Radiant Control system – temperature control guide


The house is a massive design, very slow to change temperature and the system aims to keep the house at a steady temperature all year long while allowing natural use.  This means in the cold months it keeps very precise control of heating effort using industrial algorithms to target temperature within 0.1 degree , in the cooling period it is designed to be “natural”, allowing for some drift, as if in a cave or sheltered grove, rather than strict like conventionally air conditioned space.  In the shoulder seasons, opening windows etc. when desired is anticipated.  In the dead of winter and during heat waves they should be shut.

The system does not provide dehumidification, a dehumidifier should be run during the summer months to keep the humidity in the house lower than 55-60%.

This house has significant passive solar gains in winter and was designed to be a little warm on sunny days in the winter.

The temperature control has been developed to control hydronic systems using low temperature heating and high temperature cooling strategies.  Its goal is room temperature control within 0.1 degree of setpoint in cold weather.  It is designed to compensate for high latency or high mass assemblies often found in hydronic systems and the passive effects such as solar or internal gains.

The system encompasses a physical thermostat and a system of network based sensors, accessible on the local network. It includes sensors for room temperature, humidity, outdoor air temperature, and operating temperature.

Most of the functionality for the control system is accessed over the network, through a web browser or dedicated Android App.

Temperature Control

The basic Thermostat control allows setting the setpoint turning on and off night setback, and turning the system to standby.

The thermostat setting applies to heating as well as cooling.

36 Hour Chart

The 36 hour chart gives the heating/cooling performance versus setpoint,  indoor , outdoor temperature, some analysis is possible from this screen.

By calculating from the slope of changes to the inside temperature, setpoint and HP effort can be used to adjust or tune the PID parameters.

By comparing the upper chart to the lower, specifically changes to the inside temperature vs the outdoor temperature and HP effort, one can deduce passive effect.


The settings screen allows the basic operating variables to be setup, most of these settings need only be “tuned” once or very occasionally, and with the exception of the setback times and value, should be done by a person who understands the meaning of each parameter.

Reset Balance – outside temp.

This refers to the outside temperature below which heating is needed in Celsius.  This value is used to start heat and used in calculating the proportional effort portion of the PID using the reset ratio and Proportional boost explained below.  The value depends on likely passive heat generation. Poorly insulated houses could have a balance as high as the setpoint, very well insulated homes will be lower, depending on the level of passive gains that can be relied on.   If estimating, it is better to set it a little high rather than too low.

The balance temperature for cooling is the same as the setpoint.

Reset Ratio

This refers to the design temperature of the fluid used in heating as compared to the outside temperature and setpoint.  For example for heating, if the balance point is 15, the outside temperature is 5, the setpoint is 20 and the desired fluid temperature is 30, the ratio should be 1.0 if the desired fluid temperature is 25 the ratio should be 0.5.

It can be calculated using heat loss and dividing by the surface area exposed for heating in the system and adjusting for the estimated emissivity of the radiating surfaces .  A high performance house with a low heat loss and a large radiating area will have a low ratio.

Proportional boost

The proportional boost is needed to compensate for heating system hysterisis and give some “headroom” for the system , the minimum is 2, if in doubt set it for 5.

PID Integral, seconds

The Integral is the primary way the system can compensate for the tendency of proportional systems to stop short or overshoot the setpoint.  Set this for the time it takes to heat the home 1 degree at maximum power.  A radiant system in embedded concrete slabs may be 12 hours, in seconds, a hydronic system with radiators may be 1.5 hours etc.

PID Derivitive, seconds

The derivative “softens” the PI algorithm, a shock absorber to reduce swings , should be set for less than 25% of the integral, during the tuning, try it at 0 to see if it is even a problem, then gradually ramp up the value.

Nightime setback start time

Set the time for daily setback to begin, hours in a 24 clock.

Nightime setback finish time

Set the time for daily setback to begin, hours in a 24 clock.

Setback degrees

The amount of the setback in degrees.

Use Solar Heat Minimum temperature

If your system is equiped with a solar heat transfer system, set the tank minimum temperature to use solar heat as a default over generated heat.

Healthier Air Quality

Forced-air heating and cooling systems continuously circulate air through a home’s ducts and registers, quickly distributing pet dander, dust, mold spores, and other allergens throughout the structure. By contrast, radiant heating and cooling systems don’t circulate air at all, and thus don’t keep allergens airborne as long as forced-air systems. That means better indoor air quality – a particularly important consideration for adults and children with allergies, asthma, and other conditions that can be exacerbated by indoor pollution.

Radiant heated and cooled buildings maintain more natural humidity levels.

Studies have shown that that individuals who spend more time in air-conditioned environments have an increased use of health care services. An analysis found more visits for complaints related to ears-nose-and throat problems, respiratory and dermatological problems. Hydronic cooling does not create drafts or dry out the air unnaturally so is healthier.

Heat pumps do not emit fumes, furnaces and boilers burn fuel and emit fumes.

Where electricity is generated without greenhouse gases (like in Ontario) Heat pumps provide a solution to greenhouse gas emissions from heating and cooling buildings.

More efficient

Radiant heating systems – particularly hydronic systems – often lower utility bills relative to sources of heat, such as forced air. According to Bob Vila, hydronic floor heating systems are up to 30% more efficient than forced-air systems. Water can carry a much greater amount of heat as compared to air , therefore the energy used to pump water is an order of magnitude less than fan energy used in forced air systems.

Perceived warmth is higher in a radiant system as compared to a forced air system.

Greater efficiency for heat pumps can be achieved in hydronic situations because operating heating loads are in the 30 to 40 degree Celsius range. Heat pumps don’t have to work as hard as with air to air.

Hydronic cooling is more efficient than forced air cooling ( air conditioning) since hydronic systems require demand less from the refrigeration cycle since higher temperatures will effectively cool a building, They also only use energy for sensible cooling air based systems must also remove latent heat dehumidifying the air, whether desirable or not, this leads to even greater efficiency gains. *Dehumidifying solutions must be designed in for some Hydronic buildings, although dehumidification is not required at all times.

Efficiency for air to water heat pumps is 30% greater for heating and 40% for cooling.

More Comfortable and Quieter

Most heating systems deliver heat into a room from a focused point, such as a forced-air vent or steam radiator, or a single side, such as a baseboard radiator. The adjacent area is typically the warmest place in the room.

However, as the heated air enters the room, it almost immediately begins to rise towards the ceiling, and only falls after losing much of its heat. That makes the air near the floor noticeably colder – 20 degrees or more – than the air at head level, five or six feet above the ground. The result: cold feet and hot heads. This effect is more pronounced in homes without excellent insulation and when it’s very cold outside.

By contrast, radiant heating systems heat rooms from the floors up, from the ceiling down, walls in, or some combination. The heated surfaces radiate heat in all directions and warm air at a relatively low temperature, transferring heat to other parts of the room at a uniform rate. This means less noticeable temperature contrasts within rooms, little to no vertical temperature stratification, and more comfortable rooms overall.

Hydronic systems particularly in-floor radiant or in ceiling radiant are considerably more comfortable than hot air systems and air conditioning.

Since large areas are typically heated or cooled in a radiant system perceived temperature is more effective in a radiant system as compared to a forced air system. In heating and cooling, draughts are avoided.

Hydronic heating and cooling is virtually silent indoors.

Our Mission

Welcome to Temperate Systems Incorporated.

Our mission is to help people transition to sustainable energy.  We believe sustainable buildings and homes can be more comfortable and rewarding.

The world in general, and Canada  in particular are moving away from fuel burning heating appliances and towards heat pumps.  Hydronic radiant heating is becoming more popular for new homes and renovations, due to customer benefits and efficient installation methods. Most homes that have radiant hydronic heating systems use a boiler and have a separate system for cooling using forced air.  Air to Water heat pumps are considerably more efficient than Air to Air heat pumps as sold in North America  Air to Water heat pumps are popular in Europe and Asia selling millions of units a year, but are virtually unheard of in North America in residences, they are making headway in commercial/institutional settings, particularly high end and eco projects.

The technology is proven and our mission is to help people realize the benifits.