Would a Watts Premier Hot Water Recirculation Pump (http://www.costco.com/Browse/Product...pnav=&cat=&s=1) (or any other brand name) help to increase hot water pressure if you install it directly to the hot water output pipe and then turn it on ONLY while taking a shower? I was thinking of doing this because my hot water pressure throughout my apartment is quite low (despite checking valves and so forth from reading the other related links) and since I rent the unit I (and the landlord won't) want to do any plumping changes. I thought that this pump would help water flow, but I'm worried that it might empty the gas water heating unit faster than it gets supplied... however, it would only be for 15-30 minutes, so I don't know if this would hurt or not?
Anyone know or have tried this?

I really hate to rain on your parade but a recirculating pump won't increase your pressure. That's not its function. A recirculating pump supplys hot water to a branch, (as a rule, the master bathroom) that is located so far away from the heater that it takes ages for the water to get from the heater to the fixture. All it does is move water in a loop so that there will always be hot water on demand for the farthest fixture. The pressure remains the same. Don't worry about "emptying the heater" as it's a closed system. What kind of pipes do you have and how old is the unit? Sounds like the owner hasn't flushed the heater on a regular monthly maintenance schedule and you have mineral build up in the hot water pipes that's blocking the flow. If you wish to install the pump as a in-line booster pump then if the line is choked up with mineral build up you will not be able to increase the volume and if you let it run against line pressure you will soon burn out the pump motor. If the problem affects the entire unit then the only solution might be to repipe the hot water lines. Regards, Tom

My guess it that it would only increase the pressure by the amount of added pressure this pump is rated at.
In other words this pump's function is to keep water circulating. A piping loop to keeps water hot throughout the system so you can turn on the hot water and not have cold water come out for two minutes. My guess is it will increase water pressure about 5 to 10 psi and that is not all that much - unless you only have 10 to 20 psi. To increase flow you need to see what restrictions are in the line. Most often valves or mineral build-up in the boiler or heater.

How about talking to the landlord about bringing the pressure up to a usable pressure? There have to be minimum pressures in the zoning laws or residential laws in your area.It is not up to you to "fix" this. And if something goes wrong, YOU will probably be held liable by the landlord for any damages.