Hello All! I am looking for a fuel flow meter that will measure fuel consumption on my domestic hydronic system which consists of a Kerr Saturn boiler with a Riello 40 F5 burner. The burner nozzle is a Delavane 0.5gpm. I have looked on Fleabay but there are many, many options.....a lot of them junk! I was wondering if anyone here could recommend a particular model or brand. Thanks in advance!

So I have not had heat in my Lower Zone (1st floor) while the 2nd floor Upper Zone heats just fine. This all started about 10 days ago when the temperature dipped to -10, and the thermostat setting goes down to 62 for the nite (I now know not to do this). Problem is, I cannot find any indication of a frozen spot, plus thought it may have thawed by now. Most of the pipes are in the house, and the crawlspace under the house honestly doesn't seem so cold. I even added heat tape to the longest section of exposed pipe I could find. No change. I also spent days trying to purge air in case that was it, but again, no luck. The supply side, which splits after the expansion tank but has no other valves or do-hickeys, gets cold in the one pipe after moving horizontally about 6 feet, especially when it goes back down towards the floor (boiler is on the first floor, same that doesn't heat). So more on the setup... Return has 2 zone valves, which then join to one horizontal pipe which immediately goes down thru a singular purge and balance valve (PB56) and a singular circulator before going into the boiler. When trying to purge air, I have not been able to get the water to circulate thru the loop... I'm convinced it only comes in the left side of the boiler (where the main water supply and drain pipe are, separate from return/supply.. at least externally) and out the house on the purge valve on right (return) side. While the water from the purge pipe under the zone valves starts and eventually gets cold, the temperature of the return and supply pipes does not change what is hot (near the boiler) stays hot, and what is cold several feet away stays cold. This tells me the water is just going thru the boiler, backwards, and not thru the zone loop. I apparently have nothing to force the water the correct way, as the balance part of the PB valve apparently does not keep water from coming thru. So basically, I still can't tell what my problem is. Anyone know what I can do to narrow it down without a big expense on one thing when it could be the other? Can I try an air purge with the boiler on, since then the circulator would be helpful in pushing the water thru the loop? I should also add that my pressure gauge is apparently busted, as it is just a nub of a needle that always looks like it's somewhere under 20 from my angle. So when i increase the pressure, I generally just open the pressure regulation valve and wait for the the sound of more water rushing into the system to stop, figuring it must be pretty full.