Having ample hot water is something most homeowners take for granted, until the day their hot water runs out. Determining the right size hot water system your household requires is crucial for ensuring a steady stream of hot water for bathing, washing dishes, laundry and more – even during peak usage times. Undercalculate your hot water system capacity and you’ll continually face frustration from lukewarm showers or not enough hot water to go around. Size things too large on the other hand and you’ll incur higher upfront costs and energy bills from overpowered units.
As per experts like Same Day Hot Water Service, when it comes to identifying what size hot water system you need, residential hot water experts consider a range of factors like home size, number of occupants, bathrooms/showers, peak usage times and more. Here is a guide to help determine appropriate hot water system sizing for standard homes.
How Daily Hot Water Use Is Calculated
Industry guidelines for sizing residential water heaters centre around something known as Required Hourly Hot Water Use (RHHW). This represents the total amount of hot water your household will require per hour based on the number of hot water outlets or fixtures operating at once during peak demand periods.
For example, a family of four getting ready for work and school may have up to four showers running at once, dishwashers or washing machines in operation and multiple sinks needing hot water for shaving, teeth brushing or washing up. Adding up the total hot water volume drawn during this time determines your RHHW which then dictates the minimum system size needed.
Typical Hot Water Usage By Home Size
The size of your home coupled with the number of occupants gives a reasonable baseline for estimating regular hot water requirements. Here is a breakdown of typical hourly hot water usage volumes for average modern homes:
- Small 2 Bedroom Home (up to 1500 sq ft): Approximately 30-40 litres
- Medium 3-4 Bedroom Home (1500 – 2500 sq ft): Approximately 40-65 litres
- Large 5+ Bedroom Home (2500+ sq ft): Approximately 50-80+ litres
Note that more bathrooms, higher flow rate showers, jacuzzi tubs and appliances demanding hot water can all increase usage calculations. Newbuilds also trend towards more expansive floor plans and bathrooms driving demand up compared to older homes of equivalent size.
Minimum System Size Guidelines
Given expected hourly hot water usages above, a general rule of thumb residential hot water system suppliers follow is:
- Small Home 2 Bedroom: Minimum 135-150 litre storage capacity
- Medium Home 3-4 Bedroom: Minimum 175-315 litre storage capacity
- Large Home 5+ Bedroom: Minimum 250+ litre storage capacity
Keep in mind the ranges cater to variability from usage habits in different homes. Also note that storage sizes above apply to gas or electric storage tank systems that hold a volume of pre-heated water ready for use. Tankless on-demand water heater minimums differ since they generate unlimited hot water in real-time without storage limitations.
When In Doubt, Size Up For Growing Needs
Given hot water systems last 10-15 years once installed, it pays to allocate extra capacity if your household expects to expand via kids, relatives or residents joining in coming years. This saves cost and headaches from upsizing later. Also budget for increased peak demand days around holidays or parties as required.
Conclusion
Now that you know guidelines for sizing hot water systems based on home scale and occupancy, connect with a professional residential plumbing company to confirm requirements. They can tailor recommendations to perfectly match your household’s needs both now and for years to come. Never run out of hot water again.
