Navien NHB 055 - heating SUPER slow

[Gsboorman]

I have a new installed Navien nhb 55.

I installed it myself and I’m trying to figure out the settings. Heated concrete slab in my barn.

Right now I was able to set it to Custom with outdoor sensor disabled. It heats SUPER slow. The supply temp only come out maybe around 75f and that’s after a while. Return temp starts at 45f because the slab is cold.

The unit also either times itself out and stops the burner, or my regulator freezes from it running for so long (but it’s only 20f outside so it shouldn’t right now).

When I turn the pump off and then back on the boiler doesn’t re-fire. I have to wait a long time for it to work again. Last time I let it sit over night.

Finally, I have no error codes showing.

My fluid is 80/20 glycol/water.

Thanks for any help.

 

[Fitter30]

Glycol is mix is way to high and hope u didn't use auto antifreeze. 30° temp difference is high do to the fact the pump has to work harder to pump that high of concentration of glycol. Design usually 20° . Protection only has to be to slush not frozen solid. Boiler glycol will give u that number for the mix. Lp has a vapor rate what size tank are u using? Brand and model of regulator? How many feet and size of tubing in slab?

 

[Sponsor]

 

[Gsboorman]

Thanks for relying.
No, not automotive antifreeze. Plumbing glycol.

I have dual 400lb tanks.

Slab is 1000sqft. 1/2” pex spaced 9” apart. I believe it’s about 1500ft.

I found a loose wire on what I think is the firing unit. Looked like a spark plug wire, one was loose.

It fired this time, I’ll see how long it runs for and if I run into the same problem.

My supply temp is now 22f hotter than return with High mass setting.

I’ll work on the glycol mixture if it continues to function.