Water Heating Calculator Engineering Toolbox

[Bertoldo Beyer]

Pump and Plumbing Sizing for Solar Water/Space Heating Systems Pump and Plumbing Sizing for Solar Water or Space Heating SystemDetails on solar pump/pipe sizing... This page covers the details of sizing the pump and the plumbing for a solar space or water heating system so that the system efficiently transfers heat from the collector to the storage tank without being excessively large.Details on solar pump/pipe sizing... How to Determine Collector Flow Rates This page takes you through how to determine flow rate for your collector, and what the tradeoffs are ... HVAC Pipe Flow Calculations

Air duct pressure drop calculator...Pipe pressure drop calculator... Some nicely done and generally easy to use calculators for water pipe and air duct pressure losses, channel flow, fan laws, ...

Air Duct Friction Loss Calculator

From The Engineering Toolboxwww.engineeringtoolbox.com/...

An easy to use chart to look up friction losses for flex ducts.I find this one simple chart answers most of my duct loss questions -- it even has a correction for bends at the bottom. Flex Duct Loses Due to Compression and Sags...

Static Pressure Losses in

6, 8, and 10 Non-Metallic Flexible Duct... Flex ducting is subject to extra losses compared to rigid metal ducts when it has sags between supports and when it is not fully stretched out. These extra losses can be quite larger.

This paper measures extra losses for flex ducting with sags and with compressed ducts.

Stack Effect Ventilation Calculator Estimates airflow for thermal stacks Friction loss in round or rectangular ductswww.engineeringtoolbox.com/ ...

Note: The Engineering Toolbox site has a lot of useful stuff, but also has some very scummy popup windows -- so beware. A very simple air duct pressure loss calculator.The duct calculator at the link just above is will handle a wider variety of conditions, but is more complex to use. Temperature Drop Calculator for Air Ducts...

Calculates air density for the temperature and altitude you input. Reynolds Number

Re Calculator...

A nice and flexible calculator for Reynodls number -- accepts a wide variety of units and flow conditions.

The fluid viscosity inputs that are needed can be looked up on the Engineering Toolbox website. Borst Engineering and Construction Calculators

Many Calculators... Borst Engineering has a whole raft of calculators -- HVAC, solar position, shading, and incident heat, water wheels, pipe sizing, ... Pipe Flow Copper Pipe Pressure Drop

Calculators for pressure loss in pipes and ducts, steam tables, and a Psychrometric Calculator Hydronic Heaters -- Baseboard, ... SlantFin Hydronic Baseboard Radiator OutputBaseboard output at low temps... SlantFin manual on their hydronic baseboard units showing output at lower temps that might be typical of what you would get on efficient solar heating systems.

A British Thermal Unit (BTU) is a measurement of heat energy. One BTU is the amount of heat energy required to raise one pound of water by 1F. Water weighs 8.33 pounds per gallon so we can calculate that one gallon of water requires 8.33 BTU to raise the temperature 1F.

There are an unlimited number of online tools and calculators for every mathematical formula. The internet is full of helpful resources to get the job done quicker. Here are a few links to some useful websites:

There is a lot of other information that we could add such as Steam. It is a viable heating source and there are several factors that must be considered such as operating pressure, steam trap and condensate line sizing and so on. We will have to do a separate article on Steam in a future issue.

The charts and information above are all essential to water heating. They are proven mathematical formulas of algebra and geometry. If you input the accurate information then the results will be correct. It is also good to use the online tools and calculators. They are true time savers.

I was puzzled and asked how this was possible. He answered that his 3,500-square-foot home had a high-performance building envelope. As part of determining a net heat loss, every internal source of heat gain had been factored in, and a high-efficiency heat recovery ventilator would recover the majority of the exiting Btu out of the ventilation air.

The total heat load had been calculated meticulously to be a mere 18,500 Btu/hr. From this example it is easy to see that we have moved to an era when sizing a system is now a science, and over-sizing the heating system would have been very easy to do.

Understanding how heat is lost from a building is essential to capturing all sources of heat loss and correctly determining the load requirements of our system. According to the Engineering ToolBox (www.engineeringtoolbox.com), the overall heat loss from a building can be calculated as:

Determine the construction of the building and the U values of its component parts or partitions (windows, walls, floors and ceilings) and calculate the area in square footage of the surface of these partitions.

Determine the appropriate number of air changes per hour or air change rate, which combines the losses resulting from both ventilation (Hv) and infiltration (Hi) and calculate the volume of the space in cubic feet. (Note: Stipulated requirements for forced ventilation are common in most jurisdictions, typically referring to ASHRAE Standard 62.1-2007 -- Ventilation for Acceptable Indoor Air Quality. Consult your local building code for further information.)

The National Climatic Data Center, an agency of the U.S. Commerce Department, publishes detailed weather data. From this information is derived the Winter Design Dry Bulb Temperature (or Outdoor Design Temperature) and the number of Heating Degree Days for a given location. While three occurrence values are tracked, the method taught in the RPA Radiant Basics course uses the 97.5% value, which is the temperature the outside air is at or above 97.5% of the year. The tables in Normative Appendix D, ASHRAE Standard 90.1- 2007 reflects the 99.6% values. The Indoor Design Temperature is generally accepted to be in the range of 68F to 72F with 70F the recommendation from the RPA as shown in Figure 3.

It is apparent that in any context the integrity and thermal efficiency of the building envelope will determine how high or low our peak heating load will be. At first glance the example of a low total heat load discussed earlier would seem to be counter to the interests of those of us designing, selling and installing hydronic radiant heating systems, but I feel the opposite is true.

A lower heat load means that more options are available to the designer for types of fuel and appliance, and it further makes the integration of renewable energy sources more feasible. The future is represented in determining heat loss that is net of heat gain, for systems where the peak design load may be small, but not indicative of the comfort levels demanded by building occupants. Thus the actual system capacities may be higher by default than those dictated by peak design loads.

As you move forward from heat loss to system design consider this: In areas where the heating degree days are low, the heating load may be much smaller than the domestic water load as percentage of total energy consumption. This will further influence your appliance and control selections as you look to maximize the energy efficiency of the domestic water production while integrating space heating.

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