Where Does The Heat Come From In Radiant Heating For Homes?

Q:

When you have radiant heat as the main source of heat in a home where does the heat actually come from?

A:

There are two types of radiant heat that typically are available on the market for residential homes, one is electric floor heat and the other is hot water floor heat.

ELECTRIC HEAT

Electric in-floor heating is most commonly seen in bathroom floors but there are times when people install them in all floors of a home to help heat the home. In colder climates it’s usually not enough to heat an entire home all by its self; you usually require baseboard heaters or a main forced air heating system like a furnace.

Electric heating are heat lines or “mats” that are installed on top of the sub-floor and then are hooked to a thermostat on the wall. They are powered solely by electricity. As the heat lines warm up so does the finished flooring on top of them. Electric heat is predominantly placed under tile on floors, this helps give it thermal mass. When the electric heat warms up the thermal mass of the tile and mortar that is underneath it then it starts to radiate heat outward in the air. Because the air above the tile is colder then the heat rises up towards the ceiling of the home constantly. The tile will continue to radiate heat to a limited extent even after the heat lines have stopped producing heat. Electric heating lines are limited in the amount of heat that they can create; they also require a lot of electricity to do so depending on the amount of heat that you want out of them.

HOTWATER HEAT

Hot water in-floor heating is exactly what it sounds like, it is hot water that can be made from several different kinds of sources, and it is then circulated through piping that is placed under the finished flooring of your home to heat it. Hot water heat produces enough heat for you entire home no matter how cold a climate you live in. You will not require any extra heating sources like electric in-floor.

The hot water is circulated from a central location and fed into the piping, the area’s are usually broken down into zones so that you are able to control the temperature of the zones depending on the area’s use and also depending on how warm or cold the room is because of other forces such as sunlight through windows or heat making units like fireplaces.

Hot water in-floor usually is installed in 1.5 inches of “gypcrete” a concrete product that is designed to be installed over heat lines to create thermal mass. Because it is imbedded in the gypcrete hot water in-floor is extremely efficient in its heating. Long after hot water has stopped circulating through the lines the floor will continue to radiate heat, hot water in-floor takes a while to come up to temperature from completely cold but it also takes a long time to cool down as well.

Hot water in-floor heating is one of the most efficient ways to heat your home regardless of what fuel source it comes from.

Rob Abbott
Village Builders Inc.

I’m renovating an older home, can I install radiant heating on the first and second floors of the home?

Q:

I’m renovating an older home, can I install radiant heating on the first and second floors of the home?

A:

Yes you can install radiant in-floor heating on the first and second floors of your home when you are renovating it. There are many things that you will have to do before you can do this though, to do this you should be doing a very large renovation to the home. Radiant heating is basically water lines that are placed on top of your sub-floor and then covered in a “gypcrete” which is a type of concrete.
Usually the gypcrete is about 1.5 inches thick. There is a brief list of the things that you will have to do to the home so that you can install radiant in-floor heating in it;

• You will have to completely remove the existing flooring regardless if it’s wood, tile or carpet from anywhere the radiant heat is going to be placed.

• You are going to have to make sure that the floor joist are strong enough to take the extra weight that comes with installing a inch and a half of gypcrete over the heat lines.

• You will have to remove all the trim that is near the floor. Baseboards and door trim will have to be removed to get a smooth finish.

• You will have to remove all interior doors that will be in the way. When they are reinstalled they will either have to be cut down by 1.5 inches or the whole framing of the door will have to be moved up and re-installed.

• You will have to remove drywall in certain areas of the home to install manifolds in the walls and also to install the thermostats.

• There will have to be holes made in walls and wall plates so that the piping can come from the basement (usually where the boiler is placed) to feed the upper floors with heat.

• Any hole in the sub-floor from anything like old wiring or old plumbing that was moved must be plugged or the gypcrete will leak through.

• You will have to install wood barriers at certain area’s like at the top of stairs to create an edge where the gypcrete will stop.

The installation of the piping and the gypcrete should be installed by qualified professionals that are experienced in this field of work, if this isn’t done right it can cost you a lot of money and a lot of wasted time.

After the in-floor has been installed and the gypcrete as well then you will be able to install your flooring and all your trim. You will probably have to repaint as well because gypcreting can be a messy business and your walls will be a little dirty from workers touching it or leaning on it while they were working.

Rob Abbott
Village Builders Inc.

If I lose power how fast will my house cool down when the weather is cold?

Q:

If I lose power how fast will my house cool down when the weather is cold?

A:

The rate that your home cools down depends on a lot of factors;

1. The outdoor air temperature. The colder the outside air temperature the faster that the inside temperature will be affected.

2. Shape of the house. The shape of your home will affect the amount of surface area that is exposed to the outside air. So a simple box shape for a house will perform better where a T-shape, L- shape or a long thin home will perform worse. Longer homes have more exterior walls exposed to the outside air.

3. Insulation levels and air tightness. Insulation will have more affect on how fast the inside air temperature cools then almost anything else. The more insulation or R –value you have the longer your home will be able to stay warmer. This is applies to the walls and the ceiling or attic insulation as well. The more insulation and vapour barrier the more it slows the colder air from penetrating the wall cavity into the home.

4. Thermal mass. The thermal mass of a home is basically the ability of the homes building materials and furnishings to hold heat when the heat source has been turned off. The greater the thermal mass of the building the longer it will hold heat and the longer it will take to cool down.

5. Available Sunshine. Sunshine creates heat and it is amazing how a little amount of sunshine will heat up a house. Depending on the type of your windows (if they are solar gain) you could easily warm the home slowing the rate of temperature reduction.

6. Wind speed. The higher the speed of the wind the faster your home will cool down. It is called windwash when the wind blows against the outside walls of the home; this windwash cools the wall cavity faster than the normal cold air that penetrates the wall.

7. Internal Heat Gains. When the heat fails but the electricity is still active then things such as appliances, lights and other electronic devices give off some heat that helps slow the rate of the internal temperature drop of the house.

All these factors will affect how fast or slow your home will cool down.

Remember that when you lose power or lose your heat source do not use anything that uses propane to try and heat your home. The fumes and fact that propane heat sources use up all the available oxygen in the room make them extremely dangerous to operate inside.

Rob Abbott
Operations Manager
Village Builders Inc.

Some information for this post was found in the solplan review November issue #173

Cold weather heat pumps

Cold weather heat pumps

The new generation of cold weather heat pumps are producing phenomenal cost savings even compared to natural gas heating.

Tests comparing the efficiency of new cold weather air to air heat pumps show that the new generation of heat pumps result in 49% energy savings over heating with natural gas. These results don’t even take into consideration the savings of a heat pump compared to a conventional air conditioning unit that run on electricity. Heat pumps convert to air conditioners in the summer and do it more efficiently than normal air conditioning units.

The thinking on heat pumps in the past is that they do not perform below zero very well because the old theory was that there wasn’t enough heat in the air to remove to create significant amount of heat. When a heat pump cannot remove heat from the air outside it is unable to produce heat and must rely on the homes furnace to produce the necessary heat. These furnaces can be oil, propane or natural gas. The new science on new heat pumps tells us that even air at -18C contains 85% of the heat of air at 21C. That means that when it is cold outside the heat pump still can remove enough heat from the air to heat your home, thus putting an end to the thinking that below zero heat pumps do not work very well.

If you’re wondering how a heat pump does this I will explain;

A heat pump transfers heat by circulating a refrigerant through an evaporation and condensation cycle. The refrigerant flows through an outdoor coil where it absorbs heat from the air as it is evaporated. It is then compressed at high pressure at a second coil where it condenses, this releases the heat absorbed earlier in the cycle, this then has accomplished bringing the heat from the air outside to the inside. Once the indoor coil has this heat it circulates it through your duct work to your entire home.

With this new technology it makes more sense to have a heat pump added to your heating system, this will allow you to save money on heating and cooling and depending on how little or how often you use it will tell you how fast it pays for itself in energy conservation. On average a heat pump pays for itself in under 5 years, which is a very quick turn around when we are talking about heating and cooling units.

Rob Abbott
Operations Manager
Village Builders Inc.

Information for this blog came in part from the solplan review NO. 170 May 2013