black pipe vs copper for condensing combi piping

joca

is it ok to use black pipe and fittings for the near boiler piping on mod/con boilers? I know its a closed system, but there is always some rust and sediment,right? The plate heat exchanger seems easily clogged ,as well as TRV's, and mixing valves throughout the system . Should I be concerned?

SWEI

As long as the system was properly cleaned, the pH of the water is high enough, and there's no appreciable amount of make-up water being consumed, you should not have any problems.

jonny88

Dirtmag would be recommended though

wcs5050

Fernox TF1 Magnetized. Pretty neat. Can install on a bypass.

joca

thanks SWEI, it will be cleaned and maintained,and we have great water here, so i should be ok.
Jonny88, is a dirtmag necessary if i go with copper? The only Fe would be from the panel radiators and the circulators. Is a wye strainer enough protection then? Just want to do the right job-overkill is unfortunately not in the budget.

Rich_49

Dirt mag or TF1 filter are not that expensive and cleaning and adding inhibitor is a snap with either . Cannot say that for the wye strainer , when comparing it is a terrible way to remove nasties . Cleanout of the other 2 is also very clean and easy .

jonny88

I will say I have never used blk pipe on a mod/con.any of the other posters.@Rich what is the cleaner/inhibitor HTP showed me.I loaned out my literature.Fernox?

Rich_49

It is Fernox .

unclejohn

I use a dirt mag at the return of the boiler and I put a air vent on top not the plug that comes with it. It cost about 6 cases of American beer.

joca

so ,a dirtmag is a good idea in any system is what i'm getting?
perhaps copper is best practice, i can't see any cons with copper-maybe some cons with steel. My preference is copper, but i have steel speed headers (that i 'm thinking of not using now) . I'm also going to switch out a Cast iron air scoop for a spirovent type -i didn't like the 18" lead pipe requirement anyway

Bob Bona_4

It must be regional. Dirtmags in residential aren't seen or even stocked in my part of CT. IMO, don't over think it. There's going to be some ferrous somewhere in the system. The water will become "dead" in short time.

joca

is there a dirtmag that would double as an effective air eliminator?
will have to rework the budget- can't tap into the beer budget!

HDE

I never understood why anyone would want to create unneeded turbulence and flow friction using threaded nipples and fittings on a modern system??
Its not a quicker install and then there are those potential leaks then and later down the road.
Also to me a rusting black nipple does not look nice

joca

thanks bob bona, is it that obvious , i tend to over think EVERYTHING.
Just trying to get best practice or standard practice for combi units. btw, they are small systems ,one single zone and one two zone

Rich_49

@joca . Look at the Caleffi Sep4 . Hydraulic separator , air eliminator , magnetic dirt separator all in one nice little package / component .

http://www.caleffi.com/usa/en-us/catalogue/sep4tm-4-1-hydraulic-separators-549506a

joca

thanks rich , it is nice ,a little pricey,but it does combine components and should save some space . i'll have to read up on it some more to see if it works for my system, and if its worth the redesign. This is how this discussion started- i was compelled to question the original design i was given...

Bob Bona_4

If it's a combi, usually the mfr sells flush manifolds for the domestic and the heating sides, I know navien does. I get them for every job.

SWEI

Magnets not needed if there is no iron in the system. Note that even panel rads will shed a fair bit of magnetite IME.

joca

So is the Fe in the steel panel rads enough to warrant the use of a dirt mag type component?

joca

No premade manifolds for this unit, doesn't have an integral primary pump

SWEI

joca said:

So is the Fe in the steel panel rads enough to warrant the use of a dirt mag type component?

In my experience, yes.

jonny88

Dirtmag with air eliminator.Not what I ordered as I have a spirovent.Really wanted Sep4 but unavailable .

SWEI

HDE said:

I never understood why anyone would want to create unneeded turbulence and flow friction using threaded nipples and fittings on a modern system??
Its not a quicker install and then there are those potential leaks then and later down the road.

We frequently find a bit of screwed pipe to be the best option for a portion of the near-boiler piping. If the entire rest of the system is nonferrous (don't forget unlined expansion tanks, BTW) we use Class 150 304 SS. It's less expensive than brass, the fittings are far less restrictive than either brass or iron, and it looks fantastic.

joca

I see you have both spirovent and discal. If using only the discal , where would you pipe in expansion tank and auto fill .

Tinman

Always in relation to the pump - the inlet side of the pump.

joca

I was asking because, isn't there a reason why the expansion tank and air eliminator are combined at the point of no pressure change. Not sure if I'm remembering correctly . I"ll reread "Pumping away" later...

hot_rod

The DiscalDirtMag that Jonny 88 shows is a great way to get air, dirt and ant magnetic particles which may cause issues with ECM circulator if you ever add one.

The expansion tank does not need to be at the air eliminator,but connected at the suction if the circ pump.

With some mod con. Boilers the pump is on the boiler return, so the tank connection should've there.
Air elimination should be at the hottest point in the system,boiler outlet

joca

Thanks, it's coming back to me , so,air elimination at high temp and low pressure,and expansion at low pressure( off an inline tee in the primary loop would be ok?)

Tinman

I think Hot Rod would agree? If a mod-con is piped P/S and the majority of them are, I like to put the air separator on the supply side of the system loop just ahead of the system circ., not the boiler loop.

joca

when you say "system loop," is that the primary loop,with the boiler loop and the zones being secondary loops or are you considering the boiler loop(with internal circulator) the primary?

Tinman

Most terminology dictates that the primary loop is the boiler loop and that the secondary loop is the system loop.

Tinman

Not to confuse the issue but some, myself included, prefer to think of the secondary loop as the one being fed by the closely spaced tees which is often the boiler loop in a mod-con application.

joca

that was my confusion, i consider the secondary loops the ones being fed by the closely spaced tee also. i was planning to have the primary loop pass thru the boiler-its a single zone system so i'm trying to understand how to streamline things a bit. i know i'm getting off topic, but it seems odd to do a P/S with 2 circulators to feed a single zone?

SWEI

Secondary loops are off the tees, yes. Many of the boilers and solar thermal systems we work on are by that definition secondary. Bristol Stickney showed us how to build a primary loop there which does not need a circulator.

Tinman

That's why I always refer to them as boiler loop and secondary loop to my customers. It's just so much easier.

joca

thanks, makes sense. I'll have to research stickney's piping (it's beyond my needs right now, but you got me curious)

hot_rod

SWEI said:

Secondary loops are off the tees, yes. Many of the boilers and solar thermal systems we work on are by that definition secondary. Bristol Stickney showed us how to build a primary loop there which does not need a circulator.

Just be aware with Bristols P/S, the one with check valves between the take offs, you keep putting the various pumps in and out of series as they start and stop.

It is a clever approach, just know the flow conditions you are modifying.

In Bristols August column in PHC News he shows a P/S with a primary pump. I have seen him draw it both ways.