Seeking advice on FHW Oil heat boiler (refresh or proactively replace)

House built 1997, 2 story colonial 2Kish sq ft above ground. Boston Metrowest suburb.

Weil McClain TGO-4 with Viessman Vitocell 300 indirect (42g)

Yes…the TGO-4 was WILDLY oversized. Years ago when I was doing a short zone of FHW in finished basement the installers for that zone "fixed" the system for me as it never made it between annual visits without requiring a reset on a cold morning. They installed a .75 nozzle (currently a .75 80B), Carlin ignitor and Carlin controller (which was replaced a few years ago when the boiler wouldn't start with the current contoller in pic) and cranked the pump pressure up to 150 psi with a delayed start oil valve…I have pre/post purge from the carlin. Since then it has been running great.

So…4 Taco 007s (and yes…2 are push and 2 are pull…I guess it made sense to someone at the time)…first floor approx 47' of Slantfin, second floor approx 62' of Slantfin, basement approx 14' of Slantfin…and the Vitocell indirect.

The rust on the floor….thank you 2010 14" of rain in a month and groundwater…basement got some water, otherwise I have seen no signs of any issues with the boiler…or burner…the vitocell was last summer after the Amtrol Hotwater Maker from 1997 decided it was time.

Bosch IDS heatpump is used shoulder seasons and then shutdown and sealed for the winter.

Woodstove insert is used for supplemental heating nights and weekends.

5-6 year rolling average oil usage is under 525 gallons annually for heat and DHW.

The fact that the 3 ton IDS and downfired TGO gives me adequate heat, plus knowing that the baseboard radiators total up to a certain number gives me great confidence that my back of the napkin online Manual J is correct….and that those that wanted to install a G115WS-4 were wrong…or those that wanted a 4 section Williamson or WM replacement as well.

So now the advice part…sorry it was long summary…but figured the full picture was better?

I have few quotes, wanting to have options to figure out what I wanted to do and learn those that wanted to oversize me again…a couple of the quoters suggested freshening up the current system, rather than replace. This is where I am torn.

My system is not optimally configured, the 007s are not as electrically efficient, etc…but it's seeming running great and I'm not really concerned over the energy expenses, but I am wrestling with replacement proactively versus the refresh.

The refresh quote seems good and would involve…replacing the burner motor, pump, and coupling as well as the aquastat and thermal expansion tank with the hi-vents. It is certainly a MUCH smaller number than the three other options I have…Buderus G115WS-3/Taco 007e/Carlin or Riello (two different installers), Utica TriFire TRB4075 with Riello, or EK System 2000 all using the current indirect.

The other issue is the exterior masonry clay tile lined chimney. The stack temp on the pinner is seemingly doing fine because an inspection of the oil flue when the wood flue was cleaned last year said it looks fine, but with any of the replacements, this most likely would not be true. The clay tiles take a bit of a few jogs to route down to the basement around the fireplace and I was told a 5" liner looks good, but a 6" will be problematic and require some bricks to be knocked out rebuilt in the garage. Both Utica and Buderus seem to have the same wording…6" liner. Direct venting doesn't really have any good spot…nor does the propane option with windows/porch/electrical outlets/IDS compressor for tank placement.

So…thoughts…refresh or replacement (at which point if I was going to force it in now I think I'd go Buderus since AI tells me it's likely the best choice for the unlined clay tiles until I can get that done as well.

I'm all ears for suggested folks to refresh or replace as well…between Metrowest and Northern RI.