Heating Help

Heating Help

Heating Help

Radiant Floor Heat Problem in Bathroom (11 Posts)

wanttolearn February 20, 2011 @ 1:11 PM

Radiant Floor Heat Problem in Bathroom


I have radiant floor heat in only a single area of my entire house, in the master bathroom.  This room has it own thermostat that regulates the radiant floor heat.  I moved into the house last year, so I have no idea when it was installed and how.

I set the thermostat at a constant 72 degrees all the time.  The problem that I have is that while the system seems to work ok on moderate temp days, on days when the temperature drops below 30 degrees outside, the system is not producing enough heat, and the temp in the room never reaches 72 (it mostly hovers around 70 on these cold days).

I have gone to the boiler room downstairs and there are two flexible tubes that I believe serve this radiant floor heat.  One of the tubes is red and one of the tubes is blue.  The tubes appear to be connected directly to my boiler.  There is also something that looks like a temperature knob, but it is already turned to the maximum temperature.

Two symptoms I should tell you about that I have noticed:

When I touch the red flex tube with my hand, it is defintely warm, but it is not burning hot like some of the copper tubing coming out of the boiler is.  I can easily close my fist around the red tube with no discomfort.  Is this an indication that the water passing up this tube is not hot enough?  should this tube be very hot or just moderately so?

Secondly, I noticed that not all of the bathroom floor gets evenly hot. One half of the floor gets noticably warm, the other half gets only very mildly warm.  None of the floor gets really hot, not even on the coldest of days.  Is this also an indication that the hot water serving th system is not warm enough?  Or does it just mean that the system is defective?

Any help would be appreciated, as 70 degrees is just too cold for a bathroom on a freezing winter day!  also I am concerned that the system is running all the time to reach the target temp, and that this is causing my heating bills to escalate.


Brad White February 20, 2011 @ 2:03 PM

Up against the edge

I think you are finding the intersection of your space heat loss and your available radiant floor area at that temperature.

Given the uneven heating, you may have a flow restriction or possibly (as I gather), your radiant floor area is «slaved» to the main house zone and so responds only to the main house needs, not the bathroom need. That zone should have its own circulator and it will be a small one.  When slaved to the main house, if the main house temperature is satisfied, your bathroom is left abandoned. Unloved. Alone.

Heating Help

The «feel» of pex is no nearly so warm as copper; it is hard to tell temperature through pex by the hand, although a relative difference between warm and cold is obvious.

The floor should not be «hot», but should be «neutral to warm», meaning not over 85 degrees.  80 to 82 is ideal, but for a bathroom, one can tolerate higher temperatures, 85, sometimes 90 but no more. (Spend more time in the bathroom and 90 degree floors will make the room feel stifling.)

To recap: Put the radiant floor on a dedicated circulator with a mixing valve to control the temperature. A Taco iValve is a good place to start, even the setpoint type, but they also have an outdoor reset type. Give the room its own thermostat. This will fire the boiler to meet this and will increase your heating costs, but what in life is free except love?  OK, love can be expensive too. Analogies? They are free here and worth every penny. )

«If you do not know the answer, say, «I do not know the answer», and you will be right!»

-Ernie White, my Dad

This post was edited by an admin on February 20, 2011 2:05 PM.

wanttolearn February 20, 2011 @ 2:26 PM

Further Info

I just went back to the boiler room, and there is a separate Taco ciculator for the radiant heat zone.  Like I mentioned in my original post, there is also a knob that regulates temperature, but it is already turned to the maximum (setting 2).

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