We have a gas unit in our ensuite for a hot water we can not seem to get any hot water the gas cylinders are getting low so i have asked for them to be refilled or could i there.

It is a gas heater so you need a registered gas technician to fix it.

https://www.google.com/search?q=Rheem+RTG+84XLN

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could be a faulty regulator or blocked supply line
get an accredited gas fitter to check out the problem

clogged heat trap ******?
http://waterheatertimer.org/Low-hot-water-pressure.html

Gene

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

Copy following link for possible troubleshoot resources:
http://waterheatertimer.org/Atwood-water-heater-resources.html
Might want to call service technician instead of messing with gas appliance.
Or sent to service center.
Install 20 gallon under counter electric water heater and connect to 120Volt... 1500 watt element will heat water pretty quickly. To have more hot available, turn up water heater thermostat, then that will give 2 showers because more cold will be added to very hot water, thereby stretching amount of available hot..
http://waterheatertimer.org/How-to-install-under-counter-water-heater.html
Add a comment as needed

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

Before calling service technician, open following link for Rheem troubleshooting resources.
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

List of causes MIGHT include one of following:
Bad household circuit breaker that powers electronics, or loose wire inside outlet where tankless plugs in.
Tankless fuses and control board.
Water flow rate too low. Minimum .8 gallon required (depending on model)
Tankless inlet filter clogged.
Household aerators clogged at faucets.
Crossover at single-handled faucet
If installed, there can be crossover at mixing valve.
Faulty household check valve, including check valve on re-circulation system if that system is installed.
Restriction in household water line, such as clog at elbow.
Unequal pressure in household hot and cold lines, caused by restriction in hot line. When single-handled faucet turns on, the cold water pressure is higher so hot does not flow and tankless will not turn on.
Loose wire connection inside tankless.
Unit temperature set too high.
Unit temperature set too low.
Water temperature is very hot coming out of tap, so more cold is added, but that reduces amount of hot water flow, so tankless turns off because flow rate is too low.
On some tankless, if water is preheated by solar or other indirect source, the burner will not activate.
High mineral content in water > delime tankless yearly
Misaligned temperature sensor
Low gas pressure. Wrong type of gas. Undersized gas line.
Too many faucets on at same time.
Faulty tankless water valve. Water valve stuck.
Fluctuating household water pressure, for example MUD and PUD district water pressure problems or water well pressure.
Faulty household pressure reducing/regulating valve if installed.
Faulty household pressure tank, if installed -or- pressure tank needs to be installed.

Hi,
The unit is plugged up with mineral buildup from the water going through it... it will need to be cleaned internally....this is done by running an acid solution through it to clean out the mineral buildup...

Then it will work again...

heatman101

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.

your gas supply may be to low to keep the unit firing while you are showering...especially if you have other gas appliances running while you are using the unit.

If this is happening after someone else has recently used the unit....then it may be a problem that some call stacking. The unit works on flow....not sure about that unit but they usually take between 1/2 - 3/4 gallon to turn the burner on. If someone recently used it and then you get in the shower...you will get the hot that is already in the line but then it takes that initial amount to fire again, thus loading the pipe with cold water.....it then comes out on you followed by the hot that has finally entered the line. Once it is past that point there should be no issue, unless it it a gas problem like I mentioned.

You are doing everything you can. Your dishwasher probably isn't drawing enough hot water to activate the unit so opening the faucet and flowing more water will activate the unit. Just try to adjust the flow from the faucet to a point it, plus the draw from the dishwasher, will activate the unit. This will come with trial and error as I am sure you have already experienced. Also, open the dishwasher when it does get filled and check the water temperature. You might have the unit set at a low discharge temperature. Do you have a touchpad to control the water temperature adjustment?