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Underfloor under the stove?

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Glenn Sossin_2
Glenn Sossin_2 Member Posts: 592
My $.02, radiant heat under cabinets and appliances is a wasted effort of time and money. It adds unneccessary cost to the project. Any useable heat from them would be marginal at best. I would only put it under an outside floor cabinet with a water connection to help minimize the potential for freezing - such as kitchen sink, or dishwasher.

We sometimes lose sight of the fact that when we design the heating system, we are designing to outdoor design temp which represents the worst conditions we would expect to encounter. This rarely happens during the course of the heating season. So potentially, for a few days, we may not be able to fulfill our heat ouput design. But is this really so critical ??

Not in the kitchen. We forget, this is the one room in the home where there is a substantial amount of heat gain. Typically we use the kitchen most during the day and early evening hours. The outdoor design temps, if it is reached, will typically occur in the early morning hours well after the sun goes down and we are all tucked away asleep.

There are multiple, substantial sources of heat gain in the kitchen - just look at what the HVAC guys consider. First, you have the refrigerator/freezer. Its on 24/7 constantly turning out heat. If your in the kitchen, your typically cooking. Heat gain coming from the stove, microwave, toaster, coffee maker, wall oven, etc. You also have the lights on, they can be a substantial source of heat energy. There are people in the kitchen -people alone can add several hundred btu's each. A computer, a Tv, - there are multiple sources of heat energy constantly added to the kitchen which is why I almost always use a floor sensor to maintain a warm floor.

A Kw of electricy is 3412 btu's when converted to heat energy. One hundered watt light bulb puts out approx 340 btu's of heat. Just start adding up the light bulbs and appliances and you will have a a sizeable btu gain.
We don't normally take appliances and people into account. I find that if I'm that close on the heat , this usually solves the shortage.

Doing the outside floor cabinets only ? - I suppose there will be enough heat exchange with the outside wall to prevent them from becoming stuffy and an incubator, but I still think in most cases, it not necessary when all the factors are considered.

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  • Uni R_3
    Uni R_3 Member Posts: 299
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    Any downsides?

    When I do the underfloor plates for my kitchen, are there any downsides to trying to add a few extra BTUs under where the range sits so that it ends up a bit warmed via the floor heating? I'm not sure how much heat would actually radiate from the tiles up to the range.

    The rest of the under cabinetry and under fridge areas would of course be left without underfloor heating.
  • Good question Uni,

    I`m curious too.

    Dave
  • Weezbo
    Weezbo Member Posts: 6,232
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    here is a thought,

    when installing radiant in low mass (gypcrete) i consider the area under the range and refrigerator having a certain ability to add to the heat source because of that,i would opt out of installing heat under them....instead,i would add the available pipe to the area just pass the profile of the cabinet block outs....

    were the range on an out side wall .then i see it as having an advantage to heating the thermal mass of the appliance...Radiantly *~/:)

    with plates, (i am not super keen on staple ups...) i tend to roll the loops back about a foot from the outside edge of the floor on the individual bays.....that keeps the plates back aways more...i never liked the idea of running the loops close to the insulation-at the end of the bays...the foamer guys always see the pipes as a Target...and i do not see much advantage in foaming the pipe ,for a number of reasons...

    when running baseboard(convectors) i take one of the cheesy plastic bags that they hand us at the grocery market and wrap them around the tubing...this helps on the acoustics:)
  • hr
    hr Member Posts: 6,106
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    Why not

    kitchens can be a challange to heat when you consider the heat flux. Heat flux being the AVAILABLE floor space to meet the heat load number. Cabinets and appliances square footage needs to be divided out of the kitchen square footage to get the heat flux number.

    Also many of the stoves I see installed these days Viking, Wolf, etc are up on legs and have a better ability to have that heated footage "useable"

    As`always, start with a room heat load calc, determine the heat flux, and see what the required output number is.

    I am a proponent of radiant under cabinets that are on outside walls. At least one run at the exterior wall.

    hot rod

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  • hr
    hr Member Posts: 6,106
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    Glenn, do you

    use a floor sensor only control for kitchens? I've tried a few bathrooms, including my own, with floor sensor only.

    With floor sensor only the air temperature is rather uncontrolable.

    Even with let's say a 78F floor temperature,
    fairly low if you want warm floor feel, that's 16 BTU/ft output in a 70F air space. Combined with the other "un-controlable" heat sources you mentioned fridge, appliances, cooking, etc. Sounds like the space temperature is wild?

    In my former "cold country" company we found more cool kitchens then we did excessivly warm ones. The heat from appliances is only available when they operate.

    It seems homeowners want warm kitchen floors, regardless.

    I suppose ideally all those "extra" sources could be plugged into a heat loss/ gain formula. But they are un predictable and intermitent gains. Even an inefficient fridge doesn't run 24/7.

    Dual stats could be workable in a kitchen, although wall space to mount one in not always available.

    hot rod

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  • Glenn Sossin_2
    Glenn Sossin_2 Member Posts: 592
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    Sensors in kitchen floor

    Good point about the refrig not being on all the time. I almost always recommend sensors in the kitchen especially if there is a housewife who stays home and likes to cook - especially the Italian ones with big pots of boiling water for pasta.

    This type of cooking pours loads of moist heat into the room. The thermostat is either turned down slightly, or has a tendency to be satisfied for several hours, especially when there are several women in the kitchen preparing a feast like most of us will have today. During this period, the radiant heat in the kitchen floor is typically off. If the kitchen is over an unheated crawl, the floor can/will become cool even though the thermostat is satisfied. This is why I recommmend the floor sensor.

    Setting the floor probe is a bit challenging. Usually try to set in center of the pex loops, equidistant from any source of heat. Normally will set it around 60F to start and then have customer raise by 1-2 degree increments on 60F + days until they realize they are starting to heat the room with the floor.

    With regard to unpredictable and intermittent, I agree fully - however it if there is no one in the kitchen, the need to heat it up fully is up for discussion. If a person(s) are in the kitchen, then alot of the sources of heat gain are present - i.e. cooking, lighting, plus if they are raiding the fridge, that would kick it on most of the time for a little while at least.

    Alot of times, I will go even further and put transfer plates over the pex in a mud job right in front of the kitchen sink, stove and island where the housewife is likely to be standing. It helps to minimize the striping effect.

    I have been questioned about the validity of such a practice, in particular because of the potential interaction with the aluminum and mud/concrete products. I've been doing it for several years now, - always had a positve response from the homeowner & contractors. Have you ever done this??
  • hr
    hr Member Posts: 6,106
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    You have trained your customers well

    if you can get them to tweak the controller till the desired level is obtained. I find it a moving target?

    The kitchen is the most frequently used room in the home.

    I rarely zone it (the kitchen) by itself as most homes these days have such open floor plans and the sitting areas should trump the kitchen for absolute comfort.

    It's alway a juggling act. I enjoy hearing how others tackle these tricky rooms, thanks.

    I think that cooking humidity poses a big challange also in the super tight homes we see these days. Possibly a humidistat and HVR removal device?

    Or microwave-able pasta :)

    hot rod

    hot rod

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