No hot water when heating tempreture reached.flow switch is operating, power at flow switch terminals on pcb (three wires),? but when working hot water runns for ever and heating runs ok too untill the heating shuts down on temp via room stat ..(turning hot water tap on wont bring the boiler on, even thought diverter valve spindle has activated the flow switch)...any help/ideas please....tks

Not sure about modern heaters with lots of lights but inside there is usually a pressure switch that prevents operation if the water pressure falls and a temperature switch that cuts the power if the temperature rises too high - in a single heat unit there are only two wires supplying the heater element and the temperature is controlled by the water flow. It is straightforward to use an ohmmeter to check the element but with a multi-heat unit there is likely to be a switch to contend with and several connections to the heating element.
In this case it is a good idea to draw out the circuit so it makes more sense - if the element tests ok, it is likely one or the other of the safety switches is faulty.

Communication Fault with Remote Control. At a minimum check the following: 1. Check remote control wiring for loose or damaged connections. 2. Bypass remote control cable by connecting remote control directly to remote control terminals on PCB. Replace cable if found to be faulty. Yes Either the wiring or the remote control is at fault. To rule out the wiring, disconnect the remote control and use a short, good jumper wire and connect directly to the remote terminal on the PCB. If the unit works using the remote, then the wiring is at fault. If the unit does not work, then the remote is at fault. Did the unit go to main burner? No Replace the Printed Circuit Board Remove remote control wires from wiring terminal on the PCB. Plug unit in and open a hot water source.

If when you turn power off you wait a while it is probably not the central system coming on. You have a triple aquastat that maintains a temperature level needed to provide hot water. but you are not getting the thermostat to operate the central heating. The thermostat is a switch that operates by temperature. if you have tried raising the thermostat and the system did nor kick in. try jumping the thermostat terminals in the aquastat . if that works then the problem is either in the thermostat or the wiring to the thermostat. also with a electrical tester." while the thermostat is jumped" test the c1 and c2 terminals to see if power is going to the circulator. If not then you need a new aquastat. if you have power and the pump is not moving water replace it.

you have a triple aquastat that maintains a temperature level needed to provide hot water. but you are not getting the thermostat to operate the central heating. The thermostat is a switch that operates by temperature. if you have tried raising the thermostat and the system did nor kick in try jumping the thermostat terminals in the aquastat . if that works then the problem is either in the thermostat or the wiring to the thermostat. also with a electrical tester." while the thermostat is jumped" test the c1 and c2 terminals to see if power is going to the circulator. If not then you need a new aquastat. if you have power and the pump is not moving water replace it.

You have a triple aquastat that maintains a temperature level needed to provide hot water. but you are not getting the thermostat to operate the central heating. The thermostat is a switch that operates by temperature. if you have tried raising the thermostat and the system did nor kick in try jumping the thermostat terminals in the aquastat . if that works then the problem is either in the thermostat or the wiring to the thermostat. also with a electrical tester." while the thermostat is jumped" test the c1 and c2 terminals to see if power is going to the circulator. If not then you need a new aquastat. if you have power and the pump is not moving water replace it.

http://www.rheem.com/product.aspx?id=09DF2BDD-5E11-4D32-B574-84ACFB8A4619
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82V80-2 Energy factor is .86 according to water heater industry self-regulated standards.

Rheem pdf says these water heaters are wired for non-simultaneous operation.
Except special order water heaters.
Non-simultaneous operation uses single 240V circuit as described below.
If your water heater is wired for simultaneous operation, and each element is on a separate circuit, that makes your water heater special order. I would guess the reason is for higher first-hour delivery, which implies rapid heating and would likely affect energy factor.
You might want to get serial number off model and call Rheem for specs on that special order.

Your water heater energy factor may be the same because 'energy efficiency is based on the amount of hot water produced per unit of fuel consumed over a typical day.' This means an aircraft carrier can be considered highly efficient despite overall cost. And naturally the guys making the aircraft carrier are also doing the rating.
http://www.energysavers.gov/your_home/water_heating/index.cfm/mytopic=13000

Non simultaneous operation means the upper thermostat controls heating functions.
240V goes to upper thermostat first.
When water inside tank is cold, thermostat reads temperature through tank wall.
Upper thermostat turns on upper element until top 2/3 of tank reaches thermostat set point.
Once set point is reached, upper thermostat turns off upper element and sends power to lower thermostat and lower element.
Lower thermostat reads temperature through tank wall, and turns on lower element until bottom 1/3 of tank reaches thermostat set point.
As water cools inside tank, lower thermostat is first to respond since hot water rises.
Lower thermostat turns on lower element until tank again reaches set point.
When hot water faucet is turned on, hot water exits top of tank.
At same time, cold water enters bottom of tank through the dip tube.
The heating cycle repeats.
At all times, the electricity flows through upper thermostat. And upper thermostat is powered by one 240V circuit.

With simultaneous operation, the upper and lower thermostats work in same manner.
Except thermostats are wired separately.
Lower thermostat does not wait for upper part of tank to be heated first.
Lower thermostat turns on whenever lower part of tank cools.
The advantage is more hot water available rapidly when demand is high. This is called first hour recovery.

One method for reducing electric consumption is to set lower thermostat so it only turns on during certain times of day. For example Whirlpool Energy Smart operates in this manner and shaves a few bucks off the bill each month. This says that simultaneous operation is not an energy saver, unless that circuit controlling lower thermostat is set on a timer.

The heating element sounds like it's going out. With you turning the temperature up, this will increase your power bill. The water heater will heat up until it reaches that temperature. Tankless water heaters are a good option if you are willing to pay the expense. But your heater sounds like it could just use new elements.

it uses resistive heating elements that are encased in an electrical insulation and then covered with metal, like the cooking elements in a stove, or on a cooktop range. when electricity flows through them they heat up and get hot (like a light bulb filament wire glows) When the water reaches a certain temperature set on the thermostat, it opens the electricity,turns it off to the element until the water cools down past whatever temperature it is set at, and then it turns back on. That is why if too many people take a shower you will run out of hot water because cold water is always flowing through the water heater and when all the hot water is used, you have to wait for the heating elements to heat the water back up. To make sure it heats up quickly make sure all the HOT water faucets are off so that water isn't flowing through it and is just sitting there heating up. All work on the same principle.

most likely the diverter valve.. when hot tap turned on the movement of the water through the valve operates a diaphragm which pushes a pin/button//switch to tell the boiler to fire up