Water Heaters - Propane condensing tankless vent

I want to install a Bosch GWH 800 tankless, which is a condensing unit that uses (3 inch) PVC vent pipe and requires direct vent, which can be concentric.

The vent diagrams show a few offsets - 60 inches from meter regulator's vent, 36 inches below operable window etc. I've identified a spot that is 60 or so inches from the regulator vent where I want to put the exhaust vent, I'd use the existing tank water heater vent outlet (too close to regulator) for the intake.

I see a potential problem not in the book, though; our heating oil fill pipe and vent are fairly close to the chosen vent location. Maybe 3 feet, but I didn't measure that close. Is this something I should take into consideration for a condensing exhaust pipe that will be a few feet away from the unit?

Another question. Would most plumbers be happy to come in and find that I've mounted the heater on the wall, drilled a second vent hole through the foundation, and set up a condensing drain pipe for the unit, so all they'd really need to do would be (set up & connect the gas and water pipes and configure the unit? I'd like to have someone come for an estimate, verify the locations with them, and do the non-permitted parts of the work myself. But figure that might not sit well with a licensed plumber.

Thanks much.

Charlie

Oh well, I see reg nfpa31 on fuel oil piping,

8.6.8 The vent outlet of a supply tank shall terminate at least 5 ft (1.5 m) from any air inlet or any flue gas outlet of any appliance.

Looks like I'll need to run to an alternate wall. At least it's PVC. Still would like opinions whether I should ask a plumber if I can mount the unit, drill the vent hole, maybe run the vent line. Less likely maybe do the condensing drain line. Less likely still, do a new trac-pipe manifold and 1 inch trac-pipe gas line :rolleyes:

Thanks much.

Very few plumbers are going to want to install a customer-provided water heater, especially a tankless model. If they do it is even less likely you will get them to offer any kind of guarantee.

Also, the Bosch units are generally looked upon as less than high quality units by a majority of professional plumbers.

I've settled on this Bosch because we're getting a solar hot water installed at the same time, and it is one of the few units that asserts it is compatible with pre-heated water. I has a high flow rate, 90%+ efficiency, and the simpler PVC exhaust.

I was considering a Rinnai, which is a modulating unit, but we were told by the local vendor that the factory rep says it doesn't work well with solar. Don't think I can practically install any tankless that requires cat 3/4 steel vent, if I need a longer run as I seem to require to avoid the fuel oil vent.

Thanks for your input - Chaz