• STRETCH YOUR WATER HEATER PERFORMANCE WITH A TEMPERING TANK

    Water heaters are rated by the number of gallons of water per minute (GPM) or per hour (GPH) that they can raise water 100 Degrees Fahrenheit. This measure applies to all water heaters, regardless of their construction or fuel source.

    So by definition if we can increase the incoming water temperature to our heater:

    1. The output water temperature can be increased (subject to a safe temperature limiting), or
    2. The volume of controlled temperature water output can be increased, and
    3. The total effective capacity of any heater can be increased.

    Domestic water entering your home (or business) is always significantly colder than the heated environment. Thus as an example you must let the water run a while before it gets cold to pull cooler water from the outside the building (underground) water source. The effect is similar with the hot water heater supply piping, subject to the limited water piping capacity within the heated area. When the cooler water reaches the water heater it has to work harder to elevate temperature. Therefore by increasing the amount of environmentally warmed water to the heater we increase performance and save energy.

    Placing a non-insulated water tank between the water service entrance and the water heater we allow a larger volume of water to acclimate (temper) to the ambient temperature at its location, thus a “Tempering Tank”. Its construction and configuration are simple:

    1. A somewhat taller than wide tank with two pipe openings, one near/at the bottom and the other near/at the top. Its interior finish must be compatible with passing potable (sanitary) water through it safely.
    2. The incoming (cooler) water is piped to the bottom of the tank and the outgoing (warmer) from the top to your water heater. Hot water rises and therefore the warmer water stays substantially at the top while the colder replacement water enters the bottom. Water will diffuse within itself, but at a typically lesser rate than used, protracting this effect.

    Practically, any water heater or water storage tank stripped of insulation and being glass, stone or otherwise lined for water cleanliness is suitable. There are other options as well, typically used for well pumps and wet processes. So, look around for an opportunity.

    Note: One point to remember is that the temperature differential and flow of cold water can cause these tanks to “sweat” (condense moisture on the lower exterior of the tank). The simple solution is to provide a larger pan with an inch or so of coarse sand in it under the tank to absorb and then evaporate the condensation effectively.

    Please accept that this is not a cure all for a too marginal heater or a plugging in-boiler or other heater coil. The latter will surely get worse over time, but in the meanwhile helps with comfort while saving energy.

    This “trick” is nothing new. We sometimes refer to them as “Farmer’s Tanks” when found in our older New England Homes. Thank them.

    It’s a great Do-It-Yourself (DIY) Project. So that old electric water heater with the burned out elements that you just haven’t disposed of yet may have some life left in it after all.

    Last Edit: 04/05/2017 pdm


  • BOILER RUNS JUST FOR DOMESTIC HOT WATER – WASTING ENERGY!

    During the heating season, having an Immersion Coil in your Boiler to provide Domestic Hot Water (DHW) makes a lot of sense. You are utilizing the hot water present in your boiler for area heating to additionally provide hot tap water at a very reasonable cost.

    But what about when there is low or no area heating demand? Your boiler is still hot (typically between 160 and 190 degrees F) waiting to provide occasional domestic hot water (at about 120 to 140 degrees F). Meanwhile the boiler stays at temperature, radiating heat into the boiler room and leaking heat up the chimney, neither of which can be utilized.

    A commonly used trick to save energy during the low demand period is to turn off the boiler entirely using the Emergency Switch (usually located near the main hallway door, but may vary). When hot tap water is needed the boiler is switched on and provides hot water within 15-20 minutes, typically. After use the boiler is again switched off. The really thrifty have learned to shut off the boiler before the last shower or then run the dishwasher to utilize the remaining boiler heat to advantage.

    The efficiency answer is an Indirect Water Heater, a super-insulated storage tank heated by your boiler and substituting for your Immersion Coil. The best of these are made of stainless steel, super-insulated to lose about 1/2 degree F per hour and have lifetime warrantees. Additionally your Boiler Aquastat Control (controlling boiler temperature) should be changed to a “Cold Start Aquastat”, allowing it to heat ONLY when area heating or Domestic Hot Water is demanded or used to maintain tank temperature. Your boiler is now an “on-demand” type, lowering toward room temperature between cycles.

    This storage of a quantity of heated tap water not only gives you instantly available hot water at any time but is inexhaustible, with your boiler cycling to meet any demand. No more initially hot water that cools down quickly with use caused by under-sized or sediment-clogging Immersion Coils either. Yes, the thrifty can still use the Emergency Switch trick for additional savings. In fact, one family of four with two young boys has found that they need only switch on every two days in the summer after several showers, dishwasher, wash the dog, etc.

    Your boiler runs less and runs cooler on average too, prolonging its life while reducing radiated and chimney drafted heat losses. Efficiency gains all around.

    Note: This argument also applies to separate Electric, Gas or Oil Hot Water Heaters by incorporating them into a managed, single fuel system.

    Last Edit: 10/10/2012 pdm