Should I worry about the pressure drop?

Unknown

the rings go on before the fitting is attached, so if it wasn't on when you took that picture, it's not on there now. it's just a pex ring that goes around the pipe and expands/contracts with it, not a crimp fitting.

Constantin

Another building dillema...

I recently placed an order for a GFXTechnology HX that I hope to install in the basement. I have found the team there to be very responsive, courteous, and great to work with.

Given that our hot water main is 1" in diameter, I figured I'd go for a shortened version of their G4-80-4 model, i.e. the one with a 4" DWV copper pipe and four coils of ½" copper pipe, brazed in parallel for a very low pressure drop meant for 1" mains.

Trouble is, apparently the fabricator built me a S4 model instead, where there are only two coils of ½" pipe in parallel... Up to 4 showers could be running on this thing at the same time, so the maximum expected flow is around 9GPM. Realistically, 2 simultaneous showers (i.e. 4.5GPM) should probably cover most days.

Here is my conundrum: Should I simply go for the regular S4 model and ignore the pressure drop it can develop at full flow or do I ask for a full-blown G4-72-4? Here is some of the data I gleaned from the site:

1. S4-60:
   • In/Out: 3/4" connection
   • EFF: 63%
   • P-drop: psi @ 2.25GPM</li>
2. G4-80-4:
   • In/Out: 1" connection
   • EFF: 63% @ 2.25 GPM, 52% @ 4.5GPM, 38% @9GPM
   • P-drop: 0.5 @2.25GPM, 1.2 @ 4.5GPM, 3.3 @ 9GPM

From what I can tell, the pressure drop across a S-model will be at least 4x higher than that across the 4-coil model... Furthermore, the "bottleneck-effect" of constricted piping seems to get worse exponentially as the flow increases... so, would a 10psi difference between the hot and the cold water pressure be noticable with modern ceramic-plate sink valves if the house pressure (cold) is about 50psi?

What would you do in my shoes?

hr

Your first sentence should answer your question

Sounds, to me, like the company will (should) gladly supply the correct unit. Certainly the other smaller unit is sellable. Not a special order.

They could always send me the smaller one as a demo unit

hot rod

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Bob Morrison_3

what's the pressure drop of your shower valves?

I would be concerned about the pressure drop. I would check the minimum entering pressure for the shower mixing valve (or whatever control techonolgy you're using) to be sure that you have at least that value. I would expect that mixing valves would need at least 30 psig for proper operation.

Bob

Constantin

Careful, you may get what you ask for...

Thanks for the replies, guys. I went ahead with a G4-72-4 simply because of the pressure drop.

They may or may not contact you re: the 72" S4... hee hee hee... ;-P

jerry scharf_3

my experience

with the G4-60 is that there is some lowering in flow. I have an H arrangement of ball valves and can quickly change the flow from through to bypass while the demand is running. The case where I really see it is when I've done something that has caused me to drain the indirect tank and I am refilling 100 gallons with nothing but 1" and 3/4" pipe in the way.

Since I am running my indirect at 140+, even at fairly high demand, the actual flow through the hot water tank is not that high. So I would say it's measurable but not really noticable in my place.

I am going to have a fun time measuring what I seem to get out of the unit, especially ramp to steady state.

jerry

Constantin

It

Constantin

It's here!

It arrived a week ago, but I didn't have the time to post the picture...

So here is a G4-72-4, i.e. a 4" drain pipe with 4x 1/2" Copper loops coiled about it in paralell. It is a thing of beauty and right at the hairy edge as far as length is concerned. It appears that both my contractor and I should have opened the wall before ordering the GFX!

Anyway, we're running armaflexed AquaPEX to and from it, more pics to follow as the thing is integrated into the rest of the system. The hard part is before us, i.e. scraping out all that lovely Corbond, replacing two 90° bends with street sweeps, and getting a tight fit with hubless connectors.

Many thanks to kind and friendly folk at GFXTechnology. They are all a joy to work with and I really appreciate the quick response time to manufacture a unique product. I highly recommend doing business with them.

Constantin

Now installed...

As you can see, the process of getting the GFX into place was a bit more complicated than one would hope for. That was entirely my fault, however, as I should have had the thing put in when we were installing the drain pipe. The picture below shows the GFX in the wall cavity, though not yet attached to the water system. Most of the debris is Corbond...

Needless to say, I am very excited by this technology and look forward to seeing just how much energy it's going to save me. Some telemetry will be attached to the H-manifold upstream of the cold water inlet to the indirect to see just how well it works. My biggest fear is that somehow the two PEX pipes get mixed up and the GFX does not act as a counterflow HX, as that would cut down on its efficiency.

The other pictures show how the Vitola and the combustion air-intake do double duty as a stand for an uncoiler of the 1" PEX (the plumbers love it) as well as the connections they made to attach it to the GFX. In order to save space, they ran 1" copper pipe around the GFX at the bottom and to the top to make the connections as shown. All the PEX is insulated now.

After pressure-testing, etc. the whole assembly has since vanished into the wall cavity, leaving no clue that it is hiding in there.

I had the plumbers re-insulate the space around the GFX and as the exterior wall in that area of the house is covered entirely by the deck above, I will have the contractors affix XPS to the outside and paint it black. That way, I shouldn't have to worry about frost doing funny things to the GFX during very cold conditions.

Weezbo

Constantin.....

Even though the pex can hold onto the wirsbo fitting by itself ...i think the O's are a good thing. maybe it would be better to put the O's on the 1" . during tests sometimes i will put a plug with no ring however ,it might prove dissapointing someday, were the tubing and fitting begin to leak for want of a 10 cent fitting....

Constantin

Just goes to show...

... that I should have posted these pictures before the wall cavity was closed again. At the present time, there is no way to get at that fitting. Is the lack of a clamp an issue as far as Wirsbo is concerned?

Dan Foley

Pex Ring

I would not trust the fitting without the pex ring specified in Wirsbo's installation manual. A little drywall work and patching vs. a 1" line letting loose under house pressure? A no brainer in my book. -DF

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Constantin

Well, in that case, I'll inquire.

I took these pictures before the plumbers were altogether done, so it's quite possible that they put the clamping rings on the fittings subsequently.

Given that they had been trained by Wirsbo, I'd like to think that they wouldn't make an elemental mistake like not following the OEMs best installation practices. However, the cost of figuring it out now is minor compared to the potential mess, so thanks all around for making me aware of the potential issue!

Joe Grosso

Hmmm....

So I guess what you are saying is I should contact Wirsbo and determine what the best option is to secure the present installation. As I see it I have three possible scenarios:

1) Leave as is if Wirsbo tells me it's OK at 60 psi of pressure.

2) Put a stainless ring clamp on it with a worm gear (can be retrofit, use them on the boat all the time).

3) Cut the PEX off, start over, and breathe down the neck of the installer while he installs the new connection.

Either way, looks like I have to contact the plumber, GC, and have a little talk with Wirsbo. Once again guys, many thanks for the input and the wise council. I owe you all a beer at the next get together, the least I can do when you avert a potential flooding disaster for me. Thanks again!