Most efficient way to use zoned heating with hot water baseboard radiators?

Rob_M

Hello, it's our first time in a home with both zoned heating and hot water baseboard radiators.

There's three zones on the main floor of this particular house.

We've been primarily heating only the zone we spend the most time in (the center of the house) and leaving the other two off (which are on the opposite ends of the house). The difference in temperature between the zone that is on and those that are off is quite significant. 

The water boiler is on the lower level, fairly close to the stairway that leads up to the main floor at one of the zones we usually don't heat.

We leave open both the door to the stairway and the room with the boiler to allow heat to rise up the stairway to the main level.

Is this the most efficient method with such a system/layout, or does it force the zone that's on to attempt to heat the zones that are off if the doors are open? And even if the doors are closed, they're not air tight.

Is what we're doing now forcing the boiler to come on more often and work harder, as the zone that's on is losing heat to the zones that are off? 

Would heating the other two zones, even a few degrees, put less strain on the primary zone and, in the end, use less energy?

Thank you,

Rob

EdTheHeaterMan

Any time you reduce the temperature difference between the conditioned space and the outdoor temperature, there will be a savings.

You are in the 70° space and the outdoor temperature is 30° That is a 40° difference. That will take a set amount of energy to maintain the indoor temperature.

Now you lower that indoor temperature to 60° on that same 30° outdoor temperature day. The temperature difference is now only 30°. You will use 25% less energy to heat the space to 60° than if you heat the space to 70°

So to take that a step further, if there is a room that is hotter than you need (like the room the heater is located. and you allow that heat to go to a space that is not as hot, then you will also save energy because the overheated space's temperature will be reduced and the regular temperature room calls for heat less often because it is getting heat from the overheated room. The overheated room will loose less energy to the outdoor temperature and the thermostat calls for heat less often.

Now take this one more step. The 70° space is divided into 3 zones and you decide to reduce two of those zones to 60° and keep the third zone at 70°. That means the the heat loss for the 2 lower temperature zones will be about 25% lower than it would be if the space was heated to 70° but it will also gain a small amount of heat from the connected 70° room. This will add to the temperature of the 60° room loss to the 30° outdoor temperature, reducing the energy needed to heat that zone. The 70° zone would continue to lose heat to the outdoor temperature of 30° on the walls not connected to the 60° zones.

Bottom line is, the less space you heat to 70° the more you will save.

Rob_M

Thank you, Ed

How does that factor for multiple zones (where we spend most of our time in only one zone)?

Our home layout and system may not be typical.

My question is (in our particular situation) if we heat only one zone, are we forcing the boiler to come on more often and work harder, since the zone that's on is losing heat to the zones that are off?

Would heating the other two zones, even a few degrees, put less strain on the primary zone and, in the end, use less energy?

EdTheHeaterMan

Rob_M said:

Thank you, Ed

How does that factor for multiple zones (where we spend most of our time in only one zone)?

Our home layout and system may not be typical.

My question is (in our particular situation) if we heat only one zone, are we forcing the boiler to come on more often and work harder, since the zone that's on is losing heat to the zones that are off?

Would heating the other two zones, even a few degrees, put less strain on the primary zone and, in the end, use less energy?

I added to my original post.

Now take this one more step. The 70° space is divided into 3 zones and you decide to reduce two of those zones to 60° and keep the third zone at 70°. That means the the heat loss for the 2 lower temperature zones will be about 25% lower than it would be if the space was heated to 70° but it will also gain a small amount of heat from the connected 70° room. This will add to the temperature of the 60° room loss to the 30° outdoor temperature, reducing the energy needed to heat that zone. The 70° zone would continue to lose heat to the outdoor temperature of 30° on the walls not connected to the 60° zones.

Bottom line is, the less space you heat to 70° the more you will save.

hot_rod

Unless the walls between the rooms are insulated, there will be some heat transferring between the heated and unheated room. So it is possible the heated zone will run a bit more to maintain temperature.
Should be some savings regardless with lower temperature rooms. As long as you stay comfortable in the heated spaces.

Rob_M

Thank you @hot_rod and @EdTheHeaterMan

Does my hypothesis in our particular situation seem correct?

Heating only one zone forces the boiler to come on more often and work harder, since the zone that's on is losing heat to the zones that are off

- and -

Heating the other two zones, even a few degrees, would, in the end, use less energy since one zone isn't trying to heat the others

Or would it make no difference as far as overall energy consumption in this case?

Thank you for your help,

Rob

EdTheHeaterMan

As long as you don't go so low that the pipes freeze... and you are comfortable in your home... The lower the temperature difference the less energy you will use. You will use less energy heating only one zone than if you heat all three zones. Leaving the boiler room door open to let excess heat go to the other spaces that you want to heat is also a good idea.

Leaving the doors to the cooler zones closed will also reduce the energy usage.

Rob_M

Thank you, @EdTheHeaterMan - we won't let it get that cold that the pipes will freeze :-)

Just trying to find that right balance between comfort and overall energy consumption

Have a great week,

Rob