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From: mike@amdcad.UUCP (Mike Parker)
Newsgroups: net.consumers
Subject: Re: Info on hot water heater gizmo?
Message-ID: <611@amdcad.UUCP>
Date: Mon, 4-Feb-85 21:40:56 EST
Article-I.D.: amdcad.611
Posted: Mon Feb  4 21:40:56 1985
Date-Received: Wed, 6-Feb-85 02:52:36 EST
References: <775@ut-sally.UUCP>
Distribution: net
Organization: AMDCAD, Sunnyvale, CA
Lines: 49

In response to Brian Powell's query about "tankless" hot
water heaters.

I have limited experience with them, and it's very contradictory
but I'll throw it out and see if I can at least catch a few
flames.

I tried to buy one once and found that their power output
tended to be quite low. This governs the product of flow
rate and temperature differential across the unit. My conclusion
was that a good hot pounding shower would not possible and
I ditched the idea.

Since then I've stayed in two homes with these heaters. In one
my analysis proved correct the shower provided a hot trickle
or a lukewarm shower. If I had owned that house I would have 
immediately taken an axe to that damn thing and gotten a real
water heater.

In the other place the problem was the opposite. The heater was
gas powered and was in a closet behind the tub. When I turned
on the hot water and heard the flame start, I thought someone
was warming up an F14 in the driveway. The thing put out an
incredible flow rate of steaming water. Unfortunately the 
people who owned the house had installed some antique brass
fixtures. When hot water flowed through the faucet the valve stem
would expand and the flow would reduce. The heater had only one
power setting *ON* we're talking F14 ON. So the temperature
differential across the heater was directly proportional to the 
flow rate.

The heater in combination with the brass fixtures was bistable.
If you set the thing for hot, the fixture slowed the flow 
causing the output temperature of the heater to go up and 
the fixture to further slow the flow. Ultimately all hot water flow
stopped and there you stood in a cold shower. The were other 
temperature settings that caused the fixture to gradually
increase the flow thus lowering the heater output temp and 
further increasing the flow, I was almost seriously burned
when I discovered this phenomenon.

In summary:

If you are thinking of getting one of these heaters make 
sure it is of the F14 variety and get quality fixtures that
are not sensitive to water temperature.

Mike @ AMDCAD