I have a hotpoint hot water heater it's about 6 years old. When I turn the hot water on it runs very slowly the water pressure is very low and it's like this throughout the house how do I fix this problem btw it's an electric water heater Thanks

The real question is 'How old is the water heater?'... over time, particularly in areas with hard water, sediment builds up in the water heater. Particularly electric models. typically a TPV (temperature/pressure relief valve) won't cause the symptoms you describe, but mineral deposits around the inlet tube (internal) could, by restricting the flow of water into the water heater.

A TPV is designed to prevent over pressurization which could cause the tank to rupture. I have priced new water heaters as low as $308.00 for a gas powered 40 gallon unit with a 3yr warranty. If you have good soldering (sweat fitting) skills, these are relatively easy to replace yourself. Whether electric or gas, make CERTAIN you shut off the heat source before attempting a replacement.

I do not know how old this unit is or what model but many water heaters are not sophisticated enough to measure the temperature, but heat based on water flow and temperature rise. To start, tankless water heaters turn off every time you turn the hot water off. Lets use an example. You use the facilities, wash your hands then turned off the water and take a shower. You will bring the already heated water (from washing your hands) from the pipe up to the shower. Then the cold water that comes into the pipe from the reactivation of the water heater comes up the hot water pipe with warm then hot water just behind.

If this is not your problem, keep reading. Every unit I have been called to see were installed wrong. Check your installation manual to see if the problem with the system started with the contractor.

First, check the temperature of the water from the heater. If it is too hot and you are mixing too much cold water in, the unit will turn off because there is not enough water flow to keep it running.

Second, turn off the valve at the water heater and turn on the hot water at a faucet. If the water does not stop running, there is a "plumbing cross over" usually caused by a failing pressure balance valve in a shower.

Third, if the unit has not been serviced, go to bosch-climate.us to find a tankless water heating professional in your area. Totally Tankless LLC

Probably the factory-installed heat trap nipples are clogged.
Open following links.
http://waterheatertimer.org/Low-hot-water-pressure.html
http://waterheatertimer.org/Low-hot-water-pressure.html#trap
Noisy whistling and humming and low pressure are common problem with heat trap nipples and inserts from factory.
Replace heat-trap nipples with pex-lined nipples, or remove heat trap inserts with screwdriver or needle nose... careful not to break insert so it falls into tank ... which can then get lodged in hot water line elbow or under-sink shut off.
Factory-installed heat traps are part of overall strategy so manufactures can claim more efficient water heaters, without requiring customers to any thinking.
Other strategies include foam insulation instead of fiberglass (so that wires cannot be replaced on electric units), reducing factory-set temperature from previous 130-135 to 100-120, and re-estimating downward the hot water use for average family.
So some of the strategies are useful, while others problematic or imaginary.
Call manufacturer to pay-for or provide new pex-line nipples. Warranty for fist year covers Labor and parts, and after 1st year, warranty covers parts
http://waterheatertimer.org/Water-heater-manufacturers.html
Save $10 a month in future replacement costs: maintain water heater so it lasts longer:
http://waterheatertimer.org/How-to-maintain-water-heater.html

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

1) If water flow stops when tap is off, then Sound of water running: could be factory-installed heat trap inserts or nipples: These things cause noise.
http://waterheatertimer.org/Low-hot-water-pressure.html#trap
http://waterheatertimer.org/9-ways-to-save-with-water-heater.html#heat-trap
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html

2) If sound of water continues when tap is off, then there is a broken pipe or leak somewhere in plumbing system.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Copy following link for troubleshoot walk-thru:
http://waterheatertimer.org/Low-hot-water-pressure.html

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Feb 2013
1) Copy following links for Intellivent gas control service manual, low hot water pressure, and crossover:
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#intellivent
http://waterheatertimer.org/Low-hot-water-pressure.html
http://waterheatertimer.org/Crossover.html

2) Unknown if tank has hot water > that is first thing to check.

3) Unknown if air intake screen located under burner is clogged with dust that cause combustion chamber to overheat, tripping FV lockout and breaker TRD glass vial.
Requires removal of combustion parts, replacement of TRD, blow out air intake screen, reset intellivent

4) Unknown if there is error code.

5) Rheem does not post service manuals.
However this unit can probably be repaired.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Very simple - call a Plumber. He will fix your plumbing problem, and any foreseen potential problems related to your water leak. He may also suggest replacing your 6 year old water heater. Of course ..... for a professional cost.
However, depending on your time, skills, proper tools, patience and luck, it's easy enough to perform yourself:
1. Switch off the water heater Breakers (220v) in your service panel.
2. Turn off the water supply to the water heater.
3. Attach a water hose to the drain faucet. ( a good time to flush sediment -calcium deposits)
4. Open a hot water faucet to vent (above the level of the water heater drain - kitchen sink)
5. Remove the suspected leak components. (a union connection is a good place to start)
6. Install New pipes -3 wrap all male threaded ends with teflon Tap. Tighten securely - using 2 wrenches.
NOTE: Before refilling - you can turn on the water heater supply valve for a few minutes, to flush out any lingering calcium debris.
7. Shut off drain valve - remove hose. Shut off venting hot water faucet.
8. Turn on water supply valve to fill water heater.
9. Open a hot water faucet to relieve air pressure while filling - preferably the bath tub faucet, it doesn't have a screen that might clog.
10. When water flows without air - shut off tub faucet.
11. Look for leaks.
12. Switch the water heater Breakers on.
Note: 50 gallons should take an hour or more to heat up. Turn on a hot water valve momentarily within this heat up time to relieve thermal expansion. ( the PT valve on your water heater will perform this task if pressures/temperature exceed new water heater tolerances - it's just a precaution to introduce these fluctuating pressures on your fragile 6 year old unit)

These are just basic instructions - assuming you fill in the common sense and work safe steps.
Good Luck - The Skill will only come after trying.

1) Your water heater needs to be replaced.
It cannot be repaired.
Tanks rust out after anode rod is depleted unless anode is inspected and replaced 1-3 years.
Water softener causes anode to deplete quicker, so inspect every 2 years.
Also stray household current can cause tank to rust out. Put bare copper ground wire between hot and cold pipes on new heater.

2) First thing is protect yourself from tank rupture where water heater bursts open and water runs until it's shut off. Ruptured tanks are big topic in homeowner insurance industry today because they cause major damage inside house.

- Turn off heat source so tank is not under pressure:
Gas: Rotate dial to pilot so pilot light stays lit, but burner does not turn on
Electric: turn off circuit breaker

- Turn off water going into tank using shut off above tank.
- Open hot side to bathtub to relieve pressure from tank.
- Check label on side of tank to get tank specifications for replacement.

3) What to do until replacement.
You can get by for a while on leaking tank by turning it ON only when needed.
Make sure tank is full of water before turning heat source back on.
This will buy time until replacement.
Electric tank heats 21 gallons water per hour.
Gas water heater 41 gallons per hour
Shower uses 6-9 gallons hot water, bath uses 12-15 gallon hot water.

4) Additional reading so next tank lasts longer
http://waterheatertimer.org/Replace-anode-rod.html

http://waterheatertimer.org/9-ways-to-save-with-water-heater.html

http://waterheatertimer.org/Water-at-bottom-of-water-heater.html

See image larger

-Tankless water heaters are susceptible to lime build-up if not de-limed each year.
-Hard water will clog pressure-sensor and cause failure within 2 years if filter and softener are not working.
-Water flow and water pressure sensors inside tankless are succeptible to hard water deposits.
-Low water pressure from clogged pipes to municipal water problems to water well pressure valve can affect tankless burner
-Low-flow shower heads may not engage burner.
-With tankless-gas water heaters, sensors inside combustion area detect when incoming air flow is not adequate ... inspect inflow
-Your manual probably has a troubleshoot section.
-The manufacturer will refer you to installer.
-If you self-installed unit, that will void warranty to my understanding.
-There are water heater forums 1 2 3 4
-There are plumbers who will each have a different opinion
-There are Fixya experts who get paid to tell you the above.
-And there are local plumbers who are authorized dealers of the brand of tankless who get paid to fix them

This is a great unit! Try turning the flow nob to the half way point and the flame all the way to low. Run the hot water tap and slowly turn the flame dial until you hear the unit try to light. Every house is different regarding the restrictions in the plumbing and water pressure. Once the unit tries to light that is your minimum setting. It is best to leave it there.