I am remodeling my basement and part of the project was to relocate
my gas 40 gallon HW heater over about 3 feet to free up some space.
The existing water heater will fit into the new space, but I came
across these "on-demand" HW heaters that look appealing. I have a few
1) what would be a unit that is equivelant to a 40-50 Gal HW heater?
2) Is this something I can install myself? I have done HW heaters
3) This is on an outside basement wall. Can I use the existing flue
pipe that was on the old HW heater? Any other installation
It's good you have gas because the eletric ones need a huge circuit.
They have their drawbacks. You need to size it based on fixtures and
usage rather than just comparing it to your tank one. If you're in
the more northern parts of the continent you may find it struggles to
deliver hot water in the winter. The colder entry water temp means
they have to work harder to get the water hot. I'd oversize a bit if
I lived north of the mason dixon. And prepare to shell out major
bucks for it.
They usually have a set 'rise' in temperature at so many gallons a
minute, say a 50 degree rise at 2 gallons a minute. If the water is 50
you get 100 degree water but if the water is 40 you only get 90 degree
water unless you use it slower, then it gets hotter up to the cutoff temp.
Simple job, assist the assistant of the physicist.
you will need large natural gas line, and perhaps a new meter too.
there will be a delay between water on and water hot, time lag for
ignition and heating. you wouldnt save much energy, standby losses are
actually pretty low and help to heat the home if heater is in
flue may not be big enough most water heaters 35K BTU, tankless over a
100K BTU... Tankless must do all the work heating a standard tank
does, on a flash basis in a tankless.
Check for local affordable service, newer tankless are high tech and
may need qualified service tech, and perodic cleaning heat exchanger
with acid, espically in hard water areas
heres a good experiment turn your current heater to vacation or off,
go out for day. you will find temp doesnt change much...
low flow situations may be below trip level for burner on, so no hot
on many tankless and all power vent tankless no electric means no heat
at all. power is necessary for unit to function
We all know you get a knot in your shorts every time someone brings
up tankless. But the "conditioned space" baloney has been shot down
so many times, yet you keep throwing it out there. Most people not
only use heat in their conditioned space, but also AC. And during AC
season, that heat loss from the tank heater ADDS to the cooling
requirements. Yet, you don't list that as a negative for tanks.
Whether a tankless is good for him or not depends on many factors.
I guess I'm surprised that he would even being asking, given that he's
a regular here and it's been thoroughly debated here many, many times.
As for the main issues as I see it:
Sizing: depends on incoming worst case water temp and worse case
demand. Tankless have charts showing what they will do.
Check gas line size requirements and assess based on all other gas
appliances in the house, sharing those lines, etc.
Either get a model that will fire without AC or you have no standby
hot water when power goes out, like you would with tank type
Check manufacturer for install requirements regarding chimney, but I
would expect that it can't be vented into the existing chimney. I
they are designed to be direct vent.
The gas line may be fine, a new meter is unlikely and the delay adds
about 4 seconds to the 30 second delay from removing cold water
already in my pipes. And of course you dont own one so you are not
saving money, so you just put them down like an ass.
so 4 seconds of wasted water and sewer times every time you need hot
the gas line may be fine, may not be. at minimum probably a new gas
line directly from meter to your tankless, pro testing needed. and no
hot water at all in a power failure if your tankless is a power vent
around here many neihborhoods are low pressure main lines with no
regulator at meter.
local plumbers refuse to install tankless in these neighborhoods
because of poor performance.......
so lets say your new tankless works 100% PERFECT:)
and your teenagers love their endless 1/2 showers. Gas bill be going
I have an on demand gas system for the last 30 years,
rented from the gas company, with includes yearly maintenance,
and it has not failed me yet.
It is cheaper then electric, does not fail in a power out,
it never runs out of hot water.
Now the last one can be a disadvantage when you have children,
they love it.....
ransley did you note in certain low pressure gas line areas.
my home is high pressure with a regulator
much older neighborhoods are low pressure, with no regulators on
meter, just neighborhood.
plumbers report low flow in these areas sometimes, so they refuse to
install tankless.the gas company adjusts the pressure by remote
control seasonally, this causes heavy load issues
the regulator is for 100s of homes and the infrastructure undersized
for the load.....
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