A REALLY basic hydronic question

Scott_Mountain_View_CA

Yes, I am designing a single zone parallel reverse return system.

You also commented: "When the main is higher than the emitters it is recommended that you use two diverter tees, one as a diverter on the supply and one as a venturi on the return, thereby compounding the problems associated with pressure drop on the loop." My main will be overhead throughout, with emitters dropping down 4-5 feet. I'm getting mixed messages on the need for any type of diverter in my system, and if I understand correctly any pump I buy will be way more GPM than I need (1.88 total) and therefore diverters aren't necessary. Appreciate your comments on this.

Thank you

hot_rod

Here is a crude drawing of a reverse return around the roof top.

S&R refers to supply and return.

Scott_Mountain_View_CA

Swei: "At those flow rates, you should easily be able to direct pipe the CDN040, BTW."

Swei, not certain what that means.....are you saying that primary/secondary piping near boiler isn't necessary? Sorry, I'm just not down with all the lingo.

SWEI

That's exactly what I'm saying.

Look at the p. 38 of the I-S manual and you'll see that at 2.1 GPM it only adds 3.9 feet of head. With your piping and a standard residential ECM circ (Alpha, Stratos, etc.) I suspect that should work out just about perfectly. I would NOT do this with any of the larger CDN models, but on the 040 it works.

I would also taper down your S&R loop from 3/4" to 1/2" as you near the dead ends.

SWEI

The last job we did with one of these was similar in size to yours. We used a Taco VR1816, which worked out quite well. It has a lower minimum flow rate than the other currently available (in North America) ECM circs.

Scott_Mountain_View_CA

Thanks Swei.....I see what you're talking about on the pg 38 graph. Eliminating the primary/secondary scheme would appear to simplify the boiler room setup considerably. Would I then be looking at doing the install shown on pg 36?

On reducing the supply & return piping down from 3/4" to 1/2" "near the dead ends".......does this mean reducing the supply down to 3/4" at the next-to-last radiator, and reducing the return to 1/2" after the last radiator? Is the goal to increase the flow velocity, or to increase pressure upstream?

Mark Eatherton

"When the main is higher than the emitters it is recommended that you use two diverter tees, one as a diverter on the supply and one as a venturi on the return, thereby compounding the problems associated with pressure drop on the loop." My main will be overhead throughout, with emitters dropping down 4-5 feet. I'm getting mixed messages on the need for any type of diverter in my system, and if I understand correctly any pump I buy will be way more GPM than I need (1.88 total) and therefore diverters aren't necessary. "

In a 2 pipe parallel reverse return system, it doesn't matter whether the emitters are above or below the main, although air removal can be problematic when emitters are below due to airs prpensity to want to rise UP in water. You will have to force purge each radiator back to the mechanical room, and once most of the free air is removed, circulation shoudl carry the balance back to the air elimination system in teh mechnical room.

In regards to the question that SWEI raised regarding the use of 1/2" pipe, that is to maintain a decent sweep velocity to move the air back down to the mechanical package.

So, looking at it on the beginning, your supply would be 3/4" and the beginning of the return would be 1/2" because it is only carrying the flow of one radiator. Once the return picks up the second radiator, then it can jump to 3/4" because it is now carryng the flow of two radiators, Once you get to the second to the last radiator, the supply would drop to 1/2", again becasue it is only carrying the flow of one radiator, but the return stays 3/4" all the way back to the mechanical package.

Typical acceptible flow rates for pipes are 1.5 GPM for 1/2", 4 GPM for 3/4", 8 GPM for 1", etc. These flow rates are such that pipe errosion is not an immediate concern, good sweep velocity is maintained to move debris and air back to the seperation/elimination package and a pump with a reasonable head capacity is required. Flowing too slow will cause the air to hang up in the piping system, and flows too fast will cause hydraulic erosion corrosion, and possibly a noxious hissing noise.

These charts are readily avialable in the Library. I am also attaching a drawing showing the difference between reverse return and direct return. In ALL cases, if the flow through the supply main and the return main are flowing in the same direction, it is a reverse return system. If the flows are in opposite directions, then its a direct return system, which as can be seen from the drawings, is difficult to balance.

ME

Scott_Mountain_View_CA

Good information, Mark...thx.

Getting back to your original statement: "When the main is higher than the emitters it is recommended that you use two diverter tees, one as a diverter on the supply and one as a venturi on the return, thereby compounding the problems associated with pressure drop on the loop."

When you made that statement were you unaware that I was designing a parallel reverse return system? In other words, does your statement no longer apply where the design is reverse return?

As for the air rising from the emitters, I was planning to install auto air vents above each emitter, I guess just downstream from where the 1/2" emitter outflow ties into the return. Would this make sense?

hot_rod

don't bother with air vent above each emitter, they are not needed and will be an ongoing maintenance issue.

If you can create a high point in the piping on the rooftop a float type air vent there could be helpful.

But for sure a top quality air scrubber at the boiler. Use one with a magnet for extra protection.

Mark Eatherton

"When you made that statement were you unaware that I was designing a parallel reverse return system? In other words, does your statement no longer apply where the design is reverse return?"

I wasn't sure the decision had been made yet, and added that statement for the benefit of anyone considering the use of a Monoflo system, or anyone working on a Monoflo system.

In that situation (Monoflo) you are having to counter gravity (hot water wants to rise) and airs propensity (to rise up), hence the need for more flow inducement, hence Monoflo two tees.

In your case, not applicable due to parallel reverse return configuration. As HR said, don't bother with the air vents either. In a well built, properly purged, properly designed system, you should only need one point of air removal.

Don't forget to design a method of power purging into your system design. Purge radiators one at a time, starting with the first one to see boiler supply and you will be just fine. Any micro bubbles left in the system will get worked out in short order.

And you are welcome.

ME

Scott_Mountain_View_CA

More questions:

1) I initially choose Runtal because of their reputation and sleek design. Before I pull the trigger, I'm wondering if there are other brands I should be looking at that are similar in design to Runtal but more affordable. After all, I am selling my home in about 9 mos and am becoming more sensitive to ROI on the planned upgrades ahead of the sale. I've looked very briefly at Buderus, Myson, DiaNorm and a few others, but have not priced any of these. Any thoughts on this decision?

2) Copper vs pex. I've sweated miles of copper over the years and am comfortable using it in my application. On the other hand I've never used pex and don't know how it would compare on cost and ease of installation. My design isn't going to involve any snaky turns.

Thanks

Zman

I like Runtal. They are low profile and easy to install.
Buderus and and Dianorm are the same product. They are noticeably wider than Runtal. I have never seen a Myson.

I would not even consider copper. Pex is faster to install, more resistant to freeze damage and you won't burn the house down.

If you are going to direct pipe through the boiler, take a close look at the circ sizing to be sure you adequate minimum flow through the boiler. I differential bipass valve would also avoid that potential problem.

Scott_Mountain_View_CA

If I go with pex it looks like I'll need the oxygen barrier variety, correct? Do they make the oxy type in pex-al-pex? Do I even care? Are some brands of pex superior to others? Does Home Depot or Lowes carry the good quality stuff? How about fittings....is there one type that's superior? And tools needed to put it together? Phew.

Zman

Well now you going to get a fight started.
Yes, you need an oxygen barrier.
Yes, pex-al-pex has a barrier. It also will expand a lot less, decreasing the chance of noise. Fittings are more expensive as are tools.
For a one time job, I would buy any reputable pex-a product (hepex is good). Then get a crimp tool and compatible crimp fittings and have at it.
I don't know what the big boxes carry...

Rich_49

PexA tubing is top of the line if that matters . Uponor Rehau and Mr Pex would be your choices for that type . PexB , C are what you will find at the big boxes , most have crimp ring fitting design , not what I would put in my house or a customers for that matter . Be mindful that whatever tubing you use that you use the approved fitting system with it .

Scott_Mountain_View_CA

If not crimp ring, then what is the best style fitting, and how much are the tools needed to make the connections?

Scott_Mountain_View_CA

Did some digging around....looks like press fittings are top quality, but the press tool costs $200! And I'd need two if stepping down the piping from 3/4" to 1/2". Great for a pro who does this all the time, but not for me. I guess it's going to be old school copper

Tinman

Crimp fittings are actually allowed on REHAU pex and their Tech Bulletin for it is TB231.

Tinman

Here tis.

hot_rod

Viega FostaPex is my favorite tube. It has the aluminum barrier outside the tube, with a protective layer over it. So no laminations inside the wall of the actual fluid carrying tube.

You can buy coils or straight 20 foot length, which is nice for long straight runs. They use a stainless crimp collar, a bit more connection than a copper ring.

Crimp barbed fittings work fine, properly installed, they have been used on 3000 psi hydraulic hoses for many years.

Bob Bona_4

Completely agree with HR. Affordable tools, massive availability, been around a long time.

SWEI

You should be able to borrow or rent a tool for whatever fitting system you choose. I'm partial to F1960 (cold expansion, AKA Wirsbo/Uponor) for several reasons, but at those flow rates any of them will work well enough.

RobG

I know you said it earlier but if you use PEX, make sure there is NO UV exposure. It will kill the PEX in short order.

Scott_Mountain_View_CA

Thanks for the inputs on PEX. Any recommendations on internet pex suppliers? I stumbled on SupplyHouse.com. Any other recommended sites that cater to contractors?

Swei, none of my 3 local plumbing suppliers loan pex tools.

I've got some homework to do prior to making a decision on copper vs pex.

hot_rod

You may find the cost difference between copper and pex pays for the tool? Especially if you consider type L copper.

Sell the tool on Craigslist or E-bay when you are done. Or shop for a used tool there.

Wirsbo had a tool for crimping the MultiCor with stainless rings, and you would just changes the jaw insert, not the entire tool.

There are pex crimp ring tool that have multiple sizes in one tool also, as you will need 3/4 & 1/2"

Scott_Mountain_View_CA

Do I take that as an endorsement?

Bob Bona_4

I patronize my local suppliers for a multitude of reasons.

Scott_Mountain_View_CA

For those that use a ProPex ring expander, do you use the Milwaukee tool or one of the manual expander tools (which one?)

I'm taking another look at investing in more expensive tooling; looking ahead a couple of years, I'll have some whole-house plumbing hot/cold supply work, perhaps another hydronic job. The "buy it once, buy it right" principle may apply here.

SWEI

The Milwaukee M12 tool is worth every penny IMO. I jumped to F1960 the week it was available for purchase. I then proceeded to replace my Makita Lithium-ion tools one by one with Milwaukee (in part to avoid carrying multiple chargers and in part because Milwaukee's battery warranty is much less hassle.)

SWEI

Also -- the price/performance on the Uponor EP fittings rocks, and those oddball Logic bits come in really handy at times. My only gripe is that they don't make them in 3/8".

Scott_Mountain_View_CA

SWEI said:

The Milwaukee M12 tool is worth every penny IMO. I jumped to F1960 the week it was available for purchase. I then proceeded to replace my Makita Lithium-ion tools one by one with Milwaukee (in part to avoid carrying multiple chargers and in part because Milwaukee's battery warranty is much less hassle.)

Isn't the M12 powered by a 12V battery? Are you saying that you're replacing Makita tools with Milwaukee 12V? What tools are you using that are 12V? I abandoned 12V years ago, not enough power for my driver drill and impact driver.

Scott_Mountain_View_CA

Anyone use the manual expansion tools? Are they a viable option to the Milwaukee?

SWEI

Scott_Mountain_View_CA said:

SWEI said:

The Milwaukee M12 tool is worth every penny IMO. I jumped to F1960 the week it was available for purchase. I then proceeded to replace my Makita Lithium-ion tools one by one with Milwaukee (in part to avoid carrying multiple chargers and in part because Milwaukee's battery warranty is much less hassle.)

Isn't the M12 powered by a 12V battery? Are you saying that you're replacing Makita tools with Milwaukee 12V? What tools are you using that are 12V? I abandoned 12V years ago, not enough power for my driver drill and impact driver.

The only M12 tool I have so far is the ProPEX expander. The M18 version is twice the price, much heavier, longer, and I don't use PEX over 1" anyway. The M12 fits in tighter spaces than any hand tool and you can single-hand it overhead. Check out the the M12 Press tool.

The new FUEL Line has brushless DC motors, improved batteries and ships with a combo 12V/18V charger. It's pricey but insanely powerful. The M12 FUEL stuff has about as much punch as conventional 18V tools do. The M18 FUEL line includes real impact wrenches, Hole Hawgs, grinders -- stuff you never thought would go cordless. An M18 FUEL ProPEX expander that does 3" (maybe more) is coming this fall.

SWEI

The hand tools cost almost what the M12 tool does. My arms hurt just thinking about when we used them on a couple of jobs a few years back.

Scott_Mountain_View_CA

$399 gets the M12, 2 batteries + charger, 1/2, 3/4, 1" heads

Scott_Mountain_View_CA

I just noticed "In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation."

Does this apply to discussions on alternate pex connection methods and prices? If so, I guess this conversation stops here. I was going to compare pex to copper for my project and get some feedback.

Scott_Mountain_View_CA

So let me ask this: I'm seeing 2 different brands of PEX-A that are approved for the ProPEX expander system: Mr.PEX and Uponor. Disregarding price, is there a quality difference between the 2 in a hydronic radiator application? Is Mr.PEX approved for the EB fittings?

Scott_Mountain_View_CA

"You can speak in generic terms as in comparisons between different types of systems. Specific pricing of products and services isn't permitted."

So be it. I guess the rational there is that price discussions might upset some of the site sponsors. No problem, I can get the answers I need by limiting it to a qualitative discussion.

Zman

You can certainly discuss pricing of items that are in the public domain. The idea is that no one wants or benefits from either bidding wars on jobs or revealing wholesale pricing.
You can certainly do small jobs with easy access with a hand expander tool. As SWEI pointed out they cost about the same as the cordless option.
I have one of these http://www.supplyhouse.com/Wirsbo-Uponor-Q6295075-ProPEX-Hand-Expander-Tool-with-1-23-41-heads-2412000-p with very little use that I would give you a great deal on.
Send me a message if you are interested.
Carl

SWEI

Scott_Mountain_View_CA said:

$399 gets the M12, 2 batteries + charger, 1/2, 3/4, 1" heads

That's the package. You can probably do a little better than that (like maybe $20-30) with a bit of work, but they can't advertise below that price.