When the hot and cold water is gravity fed then by crossing the water over will make getting the airlock out of the pipes virtually impossible.
Gravity fed hot water system problems.
If your shower is located above your cold water supply a negative head situation is created as this means water will have to travel upwards which it can t do via gravity.
Tried to turn on it was hard then dirty water.
The flow rate you are currently getting from your water system combined with the number and type of installations you have in your property will determine what kind of pump you require.
If the hot water is running out quickly then perhaps there is a problem with the top up supply to the tanks as someone has already suggested.
Our gravity water system spring fed has worked really well for 24 years.
As the water cools at the end of the loop where the last part of the loop is not insulated it is thermo siphoned back into the hot water heater dear tim.
Another gravity fed shower problem the shower is often the most problematic part of any gravity fed water system.
If you can physically see into the tank then you should be able to see if the make up supply is keeping the tank topped up.
Only low pressure gravity fed water systems can be pumped.
If it is not then the taps will soon lose their water.
If power is a problem gravity may be your best bet for a reliable water supply.
Gravity hot water recirculating system a gravity hot water system works because the heated water which is lighter rises through the loop.
Long before there were complicated electric pump systems for rural properties there was gravity.
I am not a big fan of cold showers.
Several weeks ago i had a problem with one of the lower frost proof hydrants.