Water doesn't flow from the hot side. Was really cold last night. Is there a way to get it to flow?

You will need to have heat in the room to thaw pipes . Cold will come in from flue pipe and freeze pipes . its a slow thaw so pipes don't split .

there must have been a power interruption during fill or while there was a flow (Water will not flow when power returns)
1. Turn of all hot water fixtures. Next press the ON/OFF button on the temperature controller twice. Will reset the fault.
Hope this does it. Let me know please.
Happy New Year!

This is dependant on the manner in which your unit is installed. In a normal system, there is nothing that would cause this except debris in the water line. If you have a water heater that is a tankless variety or other supplemental connected systems, you will have to reset those due to lack of water pressure tripping a safety feature to prevent overheating.

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
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Oh some of these there was a small black heatexchanger just for hot water they some times block up . or it could be a blockage in the water section where it flows in .I know Valliant have a very good tech line and fitters who do house calls .

Hi Bob,

You can determine if the tank is the problem by connecting a garden hose to the drain that is provided on most water heaters. Before doing this, be sure to shut of the electrical supply to the heater - otherwise you can damage heating elements if an electric type or waste fuel by heating an empty tank if a gas / propane fired type.

If you get a slow flow out of this drain, it means that somewhere in the cold water supply side to / in the tank - there is a problem. Inside the tank, the cold water is delivered by a "dip tube" that distributes the cold water to the bottom in the tank. Dip tubes are used in both electric and gas / propane fueled heaters. Here's a cut away view of a typical tank:





If the tube is clogged, or there is build up, scale or debris in the supply (cold water) side of the heater, flow rates will suffer. Likewise, if there is a problem with the output of the tank, it will directly affect flow as well.

If you get a good flow rate from the drain, then the issue is going to be on the hot water output side of the heater. Again, the same build up, scale, debris issues on the hot water out put pipe will cause problems with flow. Typcial tanks do not have dip tubes for the hot water side of the tank - as taking hot water from the top of the tank is most desireable and is furthest away from the cold water that rushes in to make up the hot hot water going out.

There's nothing really in the tank itself that can cause issues with flow outside of the dip tube, and piping to and from the tank.

Good luck!

I am going to guess you have crawl space and the you have some frozen water pipes.

Turn the water faucets on to the hot side and one of them to the cold at a trickle and add heat to the water piping area or go down there and use a heat gun/hot air not flame and apply to the pipes. If you have a part of the piping close or in an outside wall I would start there.
Good luck and hope for the best.

Most people don't know that the hot water as it cools will freeze first because the water has more air in it then cold water dose.

I had the EXACT same problem (installed my tankless last winter and worked fine, now this summer it fluctuates, have to turn the shower completely off and then on again to get any hot water and then it only lasts for a couple of minutes!) Argh - it is frustrating!

Here's what I found: the demand for hot water is lower during the summer (hot) months because the "cold" water coming in is already quite warm. You don't need as much hot water to make the shower temp comfortable. SO, my tankless was shutting off due to low flow demand. I've removed the flow restrictor from my shower head and it helped alot but didn't completely solve the prob. Next step is what has been recommended to me by several people but is much more expensive - change the pressure valve on your shower to a temperature valve. Or just wait til winter and it should work ok again :)

Bypass valve incorrectly set
obstruction or dirty tank
plugged line - lime or other! does cold flow into tank ok?
Tank is split water going somewhere you can't see - this should be obvious.

There is not really anything to obstruct the flow normally so there
would have to be an obstruction somewhere. Lime, junk, garbage etc build up .
On my coach I have lots of pressure on the cold side so hot would have to have the same unless there is an obstruction into or out of the tank. If in the bypass position you have sufficient flow than the lines are ok and the problem or obstruction is in the tank itself. Drain the tank, leave the bottom plug out, open up the pressure relief valve. Turn on the water and see if you get a lot of water draining from the drain hole on the tank. There should be a lot of water coming out of the drain hole. If so that tells you that your getting sufficient flow into the hot water tank. If so your problem is the water getting out of the tank. Like a clogged return line or an obstruction from the water tank to the faucet. A dirty scale lined tank can do a number on tank water flow. Also check to see if the water is going somewhere else, your tank could be split and you just can't see where the water is going!

You may need to replace the tap.hot water is causing the valve to expand and yours may be using a rubber seal inside which is causing expansion and hence no hot water is allowed through it..Trust me on that..