How to model water flow when only a couple of sample points available?

Bosch Aquastar AQ125-BLP or BNG conversion from natural gas or propane?

• No question here, just thought I would throw this out there in case it helps anyone else. I had a AQ125-BNG tankless natural gas water heater that I installed new (bought as a closeout) about seven years ago. A couple of years ago it developed a leak around the water regulator which I found out was very common for this model. There used to be a rebuild kit but then discovered that I would have to just buy the whole regulator which was the same price I paid for the water heater. As the leak was just a slow drip every once in awhile I just put a bucket under it and used that to flush a toilet in my basement every couple of weeks. I went ahead and started looking around on Craigslist and found another brand new Aquastar a couple of states away that some guy couldn't use and had my dad pick it up when he was in that area. I figured once the leak got bad enough I would just swap them out. After about 6 months the leak stopped on its own. Two years pass and I hear an awful noise from the pipes after a shower. Something died within the unit, probably the flow regulator which lets the unit know there is water moving. Should have failed in a safe position but guess not. Anyway went ahead and swapped in other unit, when to my surprise I find out it is for propane. How that slipped by me I have no idea. Difficult to drill out the burners on these as they are delicate slots. Went ahead and just swapped burners with the old one (which was in great condition) and works great, so wanted that info out there that you may just be able to swap out the burners.

• Answer:

  To convert appliances, you MUST get conversion kits from the original manufacturer. One of the most important things in there is the new rating plate which is their proof that the appliance is "certified" for use with that fuel. If you "Mcgyver" the appliance and try and convert it by just changing or drilling orifices etc, you will void the manufacturer's warranty. Also, the manufacturer will take no responsibility if the appliance hurts anyone or property is damaged because you have "altered" the appliance. Insurance companies will deny claims for the same reason. You should get a proper conversion kit for that appliance purely in the interest of liability.