Yellow Jacket 78075 Water Manometer

This manometer is easy to use - just connect it and add water. It comes with a magnetic clip to hold it on the side of a metal pipe, furnace cabinet, etc. for hands-free measuring.

I rarely write reviews but I liked this tool. I'm a general contractor and have no association with the manufacturer or seller. I bought this for personal (not business) use to check water column pressure on a combi boiler while it was firing at 100%. It's a simple, basic tool that does it's job perfectly - and cost effective for a DIY or only occasional user.Some folks have said they don't come with instructions. That's incorrect - they do, but they're just a few lines printed on the side of the tube (the tube is clear so they don't stand out). The magnet is also handy to mount it while you're fussing with the tubing.One thing to note: when in use, with (clear) water and clear tubes, it's helpful to have a flash light and shine it at different angles so you can more clearly see where the inner tube water level settles, showing the WC measurement.

Used this to setup the LP gas on my furnace.

Ordered one to adjust manifold pressure on my LP boiler but Amazon sent a Chi-na one instead. Returned and got what I ordered, Yellow Jacket, made in USA. Works and save money because I was the professional not a unknown service guy. You read the center tube through the water, harder with old eyes but readable. Can’t go wrong.

Works great to get your furnace gas pressure no need to worry if u got batterys or needs a charge just fill it with water to the line and attach (hose is stiff kinda hard to attach but after a couple times it slides right on) definitely buy if u in the hvac field great tool.

I used this to measure the natural gas pressure going into my backup generator. The brass fitting at the end of the hose is 1/8" male-NPT (a.k.a. 1/8" MPT or 1/8" MIP). To use this with a larger pipe size, you would either use a reducer bushing (e.g., 1/8" FPT to 1/4" MPT bushing to use in a 1/4" FPT opening), or get a different brass fitting. The hose is 1/4" I.D. so you would need a brass fitting with 1/4" barb on one end and the appropriate NPT connector on the other end. I used a 1/4" barb to 1/4" MPT fitting from Home Depot. The device has a small inner hard plastic tube inside the main tube. The flexible hose fits over the top of the small inner tube. The tubes are connected at the bottom. You fill the main tube with water to the 0" mark (water will be at the 0" mark in the inner tube as well), then fit the brass fitting to the gas pipe. When the gas is turned on, the gas pressure will push the water in the inner tube down. The number of inches by which the water in the inner tube falls is the pressure reading. The water in the main tube will rise slightly as the water in the small tube is displaced, but not above the -2" mark, so it won't overflow.

Works like it should

Excellent product. Simply fill with water, connect the tubing and test away. This device saved me a $200 visit from the HVAC company. Too easy to DIY to pay that much.