Electric Floor Heat System Contactor

[BMacky]

Had a service call this week on an electric radiant floor heating system from WarmTouch. There are three resistive elements in the system, and each are just over a 7A load. Any two elements combined puts me just under 15 A, so I need to split the three elements into 2 zones, one on a separate 15A breaker (7A load) and 2 on a 20A breaker (15A load).

I would like to find a double pole/single throw contactor and use the thermostat to switch it on and off.

Can anyone recommend a mfr name or even the correct technical name for something like this? Also, I'd like the device to be quiet, no hum. Any replies are appreciated.

Thanks!

Bob

 

[iwire]

Any reason not to use a single 30 amp circuit and a line voltage thermostat?


If you do go the contactor route they make ones specifically for this that are silent, they just take some time to operate.

 

[jumper]

I think that the floor heat needs GFCI protection also.

424.44(G) Ground-Fault Circuit-Interrupter Protection.
Ground-fault circuit-interrupter protection for personnel
shall be provided for cables installed in electrically heated
floors of bathrooms, kitchens, and in hydromassage bathtub
locations.

 

[renosteinke]

I have difficulty believing that the manufacturer does not offer controls for his product.

 

[hillbilly1]

I'm surprised that the manufacture is opening itself up to liability by only requiring a simple ohm test before and after installation. Maybe because its supposed to be imbedded in non flammable material only? For a little more cost I think I would split it out to three 15 amp gfci circuits since you have to buy a contactor anyway, that way if one heating element fails, it will not take out the other.

 

[hillbilly1]

I think that the floor heat needs GFCI protection also.

424.44(G) Ground-Fault Circuit-Interrupter Protection.
Ground-fault circuit-interrupter protection for personnel
shall be provided for cables installed in electrically heated
floors of bathrooms, kitchens, and in hydromassage bathtub
locations.

The manufacture does require it, so it's a mute point.

 

[BMacky]

I have difficulty believing that the manufacturer does not offer controls for his product.

One mfr does offer power modules for each element and a single tstat controller; power mods have gfci protection. So for around an extra $600 I can have the correct materials. Plus my labor. We're trying to make it work electrically and economically, so I was looking for a basic solution like GFCI breakers and a contactor with dedicated terminals for each zone and an adequate power source based on the loads.

I failed to mention that the original installation was done by someone who:
- double-lugged the feed to the tstats at the panel
- shared a neutral across identical phases; no handle tie
- left all j-boxes in the crawl space open
- never heard of or ran out of staples (all the cabling under the house was lying on the grade)
- used Monster Cable to extend one of the cold leads from the 120V heating elements
- ran a 14.6 Amp load to one of the factory tstats ( they are rated max 15A but still, how about a little wiggle room?)
- didn't install the floor sensors beneath the tile; I found them shoved into the wall
- ran the cold leads up through the wall without conduit
- removed the factory labels with the resistance readings from the leads

Wait, there's more!:

-The two gang cut-in box that held the two thermostats for the three elements had the side cut out so that the thermostats fit together.
- Used plastic Arlington NM clamps to hold MC in the panel and j-box under the house (looked clean!, I didn't notice it until I saw the end of the MC inside the panel with no anti-short!!!)

It's been an interesting service call to say the least. I always try to look for a little right-ness in a situation, but I was stumped by this installation.

 

[renosteinke]

I've priced 'DIY' controls vs. 'factory stuff' for Raychem heating tape, and I failed to find any econimy there.

The one heat mat I installed, the installation instructions were pretty anal- both about megger testing at various points, and about using 'factory' controls. I really don't see any advantage to re-inventing the wheel. Heck, a proper contactor will set you back a couple hundred dollars, easily. Indeed, the mat I used was sold ONLY as a complete system, including controls.

Since these mats have come on the market, all manner of DIY inquiries have appeared on message boards, as folks -aparrently- try to jury-rig damaged / discarded mats for other projects.

Not really my business, but it seems to me your CUSStomer needs to learn a lesson about "saving" money. He made his own bed - let him sleep in it.

 

[Warmsmeallup]

They are called Power Modules. They work just like you described, but you want to be sure they are GFCI protected. You can't just use a relay with a GFI thermostat because then the cables that are attached to the relay are not truly protected, the relay is. The power modules are not $600. They're $132.00. We mix and match controls all the time. The problem is that some manufacturers won't warranty their element with someone elses tstat. It may not be moral but, they can do it.

The ohm's testing is to protect you (no, I'm not a manufacturer ). Their warranty covers a defective element. When you get it, if it doesn't (closely) match the reading they had at the factory noted on the accompanying tag, don't use it, it's defective. However, you should have purchased a "buzzer" that you connect to the element while it's being installed. This will prevent you finding out after the fact that it 'went' defective while being installed. I should also say that it is very unusual that that a reputable element goes bad AND wasn't caused by a thrid party.