1. Multiple units can be installed in parallel to handle demands that exceed the capacity of a single unit. (Use reverse return piping to equalize flow/btu through the units.)
2. In commercial applications consider installing two smaller units rather than one larger one to provide backup capability. For example, a building has 80 apartments, so a single E109 could handle the hot water demand, but two E65 would provide backup. 
3. Do not oversize. The flow of water through the coils should be kept high to ensure a high level of turbulence within the coils (eg. high velocity). (This turbulence scrubs the inside of the coils keeping them free of scale.)
4. ERGOMAX should be compared to units produced by other manufacturers based on performance and not on tank size. 
5. Using a mix valve with ERGOMAX will eliminated/minimize boiler short cycling (boiler will operate more efficiently) and also provide more hot water.
6. Add four inches to basic tank dimensions to allow for utility (DHW) and boiler connections.

Frequently Asked Questions about Ergomax^®

What is an ERGOMAX?  ERGOMAX is a heat exchanger, popularly known as an indirect water heater.

What is an indirect water heater?  An indirect water heater is a heat exchanger and uses heat from an external source (i.e. a boiler, solar panels, etc.) to heat the cold (domestic) water.

How does a direct-fired water heater differ from an indirect?  A direct-fired water heater has its own firebox and must be vented to the outside (like a boiler) and creates its own heat. It operates independently of other equipment.

Which is better -- direct or indirect?  Indirect (heat exchanger) is more efficient and will produce more hot water (from the same amount of heat) than a direct fired unit. (It also has no flue.)

What makes ERGOMAX different?  ERGOMAX are different from other indirects in three ways:

Why do other indirects scale up and corrode?  Other indirects hold domestic water in the tank and heat it by immersing a coil connected to a boiler in the tank. The heat from the boiler water in the coil heats the domestic water in the tank. As hot water is used, fresh cold water enters and refills the tank. This constant refilling of the tank with fresh water provides a steady supply of minerals which precipitate out when the water is heated and attach themselves to the hottest part of the tank -- the coil -- forming a constantly growing layer of scale, reducing the heat transfer from the hot boiler water to the cold domestic water. Also, the constant temperature swings within the tank from hot to cold cause the tank (steel) to expand and contract. These thermal stresses cause cracks to form in the glass lining(which does not expand) allowing the steel to be attacked by oxygen in the water, causing corrosion.

Why won't ERGOMAX scale up or corrode?  The ERGOMAX tank is filled with boiler water. So, except for a very small amount of makeup water, no new minerals or oxygen enter the tank. No minerals means no scale build-up; and no oxygen means no corrosion.    ERGOMAX tanks do not need glass lining as they hold boiler water, and thermal stresses are minimal as ERGOMAX operates on the same temperature differential as the boiler. Also, turbulence within the ERGOMAX tank prevents stratification and cold spots.

How does turbulence affect energy consumption?  Energy consumption is reduced because heat transfer is much more efficient within a "turbulent" environment than within a "static" environment.

How is turbulence maintained within the ERGOMAX tank?  A mechanism located at the top of the tank forces the incoming boiler water to flow in spiral formations throughout the entire tank, creating turbulence.   

How many coils does an ERGOMAX contain?  The last digit of each model number represents the number of coils in that unit, so:  

Why are all ERGOMAX coils 50' long regardless of model?  Coils of this length have maximum heat transfer with minimum pressure drop.

How many GPM can each coil handle?  Each ERGOMAX coil can handle 3 - 3½ gpm on a continuous basis. Peak usage can go as high as 4-5 gpm per coil, but this output rate should not be steady-state.

How is turbulence created within the coils?  The total cross section area of all coils is less than the cross section area of the incoming pipe, causing the domestic water to flow faster within the coils and creating a turbulent flow (eg. like a wide river flowing through a narrow gorge).

Why is turbulence inside the coils important?  Turbulence inside the coils scrubs the inside of the coils, preventing formation of scale.

How does turbulence affect heat transfer?  Turbulence creates an ideal environment for heat transfer. An example will illustrate this phenomenon: You come home very tired and want to soak in a very hot bath. How do you get into the bath? Very slowly, not to cause any ripples. Once you are in the bath, you can lie in this very hot water so long as you do not move. When you start to move, you feel the heat. This movement creates turbulence which "washes away" a thin layer of water next to your skin (known as a boundary layer) which acts as a layer of insulation preventing heat from the rest of the bath water to get to your sk in. Similarly, turbulence within the ERGOMAX tank and coils prevents this boundary layer from adhering to the inside or outside of the coils, hindering the heat transfer process

What is an ERGOMAX unit's heat transfer efficiency?  ERGOMAX units operate at 99%+ heat transfer efficiency which stays constant over time.

Why is ERGOMAX 99+% heat transfer efficiency higher than that of other indirects?  ERGOMAX is much more efficient because the built-in turbulence inside and outside the coils creates an ideal environment for heat transfer. Also, ERGOMAX copper coils transfer heat at a much higher rate than other metals. Other indirects, using coils made from other metals which conduct heat at a lower rate, operate in the mid to low 80% range when new, and steadily lose efficiency as they scale up over time.

What is thermal energy and how does an ERGOMAX unit store it?  Thermal energy is heat. The hot boiler water in ERGOMAX tank contains heat (Btu) which is used to heat the incoming domestic cold water.

How does thermal storage translate into energy savings?  Thermal storage allows the boiler to run less often, saving energy. When domestic hot water is needed, the heat stored in ERGOMAX tank (hot boiler water) is used to heat the cold water entering the coils. When the demand for hot water uses up all of this stored heat, the boiler is activated to supply more hot boiler water to ERGOMAX tank to continue heating the domestic water. This makes the boiler run less often. Combined with the built-in turbulence, this capability results in minimal energy consumption to heat domestic water. The thermal storage in ERGOMAX also acts as a buffer to minimize/eliminate short- cycling in low mass boilers during periods of low demand.

How much domestic hot water is stored in each ERGOMAX unit?  Very little, each coil holds less than 1/3 of a gallon.

What is the recovery rate of an ERGOMAX unit?  With ERGOMAX, there is no need to worry about "recovery," because an ERGOMAXunit will never run out of hot water as long as the boiler/circulator are functioning and hot water demand does not exceed the boiler's capacity to produce heat.

What equipment comes with an ERGOMAX unit?  All units come with an aquastat, a 30 psi ASME safety valve, and a drain valve. E24 through E109 models are also equipped with a temperature/pressure gauge.

What is the tank made of? Is it glass-lined?  AS36 steel. A glass lining is not needed since the tank contains only "dead" boiler water.

What maintenance does a ERGOMAX unit require?  None.

Does ERGOMAX have a sacrificial anode rod?  No. None is needed as no fresh water enters the tank (it holds only "dead" boiler water).

Does an ERGOMAX need a separate flue?  No. It has no firebox and produces no exhaust.

Does an ERGOMAX unit make any noise?  No. Normal operation is completely silent. If any noise, vibrations or gurgling is heard, there is probably some air trapped in the piping or the tank. Open the safety valve until all of the air is evacuated. NOTE: Installing an automatic air vent on the tank will prevent trapped air from accumulating at the top of the tank and causing corrosion.

What is the tank standby loss?  Less than 1/2^oF per hour.

Can water conditioners, antifreeze, etc., be used with ERGOMAX?  Yes.

How long is the residential warranty?  ERGOMAX are covered by a Limited Lifetime Warranty to the original purchaser, which can be transferred to the second owner during the first 10 years following installation (see the Warranty). Note: Residential use is considered to be a single home or duplex.

How long is ERGOMAX warranted in commercial applications?  Ten (10) years, 100% for the first 5 years, then prorated 20% in each of years 6-10.

Legionnaire's Disease has been traced to domestic water systems and, in particular, storage tanks where stratification occurs. Can such bacterial growth occur in an ERGOMAX?  No. ERGOMAX does not store potable hot water, but heats it only as it is needed, instantaneously, so no bacterial growth can occur in ERGOMAX. NOTE: The ideal temperature for bacterial growth in a traditional indirect units, direct fired units or storage tanks is 120^oF.

Does ERGOMAX come in a double-wall version?  No. ERGOMAX is exempt from the BOCA and IAPMO double-wall requirements. Under BOCA, heat exchangers utilizing non-toxic heat transfer fluids are exempt from the double-wall requirement. (See BOCA - 1993 Edition, Section P-1507-13.2). Under IAPMO single wall heat exchangers are permitted, so long as a) the heat transfer medium is either potable water or a substance recognized as safe by the FDA; and b) the pressure of the heat transfer medium is less than the operating pressure of the potable water system. The ERGOMAX tank is filled with boiler water at low pressure. The higher domestic water pressure will cause the safety valve on the ERGOMAX tank to open should a leak from the coils into the tank occur.

Can ERGOMAX units be used with "low-mass" boilers?  Yes. Since the ERGOMAX tank is filled with boiler water, it acts as a buffer and prevents low-mass boilers from short-cycling.

Can ERGOMAX units be used with "cold-start" boilers?  Yes. However, as with other indirect units, if a reverse acting aquastat is installed in the boiler it will prevent boiler water from circulating into the ERGOMAX tank until the boiler water is up to temperature. This allows the boiler to "catch up".

Can ERGOMAX units be used with steam boilers?  Yes, but only with low pressure steam boilers. By tapping in below the water line on the boiler (at least 9 inches below the water line), hot water can be drawn off to supply the closed loop to the ERGOMAX tank. NOTE: Care should be taken not to draw any sediment into the ERGOMAX tank from the bottom of the boiler.

Information Source: ErgoMax