Radiant Heating in a FLW-influenced Usonian Home

Cottonwood

I am the owner of a 1952 usonian home designed by one of FLW's architects. The house is built on a slab with no crawlspace. It has zoned radiant heating. After a drop in water pressure, but no visible water, it has been presumed to have developed a leak. I am having difficulty determining the correct course of action to remedy the situation. I was quoted up to $500 to determine the location of the leak (no repair). Since there is no access to the pipes from below, a hole would need to be made in the floor to repair the leaking pipe. The problem is if the leak is under one of the tiled areas of the home, I do not have any replacement tiles to restore the floor (i do not want to replace all of the tile in an area as it would change the historic character of the house). Also, there is the additional expense to perform the pipe repair and cosmetic tile work. The money that would be spent on the pipe repair would be sizable and could be applied to the installation of a new efficient gas forced air system (the house currently has a SpacePak cooling system in the attic but the electric heat addition would be costly to operate). Once an old radiant heating system starts leaking, is it likely to continue to develop other leaks (and additional repair expenses)? Would you perform the diagnostic test to determine the leak location? Could a gas forced air unit be placed in the attic and attached to the SpacePak duct work? What other heating solutions should be considered?



I would appreciate any advice to assist in the rectifying this difficult situation.



Thank you!

Alan (California Radiant) Forbes

Slab Leak

Many of my customers have old radiant systems with copper radiant panels and I often get calls about leaks in the slab.  It's always hard for them to get over the fact that part of their floor will have to be removed to fix the leak, but ninety-nine times out of a hundred, they go ahead and have the work done.  They love their radiant heating so much, they don't want to give it up.



If that's the first leak after 58 years, that is one of the better systems i've seen.  But many people ask if this is the beginning of the end; will I start getting more leaks on a regular basis.  It's been my experience that if the system has held this long, it is an anomaly and leaks will be few and far between.



Installers of radiant systems installed after the war usually used copper tubing in the slab.  Your system is probably made from copper tubing, but please make sure you confirm this before any work is done. 



The diagnostic test is important in pinpointing the leak location.  If you know where the leak is, there is less floor covering to remove while looking for it.



I don't have an answer to your gas forced air questions.  Others more experienced will have to chime in.  You might want to have some HVAC contractors come look at it and give you their opinion.

Jean-David Beyer

I am not a heating professional.

In view of the historic value of your house, I would suggest paying for locating the source of the leak. The proper infrared camera devices are apparently very effective at this. Chances are very good that you have copper tubing in that slab. If you are lucky, they will be able to locate the leak and it will be somewhere you can hide the repair. My house has no historic value, but was built about the same time yours was, and it is not leaking. I do not know if they used soft copper tubing or rigid with elbows, but if the latter, I would suppose the leaks would be at the joints that would probably be near the walls.



If you are really really lucky, the leak is not in the slab at all. With luck, it may be in the piping near the boiler, the expansion tank, etc.



Before installing forced hot air, consider using radiant panels on the walls or ceilings.

Cottonwood

More information

I have owned the house for two years. The previous owners stated that there have been repairs done to the pipes prior to his possession of the house (tiles were cut out in the floor and the same ones were then put back in). This was in area of large bricks in the floor, not small bathroom tiles or under carpeted areas. There have been at least three leaks prior to this one.

The house is located in snowy, rural WI so it is going to boil down to finding the most efficient, cost-effective heating solution along with experienced technicians that can perform the work seamlessly. Does anyone know how much the typical charges are for leak detection and then repair?

Alan (California Radiant) Forbes

Estimate

We are not supposed to talk about money here.  Estimates will vary state to state.



How rural are you?  Are there leak detection contractors in or near your area?  Those are the people that can give you estimates.  You should also try to find a local radiant contractor that can help you.  Have you tried to "Find A Professional"?  Click on the link above.

Cottonwood

Struck out locally

Thank you for the heads up about not inquiring about pricing. I did use the "Find a Professional" search feature up to 250 miles and there were no recommendations. I am only 40 minutes from Madison WI and still no bites. I had two local contractors look at the system and neither had the newest pinpoint leak detection equipment or felt "comfortable" with the project. I was only looking for a ballpark range for the complete repair as this would factor in my decision to repair an ailing system or apply the money that would be spent on the repair to a new gas forced air system. I understand that prices vary based on locale; I was hoping some one in my area who is familiar with this type of project might see my post and give a personal account of their experience. Alan, you asked about prior leaks. I stated there have been at least three. In your opinion, is it financially savvy to continue to put money in this system?

cattledog

leaks in slab

Cottonwood--



SpacePak sells a product called "WaterPak hydronic coil" which would appear be a compatible alternative to their electric heat addition to the current fan coil and duct work.



What is the leak rate of the current system? My personal experience is with a 1949 slab on grade house with steel pipes in the floor. For several years before finding and fixing a leak I managed to keep it to a pretty low rate by running the system at 1-2 psi instead of at 12 psi. To do this will depend on the type/configuration of the expansion tank, the location in relationship to the pump, pipe sizing, the high point in your system, your boiler water pressure requirements, the make up water control, and your desire to monitor and play around with your system.



My pipe corroded from the outside in a place where it was low in the slab (cracks in the slab didn't help) and saw ground moisture. Once the ground got wet from the leak the process was self sustaining. The inside of the pipe was pristine on either side of the leaking section when I cut it out.

cattledog

leaks in slab

Cottonwood--



SpacePak sells a product called "WaterPak hydronic coil" which would appear be a compatible alternative to their electric heat addition to the current fan coil and duct work.



What is the leak rate of the current system? My personal experience is with a 1949 slab on grade house with steel pipes in the floor. For several years before finding and fixing a leak I managed to keep it to a pretty low rate by running the system at 1-2 psi instead of at 12 psi. To do this will depend on the type/configuration of the expansion tank, the location in relationship to the pump, pipe sizing, the high point in your system, your boiler water pressure requirements, the make up water control, and your desire to monitor and play around with your system.



My pipe corroded from the outside in a place where it was low in the slab (cracks in the slab didn't help) and saw ground moisture. Once the ground got wet from the leak the process was self sustaining. The inside of the pipe was pristine on either side of the leaking section when I cut it out.

Alan (California Radiant) Forbes

I can

only tell you what I would do if that were my system.  I'd keep it and baby it along, fixing leaks as they appear.  It gets easier after the first one. : O

JJ_4

Infrared

Find someone who has an infrared camera.  Typically there is someone who does energy audits or electrical panel evaluations that has one.  I have also heard that sometimes fire departments have them to check for hot spots after fires.  We accurately located a leak in a snow melt system and were able to cut open and repair in just a 1 ft x 3 ft area.

Steamhead

Now that you've had radiant

you will hate forced-air. Fix the leak, and in the future, run it at as low a pressure as you can.



There was a reason Mr. Wright used radiant in a lot of his projects.