I have a multi family house consisting of 4 apartments. The thermostat is set in the high 70's but can't seem to pass 69-70. We are currently in a cold weather season and tenants are complaining that it is cold inside. I had the unit along with all the pipes installed two years ago. The tech had gone a few times and hasn't found the problem yet. last time, he mentioned that due to the hot water continuously being on, it is affecting the temperature on the boiler. he had recommended to install a separate water heater and leave the combi as a boiler only. Please help.