doug jabor
New Member
We appear to be having a problem with our bath line hot water ever since a new boiler with hot water coil and electric actuator controlled mixing valve was installed in late 2017. They installed a mixing valve board with an electronic controller, and the system had many check valves, but they never installed a thermal expansion tank, and i saw a spike that pegged the 100 psi gauge on many occasions. A tank was added three months later and that helped the pressure considerably. Recently we started getting complaints in our 4 family building that the water temperature was going from super hot to warm. Some of the tenants actually claim that this started back when the new boiler was installed. After the tech tried trouble shooting the controller ( four months later), we shut it down for now and put the back up hot water heater on.
We have only two water risers, bath and kitchen. Now what is happening is that the bath lines are perfect! But the kitchen sink lines are doing the same thing, running at around 85 degrees. Here is what I did as a test. The hot water heater has a 1/2 inch recirculation line coming into the cold water line right before the heater. It has a check valve (old!!) and a shut off valve. The house Cold water line has a booster pump on it so that the water can get to the top floor (city pressure in is 35psi). That pressure is maintained at 50 psi ( it is a variable speed pump so it actually runs from say 48 to 52 psi under load.
I thought that maybe the cold water line was back flowing into the recirc line due to a pressure or flow issue... so I shut off the recirc line going into the cold water line right before the hot water heater inlet. I guess not surprisingly, the hot water temperature then remains constant! This is a problem, because without recirc, the hot water heater works much harder, and the tenants have to wait longer for hot water. I then throttled down on the recirc so 80 %. Now, the temperature runs from 114 degrees to 85 degrees. To summarize, when the recirc is open, i kind of get only 85, 90 degrees. When throttled it goes from hot to warm, when off i get fully hot water... Also, There is no recirculation pump when the back up hot water heater heater is on.
Can anyone offer any steps to perform next, or if they have seen this problem before? By the way, I tried shutting off all of the hot and cold water valves at the sink lines, and left one floor's hot water valve open, i get the same results, so it is not the fixtures..
We have only two water risers, bath and kitchen. Now what is happening is that the bath lines are perfect! But the kitchen sink lines are doing the same thing, running at around 85 degrees. Here is what I did as a test. The hot water heater has a 1/2 inch recirculation line coming into the cold water line right before the heater. It has a check valve (old!!) and a shut off valve. The house Cold water line has a booster pump on it so that the water can get to the top floor (city pressure in is 35psi). That pressure is maintained at 50 psi ( it is a variable speed pump so it actually runs from say 48 to 52 psi under load.
I thought that maybe the cold water line was back flowing into the recirc line due to a pressure or flow issue... so I shut off the recirc line going into the cold water line right before the hot water heater inlet. I guess not surprisingly, the hot water temperature then remains constant! This is a problem, because without recirc, the hot water heater works much harder, and the tenants have to wait longer for hot water. I then throttled down on the recirc so 80 %. Now, the temperature runs from 114 degrees to 85 degrees. To summarize, when the recirc is open, i kind of get only 85, 90 degrees. When throttled it goes from hot to warm, when off i get fully hot water... Also, There is no recirculation pump when the back up hot water heater heater is on.
Can anyone offer any steps to perform next, or if they have seen this problem before? By the way, I tried shutting off all of the hot and cold water valves at the sink lines, and left one floor's hot water valve open, i get the same results, so it is not the fixtures..
