Concrete floor / radiant heat experiences?

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Gris
Posts: 5
Joined: Sat Aug 22, 2020 10:50 pm

Concrete floor / radiant heat experiences?

Post by Gris »

Hello everyone,

I'm currently under contract to buy a much-altered early 1950's Midwestern home by a FLW apprentice, and have a ton of newbie questions. The home is in the inspection process, so I'm being circumspect. There are tons of remodel/remuddles including an addition, a c.2000 garage, a botched fireplace facelift, a new, 3/12 pitched roof, and cheap floating flooring.

However--The original radiant floor heat is in the home and does seem to work. Are there any special things I should know radiant heating and does anyone here have experience uncovering and restoring the concrete floors? I do know the concrete is reddish, from an early article about the house.

Thank you in advance for your wisdom and experience.

outside in
Posts: 1262
Joined: Sat Jul 29, 2006 9:02 pm
Location: chicago

Re: Concrete floor / radiant heat experiences?

Post by outside in »

radiant heating systems are wonderful when they work, disasters when they don't. The heating systems that many owners love to hate. Ultimately they are destined to fail - oxidation in piping, be it steel, wrought iron or copper will eventually cause leaks and require repair and/or replacement. There are some measures you can take to slow the process, however, such as chemicals that remove oxygen from the water in the system, etc. I believe the topic has been discussed many times on this forum if you search.

Roderick Grant
Posts: 10340
Joined: Wed Mar 29, 2006 7:48 am

Re: Concrete floor / radiant heat experiences?

Post by Roderick Grant »

Gris, This is the sort of problem I am sure the Conservancy has dealt with many times. Give them a call, and perhaps they can refer you to an expert.

Modmom1
Posts: 132
Joined: Sun Dec 03, 2017 1:09 pm

Re: Concrete floor / radiant heat experiences?

Post by Modmom1 »

We purchased a "gravity heat" apprentice house that was designed in 1940 and had been abandoned for many years that had a failed heating system. Our restoration included removal of the concrete floor, leaving a six inch piece around the periphery to support structure as well as the flooring over the central core basement. We discovered the original cast iron pipes (IAN an architect so excuse me if I use the wrong term, my architect husband is out working on another structure on the property) had deteriorated so it was good that we went to this extreme. This was BY FAR our greatest expense and source for headaches. When we started in '14 no residential plumbers wanted to take on the large job and we finally went to a commercial plumbers who started, then won a big contract leaving us in limbo for several months.

Perhaps if your system works or you some areas that have failed, you can modify this approach. On this site DRN, the owner of the FLW Sweeton House was able to repair a certain area that failed instead of the whole system.

That said despite the headaches and great expense (several hundred thousand includes 7 zones hydronic system and new copper plumbing in our 2,200 sq ft house in Ohio) we love the heat. (*plus removal of old floor and repour new with grid pattern was about $32k)

Good luck!

Gris
Posts: 5
Joined: Sat Aug 22, 2020 10:50 pm

Re: Concrete floor / radiant heat experiences?

Post by Gris »

outside in wrote:
Sun Aug 23, 2020 7:53 am
radiant heating systems are wonderful when they work, disasters when they don't. The heating systems that many owners love to hate. Ultimately they are destined to fail - oxidation in piping, be it steel, wrought iron or copper will eventually cause leaks and require repair and/or replacement. There are some measures you can take to slow the process, however, such as chemicals that remove oxygen from the water in the system, etc. I believe the topic has been discussed many times on this forum if you search.
Thank you very much for your reply; I've slogged through "radiant heat", "gravity heat", and associated terms as a search but I will keep looking for the de-oxiginating chemicals that might extend the life of the system. I appreciate your help.

Best,

Gris
Posts: 5
Joined: Sat Aug 22, 2020 10:50 pm

Re: Concrete floor / radiant heat experiences?

Post by Gris »

Roderick Grant wrote:
Sun Aug 23, 2020 1:23 pm
Gris, This is the sort of problem I am sure the Conservancy has dealt with many times. Give them a call, and perhaps they can refer you to an expert.
A wonderful (and sensible) idea; thank you! I'll do that.

Best,

DRN
Posts: 3994
Joined: Mon Jul 10, 2006 10:02 am
Location: Cherry Hill, NJ

Re: Concrete floor / radiant heat experiences?

Post by DRN »

Welcome Gris!
As outside in noted, nothing lasts forever, but there are some ways to care for the system to prolong its service life and to make spot repairs as needed.
This is a link to a Wright Chat thread in which we chewed on the subject a bit, and I discussed one of my two repairs to my system:
http://wrightchat.savewright.org/viewto ... es+radiant

Also, here are some bullet point-ish observations from one of my posts:
Radiant pipes...from the homeowners I have met and discussed the issue with and the two repairs we have made, I can confidently assert the following:
1. Steel/iron pipes tend to fail as a result of wetting from their outsides (ground water, roof drainage seeping under or through slabs/shallow foundations, leaking fountains or pools)
2. steel/iron pipe systems should NEVER be drained and left empty as corrosion of the inner pipe surface will start immediately...fully charged with old funky black water at all times is GOOD.
3. steam heating in steel/iron pipes as at Jacobs I originally sets up interior corrosion when the system is powered down each summer.
4. Copper pipes are not fail proof either...a Louis Kahn house owner in Cherry Hill and about a thousand Levitt homeowners will attest that copper pipes and the chemical reaction with concrete and its admixtures can cause systemic failure of in slab copper piping.
5. Nothing lasts forever...all systems fail eventually. We just maintain it as best we can, fix it as possible and practical, knock on wood a lot, and enjoy it immensely while it lasts.
Please don’t be bashful about asking questions here on Chat, at times this can be like the tech corner of a car club. I can share more about my adventures if requested, including gory pics of saw cut concrete and exposed pipes....
Wright client Roland Reisley put it this way to me: If the leak is isolated, you find it, open the floor, splice the pipe, patch the floor and move on.

If calling the Conservancy, ask for John Waters

Gris
Posts: 5
Joined: Sat Aug 22, 2020 10:50 pm

Re: Concrete floor / radiant heat experiences?

Post by Gris »

Modmom1 wrote:
Sun Aug 23, 2020 1:58 pm
We purchased a "gravity heat" apprentice house that was designed in 1940 and had been abandoned for many years that had a failed heating system. Our restoration included removal of the concrete floor, leaving a six inch piece around the periphery to support structure as well as the flooring over the central core basement. We discovered the original cast iron pipes (IAN an architect so excuse me if I use the wrong term, my architect husband is out working on another structure on the property) had deteriorated so it was good that we went to this extreme. This was BY FAR our greatest expense and source for headaches. When we started in '14 no residential plumbers wanted to take on the large job and we finally went to a commercial plumbers who started, then won a big contract leaving us in limbo for several months.

Perhaps if your system works or you some areas that have failed, you can modify this approach. On this site DRN, the owner of the FLW Sweeton House was able to repair a certain area that failed instead of the whole system.

That said despite the headaches and great expense (several hundred thousand includes 7 zones hydronic system and new copper plumbing in our 2,200 sq ft house in Ohio) we love the heat. (*plus removal of old floor and repour new with grid pattern was about $32k)

Good luck!
Thank you very much for your detailed response. Your home is so beautiful and I'm loving your journey.

We are also in Ohio (though 100 miles away) and the thoroughness of your reply (including the eye-popping inve$tment) is super-helpful and a real wakeup call. The home we are buying has thankfully not been long-abandoned but it was foreclosed upon twice in its history, suffered at least one sewage backup we are aware of and was flipped then sold then rented out. Whew. The home is over 3000 square feet (with its additions). We definitely wouldn't have the budget to completely replace the concrete so I'm hoping it's salvageable under its current layer of floating floor. We definitely can't replace the entirety of the radiant heating system either, so I'm really hoping we don't have to abandon the system in favor of (gulp) baseboard heaters throughout.

Really, this is a rough and ready education. The home was being marketed as "contemporary", "unique" and a good value due to price per square foot-- with no mention of FLW or the Apprentice who was the home's architect. We discovered that only through quite a bit of digging. We expected plywood subfloor and forced air, not red concrete and radiant floor heating. So I'm both excited and anxious to potentially be digging on a house with systems and finishes we honestly didn't know existed before a few weeks ago.

Neither of us are architects, nor outstandingly handy, and I'm hoping we aren't biting off more than we can potentially chew. We'd love to restore as much of the original look of the house as possible -- but budget is a large consideration. I appreciate the time you took to outline your process.
Last edited by Gris on Sun Aug 23, 2020 10:18 pm, edited 1 time in total.

Gris
Posts: 5
Joined: Sat Aug 22, 2020 10:50 pm

Re: Concrete floor / radiant heat experiences?

Post by Gris »

DRN wrote:
Sun Aug 23, 2020 7:51 pm
Welcome Gris!
As outside in noted, nothing lasts forever, but there are some ways to care for the system to prolong its service life and to make spot repairs as needed.
This is a link to a Wright Chat thread in which we chewed on the subject a bit, and I discussed one of my two repairs to my system:
http://wrightchat.savewright.org/viewto ... es+radiant

Also, here are some bullet point-ish observations from one of my posts:
Radiant pipes...from the homeowners I have met and discussed the issue with and the two repairs we have made, I can confidently assert the following:
1. Steel/iron pipes tend to fail as a result of wetting from their outsides (ground water, roof drainage seeping under or through slabs/shallow foundations, leaking fountains or pools)
2. steel/iron pipe systems should NEVER be drained and left empty as corrosion of the inner pipe surface will start immediately...fully charged with old funky black water at all times is GOOD.
3. steam heating in steel/iron pipes as at Jacobs I originally sets up interior corrosion when the system is powered down each summer.
4. Copper pipes are not fail proof either...a Louis Kahn house owner in Cherry Hill and about a thousand Levitt homeowners will attest that copper pipes and the chemical reaction with concrete and its admixtures can cause systemic failure of in slab copper piping.
5. Nothing lasts forever...all systems fail eventually. We just maintain it as best we can, fix it as possible and practical, knock on wood a lot, and enjoy it immensely while it lasts.
Please don’t be bashful about asking questions here on Chat, at times this can be like the tech corner of a car club. I can share more about my adventures if requested, including gory pics of saw cut concrete and exposed pipes....
Wright client Roland Reisley put it this way to me: If the leak is isolated, you find it, open the floor, splice the pipe, patch the floor and move on.

If calling the Conservancy, ask for John Waters
Thank you so much for the warm welcome, the detailed explanation of various types of failure, and the name of Mr. Waters. Very, very helpful. The photos are super-helpful and if you have any more gory war stories or photos to share, I'd love to see them.

SDR
Posts: 19703
Joined: Sat Jun 17, 2006 11:33 pm
Location: San Francisco

Re: Concrete floor / radiant heat experiences?

Post by SDR »

Modern hot-water radiant floors make use of plastics like PEX tubing, which presumably could last almost indefinitely ?

It seems that the idea of making a masonry floor of individual paving units, ready to be taken up (or if too large for that, broken up) in case of failure, never occurred to Mr Wright. I suppose he thought that failure wasn't an option. Is anyone today working with such a flooring system ? Commercial space---office floors---are sometimes paved with units resting on pedestals, to provide access to utilities. Why wouldn't the same sort of system work in residential settings ?

S

jay
Posts: 299
Joined: Mon May 02, 2016 8:04 pm

Re: Concrete floor / radiant heat experiences?

Post by jay »

I'm curious as to what would happen if an old radiant system, which say had 1 inch steel pipes, was drained and had 3/4 inch PEX tubing snaked through (inside of the old pipes)? Would the heat transfer be insufficient in such a scenario? Has anyone tried this? Are there issues I'm not thinking of?

SDR
Posts: 19703
Joined: Sat Jun 17, 2006 11:33 pm
Location: San Francisco

Re: Concrete floor / radiant heat experiences?

Post by SDR »

I think it's a great idea. Unfortunately, the job of snaking hundreds of feet of pipe, with a dozen or more 180-degree bends, is probably going to be rejected by all but the most optimistic plumber. Most Usonian pipe-layout plans I've seen show full radiused sweeps at the ends of the runs; this drawing for Goetsch-Winckler makes the prospect even worse, with 90º elbows at every bend.

Maybe a very well-trained mouse, with strong legs, could be put to the task ?


Image

outside in
Posts: 1262
Joined: Sat Jul 29, 2006 9:02 pm
Location: chicago

Re: Concrete floor / radiant heat experiences?

Post by outside in »

the technique of sending a mouse with an attached wire through the 1-1/2" piping is feasible only if the pipes have radiused corners, which many of them do. It was first successfully used in refrigeration warehouses in california, and would certainly work on radiant heating systems as well. The inside of the pipe would reach the temperature of the pex, so the existing wrought iron would act like conduit. I'm still waiting for someone to try it.

Roderick Grant
Posts: 10340
Joined: Wed Mar 29, 2006 7:48 am

Re: Concrete floor / radiant heat experiences?

Post by Roderick Grant »

SDR, in answer to your question about removable slabs, FLW used them at Walter, at least in the main room. I imagine the only drawback might be ensuring that there is no slippage between slabs, which could make the floor uneven.

Roderick Grant
Posts: 10340
Joined: Wed Mar 29, 2006 7:48 am

Re: Concrete floor / radiant heat experiences?

Post by Roderick Grant »

I believe the number I read somewhere was 85% of all new residential construction is now forced air, which allows heat and central A/C to use the same set of ducts. I have never understood why so many people favor water or steam. The systems are more complicated and vastly more expensive to fix when they inevitably fail. My family home, a humble frame without a shred of insulation, was perfectly comfortable for all the Minnesota winters we lived in it. Of course, we had one advantage: the thermostat was set at 65 during the day and 60 during the night. Anything hotter than that is uncomfortable in my book.

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