Can coil be cleaned!

I have a hot water tank which circulates water to boiler coil to heat.
There is low pressure at fixtures only on hot side.
Can this only be caused by build up in coil?
I tested water not hard.
Coil was replaced 9 years ago.
Which tells me it may not be the coil.
Is there anyway to clean it to dissolve any sediment?

Also, I have a Well-Rite pressure tank wich is loosing pressure after draining and pressurizing twice to 50lbs as the cut on is 52lbs, off 78lbs.
The tank is only 5 years old, second home not alot of use..
I heard a leak which seemed to be coming from top air fill valve.
Coud this be the cause not the diaphragm?

Thanks in advance for any help you can give me.

 

I think they use an acid. There needs to be valves on each side so the proceedure can be achomplished. Hopefuly someone else will be more specific...I'm no expert. I had a system where I shut down the hot water production from the boiler and installed 2 electric hot water heaters. Now tenants pay hot water.

 

The hot water coil could be the source of the hot water problem & usually they can be acid cleaned but it is NOT a DIY job.

The air valve could be leaking. Any auto parts store thas replacement valve cores & a tool for doing it.