Today I arrived on site to address the issue of the DHW not getting hot. Service Actions: Identified air bubbles in the DHW lines as the cause. Bleed out the air bubbles from the DHW lines. Confirmed the DHW lines are now getting hot. Upon arriving at the property, the client mentioned that she does not have hot water. I proceeded to verify the system. I found an air bubble on the DHW line. Purge the DHW lines. The lines began to heat up. Him I showed the client and recommended replacing the Spirovent of this system. The Spirovent is not doing its job. The client asked to be sent an estimate of the cost of repairing this system. I explained to the client that I would send all the information to the office to be contacted to provide an estimate of the installation of a Spirovent 1-1/4. The client was left with DHW operating normally at this time. Note: I warned the client that it is possible that this situation continues to occur since the Spirovent is not bleeding the microbubbles of