I recently installed, for the first time, a STEP Warmfloor system in a newly constructed house that I wired for a general contractor. The 1000W transformer for one of the zones is randomly blowing fuses on the output side and I am unable to determine why. I have gone over the design specs a number of times including checking the temperature vs resistance curves and correlated them with the resistances I recorded for each element when it was installed. I have also checked the amperage on both the out and the in sides on the transformer when it was presumably under highest load; that is when the floor was cold. In all cases the numbers seem to check out. The fuse-blowing seems to be independent of the temperature anyway. The circuit breaker for this circuit is not tripping. On the 1000W transformer there are two output legs with a 25A slow-blow fuse on each one. One of these seems to be blowing, but I believe the owner said the other one blew at least once as well. The design specs do cut pretty close to the maximum allowable for the 1000W. Even so, my understanding is that the maximum allowable usually contains about a 20% of a fudge factor. Since your site points out that transient draws can be pretty high on this system, does that mean that you need to design in even more of a fudge factor? Does the owner need to replace the 1000W with a 1500W and reallocated the elements among three legs? Or is there another possible issue?

The 1000W transformer is not as you describe.  It is in a steel enclosure and no heat-sink.  It is connected to a dedicated 20amp circuit breaker.  To reiterate, it has operated without any circuit breaker trips for about one year, the first one being about a month ago, then again last week.  It has not tripped since then.  Note that the breaker on the underside of the transformer has never tripped.  Could it still be possible that something has gradually changed inside the transformer?

Is the 1000W transformer silver with an extruded aluminum casing and heat sink?  If so, the system is using one of our newer style transformers with toroidal coils.

Toroidal transformers are highly efficient transformers, but they do like to surge on startup.  For this reason, use a high magnetic circuit breaker to avoid tripping in the service panel, GE THQL1120HM or equivalent (Search with Google).  This should solve your problem, and these types of breakers should be available at your local electrical supply house.  As a dedicated circuit breaker with a 1000W transformer, your breaker size should be rated at 20 amps to allow for the surge.

Just to let you know, we are open Monday through Friday between the hours of 8 a.m. and 5 p.m. (CST), and our toll-free number is 877-783-7832.

The service panel breaker, not the one on the transformer.  Sorry that I was not clear on that.

Dave, I am sorry to hear that you are having problems with your STEP Warmfloor system.  I have a question for you to further investigate the problem at hand.

Which circuit breaker is tripping - the service panel breaker or the transformer breaker?

My Warmfloor has been installed in our single faminly house for about one year.  It was installed by a local contractor who worked with the local Warmfloor representative in Brookfield, WI.  Included is a 1000W transformer and a Microreg controller.  We have used the system in 2007 during January-March and then again since the end of November.  It has been working very well and we are quite pleased with it.  However, in the past month, there have been two times that the circuit breaker has tripped.  Once I reset the circuit breaker, the Warmfloor operates again.  The time between the first breaker trip and the second one was about 3 weeks.  The Warmfloor installation is on a dedicated breaker (i.e nothing else is connected to this circuit).  If this continues or gets worse, I'm thinking of replacing the Microreg switch myself, before calling in an electrician to check/replace the breaker.  I know of no abnormal load on our electrical system that might have caused a surge, unless it was caused by the power entering the house.

Jim, thank you for your question.  One of the greatest benefits of the STEP Warmfloor product is its versatility and ease of installation.  Installing the product between joists is not a problem.  You can staple the heating elements under the floorboards; the elements are one foot wide and fit between the joists.  Do not puncture the bus braids on each side of the element.  Since heat is transmitted by conduction rather than radiation, it is very important to place insulation snug under the heating elements with no air gaps to force the heat up.

We do free quote requests (http://www.warmfloor.com/content/view/44/77/), and I would suggest sending us your dimensions so we can get started on your project.

I would like to install warmfloor in two existing bathrooms that I am going to remodel. I have a basement beneath each bathroom and would like to know if the system works well between floor joists (16" centers). I have 3/4" tounge & groove plywood subfloor and am going to put down ceramic tile. Especially in one bathroom there is nowhere to put transformer except in vanity cabinet, but if able to install heating elements with good heat results between floor joists this would rectify transformer location problem. One bathroom desired floor heating area is 6' long by 3' wide. The second bathroom area would be 7' long by 4' wide. The second bath has an adjoining closet which would make it possible to mount the transformer in if recommended, but I like the idea of putting everything underneath the subfloor. The second bathroom floor joists run the width direction whereas the first bathroom joists run the length direction. Please advise for best results. Thank you.

Good morning.

The transformer used for the SYS-120 kit is a 1000 watt transformer.  Can you tell me where and how the transformer is installed?

It is completely normal for transformers in operation to have a surface temperature between 158 and 176 degrees Fahrenheit (70-80 degrees Celcius).  Also, do not place the transformer in an area where the ambient temperature is higher than 104 degrees Fahrenheit (40 degrees Celcius).

Also, is the noise caused by vibration?  Good mounting points are concrete pillars, brick walls, steel girders, and wooden beams.  Rubber standoffs (between the mounting holes of the transformer and the mounting surface) will reduce vibration as well.

I hope this helps.  Give our technical support a call for more suggestions and ideas to your problem, toll-free at 877-783-7832.

Good morning,

customer installed a SYS120 system and in concerned with the amount of noise and heat being generated by the transformer. They are using a switch to turn the power on and off.
    Can you give me an idea of what might be causing the issues.

Regards,

Chris Fasnacht
Minnesota Electric
(612) 804-4305