Moth to a flame
New Member
Hello. I am new to the forum. I manage apartment complexes and have done a lot of related plumbing. I recently came across a situation that I can not solve.
This is in a three story garden style apartment building. The hot water and heat are supplied by a central gas boiler (Burnham). The domestic water goes out of the boiler room via a 1.25" diameter pipe into the centered hallway where it tees off to 1/2" piping to supply each set of three apartments in a stack. In other words, the 1/2" OD pipe goes into the first floor apartment, branches off to supply kitchen sink, bathroom sink and bathtub, and continues upward to the second apartment where it branches off in like manner and continues upward to the third unit. The rise of this line from the first floor unit ceiling to the third floor fixtures is about twenty feet.
Here is the problem I'm facing: we got a complaint from the second floor tenant that he wasn't getting hot water from his two handle lavatory faucet. He has water under pressure but it is cool to the touch. I soon come to find out that both the first and third floors are experiencing the same thing. No hot water in the sink only. This isn't building wide. It is only in the three units in the stack and is a recent occurrence. So what changed? I don't know. The kitchen hot water and bathtub hot water are both fine.
In searching for an answer, I removed the drop ceiling in the hallway of the first floor. It is there that I observe the 1.25" OD domestic supply line. There is a circulating pump in the boiler room which brings the water back to the boiler.
What I discovered is if you touch the 1.25 OD pipe, it is HOT to the touch. Duh. What's fascinating is where the 1.25 x 1/2 tee connects to this line. Directly attached to the HOT 1.25 pipe, the tee is cool to the touch. How can this be? Logic says the hot water line is being tempered by cold water somewhere in that 20 feet of pipe. I further noticed that in running the lav faucet on the third floor, the hot side was cool but If I leave the hot water on and open the hot water in the tub (three handle Gerber diverter) suddenly the sink water gets hot. If I shut the tub off, the sink goes back to cool. I suspect one of the diverters is letting cold water cross over but I can't figure out how? If the cold tub valve is closed and not leaking, how can the sink suddenly go from cool to hot by opening up the hot tub valve. I changed the washer on the diverter valve stem (the one in middle) on all three floors. Nothing changed. I feel like I am on the right track. That somehow the how water is being tempered in that plumbing stack. I'm not able to confirm the routing of the pipes in the walls but I don't believe it's coming from another stack. This is a 50 year old building. Something changed recently. A worn washer letting cold water contaminate the hot side make sense to me but I haven't found it yet. Any ideas?
This is in a three story garden style apartment building. The hot water and heat are supplied by a central gas boiler (Burnham). The domestic water goes out of the boiler room via a 1.25" diameter pipe into the centered hallway where it tees off to 1/2" piping to supply each set of three apartments in a stack. In other words, the 1/2" OD pipe goes into the first floor apartment, branches off to supply kitchen sink, bathroom sink and bathtub, and continues upward to the second apartment where it branches off in like manner and continues upward to the third unit. The rise of this line from the first floor unit ceiling to the third floor fixtures is about twenty feet.
Here is the problem I'm facing: we got a complaint from the second floor tenant that he wasn't getting hot water from his two handle lavatory faucet. He has water under pressure but it is cool to the touch. I soon come to find out that both the first and third floors are experiencing the same thing. No hot water in the sink only. This isn't building wide. It is only in the three units in the stack and is a recent occurrence. So what changed? I don't know. The kitchen hot water and bathtub hot water are both fine.
In searching for an answer, I removed the drop ceiling in the hallway of the first floor. It is there that I observe the 1.25" OD domestic supply line. There is a circulating pump in the boiler room which brings the water back to the boiler.
What I discovered is if you touch the 1.25 OD pipe, it is HOT to the touch. Duh. What's fascinating is where the 1.25 x 1/2 tee connects to this line. Directly attached to the HOT 1.25 pipe, the tee is cool to the touch. How can this be? Logic says the hot water line is being tempered by cold water somewhere in that 20 feet of pipe. I further noticed that in running the lav faucet on the third floor, the hot side was cool but If I leave the hot water on and open the hot water in the tub (three handle Gerber diverter) suddenly the sink water gets hot. If I shut the tub off, the sink goes back to cool. I suspect one of the diverters is letting cold water cross over but I can't figure out how? If the cold tub valve is closed and not leaking, how can the sink suddenly go from cool to hot by opening up the hot tub valve. I changed the washer on the diverter valve stem (the one in middle) on all three floors. Nothing changed. I feel like I am on the right track. That somehow the how water is being tempered in that plumbing stack. I'm not able to confirm the routing of the pipes in the walls but I don't believe it's coming from another stack. This is a 50 year old building. Something changed recently. A worn washer letting cold water contaminate the hot side make sense to me but I haven't found it yet. Any ideas?
