Toilet leaking into the rug and is the hotwater

this is in washing machine section
if the washing machine is off
if there was a water leak in the house you would know where the
flood is by now
building wise
are people above or beside with water service

is there a basement heater /hotwater system
or is there a dishwasher

gas valve sticking

Any gas leak is dangerous, call him back!!!!

electronic thermostat?
What brand model and type heater?
http://waterheatertimer.org/How-to-replace-thermostat-on-gas-water-heater.html

http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html

Gene

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Check for water leak.
Turn off all taps and put ear against pipe.
Leak would run hot out of tank, causing water heater to run constantly, and shortage of hot at tap.

Check for crossover
http://waterheatertimer.org/Crossover.html

Troubleshoot by type of gas control valve:
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#intellivent
http://waterheatertimer.org/How-to-install-gas-water-heater.html#install
http://www.thetankatwaterheaterrescue.com/forums/forum3/

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Usually toilets do not require hot water.
Is the plumbing divided into hot and cold water pipes?
If toilets are hooked to hot water, how many flushes and how many gallons per flush per day.
What is the expected consumption per each worker?
What is the latitude from equator, and expected solar input. Further north, and hazy atmosphere reduce input. Beijing has smog I believe.
How often is the solar panel going to cleaned of smog and dirt for maximum collection?
If the area has hard water, then the entire system is prone to sediment build-up and failure unless water is artificially softened.
Solar water heater temperatures can exceed 180 degrees at times. This temperature will damage storage tank that is not made for that temperature.
Most solar water heater systems have pressure regulating valve and expansion tank to accommodate occasional high temperature and pressure.

A good fellow to contact might be at following website:
http://www.builditsolar.com/Projects/WaterHeating/water_heating.htm

Solar collectors are usually connected to a circulating pump, and then the heated water is stored in a tank.
The pump circulates water continually from solar collectors through a storage tank.
This type of system would use ordinary tank-type water heater for storage.
Most of these systems also utilize a back-up heating element inside the tank.

More complicated systems circulate special liquid through spiral tubes inside the water heater.
This type of heater would be an indirect water heater.
Indirect heaters are used for solar collectors, and used with boilers, or any outside heat source.
http://www.bockwaterheaters.com/Products/products_coil_tank_water_heaters.html
http://www.hotwater.com/products/residential/cirrex_solar.html
http://waterheatertimer.org/images/solar-water-heaters-on-roof_lbiRv_5784111-500x282.jpg

Thank you for providing clear description of product:
Your water heater has intellivent gas control thermostat.
There are always problems with water heaters. It is a huge field.

1) Open following link for AO Smith service manuals.
I do not see service manual specifically for the GP series.
http://www.hotwater.com/resources/product-literature/service-handbooks/

2) Open following link to identify gas valve and download typical service manual:
Some AO smith power vent models have intellivent gas valve, and some have smart valve gas vent. Older models might have knob-type gas valve.
http://waterheatertimer.org/How-to-adjust-water-heater-temperature.html#intelli

3) More resources:
http://waterheatertimer.org/How-to-install-gas-water-heater.html#troubleshoot

http://www.rheem.com/products/tankless_water_heaters/customer_support/

Unplug unit from wall. Disconnect remote wires from circ board, and let unit set for about 5 minutes. plug back in. run water and see if unit comes on.

it sounds like the gland on the valve is leaking unusual in a valve so young but it does happen. is the valve electrical operated or water pressure. you should be able to get a complete diaphram kit with all seals etc .