If the water heater is producing hot water (the hot-water outlet pipe will be hot to the touch), then it sounds like there’s an issue with the water getting to the entire facility timely – you probably need a circ pump. But before we make assumptions, let’s clarify… The complaining tenants are most likely the ones situated farthest from the water heater; it’s likely they have hot water, but they didn’t wait long enough for the water to arrive before reporting an issue.
In an apartment building or hotel, the distance water must travel from the water heater to all end users is much greater than in a typical residential setting. Due to the great distance between the water heater and the tenants’ fixtures, the hot water left in the pipes cools between uses. The next time a tenant calls for hot water, the residual cooled water has to get flushed out before the new hot water arrives; the further the tenant is from the water heater, the longer it takes to clear that water from the pipe.
The remedy is a hot water recirculating system or “circ pump” for short – a closed-loop system that uses a circulator pump to recirculate the residual water from the hot water line back into the water heater. This allows a small amount of hot water to circulate through the pipes 24/7, from the heater to the farthest fixture and back to the heater, ensuring anyone that turns on a faucet will have hot water within seconds, regardless of where they are located in the building. Any hot water that isn’t used ends up back in the water heater to be reheated, rather than flushed down the drain.
Many apartment complexes may already have a recirculating system installed and it’s just not operational, either because the pump was turned off or has failed and needs to be replaced. (We’d be happy to help with that!) If there isn’t an existing system, one can be installed. Some commercial buildings & multi-story facilities may already be piped with a dedicated hot water return line, so adding a circulator pump to that line is fairly straightforward. However, often in older constructions there isn’t a hot water return line present meaning one would need to be installed from the farthest fixture back to the water heater to create the closed-loop for circulating. Unfortunately installing new copper piping within existing structures can get rather costly, but advances in technology now allow for PEX tubing to be installed as a hot water return line providing a more flexible & therefore less-expensive option than the copper alternative.
In addition to saving the pain of waiting agonizing minutes for hot water, a recirculating system will also save you money on your water bill because tenants won’t be running their showers for 5 minutes to let the hot water reach them. With this system, the water is at their faucet, hot and ready within seconds.