Shower can't get hot until sink runs hot water.

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Shower can't get hot until sink runs hot water.

Author: NeedsHotH20 (VA)

I just moved into a house with a tankless water heater in the basement. There are 2 bathrooms with showers on the upper floor. Bathroom #1 gets hot water in the shower. In bathroom #2, you can let the shower run for 5 minutes and it will never get hot. However, if you turn the hot water on in the sink (of bathroom #2) and then turn on the shower, the shower water will get hot. Does anyone have any idea why this is happening, or what to do to fix it. Thanks, and I appreciate your help.

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Re: Shower can't get hot until sink runs hot water.
Author: packy (MA) while the shower in bath one is running nice and hot, turn on bath two shower. what happens ? /?
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Re: Shower can't get hot until sink runs hot water.
Author: NeedsHotH20 (VA) I just tried it. When I run the shower in bathroom #1 nice and hot, and then turn on the shower in bathroom #2, it also runs hot. Then I turned the water off in shower #1 and shower #2 continued to have hot water. Edited 1 times.
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Re: Shower can't get hot until sink runs hot water.
Author: bernabeu (SC) try a higher flow shower head, the existing 'water saver' does not have enough flow to 'trip' the on demand heater (you may, or may not, have a 'removeable' water saving device in the head assembly) ============================================== "Measure Twice & Cut Once" - Retired U.A. Local 1 & 638
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Re: Shower can't get hot until sink runs hot water.
Author: packy (MA) yeah.. it sure sounds like the 'on demand' water heater is not seeing enough 'demand' to start when only shower 2 runs. if you can, remove the shower head in 2 and try with no head. while you have the head off, check inside for debris.
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Re: Shower can't get hot until sink runs hot water.
Author: NeedsHotH20 (VA) I'll try the higher flow shower head. Thank you for your help!
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Re: Shower can't get hot until sink runs hot water.
Author: bernabeu (SC) before you install a new head try the shower w/o a head at all if it then works you will KNOW it is a flow rate issue then first step: remove a flow restrictor from the existing head = problem solved ============================================== "Measure Twice & Cut Once" - Retired U.A. Local 1 & 638
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