How to connect Klein ET180 to SIT 610-AC3 water heater?

Thank you so much for your help everyone! 

Grit_dog, I'll try to replace the gas regulator and let you know. 

I have also tried the furnace and the furnace works well. 

Sophia 

Did you check to see if it’s doing the same thing on the other gas appliances?

It’s great you’re trying to diagnose the issue, but save your $ and return the pressure meter. 
The gas pressure is regulated at the regulator by the tanks. 
if in fact it is an excessive pressure issue, the regulator is the problem. The water heater/stove/furnace etc just take what the regulator gives them. 
Regulator is cheap and easy to replace. 
IMO worth just replacing it even if you later find out the water heater has a different problem. They’re like $20-30 only. 
good luck!

I second what Grit says above. 
But to answer your question in order to use the Klein you would need to be able to hook it up to the gas system. So yes you will have to go get some vinyl tubing and some small hose clamps and possibly some brass connectors from Home depot to link the Klein to the gas line.  

It’s great you’re trying to diagnose the issue, but save your $ and return the pressure meter. 
The gas pressure is regulated at the regulator by the tanks. 
if in fact it is an excessive pressure issue, the regulator is the problem. The water heater/stove/furnace etc just take what the regulator gives them. 
Regulator is cheap and easy to replace. 
IMO worth just replacing it even if you later find out the water heater has a different problem. They’re like $20-30 only. 
good luck!