djwbd92
New Member
My home has a hot water recirculation pump installed that doesn’t use a dedicated return line (The Grundfos Comfort System). This setup uses a thermostatic bypass valve at the far end of the loop in the 2nd floor master bathroom, so that the cooled water in the hot water line is pushed back to the water heater when the pump is running. Once the water in the hot water line gets hot, the bypass valve closes to prevent the hot water from continuing to flow into the cold water line. I’ve had this pump installed for 6-7 years, and during much of that time it’s worked very well. At worst the cold water might get slightly warm once the pump had been running for a while.
Unfortunately, sometime in the last 1+ years, something has changed such that the cold water actually becomes uncomfortably, if not dangerously, hot if the pump has been running for 10 or more minutes. I have replaced the thermostatic valve, and tested that the new valve is properly shutting off once the water in the hot water line gets hot, so I’m fairly certain that is not the problem. Could the hot water be bleeding into the cold water somewhere else in our plumbing system, like in one of the shower cartridges or shower valves?
I had a plumber come by to look at this, and despite my telling him that the bypass valve was new and showing him how the water being pushed up the hot water line stopped once it reached temperature and the valve closed, he insisted that the bypass valve was the problem and told me we should get a dedicated return line installed, to the tune of $3800, since that is the “right” way to do it. He insisted they could install the return line without punching holes in my walls by installing it from the crawlspace, which I’m not even sure if that makes sense.
I’d greatly appreciate any thoughts on other explanations for why the current recirculation setup is causing our cold water to become so hot. Also, I realize that a dedicated return line would work better in that it would avoid causing any temperature changes to the cold water, but is it really possible to install a dedicated return line in an existing house without opening up the walls and generally making a mess?
Unfortunately, sometime in the last 1+ years, something has changed such that the cold water actually becomes uncomfortably, if not dangerously, hot if the pump has been running for 10 or more minutes. I have replaced the thermostatic valve, and tested that the new valve is properly shutting off once the water in the hot water line gets hot, so I’m fairly certain that is not the problem. Could the hot water be bleeding into the cold water somewhere else in our plumbing system, like in one of the shower cartridges or shower valves?
I had a plumber come by to look at this, and despite my telling him that the bypass valve was new and showing him how the water being pushed up the hot water line stopped once it reached temperature and the valve closed, he insisted that the bypass valve was the problem and told me we should get a dedicated return line installed, to the tune of $3800, since that is the “right” way to do it. He insisted they could install the return line without punching holes in my walls by installing it from the crawlspace, which I’m not even sure if that makes sense.
I’d greatly appreciate any thoughts on other explanations for why the current recirculation setup is causing our cold water to become so hot. Also, I realize that a dedicated return line would work better in that it would avoid causing any temperature changes to the cold water, but is it really possible to install a dedicated return line in an existing house without opening up the walls and generally making a mess?