DCpete816
New Member
For the last year or so our shower will not get hot unless we also run hot water from the sink in this bathroom in advance of taking a shower. We run off of a tankless water heater and have a Thermostat controlled mixer. It's probably about 10 years old now. The part number on the mixer appears to be 47 379 which is a 3/4" version. When the handle is all the way to the left (cold), the water flow is great. when the handle is all the way to the right (hot), the water flow is greatly reduced and I presume doesn't draw enough to engage the Tankless water heater without some help (ie. turning on hot water in the same room from the sink). We also have a hand shower connected to the same manifold with it's own flow handle and it exhibits the same problem.
The sink in this bathroom has great water flow on both hot and cold water. And no other faucets in the house has any issues with hot water flow. So I am presuming it has something top do with the mixer in the shower. I have all the manuals which have part numbers, etc. Before disassembling, I'm just wondering what the "best-guess" is on my problem from the experts. That part is surprisingly expensive and don't want to just replace it, if it's something else.
The sink in this bathroom has great water flow on both hot and cold water. And no other faucets in the house has any issues with hot water flow. So I am presuming it has something top do with the mixer in the shower. I have all the manuals which have part numbers, etc. Before disassembling, I'm just wondering what the "best-guess" is on my problem from the experts. That part is surprisingly expensive and don't want to just replace it, if it's something else.