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Paul S_3 · August 2013

Hey everyone I rarely do any radiant jobs but lately I've been getting more and more....I've been reading Dans radiant heat book....My question is and I posted this on the main wallalready....the contractor ran all the pex and buried it in concrete....he ran 4 loops all around 225 feet each....I'm using a Navien condensing boiler piped primary secondary....it has one secondary loop the radiant manifolds.....I'm using a mixing valve add you can see on the pic below ( job is not finished) after the mix port I will be putting the circulator.....I piped the manifold in reverse return piping....the question is what water temp should I be running at?(for the manifold) should I be using flow checks? On the secondary loop?....and also any criticism welcome please.....thank you Paul S.....

Zman · August 2013

Mixing?

Maybe I am looking at the wrong install manual. Does your boiler have an outdoor sensor and reset capabilities? If so you don't need a mixing valve. It does not look like you need flow checks. Make sure you give yourself a way to purge the radiant loops and the boiler.

Carl

Paul S_3 · August 2013

outdoor sensor

I believe we do have one....so I would just use that feature and set up curve accordingly.....what should the max temp be? And this boiler have a internal reducing valve? Thanks Paul S

Zman · August 2013

Condensing

Paul,You have a condensing boiler with a very high efficiency rating. You only get that efficiency if you are returning cold water. Check this out

www.pugetsoundashrae.org/PDF_files/AshraeCondensingtechnology.ppt

The boiler will only fire to the temp calculated by the outdoor reset.

The warmer the day is the lower the temp you will have to run, the more efficient the boiler. No mixing involved.

As for the temp, it really depends on the design. I realize you don't have all the info.

Your high will likely be around 120.

Carl

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