Can someone look over the piping on my Navien Combi?

[Thekid1]

So I installed this myself in my home. A plumber friend of mine pointed out a few things and I would like to know what you guys think before I change things.

Here are the things he pointed out:

1) The stainless bushings that come off the naviclean's female adapters will galvanic corode because its touching brass.
(My thoughts)
I thought in general going with the stainless steel bushings would be least likely to corrode? Also, the Naviclean came with those brass female adapters and they are compression. It looks to me like they are touching stainless on the naviclean itself. Or is that galvanized?

2) The stainless steel bushings that come off the near boiler loop are touching brass and will galvanic corode.
(My thoughts)
Same thing. I thought stainless would be ok?

3) Stainless hose needs to be removed in general and it will also galvanic corode.
(My thoughts)
I agree about removal, but corroding?

4) Add additional shut off valve separately for boiler feed.
(My thoughts)
Agreed

5) Said he would remove the backflow because if it goes bad it will cause problems and also because the navien has a built in backflow.
(My thoughts)
Can someone confirm this?

6) Said he wouldnt do pvc for exhaust as heating up the glue joints over time is not good.
(My thoughts)
Not sure. The manual says this is ok.

So i appreciate if you guys can help. I want to sleep at night knowing this is ok or not before I add water.

Should I simply swap the stainless steel bushings out for brass?

Unfortunately the photos are too large to post here, so here is a link to the photos on dropbox:

Dropbox

www.dropbox.com

 

[GReynolds929]

Your "plumber" friend is an idiot. Stainless steel, brass, and copper can be directly connected with no issues. PVC is fine for venting as long as it is solid core schedule 40. Page 20 of the manual answers the backflow preventer issue.

 

[Sponsor]

 

[Reach4]

The surprising thing to worry about might be stainless to stainless, probably more for tapered threads. https://terrylove.com/forums/index.php?search/8634130/&q=galling+stainless&o=relevance

Also, if you use a flex line, corrugated is better than braided stainless over rubber/plastic. I expect there are some that are OK for water heaters, but some produce little oily black stuff. https://terrylove.com/forums/index.php?search/8634151/&q=braided+oily+black&o=relevance

 

[Thekid1]

Your "plumber" friend is an idiot. Stainless steel, brass, and copper can be directly connected with no issues. PVC is fine for venting as long as it is solid core schedule 40. Page 20 of the manual answers the backflow preventer issue.

Lol. Thank you, I'm glad to hear it will be ok the way it is.

The surprising thing to worry about might be stainless to stainless, probably more for tapered threads. https://terrylove.com/forums/index.php?search/8634130/&q=galling+stainless&o=relevance

Also, if you use a flex line, corrugated is better than braided stainless over rubber/plastic. I expect there are some that are OK for water heaters, but some produce little oily black stuff. https://terrylove.com/forums/index.php?search/8634151/&q=braided+oily+black&o=relevance

The only stainless to stainless I believe I did was the stainless bushings coming out of the primary loop manifold on each end. See the manufacturer's stainless female adapter? I have a stainless bushing coming out of each one.

1) In the grand scheme of things, will I be ok the way it is? I do plan to add the boiler commisioning protectant after fill up.

2) If I did change the bushings out, I guess I should have went with "brass" bushings instead on both the Naviclean and the primary loop manifold?

 

[Fitter30]

The only problem with stainless is a leak. Trick with stainless is nickel teflon tape with a good dope. When tightening when it starts to turn tight stop for 15 seconds try again do this till it gets tight. Stainless gets hot threads begin to gall stopping lets the joint to cool.