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OT: Odd Shower + Hot Water + Tankless Heater Issue Posted by Justin VanAbrahams [Email] (#32) [Profile/Gallery] (more from Justin VanAbrahams) on Mon, 14 Oct 2013 16:39:46 Members do not see ads below this line. - Help Keep This Site Online - Signup
I'm good at a fair number of things, but not plumbing. I'm hoping someone can shed some light on my problem before it drives me insane! :D
April '12 I replaced a very old Sears water heater installed, essentially, in the middle of the house with a reasonably high end AO Smith/Takagi condensing tankless system. It was really the only option aside from interior demolition and a very expensive retrofit. Downstairs I have 1.5 bathrooms, the kitchen, and a laundry room. Upstairs, 1 full bathroom. Every faucet in every one of these rooms works perfectly and predictably, *except* the upstairs shower.
The upstairs shower has a hard time getting hot water. Every other spot on the house - whether sink or shower - gets hot water in a matter of a minute or two, and the water stays hot until you turn the faucet off. The upstairs shower, however, takes an ETERNITY to get got - 10 minutes sometimes - and every so often the water will start cooling down or flat-out cold. When this happens, the water stays cold. Turning the faucet to full hot does nothing. What's weird is that if you turn the sink on in the *same bathroom*, it will still have hot water. If you leave the sink on running hot water, the shower will get warm again quickly!
Generally speaking, if the shower is on "full hot" the water will stay hot, but of course that's unbearable to stand in. If it's even slightly to the cold, there's a high chance the hot water will disappear.
We did not have this problem with the tank water heater. It's somehow
related to the tankless system. But it's a combination of the tankless
system and this particular faucet, because it doesn't happen anywhere
else in the house. Also, this happened randomly last year, but has grown worse over time. It's TERRIBLE now - taking a shower means leaving the water at an uncomfortably hot setting, or letting the sink faucet run as long as the shower faucet does.
I think this is a flow issue. The heater takes (IIRC) .5gpm to engage and
.3 or .4gpm to make it stay on. What I *think* is happening is that the valve in the upstairs shower "favors" cold water. I think cold water pressure/flow is greater than the hot water pressure/flow. The reduced hot flow results in the water heater taking longer to "engage," and then an abnormally high ratio of hot vs. cold to keep it running.
It's a single handle - left for hot, right for cold. Is it possible the
valve is worn out or otherwise "off balance?" Does that even sound like
it could make sense?
posted by 12.195.130...
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