DIYbanter - View Single Post

RBM[_3_]

On 12/11/2011 9:05 AM, wrote:
On Dec 11, 9:00 am, wrote:
On 12/10/2011 10:34 PM, croy wrote: My new wall heater has a gas valve that is thermostatically
compatible. The most common thermostat for this heater is
called a "microvolt" thermostat. It apparently get its
microvolts from something heated by the pilot light.

What I can't seem to get my head around, is how can such a
small amount of power manage to horse-open the rather high
flow gas valve?

It uses a pilot generator to make electricity which powers the coil on
the valve. The down side is that it generally takes a while to operate,
unlike a 24 or 120 volt coil valve

Sounds like it's the same type of system used on most
water heaters that also don't have any external power
source to open the gas valve.

It is. I don't see them on conventional heating systems anymore. They
were great when the power went out. Once the thermostat called for heat,
it took a minute or so for the valve to open