Turn Down Ratios for Bosch Greenstar Straight & Combi Boilers

The turn down ratio can be calculated by dividing the input rating by the minimum input. See below for the appropriate turn down ratio for each boiler in the Greenstar series. The figures outlined in this bulletin are calculated using NG inputs and rounded to 2 decimal places.

Turn down ratios for Greenstar Condensing Combination (Combi) Boilers:

Bosch Greenstar Wall-Hung Combi 100 - ZWB28-3A23S3123

•    Part number: 7738 100 002
•    Input Rating: 100,800 BTU
•   Minimum Input: 24,600 BTU
•    Turndown Ratio: 4.1 : 1

Bosch Greenstar Floor-Standing (FS) Combi 100 - KWB28-3A23S3123

•  Part number: 7-733-600-082
•  Input Rating: 100,800 BTU
•  Minimum Input: 24,600 BTU
•  Turndown Ratio: 4.1 : 1

Bosch Greenstar Wall-Hung Combi 131 - ZWB35-3A23S3123

• Part number: 7738 100 256
• Input Rating: 131,900 BTU
•  Minimum Input: 36,000 BTU
•  Turndown Ratio: 3.7 : 1

Bosch Greenstar Floor-Standing (FS) Combi 131 - KWB35-3A23S3123

•  Part number: 7-733-600-083
•  Input Rating: 131,900 BTU
•  Minimum Input: 36,000 BTU
•  Turndown Ratio: 3.7 : 1

Bosch Greenstar Wall-Hung Combi 151 - ZWB42-3A23S3123

•  Part number: 7713 331 041
•  Input Rating: 151,600 BTU
•  Minimum Input: 36,000 BTU
•  Turndown Ratio: 4.2 : 1

Bosch Greenstar Floor-Standing (FS) Combi 151 - KWB42-3A23S3123

•  Part number: 7-733-600-084
•  Input Rating: 151,600 BTU
•  Minimum Input: 36,000 BTU
•  Turndown Ratio: 4.2 : 1

Turn down ratios for Greenstar Condensing Straight Boilers:

Bosch Greenstar Wall-Hung 57 - ZBR16-3A23S3123

•  Part number 7712 231 416
•  Input Rating: 57,200 BTU
•  Minimum Input: 12,900 BTU
•  Turndown Ratio: 4.4 : 1

Bosch Greenstar Floor-Standing (FS) 57 - KBR16-3A23S3123

•  Part number 7-733-600-077
•  Input Rating: 57,200 BTU
•  Minimum Input: 12,900 BTU
•  Turndown Ratio: 4.4 : 1

Bosch Greenstar Wall-Hung 79 - ZBR21-3A23S3123

•  Part number: 7738 100 322
•  Input Rating: 79,200 BTU
•  Minimum Input: 24,600 BTU
•  Turndown Ratio: 3.2 : 1

Bosch Greenstar Floor-Standing (FS) 79 - KBR21-3A23S3123

•  Part number: 7-733-600-078
•  Input Rating: 79,200 BTU
•  Minimum Input: 24,600 BTU
•  Turndown Ratio: 3.2 : 1

Bosch Greenstar Wall-Hung 100 - ZBR28-3A23S3123

•  Part number: 7712 231 415
•  Input Rating: 100,800 BTU
•  Minimum Input: 24,600 BTU
•  Turndown Ratio: 4.1 : 1

Bosch Greenstar Floor-Standing (FS) 100 - KBR28-3A23S3123

•  Part number: 7-733-600-079
•  Input Rating: 100,800 BTU
•  Minimum Input: 24,600 BTU
•  Turndown Ratio: 4.1 : 1

Bosch Greenstar Wall-Hung 131 - ZBR35-3A23S3123

•  Part number: 7712 231 414
•  Input Rating: 131,900 BTU
•  Minimum Input: 36,000 BTU
•  Turndown Ratio: 3.7 : 1

Bosch Greenstar Floor-Standing (FS) 131 - KBR35-3A23S3123

•  Part number: 7-733-600-080
•  Input Rating: 131,900 BTU
•  Minimum Input: 36,000 BTU
•  Turndown Ratio: 3.7 : 1

Bosch Greenstar Wall-Hung 151 - ZBR42-3A23S3123

•  Part number: 7712 231 413
•  Input Rating: 151,600 BTU
•  Minimum Input: 36,000 BTU
•  Turndown Ratio: 4.2 : 1

Bosch Greenstar Floor-Standing (FS) 151 - KBR42-3A23S3123

•  Part number: 7-733-600-081
•  Input Rating: 151,600 BTU
•  Minimum Input: 36,000 BTU
•  Turndown Ratio: 4.2 : 1

Bosch Greenstar Floor Standing (FS) Combi & Straight Boilers

Global Protankless Supply is pleased to announce the highly anticipated Greenstar Floor Standing (FS) series boilers. The Greenstar FS Boilers are fully modulating heat only or combi floor standing gas condensing boilers with many of the same features and customer benefits of the Greenstar wall boiler, with some additional innovations.

Installation has been simplified, with two new innovations:

  a. The Greenstar FS includes an integrated supply return manifold that can be field converted into a low loss header (LLH) to accommodate existing pipe work.

  b. All line and low voltage connections have been relocated into junction boxes on
  the back of the boiler for easier access and wiring.

Venting options have been expanded from PVC, CPVC, concentric & ridged PP to also include flexible PP venting. This provides a quick and easy venting solution for retrofit applications where the boiler and piping is not relocated.

The FW200 Weather Compensation Boiler Control (87182262150) is an optional accessory and is not included with the Greenstar Floor Standing Boilers. The New System Control (NSC), capable of controlling multiple zones, will be launched around the same time as the new Greenstar FS to provide a flexible heating combination.  Please call Global Protankless Supply at 866-289-4652 for further details and to place your order.

Calculating Combustion Air Needed for Bosch Gas Tankless Water Heaters

The amount of combustion air today is very limited due to our attempt to reduce our fuel consumption. We are replacing our windows, doors, weather-stripping, caulking and adding insulation. Years ago there were no double pane windows in the basements much less steel insulated doors in the basement leading to the outside. There were old single pane glass windows and old wooden doors which, a lot of times you could see daylight around the door frame.

Today we have added thermo pane windows in the basement, new steel doors complete with magnetic seals. We even insulate the exterior perimeter between the floor joists. All these ideas are good, but they steal much needed combustion air required for a safe combustion process needed for a gas appliance. If your heating appliance is using indoor air for combustion you must be aware of the amount of combustion air that is required.

The combustion process requires the air being burned to contain 20.9% oxygen. If it does not, the flame will start producing CO (carbon monoxide). This is an odor free gas which gets inhaled and stops the body from absorbing oxygen. CO poisoning happens every year. We must be more concerned about this when we tighten up our homes and have appliances which use indoor air for combustion.  Gas appliances should never be installed in bathrooms or bedrooms where doors are normally kept closed.  This is stated in the National Fuel Gas Code (NFGC) manual.  Please also consult local codes for further clarification.

The federal code requires 50 cu ft. of space per 1000 Btu's input from your gas heating appliance. Your state or local code may exceed that. If we know what the input of the appliance is and divide it by the total cu. Ft. of the mechanical room say where the appliance is installed the answer would have to be at least 50 cu ft. per. If we do not have 50 cu. ft. per thousand Btu's, we must bring combustion air in from the outside. If there are hallways and other rooms available due to no door being on the mechanical room we can also calculate these other areas.

We need to measure all the areas we can get combustion air from, until we come to a doorway with a door. The code states even if it is a louvered door, we still stop when we come to a door. If the utility room has a door mounted, even if it is open all the time you stop at the door. Since the formula uses Btu's as MBH (thousand btu/h) we do not use the last three (3) zero's. For example 130,000 would be just 130.

As an Example:

If we do the math it would look like this; 

Room = 32 feet long x 25 feet wide x 7 feet high 

Boiler = 130,000 Btu input and a 40,000 Btu Water Heater

Volume = Length x Width x Height 

Volume = 32' x 25' x 7' = 5600 Cubic Feet

Total BTUH Input = 130 MBH + 40 MBH = 170 MBH 

5600 Cubic Feet / 170 MBH = 32.95 Cubic Feet per 1000 BTU

Combustion Air will be Required!!

Any additional combustion air needed beyond what is already available must be taken from the outdoors.  When bringing air from the outside you only need to bring in the balance of what you need. When in direct communication with the outdoors you need 1 sq in of free space for every 4000 Btu's.

Global Pro Tankless Supply 4th of July Sale

Global Pro Tankless Supply is pleased to announce our 4th of July Sale that will be running from June 30th through July 6th 2015 at midnight ET. Everything will be marked way down for this special sale period.  Global Pro Tankless Supply will meet or beat any other authorized distributor's price as part of this promotion.  Global Pro Tankless Supply would need to verify the competitors discounted price either in e-mail or through a website.

Global Pro Tankless Supply will be knocking prices down on all our Bosch Gas tankless water heaters, electric tankless water heaters, Bosch Greenstar Boilers and Combi Boilers.  You can call us for an extra discount of $25 off for the Bosch Greentherm and Greenstar Boilers by referencing coupon code:  PRO2015.

We also have special July 4th sale pricing on our Humphrey gas lights & accessories, Danfoss electric in-floor heating mats, Z-Vent Stainless Steel Venting and Virgo water filtration systems.

Please feel free to e-mail us with questions at info@prowaterheatersupply.com  or call us at 866-289-4652. We are open 24-7 to assist you in selecting the best product for your needs.