Navien nhb-80 boiler install


Old 10-31-16, 01:12 PM
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Navien nhb-80 boiler install

Hello all
Looking for some help on piping this wall hung boiler. Location of the expansion tank? Does the system need two pump's? Has anyone installed one of these. This is for a small 300 square-foot room. The old cast-iron boiler is coming out and this is going in. Existing system is in the floor heat which is copper not pex tubing. Three-quarter inch copper is running to the manifold and the return is also three quarter inch. I will be using Navien primary loop manifold.
Thanks all
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Old 10-31-16, 04:09 PM
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Welcome to the forums.

Looks like a pretty sophisticated tankless boiler. Not what I'd want to install as a first time installation project. It also looks a little large for the application. I see they can be throttled down but I don't know how much. You are going to need a critical bypass line to keep the hot water flowing thru the boiler. With one zone you'd only need one circulator pump.

I've left a link to the manual.
Navien Products/NHB-Series/Installation-Operation-Manual.pdf

Maybe one of the other pros can fill in more information for you.
Old 10-31-16, 05:03 PM
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Most manufacturer's installation instructions have recommended system arrangements.

This boiler is for 300 sq ft? That is unheard of.
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