Hi,
I just moved in to a 40 yr old house. And hot water pressure is low. Cold water is OK.
When I use the shower if any hot water is running in other fusset, show will be so cold.
I use hot water tanks which uses gas.
Please help me.

Thanks

The first thing we should do is move you to plumbing where some plumbers will read your post. Is the hot water pressue low at just that shower head or do other hots have trouble too? If just the one I'd say we will need to take apart your mixing valve. If all hots are bad we'll take a look at your water heater. Which one fits your situation? In the meantime how about draining the water heater. Add a hose to the drain valve at the bottom of the tank. Direct the hose to a drain and open the valve for a few minutes until the water runs clear, no color or debris at all, then shut it down.