No hot water at indirect water heater due to bad zone valve, stem was not making connection to end switch inside valve causing system to only heat hot water when heating zones are calling for heat, noticed corrosion on other two zone valves for 1st and 2nd floor which would of caused zones to receive no heat or too much heat, replaced all three zone valves, purged lines and added antifreeze back into boiler, tested antifreeze levels and found levels to be satisfactory. Explained in details to customer why zone valves needed to be replaced and why zone valve for water heater isn’t making contact to end switch. Also recommended replacing 1inch ball valve at indirect water heater, looked like it was leaking.