radiant floor heat system

[rmattix]

I am a homeowner. I have recently had an electrical floor heating system installed under a new tile floor. The system came from WarmlyYours http://www.warmlyyours.com This is a 15 watt system, which had been encapsulated in concrete. The contractor made "on-site adjustments" to the plan for the floor grid provided by the manufacturer. His adjustments have placed the wiring under the location where the cabinets are to be installed (despite specific instructions in the manual not to do so).

The contractor (as a remedy) is recommending the wiring under the cabinet locations be excavated, cut to remove it from that location, spliced, reburied in concrete and retiled.

Since cutting the wire and shortening the system will decrease the resistance in the system: the result will be an increase in the wattage of the system. Per a discussion with the manufacturer, they believe the watts may increase to approximately 17+/-.

My question...

Is there a limit to the allowable wattage of such a system that serves as radiant heat for a floor?

Are there other problems with the remedy as proposed by the contracor?

Thanks in advance.

RM

 

[bonding jumper]

Re: radiant floor heat system

Well, unless these cabinets are large, I don't see much of a decrease in resistance due to wire being eliminated. I would opt that he will be increasing the overall resistance based on how many splices/connections he will be making. If he's eliminating a few feet of wire but adding 5 splices, the splices will greatly outweigh the footage of wire.

 

[bonding jumper]

Re: radiant floor heat system

I'm not quite sure I'm following u, these pads can't be cut and spliced by an electrician, they are factory manufactured pads, he shouldn't be cutting the pads and splicing, over time those connections are gonna fail, especially cuz they are used in heating applications, where your floor will be expanding and contracting with each cycle of use.

 

[rmattix]

Re: radiant floor heat system

From discussing this with the Mfg....for every 2" of mat (pre wired grid) there is about 1.5' of wire. The contractors recommendation would eliminate approximately (and assuming) 4' of mat. This would equate to about 36' of wire.

RM

 

[bonding jumper]

Re: radiant floor heat system

Ask the manufacturer, I don't think this is the best way, maybe they have a smaller mat the contractor can use. Make him pay for it cuz its his screw up. They won't warranty a product that the electrician is gonna hack up.

 

[rmattix]

Re: radiant floor heat system

Of course, I'd like him to pay for it, but as of now, he does not think there is a problem. I'm guessing that he has not taken the max wattage per NEC into consideration. If that is the case, then his "remedy" does not hold water. But I'm only guessing 'cause he's the CONTRACTOR and I'm just an ignorant homeowner...

RM

 

[don_resqcapt19]

Re: radiant floor heat system

bonding jumper,

If he's eliminating a few feet of wire but adding 5 splices, the splices will greatly outweigh the footage of wire.

Can you cite a source for that information?
Don

 

[bob]

Re: radiant floor heat system

Is there a limit to the allowable wattage of such a system that serves as radiant heat for a floor?

The NEC does not have a limit as to the maximum amount of heat required to heat your home. The designer will caculate the required amount. You mention in your post that this was a 15 watt system. Is this 15 watts per tile?

[ August 04, 2003, 07:31 PM: Message edited by: bob ]

 

[goldstar]

Re: radiant floor heat system

Just my opinion, but I would not excavate the area and splice this cable. This cable is a single conductor with a shield wrapped around it (which is bonded to ground). This should also be on a GFI protected circuit (either via a thermostat or breaker). If you are lucky enough to expose the cable without damaging it and you then splice the cable, how do you then wrap the shield back around the splice ? The cable is designed so that should water somehow seep into the cable, the energized wire will come in contact with the grounded wire and trip the GFI. You're now going to bury the exposed splice in thin set and lay tile over it .........not a good idea in my opinion. I would leave the cable the way it is. What's the worst that could happen ? The cabinet gets a little warm ?

By the way, tell the contractor that if he ever does this again, mark out the floor with spray paint so he'll know where the cabinets go as well as any other obstructions.

Hope this helps. Good luck !!!

 

[electricmanscott]

Re: radiant floor heat system

I would not cut it either. If the issue is heat buildup under the cabinet, cut out the toe kick area and install some sort of grate to let the heat out. This is not as big a deal as you are making it out to be.

 

[bonding jumper]

Re: radiant floor heat system

Can you cite a source for that information?

http://www.arcfaulttester.com/pdf/tecno105.pdf
Is the only thing i can find here, and this states that

Pig-tail taps are not considered to add significant
resistance to a branch circuit. A mechanically secure wire nut with 3, 14 Ga. wires is the
equivalent of 6" of 14 Ga. wire. However a poorly applied wire nut can cause significant
voltage drop and can pose a fire hazard.

I imagined a mat with a wire running through it, and a contractor cutting across that wire adding maybe 20 connectors. With low power applications, the number of breaks in a wire can be vital, ie. cable tv, telephone, data. But as far as branch circuits and 120volts goes, its not as bad.

 

[brian john]

Re: radiant floor heat system

The only problem from having this under the cabinet might be, Anchoring the cabinets to the floor in lieu of to the wall (cutting the cable)and excessive heat build up, which might short life the cable and/or cause the wood to dry out in a non-uniform manner (door issues and cracking at glue joints)

These should be addressed to the manufacture.