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HOT WATER TEMPERATURE AT SINKS ONLY 85 DEGREES

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dougandrews

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We appear to be having a problem with our hot water ever since a new boiler with hot water coil was installed in late 2017. The 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 spike that pegged the 100 psi gauge on many occasions. We started getting complaints in our 4 family building that the water temperature was going from super hot to warm. After the tech tried trouble shooting the controller, we shut it down for now and put the back up hot water heater on.

Now what is happening is that the bath lines are perfect! But the sink lines are doing the same thing, running from say 114 degrees to 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 Cold water line has a booster pump on it so that the water can get to the top floor . 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, somehow 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 water valves at the sink lines, and left one hot water valve open, i get the same results, so it is not the fixtures..

Thank you!!
 

Grim Reaper

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Did you solve the problem? The building I live in, 10 storeys with 58 units, has the same problem which plumbers have been trying to fix for 2 years without success.
 

Geofd

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We appear to be having a problem with our hot water ever since a new boiler with hot water coil was installed in late 2017. The 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 spike that pegged the 100 psi gauge on many occasions. We started getting complaints in our 4 family building that the water temperature was going from super hot to warm. After the tech tried trouble shooting the controller, we shut it down for now and put the back up hot water heater on.

Now what is happening is that the bath lines are perfect! But the sink lines are doing the same thing, running from say 114 degrees to 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 Cold water line has a booster pump on it so that the water can get to the top floor . 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, somehow 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 water valves at the sink lines, and left one hot water valve open, i get the same results, so it is not the fixtures..

Thank you!!
Do you have single handle faucets or two handle faucets, sometimes single handle faucet cartridges can fail and cause hot and cold water to crossover
 

House Doc

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The codes may have changed in 20 years, but I think that most multi-family water heaters are only allowed to be set at 120 degrees MAX. The water can lose a lot of heat traveling 100 to 150 feet to your faucet. They probably should have been installed with a re circulating line from the farthest faucet.
 

Grim Reaper

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Do you have single handle faucets or two handle faucets, sometimes single handle faucet cartridges can fail and cause hot and cold water to crossover
Apparently that has happened in the building. It is difficult to determine because it requires the condo Board to get a plumber to do it and the residents have to be notified and it costs a lot of money which the condo Board doesn't want to spend.
 
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