What You Need to Know About Heating System Fuel Consumption – Part 2

Here are the proper steps to designing an efficient and cost effective heating system:

1. Through in depth discussions with the GC and building owner, determine exactly what the building owner expects from the new heating system – what type of system will it be? There are numerous options for system types and the type of fuel it will utilize. What level of efficiency will the system be capable of? What level of equipment quality is expected? How many heating zones are desired? How will potable water will be heated – through the boiler and indirect-fired water heater, or a separate heating source like a direct-fired water heater – gas, electric, oil, or solar? In the case of an “indirect” water heater, I will be sure to add the requisite BTUs per hour for the domestic hot water as needed. Basically, all relevant information will need to be conveyed with person-to-person discussions, and the HVAC subcontractor should be able to drive the discussions to the point that all questions will be satisfactorily be answered so he can proceed to the next step.

2. The HVAC sub needs to obtain a complete set of working construction drawings that include all floor plans, elevations drawings, window, door and insulation schedules, and geographical orientation.

3. The HVAC designer will then interpret the drawings and harvest all of the necessary data from it to be used in the heat loss calculation software. The software will tell him how many BTUs/hour the building will require on the coldest day and will break the total down by individual room “loads”.

4. The designer will then select the proper equipment based on fuel type, “net” heating output capacity (in BTUs/hour) and how the heating appliance will be vented – through a chimney, sidewall-vented or power-vented out the side of the building or direct-vented through the roof. He will also account for quality and efficiency rating.

5. Then the heat distribution aspect of the design will be worked through. For FHW, he will determine pipe sizing and type, circulator (the ‘pump’ that moves hot water from the boiler to the terminal units) performance characteristics, flow control devices and terminal unit type(s) and sizes.

6. The designer will then choose the control systems based on number of zones, energy-savings and safety and code requirements.

7. The fuel storage type and capacity will be selected.

8. A total cost estimate will be generated and a proposal listing all of the major components will be drafted and submitted.

This is a basic list of steps. In reality, there are so many details to creating a competent design and estimate that delineating all of them goes beyond the scope of this article. The most important point is that the heat loss calculation must be competently performed before any other design step can be taken. The other important thing is that the proper equipment be selected that answers to the heat loss calculation. If the equipment heating capacity is guessed at, then the system will most likely be over-sized…for the life of the system. Next is as important – the efficiency of the equipment is crucial to future fuel consumption and a true professional HVAC system designer will promote the highest efficiency available. Spending a few hundred dollars initially is always more advantageous financially than forever burning more fuel due to poor efficiency. Consider higher efficiency equipment as an investment in future fuel savings.

If any of the steps outlined above are skipped, then greater operating and service costs will result. Some HVAC subs do not design the systems they install, their equipment/parts suppliers do the calculations for him and he automatically believes they did the calculations right. Often a lot of rounding up gets done in the HVAC design world, as nobody wants to be left holding the bag if too small a system is installed, then doesn’t sufficiently heat the house on the coldest days of the year. And that rounding can account for 25% of the system capacity – it will be too over-sized and cost the building owner more money to heat. Heating and cooling parts near me

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