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Radiant Heat In-slab Help

 
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Old 09-05-2020, 04:59 PM   #1
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Radiant Heat In-slab Help


Hello,

A residentual unit has radiant heat installed in-slab that services two rooms. I want to consider the possibilities of converting the second room into a dedicated master bathroom. Currently one radiant heat zone services both rooms and the room I want to convert is at the end of the radiant pipe loop. My problems is that I am looking to construct drain lines for the new bathroom fixtures (shower, tub, sink, and toilet).

Is it possible to break into the slab near the door threshold, cut the radiant heat line in two places ("supply and return"), chip away the concrete to expose pipe lines, cap the the two pipe ends during construction, break up slab in desired bathroom, build out bathroom and reconnect radiant pipe lines to use in the newly poured slab of said bathroom?

Sounds problematic, but has anyone actually done something like this before? Other possible solutions? Thanks.

EDIT: The more I think about how PEX is coupled, it doesn't seem to be appropriate for in-slab use. Still hoping for a solution...

Last edited by sbmmm; 09-05-2020 at 06:02 PM.
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Old 09-06-2020, 09:05 AM   #2
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Re: Radiant Heat In-slab Help


It would require covering the new connections with concrete? It seems like a disaster waiting to happen.

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Old 09-06-2020, 11:45 AM   #3
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Re: Radiant Heat In-slab Help


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It would require covering the new connections with concrete? It seems like a disaster waiting to happen.
Without having done this specific repair before, that was my sense too.
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Old 09-06-2020, 06:06 PM   #4
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Re: Radiant Heat In-slab Help


Maybe a "Vault" to cover the added plumbing that would be left FREE of concrete? And serviceable without a demo saw.....
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Old 09-06-2020, 06:21 PM   #5
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Re: Radiant Heat In-slab Help


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Maybe a "Vault" to cover the added plumbing that would be left FREE of concrete? And serviceable without a demo saw.....
I was involved with a job that was done that way, the connections were covered but accessible. it was in the wall behind the door close to the floor. Luckily the guy who did it was the original installer.

He accessed the original line past where the access point was going to be and peeled the pipes back to the access point to limit connections
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Old 09-06-2020, 09:47 PM   #6
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Re: Radiant Heat In-slab Help


I was thinking the same thing. A vault box to access the joints in case a leak occurs. Whatever floor covering you put in there would have to be removable for access. Kinda eliminates tile. Or it could be a destructive access, where you have to destroy the floor to get at the vaults.
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Old 09-07-2020, 08:00 AM   #7
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Re: Radiant Heat In-slab Help


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Maybe a "Vault" to cover the added plumbing that would be left FREE of concrete? And serviceable without a demo saw.....
Is your "vault" idea like a (metal) box in the floor with a removable cover for future access? And the spliced connections would be accessible in that box?
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Old 09-07-2020, 08:13 AM   #8
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Re: Radiant Heat In-slab Help


Quote:
Originally Posted by rrk View Post
I was involved with a job that was done that way, the connections were covered but accessible. it was in the wall behind the door close to the floor. Luckily the guy who did it was the original installer.

He accessed the original line past where the access point was going to be and peeled the pipes back to the access point to limit connections
What I need to verify is the exact path/position of the pipe. I don't own one, but I am going to rent a handheld thermal image camera from Homedepot and map it out.

Has anyone carefully chipped away at concrete to expose in-slab pex pipe? As I type this, I'm just wondering if the integrity of the post-demo pex "stubs" would be reliable even if I peeled enough back to put in a vault box.

EDIT: One additional question - Did that installer have to demo slab work and chip away concrete to expose and peel back the pipe?

Last edited by sbmmm; 09-07-2020 at 08:33 AM.
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Old 09-07-2020, 09:11 AM   #9
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Re: Radiant Heat In-slab Help


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EDIT: One additional question - Did that installer have to demo slab work and chip away concrete to expose and peel back the pipe?
yes he did

he had an idea where pipe was but sprayed a little water on slab to get exact location
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Old 09-07-2020, 10:35 AM   #10
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Re: Radiant Heat In-slab Help


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yes he did

he had an idea where pipe was but sprayed a little water on slab to get exact location
Interesting, thank you.

I'm guessing by spraying water on the slab pre-demo that the water reacted enough to heat coming from the pipes? Was that the idea or did the water indicate where the pipes were for some other reason?

EDIT: Or did the water dry faster above the heated pipes and leave "pipelines", kind of like a negative image on the wet slab?

Last edited by sbmmm; 09-07-2020 at 10:41 AM.
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Old 09-07-2020, 12:06 PM   #11
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Re: Radiant Heat In-slab Help


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Interesting, thank you.

I'm guessing by spraying water on the slab pre-demo that the water reacted enough to heat coming from the pipes? Was that the idea or did the water indicate where the pipes were for some other reason?

EDIT: Or did the water dry faster above the heated pipes and leave "pipelines", kind of like a negative image on the wet slab?
yes
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Old 09-07-2020, 12:23 PM   #12
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Re: Radiant Heat In-slab Help


Yes done modifications to in floor radiant heat. Even have done copper to Pex loop back to copper with concrete over. One is over 15 years and no leaks.

You will have to make a connections in the floor and cover with concrete then run the new pex to an access vault-area for the zone valve. Best to do that in a wall, imo. And make dam sure your connections are made properly and don't cheap out on materials and equipment.

Or dig a hole under the slab and well do it all from underneath
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Old 09-08-2020, 07:27 PM   #13
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Re: Radiant Heat In-slab Help


Why wouldn't you just install the valving UNDER a cabinet?????
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Old 09-09-2020, 07:45 PM   #14
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Re: Radiant Heat In-slab Help


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Why wouldn't you just install the valving UNDER a cabinet?????
Super good idea!

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