We've blogged about the virtues of on-demand hot water heater, and Re-nest readers contributed to the discussion with their own experiences. Now that we're living with it, we'd like to chime in.
Living With On-Demand Hot Water Heater
We love that we're not wasting energy, but we're having the same issue as chandru, who experienced the water heater shutting off in low flow conditions. Flush one of our toilets or switch on the dishwasher if an unlucky soul is in the shower, and they get alternately frozen and boiled.
It's a rental, so there's not so much we can do to increase the water pressure. We're thinking we'll reduce the water flow rate to the toilets by closing down the supply valves to see if that preserves enough water for the on-demand heater to do its thing.
We can't be the only people out there with this problem. What do you suggest for a fix?
Comments (6)
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... I tend to associate the freeze-boil cycle with tank heaters. I was hoping an on-demand wouldn't do that. I hope someone has a solution for you!
view Tiamat_the_Red's profile
Not sure what the fix is, but we don't have that problem with ours, so maybe it is fixable.
view SFGail's profile
I remember the low water pressure I used to have in San Francisco and can relate.
No ideas for a quick fix, but I ran 3/4" copper pipe for all my hot water lines (many houses are plumbed with 1/2") so it provides enough flow to supply my low flow shower head with consistently warm water.
Many electric water heaters need a certain flow rate to activate, and this might be your problem when that is reduced below the threshold.
Are you already using a low flow shower head?
view ttbj's profile
we have never had this problem with ours, the only issue is that its connected to the ventilation system for the whole building (its a gas heater) and if that somehow registers as not venting enough air it shuts off all the heaters, in 2.5 years i think its happened 2 or 3 times, a bit of a pain, but worth it for the fact we spend about 10 euros/month on all the hot water and heating we need (its connected to the radiator system)
view CaliinFrance's profile
One problem that we had was that the instant hot could increase the temperature of the water x degrees. Fine in the summer, but even in a warmish northern California winter, it couldn't get it up to warm enough. We ended up installing a second one.
view 44ounce's profile
I had the same problem as 44ounce in my previous apartment - the shower was hideously cold in winter.
view Rebekkap's profile