losing hot water pressure is it my storage tank or boiler(water psi is fine on boiler)?
it could be the circulating pump , if your boiler and storage tank are using the same pump.next if you own a older home check to see if all your piping from the water main to boiler is copper,in older homes they could have used galvinised piping which could build up rust from the inside and reduce flow.also check to see if there is any air locks in the system.
