Mothballing radiant heating in a new slab

[Tobymonster]

I've read a few threads on here where people have installed radiant heat but waiting a number of years but using it. As it's pressure tested during installation and slab pouring, what is done to the water that is still in system after this test is done - is it treated with anti mould or is it somehow removed. And the big question - how long will it last in this state?

I ask because I'm in the process of planning a house build in Melbourne Australia, where winter temps are between 30 and 50 degrees F. Frosts do happen but not severe. Most houses here have forced air that are noisy and spread dust and pollen around and are not that efficiently insulated. I'm looking into radiant heat as I love the type of heat it gives off - I installed electric radiant heating in my kitchen and bathroom in a house when living in the uk. There are a few companies that offer the system here in the cooler Australian states and these hydroponic systems are gaining in popularity (so these people say!) Its only going to be a couple of thousand dollars extra and 1 more day on the slab so worthwhile, but I'm also keen to keep costs down. If this means having their own off the shelf heating system and not going off plan (expensive) then I'll consider it as I can have evaporative cooling too. But I don't want the ******** scenario of paying for three gas heaters (2 for heating, 1 for water) servicing my house! Obviously I'm thinking when the wallet recovers in can commission the radiant side later.

 

[pstnbly]

We use air for pressure testing and to pressurize the tubing during the placement of concrete. I would blow out the lines if water was used.

 

[shelteredV]

I agree. Make sure the manifolds and mixing valve are blown out completely too

 

[Tobymonster]

Thanks for the replies, I will ask that they use air during the installation phase.


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[thammel]

Yep, I just used to pressurize mine during the install. I think this is the standard approach.
Tom

 

[rburke65]

My tubes have been installed and connected to the manifold for 3 years. Hopefully by next winter.

 

[shooon]

Air is useful during installation and so is having isolation valves on each loop. It's recommended to pressure test at least a day before and during the pour.

Reason being, if you spring a leak you can usually quickly locate source of air bubbles while they are pouring the concrete and make a splice repair. Since pouring concrete is time sensitive you will want to have a splice kit on hand just in case the worst happens (someone steps on a tube and punctures it somehow)

Things to keep in mind while pressure testing:
It's normal for pressure to fluctuate a little bit, especially after the pour since the concrete will generate heat you will see slightly increased pressure.

Before the pour, if you pressurize the loops on a sunny day and check them the following morning when things cool down you may lose a few PSI, normal as well.

I prefer to pressurize everything as far ahead of the pour as practicable and just keep an eye on pressure just to make sure it doesn't drop continuously. The extra isolation valves come in handy if you have a really slow leak since it allows you to narrow it down to which loop is giving issues.

 

[Chris Stapley]

We install radiant floor heating in Canada and we always pressure test our per line installation for a minimum of four days prior with 15psi of air and as one poster advised,leave it in during the pour so as to prevent line collapse..no water for testing!