ndubs02
New Member
Hi everyone,
First time posting here, and I appreciate any responses in advance. I'm come here lots of times looking for troubleshooting tips and have usually found what I needed without posting. But my current situation has got me stumped.
I live in a house that was built 7 years ago with a Navien NPE 240A tankless water heater and a recirc line, water heater is set at 130F. For the most part - the water heater seems to work well and the recirc lines do provide warm water quickly. However, in our second bathroom (which the kids use, not me), the kids starting complaining that the water doesn't heat up for a long time. This bathroom has a Grohe pressure balancing shower valve. At first I didn't believe them because I would try it and everything seemed OK, but then I was able to observe the issue myself, and have been able to get it to happen multiple times since then (not every time, but most times). This fixture is the furthest or second furthest in the house from the water heater - two floors above, and about 30ft away.
What happens is that when you turn the shower on full hot, the water starts warm (about 100F). then after about 2 minutes on full flow, it starts to cool down, I've used a thermometer and it gets down to 80-85F. Then after about 5-7 total minutes it starts to warm up and gets back to 110-115 after nearly 10 minutes. If I contrast this with the shower that I use, when you flip it on all the way hot, it starts at about 100F, then maybe drops just a touch for 10-15 seconds, then back to 105-110 within a minute and settles out at 120 or so when you need to turn it down a touch for comfort.
For a while, I suspected, something was going on with the water heater, but then this weekend I had my daughter assist me and I was able to watch the info screen on the water heater while she turned on the shower and watched the thermometer. At the info screen, I could see the water heater turn on, measuring 1.4gpm output, 58F input and 128-129F output. I didn't see any issues where the heater cycled off or anything, it seemed perfectly stable sitting at 1.4GPM and 128F out.
So now I am maybe suspecting either that the pressure balancing valve at the shower might be malfunctioning in some strange way - or I have wondered if the original install was done incorrectly, maybe the water is coming backwards from the cold supply the wrong way through the return line? (although then I don't know why the water heater would measure 1.4GPM output.
Any ideas here about what are the likely culrits and how I can debug further? I have thought perhaps I should just change the shower cartridge (I can order that and probably can change it myself), but not sure if there is anything else obvious that I could try to narrow down the offending system.
Thanks!
First time posting here, and I appreciate any responses in advance. I'm come here lots of times looking for troubleshooting tips and have usually found what I needed without posting. But my current situation has got me stumped.
I live in a house that was built 7 years ago with a Navien NPE 240A tankless water heater and a recirc line, water heater is set at 130F. For the most part - the water heater seems to work well and the recirc lines do provide warm water quickly. However, in our second bathroom (which the kids use, not me), the kids starting complaining that the water doesn't heat up for a long time. This bathroom has a Grohe pressure balancing shower valve. At first I didn't believe them because I would try it and everything seemed OK, but then I was able to observe the issue myself, and have been able to get it to happen multiple times since then (not every time, but most times). This fixture is the furthest or second furthest in the house from the water heater - two floors above, and about 30ft away.
What happens is that when you turn the shower on full hot, the water starts warm (about 100F). then after about 2 minutes on full flow, it starts to cool down, I've used a thermometer and it gets down to 80-85F. Then after about 5-7 total minutes it starts to warm up and gets back to 110-115 after nearly 10 minutes. If I contrast this with the shower that I use, when you flip it on all the way hot, it starts at about 100F, then maybe drops just a touch for 10-15 seconds, then back to 105-110 within a minute and settles out at 120 or so when you need to turn it down a touch for comfort.
For a while, I suspected, something was going on with the water heater, but then this weekend I had my daughter assist me and I was able to watch the info screen on the water heater while she turned on the shower and watched the thermometer. At the info screen, I could see the water heater turn on, measuring 1.4gpm output, 58F input and 128-129F output. I didn't see any issues where the heater cycled off or anything, it seemed perfectly stable sitting at 1.4GPM and 128F out.
So now I am maybe suspecting either that the pressure balancing valve at the shower might be malfunctioning in some strange way - or I have wondered if the original install was done incorrectly, maybe the water is coming backwards from the cold supply the wrong way through the return line? (although then I don't know why the water heater would measure 1.4GPM output.
Any ideas here about what are the likely culrits and how I can debug further? I have thought perhaps I should just change the shower cartridge (I can order that and probably can change it myself), but not sure if there is anything else obvious that I could try to narrow down the offending system.
Thanks!