ashlatz wrote:
Would the line connect in the back. If it does how do I even get at it there is no access from outside or under the sink
Yes..all water lines connect on backside of water heater tank(inside RV).
The 3 valves under your sink are the cold inlet, bypass and hot outlet.
Follow the lines to the WH Tank. May have to remove a panel, drawer etc. but there is some sort of access to the backside of WH tank.
As I stated in earlier post.....with 3 valve system you may NOT have any check valves, just the shut off valves.
If you do have check valve it is internal of the nipple screwed into tank and then line connection screws on to nipple.
You may just have a plugged fitting due to calcium/scale etc.
Do you have a Suburban WH with an anode rod (attached to drain plug) if so it may have fallen apart and clogged the hot outlet.
How often do you drain/flush water heater???
You can try to 'backflush' (before having to disconnect any fittings/lines)
Turn water supply off
Remove drain plug
CLOSE the cold inlet valve
OPEN the 'bypass' valve
Leave hot outlet valve OPEN
Leave all faucets CLOSED
Turn on water supply
Water will go thru bypass valve and to hot outlet line....with all faucets closed you may be able to get water to back feed thru hot outlet valve into WH and out drain hole and hopefully flush the debris out.
IF you do not get an water to flow then you have a severe blockage OR a check valve....then you WILL have to disconnect hot outlet line and fix/remove the blockage