Friday, April 3, 2015

Bosch Tankless Water Heaters with New Built-In External Water Filters

Bosch Thermotechnology is always improving the gas-fired tankless water heaters and has recently improved all the sealed combustion tankless water heaters and have added a new hydraulic block on the bottom of all the units that incorporates a new built in external water filter.

The Bosch Greentherm C950ES and Bosch Greentherm C1050ES condensing heaters were designed with the new hydraulic block and external water filter built in.  The Bosch Therm C1210ES/ESC, Bosch 940ES and the Bosch 830ES have recently had the new hydraulic block and external water filter added.  After Serial number beginning with "301" will have the built in external water filter.
Built-in External Water Filter
All of the older Bosch "Therm" models before serial number 301 had the external water filter, part #8703035356 and was sold as an accessory.

Please contact Global Protankless Supply with any questions at 866-289-4652.

Thursday, March 26, 2015

Backdraft Reducer #9301BFP for Bosch Tankless Water Heaters

The Heat Fab backdraft reducer (9301BFP) is the preferred option for limiting backdraft for the Bosch Condensing tankless water heaters (see fig. 22).

Note: The following solution is available only for 3" diameter venting.

In cold climates, components of a tankless water heater can freeze and burst from negative draft. A leading cause of negative draft is combustion appliances in the building not being supplied with sufficient combustion air. A wood stove or furnace can pull its combustion air from the water heater‘s vent pipe, allowing the cold incoming air to freeze the cold water in the heat exchanger. The best prevention for this risk is two pipe venting which draws the appliance combustion air from outside creating a positive pressure inside the unit.

For this solution to be effective, the internal flapper must be 100% closed when the water heater is not running. Refer to Figures 24 and 25 for preferred installation positions in the vent system.

Installation considerations:
• Install damper per the supplied manufacturer‘s instructions.
• The damper is only to be used in the exhaust vent piping.
• Ensure directional arrow on damper label faces in the same direction as exhaust flow.
• If installed horizontally, the axis must be horizontal or slightly pitched up towards termination to ensure damper closes 100% when heater is not running.
• To allow accessibility, damper must not be installed in an enclosed section of vent pipe.
• Do not install damper in unconditioned spaces (e.g. attics) Condensation can build up while the heater is running which can later freeze and potentially block the flapper.

The Bosch C1210ES/ESC, C1050ES & C950ES are all approved to use the Backdraft Reducer. 

Thursday, March 19, 2015

Phasing out of Bosch Therm 940ESO Outdoor Unit

Bosch is phasing out the Therm 940ESO model tankless water heater in Natural Gas, Part Number 7738000001 and Liquid Propane, Part Number 7738000002.

Bosch will continue to still make the Bosch Therm 940ES NG & LP tankless water heaters. The Bosch Therm Outdoor Kit (BTOK) will be sold as an accessory for outdoor installations.

The Phase out of the Bosch Therm 940ESO outdoor unit will be immediate. Please see the list below for model numbers, color changes by manufacturing date and BTOK model numbers.

Bosch Therm 940ES NG - #7703311076
Bosch Therm 940ES LP - #7703411073
(Gray Models, FD prior to FD420 - White Models, on or after FD420)

BTOK Outdoor Kit - Gray #7709003913
BTOK Outdoor Kit - White #7736502448

Please call Global Protankless Supply at 866-289-4652 for further questions or ordering.

Friday, March 13, 2015

Bosch Greenstar Intelligent Cascade Module (ICM) #7719003528

Bosch is always working on new ways to improve their products and has recently came out with an Intelligent Cascading Module (ICM) part #7719003528 for the Bosch Greenstar gas-fired wall-hung boilers.  The ICM modules are designed to control cascade systems.  A cascade system is a heating system where several smaller boilers are connected in parallel to achieve higher output.  The Bosch ICM modules are only suitable for controlling Bosch Greenstar boilers with BUS-enabled Heatronic 3 systems.
One Bosch ICM module can control up to 4 Greenstar boilers.  By conecting up to 4 ICM modules, up to 16 boilers can be linked to form a single cascade.  Depending on the heating system controls used, a cascade system with up to 4 or up to 16 boilers can be created.  The maximum number of boilers that can be connected and the number of ICM modules required for the different systems are shown in the table below.

Tuesday, January 20, 2015

Bosch Tankless Water Heaters and Pressure Regulating Valves

  1. Pressure Regulating Valve is a valve that automatically cuts off the flow of a liquid or gas at a certain pressure. Regulators are used to allow high-pressure fluid supply lines or tanks to be reduced to safe and/or usable pressures for various applications.

  2. Bosch tankless water heaters work on water pressure and flow.  Some people experience fluctuating temperatures sometimes if they are on a well system as the well pump has a high and low setting for when the pump comes on and off.  Most common well pumps are set to like 30 - 55 psi of pressure.  So when you are using the hot water and if the pump kicks on during this time you could see a change in flow and pressure which will change the flow and water temperature out of the Bosch tankless water heater.  
  3. A Pressure Regulating Valve installed on the cold water line before the Bosch tankless water heater can be set at the low PSI such as 30 psi and then will always maintain that 30 psi consistently whether the pump kicks on or not.
  4. There are all sorts of different pressure regulating and pressure reducing valves on the market.  

Friday, December 19, 2014

Wattages and Ohms Law for Electric Tankless Water Heaters

Electric Heaters and heating elements become hot due to a voltage being pushed through a wire.  The resistance in the wire measured in Ohms creates the heat.  The more resistance the hotter the wire gets. The more voltage pushed through the wire, the hotter the wire gets. Simply the smaller the wire (or the longer the wire run) the more resistance it gives to the voltage passing through.

So as voltage increases the wattage will increase four-fold.  As the voltage decreases the wattage will decrease by a factor of 4 as well.  The below table shows the percentage of drop or gain with different applied voltages to a heating element.

Rated at 277 volts the expected wattage % is
277 applied 100% (rated Wattage)
240 applied  75%
230 applied  69%
208 applied  56%
120 applied  19%

Rated at 240 volts the expected wattage % is
277 applied 133%
240 applied 100% (rated wattage)
230 applied  92%
208 applied  75%
120 applied  25%  (1/4 wattage)

Rated at 120 volts the expected wattage % is
240 Applied  400%  (4 times wattage - Dangerous) 
208 Applied  300%  (3 times wattage - Dangerous)
120 Applied  100%  (rated Wattage)
110 Applied   84%

This is all based on Ohm's Law.

Simple Ohms Law equations are:

Watts = VOLTS x AMPS
Volts =  AMPS x OHMS

A Conductor Wire's resistance is constant based on wire size and length.

A heater's watt rating is based on the wire used in the heating element and the voltage applied.

To get a 9.5 kilowatt rated heater run at 240 volts; a wire with a resistance of 6.6 Ohms is used. (If there are two elements in the heater, then each is rated at 4.75 kw and the resistance of the wire would be 12.12.)

Saturday, December 13, 2014

Calculating the Volume of Water in a Water Line

Whenever you turn on a gas, propane or electric tankless water heater the hot water starts heating up as soon as the minimum flow rate is met for the hot water demand. It takes a few seconds for the water to get heated up to the requested temperature. But, before the hot water starts to flow out of your shower or sink faucet the cold water that is in the pipe has to be pushed through your faucet. This is often referred to as pushing a "cold water slug".

Customers frequently ask us how much water is contained in this cold water slug and how long it will take to push this slug through their faucet. This can be easily calculated by using the formula for the volume of a cylinder.

The formula for the volume of a cylinder is V = Pi x r x r x h

where Pi = 3.1416; r = the radius of the water line; and h = height (or in this case the length) of the line

If your water line is 1/2" then r = .25" and r x r = .0625" and Pi x r x r = 0.19635 square inches
If your water line is 3/4" then r = .375" and r x r = .1406" and Pi x r x r = 0.4417875 square inches

Now to get all units in inches calculate h (the length of the water line) by taking feet x 12". As an example let's assume we have a 40' water line of 1/2" pipe. 40' = 480" so we calculate the Volume as:

V = 0.19635 square inches x 480" = 94.248 cubic inches

Now there are 1728 cubic inches in a cubic foot and there are 7.48 gallons in a cubit foot. Therefore there are 0.0043 gallons in a cubic inch.

So, 94.248 cubic inches * 0.0043 gallons = 0.4 gallons of water.

If you are running this cold water slug through a 1 GPM sink faucet then it will take .4 x 60 seconds or 24 seconds to push the cold water slug through the 1 GPM faucet. Add a few more seconds for the tankless water heater to bring the water up to temperature and remember that there are about 15' of internal pipe in a gas or propane tankless water heater that also starts out with cold water. In this example it will take just more that 1/2 minute to get the hot water flowing out of the faucet.