TPRVs (Temp/Press Relief Valves) on RV Water Heaters leak due to scaling/calcium build up on valve/seat, will weep due to loss of air pocket on top of tank or because of high temps/pressures
With water supply on and tank cold you can open TPRV via lever allowing full water pressure to blow out and then let it snap closed by letting go of lever.
Do several times to clear valve/seat of build up
Air pocket by design
Hot outlet is lower than top of tank so that there is space for an air pocket.
Water expands when heated..water can not be compressed so w/o air pocket pressure will increase causing TPRV to weep
Air Pocket
Turn water supply OFF
Open closest faucet hotside to relieve pressure in hot water system
Open TPRV via lever......let it snap closed when water stops running out
Close faucet and turn on water supply
TPRV
Set to OPEN at 210*F, 150PSI -----rarely do they reach those conditions
Bad TPRV
Try tightening first then loosing
Sometimes it easier to break 'seal' by tightening
Easiest is to remove exhaust shielding so that you can get better access with wrench on 'flats'
BUT CAUTION:
Atwood uses an Aluminum Alloy Tank with aluminum threaded bungs
Suburban uses a Steel Tank with steel threaded bungs.....and inside of tank is glass-lined
