I might be wrong (excuse me if I am) but I would like to question how the Temp. and pressure valve is installed. But I was always taught that the thermal element of the T&P valve should be inside of the water heater and that it is improper to install it in a stubbed out section of pipe.
I agree. The thermal element should be in the tank. But my main reason for posting it was the boiler being on the garage floor. That's not OK around here.
Please clarify, is this a water heater or indirect tank?
Per 2009 IRC: A water heater or tank must be set in a pan where leakage could cause "damage"-period. The pan must be 1.5" tall of galv. steel or listed to CSA LC3. It must drain min. 6" above grade/ max. 24". Approved piping min. 3/4" and per table P2905.5.
WH's having an ignition source shall be elevated such that the source of ignition is not less than 18" above the garage floor. The electrical heating element is considered an ignition source by some but not all AHJs. If indirect tank, the AHJ usually wants all circulators above 18" in garages.
Double check seismic zone requirements if they apply. Good practice to strap anyway.
Maintain access around WH for inspection and service.
Appliances designed to be fixed in position shall be fastened or anchored in an approved manner. When is the last time you Tapconned a furnace or boiler to the floor or a condenser to a concrete pad outside? See your AHJ for what is "approved" locally.
Appliances shall not be installed in a location subject to vehicle damage except where protected by approved barriers (bollards)
TPR valve max. 150 psi/ max 210F and must be mounted within top 6" of tank.
No check or relief valves btw tank and TPR discharge.
See all 13 points on discharge pipe requirements.
Bottom fed tanks required to have vacuum relief valve that complies with ANSI Z21.22
See TX tank mfr. for listed instructions on orientation approvals (upside down or not. Non-pressurized tanks require support fastened to the structure capable of holding twice the weight of water capacity. All tanks should have isolation valve for testing and service without draining system.
Electric WHs see IRC Chs 34-43 (NEC).
Circulating hot water systems require min. R-2 on pipes and must have either automatic or readily accessible electrical disconnect switch.
Mechanical system piping capable of carrying fluids above 105F or below 55F shall be insulated to min. R-3
Vent connector on boiler is in unconditioned space so must be B-vent whole way. Requires proper support, listed firestops, etc.
Automatic vent dampers installed per mfrs listed instructions, which is usually downstream of any draft control.
foil tape, insulation or other coverings not approved over vent connectors.
Usual CAZ stuff for MUA, switched service light at entrance to CAZ, 120 vac grounded outlet within 25 lf of equipment (GFCI of course when outdoors), etc.
Do you have pics of near piping and venting of boiler?