# Where does my tankless hot water heater get its power?

#### spinnaker

Joined Oct 29, 2009
7,835
I have a tankless gas hot water heater that is mounted to an outside cinder block wall in the basement. The heater has a control panel with status lights, so obviously it is powered. I can see no electric service going to the heater. This is a 1950s era home so I can't imagine why they would run service through a cinder block wall as the original heater was likely to be gas.

The panel only lights when there is power. I am thinking the heater makes its own power from water flow with an impeller. Is this likely?

Joined Jul 18, 2013
22,855
Very much doubt it due to the high wattage needed for a tankless htr.
It is/was common to run a supply through a cinder block wall, is there no breaker marked as such in the panel?
Max.

#### spinnaker

Joined Oct 29, 2009
7,835
Very much doubt it due to the high wattage needed for a tankless htr.
It is/was common to run a supply through a cinder block wall, is there no breaker marked as such in the panel?
Max.

See above. It is gas. The only thing being powered is the control panel. Doubtful that take a lot of current.

Joined Jul 18, 2013
22,855
What threw me when you said the 'Original Heater' was Gas!
Sort of implying it could have been replaced, possibly by electric!
Are you sure there is no service to it at all?
Max.

#### tcmtech

Joined Nov 4, 2013
2,867
Some of the very basic gas fired tankless units use a simple thermoelectric generator that is powered off the pilot light or simply the temperature differential of the hot water chamber and ambient air . Fair chance that how yours may be powering its monitoring and control circuits.

#### spinnaker

Joined Oct 29, 2009
7,835
There is no pilot light. It is a piezoelectric starter. Where does the starter get its power? And the light goes no immediately when the "hot" water starts to flow but the heater has yet to fire so the water is still cold.

#### markdem

Joined Jul 31, 2013
113
Easy way to check this. Turn off the power to the whole house and check if the panel is still working.
You many need to reset some clocks after..

#### spinnaker

Joined Oct 29, 2009
7,835
Easy way to check this. Turn off the power to the whole house and check if the panel is still working.
You many need to reset some clocks after..

I am not THAT curious.

#### BR-549

Joined Sep 22, 2013
4,938
I never heard of a gas instant hot water heater, other than conventional. Had a friend put an electric in.....it drew juice. I think it was 40-60 amps worth. And it did save him money.

#### markdem

Joined Jul 31, 2013
113
I am not THAT curious.
oh come on, where is you since of discovery.

Here is a easier way, turn the main water off and see what it does. If the led goes on for the short time there is pressure in the pipes then goes off, there could be a turbine of some form. If the led stays on, power is coming from somewhere else.
No resetting of clocks needed for this method.

These the hot water unit have a model on it anywhere?

#### SLK001

Joined Nov 29, 2011
1,548
I am thinking the heater makes its own power from water flow with an impeller. Is this likely?
Not likely (and not possible). If it did, the energy crisis would be solved, but then the water company would charge accordingly for the secondary use of their flowing water.

Electric tankless WHs have very large wiring running to them - much larger than a standard electric WH. If it is a gas tankless, it will have both the gas service plus venting to the outside.

#### #12

Joined Nov 30, 2010
18,217
I never heard of a gas instant hot water heater,
They exist. There are some very high efficiency gas, instant-on water heaters. I did the math once, a long time ago, and came up with something like: flammable gas can produce 6X the heat you can get with a similar size pipe full of electric wires.

240VAC, 60 amp breaker running 6-2-g in a 3/4 inch conduit vs a 3/4 inch gas pipe. Something like 40,000 BTUs per hour compared to 240,000 BTU's per hour. This certainly explains why flammable gas becomes easier to install as soon as you need more than 30 or 40 thousand BTUs per hour.

#### spinnaker

Joined Oct 29, 2009
7,835
Not likely (and not possible). If it did, the energy crisis would be solved, but then the water company would charge accordingly for the secondary use of their flowing water.

Electric tankless WHs have very large wiring running to them - much larger than a standard electric WH. If it is a gas tankless, it will have both the gas service plus venting to the outside.

How many times do I need to say it is gas? I am not an idiot.

#### spinnaker

Joined Oct 29, 2009
7,835
oh come on, where is you since of discovery.

Here is a easier way, turn the main water off and see what it does. If the led goes on for the short time there is pressure in the pipes then goes off, there could be a turbine of some form. If the led stays on, power is coming from somewhere else.
No resetting of clocks needed for this method.

These the hot water unit have a model on it anywhere?

I don't see how this solves anything. The LED is only on when water is flowing.

#### spinnaker

Joined Oct 29, 2009
7,835
They exist. There are some very high efficiency gas, instant-on water heaters. I did the math once, a long time ago, and came up with something like: flammable gas can produce 6X the heat you can get with a similar size pipe full of electric wires.

240VAC, 60 amp breaker running 6-2-g in a 3/4 inch conduit vs a 3/4 inch gas pipe. Something like 40,000 BTUs per hour compared to 240,000 BTU's per hour. This certainly explains why flammable gas becomes easier to install as soon as you need more than 30 or 40 thousand BTUs per hour.
I'd like to see something on the savings of these devices. First there is the amount of water lost while the device senses the need for hot water, then actually heat it to usable temperature.

Then there is maintenance. Descaling is recommended once a year. That is a couple of hundred Of course you can do it yourself but not everyone can. Then there is pump lubrication every couple of years. That is a few hundred. Then a total pump rebuild, that is every 5 years and $400 or$500. That is what at least is recommended by the manufacturer.

#### #12

Joined Nov 30, 2010
18,217
Are you sure, or is this what mommy told you ?
Oh dear my year has been destroyed.
If you're going to do insults around here, they need to be much more clever than what a snotty 10 year old would say on the playground. And besides that, you need to establish some level of familiarity with your jousting partner. With 35 posts under your belt, you're insulting strangers, and that doesn't pass for clever.

#### markdem

Joined Jul 31, 2013
113
I don't see how this solves anything. The LED is only on when water is flowing.
When water is flowing or when the pressure in the input pipe falls?

So, does the unit have any model numbers? We could just look up the installation instructions..

#### spinnaker

Joined Oct 29, 2009
7,835
When water is flowing or when the pressure in the input pipe falls?

So, does the unit have any model numbers? We could just look up the installation instructions..

When water is flowing.

It is a Bosch Aquastar GWH 1600 H. I found the install guide. It lists venting, gas connection and water connection but no electrical connections.