Heating Helper

INTRODUCTIONSizing for Tankless Heaters...Consider adding somestorageWhen sizing boilers for heating and domestic hot water production bymeans of an immersion type tankless heater, one must bear in mindthat you cannot cheat the laws of physics. In order to raise the temperatureof a gallon of water flowing through a tankless coil from 40°F to140°F, you will require 50,000 btuh of boiler capacity. Therefore to beable to produce 3 gpm or 5 gpm of hot water through this coil the boilercapacity will need to be 150,000 btuh or 250,000 btuh respectively.Unfortunately there are an abundance of oversized boilers out therewasting valuable energy dollars just sitting there waiting to produce "ondemand" domestic hot water with no provision for storage. A muchbetter alternative would be to add an aqua booster or storage tank andcontrols to maintain a volume of hot water to fulfill those larger needswithout the need for a larger tankless coil and boiler. The end result,once again, will be substantial fuel savings due to less short burnercycles in the long run.Steam Boilers...Size it by connected loadThe function of a steam boiler is to create steam vapor which in essenceis water that has turned to a super heated gaseous state. Whenenough latent energy, in the form of heat, has been applied to waterit changes it’s state from liquid to a vapor state. The steam vapor inturn gives up its latent energy to the radiators and other heat emittingdevices connected to the boiler piping by means of conduction. Thesein turn transfer their heat to the surrounding air and objects by meansof convection and radiant principles. You only need to size the boilerbased on the capacity of steam vapor needed to fill all of the connectedradiation and related piping. Therefore it is absolutely imperative thatyou check each and every radiator or heat-emitting device to establishits capacity of steam in Square Feet of Radiation or Equivalent DirectRadiation (EDR). There are a number of tables in Chapter 5 of thispublication to help you in accomplishing this. You do, of course, haveto take into effect that there will be some steam required to fill theconnecting pipes and that there will be standby losses related to thatpiping, but these factors have already been built into the Net IBR boilersteam ratings to the capacity of 33%. This means that unless there is alarger than normal amount of piping, pipes that run through