# Recirc Line On PEX Manifold System



## Mr Plumber (Oct 20, 2011)

I have a home owner who wants to install a PEX manifold system with a hot water recirculating line and pump . He wants the mainifold with all of the individual lines of 1/2 inch. 

This is a huge ranch of 4500 square feet.
I was curious if anyone has any experience with a recirc line on a PEX mainfold system. Does it work like it should or is it only gonna recirc the hot water to front of the manifold. 

Thanks


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## OldSchool (Jan 30, 2010)

Mr Plumber said:


> I have a home owner who wants to install a PEX manifold system with a hot water recirculating line and pump . He wants the mainifold with all of the individual lines of 1/2 inch.
> 
> This is a huge ranch of 4500 square feet.
> I was curious if anyone has any experience with a recirc line on a PEX mainfold system. Does it work like it should or is it only gonna recirc the hot water to front of the manifold.
> ...


A word of caution... 

If the water has been chlorinated .... the pex over time will wear out on a hot water return line...

Contact the pex manufacture to verify if the pex is approved on a recirc line 

I know Upnor/Wirsbo is not recommended for hot water return lines with chlorinated water


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## Smitty (Jan 13, 2012)

*Return line*

Wouldn't a return line only benifits the fixture that it was returning from? Thus leaving all other fixtures from the manifold with no benifits of even installing said return? Unless of coarse all intentions are to only benifit one fixture. ( scratching head)


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## pdxplumber (Nov 21, 2009)

To bad nobody told my old boss that you couldn't use pex for recirc lines. I must have installed hundreds of feet in the attic of a large nursing home about 10 years ago.


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## user8031 (Dec 14, 2011)

Mr Plumber said:


> I have a home owner who wants to install a PEX manifold system with a hot water recirculating line and pump .


How deep are you going to allow the HO trying to get involved with the job?


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## MarkToo (Dec 17, 2011)

I know there are certain TV personalities (at least up here) that have endorsed and championed manifold - or home run systems but, I don't much care for them. 

While there are certain potential advantages of control within the mechanical area, I feel they are a waste of material for one and secondly, it can take far too long for hot water to reach a given fixture - especially in a sprawling house.

I feel a better way to go is to plumb a single oversized (3/4 or larger), line with the required 1/2 or 3/4 take offs (kept short) around the entire house with a return line take off near the last fixture. This keeps the water moving in the lines, provides almost instant hot water to any give fixture and minimizes materials while supplying great volume. A simple Grundfos comfort pump on the return and you're good to go.

My .02 CAD

Mark


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## Widdershins (Feb 5, 2011)

Mr Plumber said:


> I have a home owner who wants to install a PEX manifold system with a hot water recirculating line and pump . He wants the mainifold with all of the individual lines of 1/2 inch.
> 
> This is a huge ranch of 4500 square feet.
> I was curious if anyone has any experience with a recirc line on a PEX mainfold system. Does it work like it should or is it only gonna recirc the hot water to front of the manifold.
> ...


 I centrally locate a flow-through manifold as close to the destination as possible, usually within 20' and then use the outlet of the manifold as the return.

Insulating the main trunk and the return are a must.


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## highpoint (Mar 3, 2009)

Widdershins said:


> Insulating the main trunk and the return are a must.


I disagree. It's better than bad,sure , but not a must.
I would recommend the HO to do this if u want but there's no way I'd put it in my quote. You would never compete. 
My .01989


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## Widdershins (Feb 5, 2011)

highpoint said:


> I disagree. It's better than bad,sure , but not a must.
> I would recommend the HO to do this if u want but there's no way I'd put it in my quote. You would never compete.
> My .01989


 It's a requirement under my local building code's Energy requirements.

As for being competitive -- Insulation is inexpensive, as is the labor to install it.


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## Mr Plumber (Oct 20, 2011)

wyefortyfive said:


> How deep are you going to allow the HO trying to get involved with the job?


Exactly once the guy started telling me how i should do the job I knew i wasn't and am not going to do it. I was just curious to his idea of the manifold and the recirc line. It doesn't seem like it would work properly to me and Im not going to be liable when it does not work properly :no:.


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## Mr Plumber (Oct 20, 2011)

Smitty said:


> Wouldn't a return line only benifits the fixture that it was returning from? Thus leaving all other fixtures from the manifold with no benifits of even installing said return? Unless of coarse all intentions are to only benifit one fixture. ( scratching head)


kind of thinking that myself


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## ZL700 (Dec 8, 2009)

OldSchool said:


> A word of caution...
> 
> If the water has been chlorinated .... the pex over time will wear out on a hot water return line...
> 
> ...


That's a joke right?

Nothing in the design manual and warranty on that. By theory the supply line would see the same temperature chlorinated water flow, what makes the return line susceptible to damage?


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## Redwood (Sep 8, 2008)

I would consider a Trunk & Branch System with Remote Manifolds and recirculation from the manifolds to be the best system in this application.

Check this link below...
http://www.toolbase.org/pdf/designguides/pex_designguide.pdf
Page 30 Figure 6.3


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## OldSchool (Jan 30, 2010)

ZL700 said:


> That's a joke right?
> 
> Nothing in the design manual and warranty on that. By theory the supply line would see the same temperature chlorinated water flow, what makes the return line susceptible to damage?


No joke ZL700

The last training coarse I took with Upnor/Wirsbo... they said right in the coarse that they are experiencing problems with the pex on the return line system..... they will not warrantiy their product on return pipe...

I must assume that all pex must have the same problem... as they are made of the same material...

I would check with the manufacture as there has been no published articles about this that I am aware of.


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