• Tag Archives Plate Exchanger

    Optimization of heating efficiency first requires determining your specific requirements. In general terms there are two or more distinct heating energy uses:

    1. Area Heating – Warming occupied areas fully, or selectively as living habits occupation or use may demand.
    2. Domestic Hot Water  (DHW)– Heated, potable (drinkable) for baths, showers, laundry and personal consumption.
    3. Special Uses – High temperature power washing, sanitizing, etc. (Refer to prior blog.)

    All of these requirements can ideally be met by using a hot water boiler system as a single, central source but the question arises of how to accomplish this efficiently. Specifically, varied heating demands that may range from continuous (?) DHW to very occasional (seasonal?) and selectable area warmth can become a challenge, particularly economically. However occasional demands can “lighten your wallet” to execute and maintain. Let’s address this problem systematically.

    Arguably the most important decision has to be your heating fuel selection. We cannot overemphasize this and the use of a Heating Cost Comparator to define your choice. (See our other blogs.) The standard unit of measure is the “Cost per Million BTU” expressed as a dollar figure. We use the NH-OEP Calculator for our area usage, but similar ones are available online. Use your current or projected new heating appliance efficiencies (AFUE) to get an accurate calculation. New Gas (Natural or LP) AFUE’s are typically 95% for top end (condensing) boilers and 87% for Oil Triple-pass boilers.

    The current and foreseeable heating fuel choices have become quite obvious in the northern climates:

    1. Natural Gas (where available) is the accepted baseline. But BE CAREFUL! Natural Gas is a “distributed fuel” (through a pipeline). Your actual bill will be considerably higher due to service and distribution costs added to your actual therm usage. Get a billing estimate from your gas provider first! (Our local multiplier is up to 2.0 or 100% added for your actual natural gas billing costs.)
    2. Heating Oil is the predominant fuel where natural gas is not available.
    3. Liquid Propane (LP) Gas is another option along with oil where natural gas is not available. LP has been used predominantly for domestic cooking and somewhat for DHW generation. As an area heating and DHW fuel it has traditionally been up to a 100% premium over oil. It is a heating option of choice in our experience.

    Note that solid fuels (wool, coal, peat, waste, etc.) have been purposefully omitted from this discussion. Insurers typically disallow continuous firing fuels using interior combustion equipment. External or “outdoor boilers” are “zero pressure” and require a “plate exchanger” interface with an internal power fired system to assure continuous heating maintenance. Verify these statements and weigh potential penalties for your particular situation.

    Consumers predominantly identify their area heating options as Forced Hot Air (FHA) Furnace or Forced Hot Water (FHW) Boiler Systems. Similarly DHW options as Electric, Gas or Oil stand-alone Water Heaters or from an immersion coil within a boiler. So therefore we usually find the typical FHA System with a stand-alone DHW Heater as a combination. FHW Systems usually provide DHW from an internal Immersion Coil, as previously noted. Currently we are seeing the emergence of the Indirect Hot Water Heater, supplied by a boiler as the efficiency choice.

    But in fact our heating options are more extensive. They include:

    1. Air Handler– A FHA Furnace without a fuel-powered heating source. Instead it has an internal large radiator (heat exchanger) that is externally supplied with energy from a FHW source (boiler).
    2. Unit Heater– A radiator with fan, typically found as an overhead heater in a garage, warehouse, etc. There are also variations of these with provisions for attaching ducting – otherwise similar to an Air Handler.
    3. Plate Heat Exchanger– Basically two (or more) mutually integrated radiators allowing the interchange of heat from varied sources. Source variation attributes may be pressure, temperature, flow rate(s) and composition. Their composition may be aqueous (or not) and adjusted for properties such as freezing and/or boiling resistance.

    Utilizing these latter devices allows us to employ higher efficiency or lower cost hot water generation sources (or both) for all our area and DHW heating requirements. We respectfully suggest that where a single, efficient energy source is desirable or necessary for continuous demand a FHW boiler should be employed. Further, that this source then be applied to all your structure’s heating demands with all the resources detailed within.

    The unmentioned physical fact is that utilizing water as an energy conductor is inherently and significantly more efficient than air. Thus an HVAC System (air heating/cooling) is less efficient than a hot water boiler (heating) coupled with an air handler (cooling) combination. This can be witnessed in their assigned AFUE values.

    So, let us wrap it up by considering some common scenarios for our FHW boiler system source:

    1. A Central HVAC (Heating,Ventilation & Air Conditioning) System Upgrade.

      • Upgrade the existing FHA Furnace with an Air Handler, if desirable, or
      • Install a FHW Heat Exchanger (radiator) into an existing FHA Plenum, plumb and rewire as necessary.
      • Install a “Chiller” in the Hydronic System to provide an A/C source.
    2. Existing or planned FHA System Upgrade – Same as 1. without A/C.
    3. FHA installation into a seasonal, incremental, unheated area or as an expansion.
      • Install an Air Handler or Unit Heater variation to suit.
      • Where freezing protection is desirable, employ a Plate Heat Exchanger with anti-freeze as necessary.
    4. Use a Plate Heat Exchanger to couple “incompatible” secondary heated water sources such as exterior wood & coal boilers, solar & geothermal loops, etc.
    5. In all cases, move to an Indirect Water Heater for efficient DHW generation.

    By the way, these new high efficiency boilers do not necessarily need a chimney. Condensing Gas Boilers typically use PVC pipe for venting and Triple-Pass Oil Boilers with Pressure-fired Burners can use a direct exhausting vent kit.

    Have we run you out of options yet?

    Last Edit: 10/18/2018 pdm


    Reviewing all of our installations in recent years, every customer has reported fuel usage reduction of 40% and more. Impressive — and yet humbling. More importantly is how we have achieved these and sharing our experiences with others.

    Predicting the economics of an energy efficiency product, whether you’re proposing insulation, window or heating upgrades is a difficult and potentially an “egg-in-your-face” task. It would seem that claims range from the modest to the scientifically unachievable, qualified only by the sales skill of the presenter. Ultimately, putting it down on paper is the only real documentation. Admittedly we are conservative as well, opting on the side of caution, but predictable. In reality all of the energy product upgrades in combination must be considered.

    It has also become apparent that we personally are in a niche market by default. The predominant activity of “swapping boilers” by dealers and service tradesmen eludes us. We seem to get the “tough ones”, and love it! This also provides us with a developed and unique skill-set to apply. Watching the online forums and fielding direct questioning reinforces this contention. Also consider that our commitment is to efficient, high-end hydronic (hot water) oil, propane and natural gas heating systems by Weil-McLain ONLY, and more specifically their Ultra Series. Reading our prior blogs on this website will clarify and further detail our activity.

    ALWAYS CONSIDER YOUR HEATING REQUIREMENTS AS PART OF A SYSTEM. By a system we mean all of your energy requirements, typically heating (and cooling), domestic hot water, pool heating, spas, etc. Firstly,

    1. You must define where you are now, heating-wise
    2. Where do you intend to go, then
    3. How are you to get there?

    In simplistic terms, your heated space is a “box” to be maintained at a comfortable temperature regardless of external influence. The influences to the “box”, in general order of importance are:

    1. Infiltration: Air leakage is the most significant robber, moving both warmed and exterior air into and out of the structure. Seal these as much as possible. The technical measure is ACH (Air Changes per Hour) and is difficult to field measure, requiring substantial equipment. An ACH of 1 is considered good, 2 or more poor and below 1/2 or so requiring air exchange. Things can get too tight — and unhealthy!
    2. Cap Insulation: Heat rises and consequently the ceiling level temperatures and hence losses are significant.
    3. Windows & Doors: Energy efficiency of these has improved significantly in the last 25 years or so and can substantially improve things. Note that Infiltration (No. 1) is a significant consideration of these as well.
    4. Sidewall Insulation: The remainder of the vertical heated exterior wall structure.
    5. Sills and Floors: Tightened structure to the ground (and below) level, including basement windows & doors.

    To determine where you are (or plan to go) requires measuring the “box”, hence using a Heating Loss Calculator.  (Refer to our prior blog on its use.) In so doing you can “play the numbers” by changing values therein to determine effect(s) and hence a strategy. This is the standard tool of Heating Professionals and some free software is available on-line. Don’t let it scare you. If you can use a measuring tape, fill out a form or translate a recipe you’ve got it made. If you’re still bashful let that geek kid loose at it.

    The Heating Calculator not only tells you where you are but where you are going, as prior mentioned. Remaining then is how do we get there?

    AGAIN OUR TENET: ALWAYS CONSIDER YOUR HEATING REQUIREMENTS AS PART OF A SYSTEM. You have many tools to work with, not just replacing a boiler or a furnace to satisfy all of your energy requirements. Again consider ALL available tools to meet your heat energy requirements and maximize efficiency. Generally, they are:

    1. Furnace — A fuel fired appliance that heats and circulates warmed air to maintain comfort.
    2. Space or Unit Heater — A self-contained gas or oil-fired heated air appliance dedicated to a room area.
    3. Air Handler — A furnace that utilizes an internal heater (electric, hot water or steam) supplied by an external energy source (wired or piped to it).
    4. Boiler — A fuel fired appliance that heats and circulates heated water (or steam) through radiation to maintain comfort.
    5. Heat Exchanger — A device to transfer heat from a differing medium to another without mixing and therefore isolating them. (Useful for special environment applications and situations that we will detail.)
    6. Tankless Heater — A coil immersed internally into a boiler to also provide domestic hot water service.
    7. Indirect Heater — A detached water storage tank heated by a boiler to provide domestic hot water service.
    8. Demand (Instantaneous) Heater — A gas-fired appliance that heats domestic water on demand (no storage).
    9. (Common) Water Heater —- A fuel fired (electric, gas or oil) appliance that heats domestic hot water directly.

    As you review your requirements in lieu of these tools, you will note that there are two (2) distinct scenarios:

    1. Separate appliances for heating and hot water. (A furnace or space heaters with separate demand or common water heaters in combination to suit your local and peculiar fuel economics.)
    2. A combination system utilizing a single fuel source boiler providing all demands.

    First, determine fuel selection. Referring to our other blogs you will note that we are in the higher heating demand New England, and are further restricted by available fuel options and economics. Briefly, in cost order:

    1. Electric rates are very high and not considered for efficient area or domestic hot water heating.
    2. Propane (LP) is generally available but of significantly higher cost as a heating fuel. It is considered a fuel-of-choice, typically providing cooking and/or hot water requirements.
    3. Natural gas has limited availability but is currently the lowest cost heating fuel option. Where available, its choice is obvious with a single caution: Get an actual billing estimate! As a distributed fuel (like electricity) its total delivered cost will be higher than the mere cost of the “fuel”.
    4. Fuel oil is predominant and is a low cost option, competing with natural gas only. Note: Heat pumps, photovoltaic, geothermal, wind and solar are very economically protracted options and not considered currently competitive.

    Scenario 1 (FHA Furnace & Separate Water Heater) can be well executed particularly where natural gas is available and used in “Demand Appliances” i.e. Condensing Gas Furnaces @ 95% and “On-Demand” Water Heaters @ 83%. Propane (LP) efficiencies are of course similar, but at a significant fuel cost premium.

    Scenario 2 (Single-source FHW Boiler) offers the most viable option both economically and physically and is the basis for our system configurations. Selecting the most cost-effective fuel, an efficient appliance to convert, the best medium to distribute and the appropriate devices to transfer energy equate to a “win-win” solution. Using water as the heating medium is ideal for efficient and flexible distribution. Specifically:

    1. A Condensing Gas Boiler @ 93+% or a Triple-Pass Oil Boiler @ 87% providing the heated water.
    2. An Indirect Water Heater providing Domestic Hot Water efficiently and on-demand.
    3. Conventional Radiation to warm full usage areas.
    4. An Air Handler to adapt existing FHA (Forced Hot Air) ducting and distribution without alteration, or to heat an occasional usage area where cold and/or freezing is not detrimental in the off-use cycle.
    5. A “Plate” Heat Exchanger to adapt heated water to physical conditions:
      • Freezing applications such as deep cold areas, selective seasonal shutdowns, snow removal and some pool applications by using glycerol (anti-freeze) as a medium without passing it through the boiler.
      • Adapting zero-pressure sources (steam and exterior wood boilers) to deliver to pressurized systems.
      • Couple a cold-environment source such as an external Solid Fuel Boiler (Wood/Coal/Corn/Peat, etc.) to hydronic (hot water) distribution.

    Existing Systems vary widely in configuration and so must be approached individually. However there are a few distinct patterns and approaches:

    1. The existing Scenario 1 above, i.e. a Forced Hot Air System and Conventional Water Heater. Consider a High-Efficiency Boiler, an Air Handler and Indirect Water Heater combination. This is typically a one-step option — all or nothing vs. individual unit upgrades.
    2. Let’s call this Scenario 2A. An older, inefficient boiler system in poor condition and in need of replacement. Upgrade in entirety when the existing boiler (the high-ticket item) is in jeopardy and fuel efficiency is poor.
    3. Scenario 2B is an existing stand-alone boiler in fair shape with either an internal Tankless Heater or a detached Conventional Water Heater. This common combination offers a step approach to higher efficiency. Consider replacing your Domestic Hot Water Source (Internal Coil or separate Heater) with an Indirect Water Heater and converting your boiler to a “Cold-Start”, On-Demand System. This requires additional plumbing and wiring but you now have attained most efficiency gains minus the boiler efficiency gain itself. Stand-by heat losses are now minimized. You’ll love the savings.

    A story to make our point. We replaced an old, terribly over-sized boiler recently with raves from the customer — with one exception. An adult daughter had moved into an open room next to the “Old Dragon” in the basement. Now she is cold. The next step is to finish off the basement and provide heat only where it is needed (and more efficiently).

    This analogy brings us to our last point. As you make energy improvements to a structure you do two (2) things:

    1. You improve its energy efficiency, the desired result. But,
    2. You also effectively increasingly oversize your boiler for your heating application, an undesirable result. Considering that the Old Dragon was likely over-sized by practice initially, you are now incurring very substantial “stand-by losses”. These energy losses up the chimney, into the surrounding area and poorer energy conversion become substantial indeed, inviting the greater improvement opportunity. Change the boiler.

    We trust this is of some help to you in assessing your energy needs and determining a course of action.

    Last Edit: 10/12/2012 pdm