Question 1

Hooked up to wh conn. it read 7.5”. fired up furnace & dryer. it dropped to 6.5”. excellent reading. should i trust? seems so high for residential.

Accepted Answer

A good reading would be one above the minimum gas supply pressure specification on the water heater. I have seen a drop in pressure when the air heater comes on. This may have something to do with a shared gas supply branch pipe in my case.  I think the gauge is accurate.

Question 2

Will this measure positive and negative static air pressure in an air handler? What do you use for a probe?

Accepted Answer

I used the manometer to measure and then adjust the regulated propane pressure at a back-up generator. You should be able to measure the pressure inside of an air handler plenum as long as the pressure doesn't exceed the range of the manometer. The manometer comes with a plastic tube along with a 1/4" npt brass fitting with a hose barb. I would think you could drill a hole in the wall of the plenum where the diameter is such that you could get an interference fit with the plastic tube - at least with a good enough seal. The air handler will be moving enough air so that a small leak would not compromise the reading. For the suction that you are trying to measure, maybe fill the manometer only halfway with water so that the water is drawn up the column - wouldn't be able to measure much suction though. Remember, the manometer is only measuring the pressure differential between atmospheric and what you have connected to the plastic hose. Good Luck!

Question 3

Feeling a little dumb here. but how exactly does this hook up? (I want to check NG pressure out of a 1/2" black pipe)

Accepted Answer

Get a reducer 1/2"by 1/4" and conect the brass 1/4 that comes with this manometer and add water on your glass up to the 0 mark and open your gas and test your pressure.

Question 4

Is there a standard type of fitting for connecting to the system? videos show people using diy fittings w/ stems. isn’t there a ready-made product?

Accepted Answer

I believe it has a standard fitting for relay driven gas valves like the ones used to control furnaces. If you want to measure pressure in a pipe, you need to build an adapter. Any good plumbing supply house or home center has the parts. They aren't expensive, and are reusable. Pro tip: pick up a roll of gas rated Teflon tape and use as directed. Tighten all joints securely.

ASIN	B0038QHTK2
Best Sellers Rank	#167,217 in Industrial & Scientific ( See Top 100 in Industrial & Scientific ) #43 in Manometers
Brand Name	Yellow Jacket
Customer Reviews	4.6 4.6 out of 5 stars (192)
Global Trade Identification Number	00686800780757
Included Components	Manometer
Item Dimensions	10 x 1 x 1 inches
Item Type Name	Made of a durable plastic
Item Weight	8 ounces
Manufacturer	YELLOW JACKET
Material Type	Plastic
Model	78075
Part Number	78075
Thread Style	1/4 Npt
UPC	686800780757
Unit Count	1.0 Count

Yellow Jacket 78075 Water Manometer

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