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Tankless Heater Proximity to Oil Tank

Hello All,

I am looking to install a tankless water heater in a utility room. The only available wall space is above the oil tank. The bottom of the unit would be approximately 1 foot above the tank. I've tried researching this topic online and I cannot find any explicit references to this being an issue, so I'm looking for others opinions/experience. Thank you in advance.


  • icesailoricesailor Member Posts: 7,265
    Location, Location, Location:

    Where are you located?
  • limitedrealitylimitedreality Member Posts: 4

    I'm in Baltimore MD. The heater is electric if it helps as I know that requirements are different for gas and electric. Thank you.
  • SWEISWEI Member Posts: 7,356
    edited September 2014
    Sizing, sizing, sizing

    Is this a post-heat for an existing tankless coil in the boiler?  If not, you may want to take a look at your hot water requirements before you purchase an electric tankless.  I'm a big fan of them when properly applied, but I've seen a lot of disappointment from contractors and end users who aren't familiar with the math.  The biggest single coils sold in North America require a 60A two pole breaker (there are both practical and code reasons for this limit.)  A 60A breaker is allowed to supply a 48A maximum load.  At 240V, this comes out to 11.52 kW, or 39,308 BTUs per hour.  If your incoming water is 45 F, and you want water at 115 F, that coil will heat 1.12 GPM of water.  Use two in parallel and you double that.  Use three and you'll need to upgrade to a 300A service.

    Now install one at the output of a solar thermal system.  It will rarely run in the summer, and in winter, it might receive 80 F water from the tank.  Now it can heat 2.25 GPM, and two of them will take care of most houses quite well (and work on a 200A service.)
  • limitedrealitylimitedreality Member Posts: 4

    Correct. This is a post heat source in combination with the tankless coil. The thought being it will only engage when needed to boost hot water and as a bonus may be sufficient for heating water in our small home stand alone in summer. So, anyone know of any issues with mounting the unit above an indoor oil tank?
  • icesailoricesailor Member Posts: 7,265

    Now, you've done all your math homework? You've computed how much you hope to save each month by switching water heaters, and divided that into the cost of the new water heater to find out how many months it takes to pay it off in savings?

    I just spent $1700to have more insulation in my attic to cut down on heat with my AC. My electric bill went down $10.00 per month. That's $120. per year. But the AC only runs heavily for the Summer. Best hope is that it will pay off in 14 years. I won't live another 14 years.

    That's after spending over $5,000 on a new, more efficient AC system that cost more to run than the old one.

    An old dead guy I knew used to say "Be careful what you wish for. You might get it".
  • limitedrealitylimitedreality Member Posts: 4
    No One Knows?

    Hi Icesailor, I have thought about the cost vs. savings but that's not honestly why I'm doing this. The tankless coil in the oil burner cannot maintain hot water long enough for my wife to take a bath. I've had several HVAC guys out and they said it's working as it should and we should just use less hot water :-p So instead, I'm going to install this electric heater after the tankless coil to extend our hot water supply.

    It appears nobody knows the answer to this question or has any experience with this situation. Thank you anyway.
  • icesailoricesailor Member Posts: 7,265
    Hot Water:

    So, how much does a 30 Gal., 40 Gal., or 50 gallon electric water heater cost? ( I always used 50 gal. Biggest bang for the buck). Pipe the electric water heater into the house plumbing so that it gets full system pressure. Connect the tankless coil into the water heater like a side arm heater of old, have a small circulator pump water through the coil controlled by a thermostat already in place in the water heater, and then have 50 gallons of hot water at all times. It will fill a Kohler K-795 Steeping Bath Whirlpool without slowing down. And that should keep the partner happy. Or, two adults and two teenagers taking showers without any screaming matches over who used up the last of the hot water.

    You don't have to drain the water in the boiler, and the only electrical connection can be an extension cord plugged into a standard 120 volt outlet. The water heater electrical isn't connected to the boiler wiring. You turn the "LO" down to 140 degrees from the 180 degrees it is probably set now, and you turn the "HI" down from 200 degrees (where it probably is now) to 160 degrees. In January, if the house won't maintain temperature, turn the "HI" up 10 degrees or more. Leave the "LO" alone.  You maintain cooler standby water temperatures, the toasty boiler is cooler but stays cleaner. When the water heater circulator to the tankless comes on because the tank temperature drops, the boiler will start to cool. The "LO" senses the temperature drop and starts the burner. It maintains boiler temperature based on the 140 (or higher setting) and the differential setting. I did this for 40 years. I had 4 teenagers, 3 girls. We never ran out of hot water. No customer I ever had ever complained about a lack of adequate hot water.

    We don't discuss prices here. Price up an electric water heater and a brass or stainless steel pump like a Taco 006. Then, whatever else you think might work. Those beer cooler water heater things are a thing of wonderous beauty. And just as much fun to water pipe, gas pipe and vent.

    If your knicks are twisted over oil vs. Nat Gas prices. it is sold by the BTU content. And supply and demand. Take note, some adolescents become aroused by looking at scantily clad members of the same or opposite sex. The same arousal that that the Wall Street Banksters and their Crime Syndicate are having over the thought of compressing and shipping all that US Shale Gas to Europe to stick it to Putin for trying to choke the Western Europe gas supply. Its unregulated if it is shipped out of the USA. The Banksters used to ship Algerian LNG to the USA and into ports all along the East Coast. You think they couldn't just compress that US Shale Gas into LNG and ship it back out of the same ports? And add it to the European pipe lines? Like they already with Algerian Gas?

    Points to ponder.
  • billtwocasebilltwocase Member Posts: 2,385
    I would say no to installing above the tank. Is space that cramped? I would also separate the two. You are paying twice to make hot water, if you are preheating thru the boiler. Go indirect

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