Water Flowing Backwards Navien Boiler

Poolman21

Hey All

I am a rookie DIYer and this is my first install so I apologize if this is a stupid question. I just installed this Navien combi boiler and it seems like the space heating water is flowing backwards. When the thermostat calls for heat, the pipe coming out of the right side of the manifold gets hot first, then it takes several minutes for the pipe on the left to start to get hot. Also the thermometer on the top of the PEX manifold (blue handle) is always higher in temp than the one on the lower PEX manifold (red handle). To me those indicate that the water is flowing in that direction. It seems backwards to me because the supply valve on the boiler is on the left so I guess I expected hot water to flow in that direction. I guess I don't really care if it won't hurt anything, however I did install my air separator and expansion tank on the left side of the manifold as that seemed logical since I expected the hot to flow that way and also every installation example I've seen is set up that way. So my question is, does it matter? And what are my options for fixing it? BTW, this is a 1,000 sqft garage with in floor heat. 1 zone using only the internal boiler pump for circulation. Thanks in advance.

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HVACNUT

You need a system pump. The only time you don't is when its piped to a hydro coil in close proximity to the boiler.

Check the manual.

Do you have any way of testing combustion?

Poolman21

Thank you for the input. I did read the manual, and I saw a few examples of multiple zone systems with external pumps, but not much for a 1 zone system. I don't have any way of testing combustion. Can you let me know what I need to do to check for that?

HVACNUT

https://forum.heatinghelp.com/discussion/comment/1809074#Comment_1809074

Testing and adjusting combustion is easy. All you need is years of training and experience... and a digital combustion analyzer. The pay isn't bad either.

EdTheHeaterMan

I think The NUT is saying that you should pay a pro with the proper training and the proper equipment to set up your equipment. Those Combustion analyzers can be pricy. But you should add a system pump before calling in a pro.

This illustration will show why you need a system pump.

Without the system pump, there is nothing to make the water flow into the radiant heat tubing.