, if someone can point me to a drop in replacement for the existing natural gas direct vent Penfield that would be great.

    the existing tank is 49" tall, and the measurement from the floor to the center of the direct vent (horizontal portion) is 60". 

    if i opt to go with a replacement direct vent natural gas that requires a new hole in the wall, a hose bibb that is right above the tank may have to be re-routed.  so a new, taller tank would result in a new hole for the direct vent, an old hole to patch, and some plumbing re-routing.

    i could go with an electric replacement.  i would prefer natural gas since is is so much less expensive than electricity however for this tank that gets relatively little use i don't think that the electricity usage would be too bad.

    i think that the 1/2" gas line from the outside meter has a run of about 70 feet to the existing tank.  i can get the exact measurement if needed.  the rep from the gas company said that is too far to supply a tankless system, even if the pipe was replaced by a larger diameter.  so he said that if i want tankless i would have to have regulators installed on existing gas line appliances (6, i think) too keep them getting 1/2psi while bumping the system overall to 2psi to get enough supply to the tankless.  in addition to the extra expense of the regulators, i am concerned about the added complexity and possible problems with the overall higher gas pressure -- might be a needless concern on my part, if so please tell me.  additionally, if true, the comment about having to run 3 gallons of cold water before the hot starts to come in does not sound like a great plan to me.

    a Nuvien system salesman is visiting today to look things over.  on the phone he said that the Nuvien will work fine with the 1/2" line OK due to its design.

    i am getting a number of conflicting stories depending on who is selling what.  for example, i have two quotes for identical replacement Rheem 40 gallon tanks with one quote about 2.5 times more expensive than the other.

    my goal in posting here was to try to get some objective guidance on what would be the best, most cost effective system for the long run.
  • kcoppkcopp Member Posts: 2,744
    You could try....

    looking on Craigslist for either a replacement tank or a tankless unit. that would save you some coin. I look plenty often.
  • SWEISWEI Member Posts: 7,356
    edited July 2013
    1/2" line from the meter

    Seems wrong somehow.  There's no larger trunk?  How hard would it be to replace?

    Our town got gas service in the late 1930s and I regularly see 900 sq ft houses with 1" or even 1-1/4" feeders.
  • tm3tm3 Member Posts: 7
    Follow up

    turns out that the heat pump electric is not an option as my site does not meet requirements.

    there is no "drop in" replacement for the existing Penfield tank so a new NG tank would require new venting and some patch work in the outside wall.

    the Nuvien salesman confirmed that with a tankless the gas pressure would need to be brought up to 2# with half a dozen regulators put on existing appliances.  these regulators are 30% of the cost of the tankless install.  he also recommended the Rinnai over the Nuvien and provided a quote.

    the tankless system quotes end up being about 2 to 2.5 times the price of a tank system.  this, along with the fairly large number of complaints that i have read online, is of concern although i like the concept of the tankless (heat only what you use, longer life span).

    am i missing anything as far as the tankless goes, and if i elected to go that route how would i be most assured of getting an install that works properly?  there are a lot of dealers selling Rinnai in this area.

  • Charlie from wmassCharlie from wmass Member Posts: 3,911
    Why not just run the right size of gas line?

    why risk high pressure gas pressure when running a larger pipe will suffice?
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • tm3tm3 Member Posts: 7
    edited July 2013
    not feasible

    two installers say new line "not feasible."  i believe that the reason given was that due to the length of the run, the larger diameter pipe would not be sufficient.

    what is the risk of 2# gas pressure line?
  • ZmanZman Member Posts: 3,476
    Nothing wrong...

    With going to a 2# line. It is actually done pretty often in commercial work.

    It does require regulators at all appliances. I would only use it as a last resort. It sounds like it is your last.

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • RichRich Member Posts: 2,220
    How many

    inches water column is supplied by the utility ?
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC 732-751-1560
    Serving most of New Jersey , Eastern Pa .
    Consultation , Design & Installation
    Rich McGrath 732-581-3833
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