Fired up the OWB today...
I cannot, for the life of me, get hot water from the OWB into my DHW HX, nor can I get it into my Water -> Air HX.
This is my 3rd season using the OWB (Central Boiler 5036). I did all the plumbing and installation myself. It's a very simplistic set-up and I'm very familiar with it. Water exits the boiler via a Taco pump, runs underground through my Thermopex, enters the house, comes through my Thermostatic Mixing Valve, enters a plate HX for DHW first, continues into my furnace plenum via a water -> air HX, then exits the house through the aforementioned mixing valve. Basically, everything was installed to manufacturer recommendations.
Hot boiler water is making it to the mixing valve just fine. At first, I figured my loop (past the mixing valve) was vapor locked since it is physically higher in elevation. This is not the case, I have bled the line. I've also purged both HXs using an external water supply (backflushed, if you will).
Furthermore, I can break my loop in multiple spots to verify flow. If I break my loop before the DHW HX, I get boiler water to come out. If I break it after my DHW HX, I get the same result (proving to myself that the HX isn't plugged). I can do the same thing for the water -> air HX with the same results. Point being, neither HX is plugged. This also proves that the mixing valve is working since boiler water will make it to the broken loops.
When I piece everything back together, however, I get the same problem - no flow to either HX.
I'm left with very few things to check: Either my pump doesn't have enough a** to get water through the system effectively (although, it appears to have more than enough pressure when broken) or perhaps my mixing valve isn't working as well as I think it should? Or... am I completely missing something?
Does anyone have advice? I'm getting a little desperate; burning propane isn't nearly as fun as wood (or as cheap).
I really don't want to start mindlessly replacing parts until I find a cure either...