Need help with heat balance

Jerry Olsen

Then what do you suggest to keep the "warm air" from rising and staying in the second floor?

Jerry Olsen

Need help with heat balance

I have a townhouse condo with 12ft ceilings on the first floor and 8ft ceilings on the second floor. In the winter, the upstairs is always too hot and the downstairs is always too cold.

The only air return is ½ way up the stairs.
The vents downstairs are in the floor and the vents upstairs are in the ceiling.

There is a handle on the air intake to the furnace that switches from the cold air return to outside air from the roof. It doesn’t make a difference to the temperature, if it’s set to the outside air or the air return.

The thermostat is downstairs and tends to turn on a lot. We’ve learned not to open the windows upstairs if it’s too hot, because the cold air moves downstairs and triggers the thermostat and makes it even hotter upstairs.

I’ve tried closing all the vents upstairs.

I’ve tried running the furnace fan 24 hours a day and evens out the temp a little but not enough.

I’m thinking of disconnecting the air intake from the vent for outside air on the roof and putting in a warm air return at the top of the stairs.

I have 2 questions: First, does anyone think this will solve the problem?; and second, what is the best placement, close to hallway at the top?.

Brad White

Balancing Air Systems

can be like herding cats sometimes..

It really gets down to this: A. What is the heat loss in BTU's per Hour of each isolable or definable space? and B. How many BTU's per Hour are you delivering to each?

Know A. Balance for B.

Without instruments, it is a matter of tweaking dampers and waiting a few hours for temperatures to settle.

If you can isolate and identify ducts specifically serving the different levels, you can also install motorized dampers which will respond to the needs of each space. Arzel is one company, there are others.

Adding a return is often a good idea too, especially if the spaces are remote or isolated from each other. Often a single large return at the bottom will impose a greater negative pressure there. Lower levels of multi-story buildings are already slightly negative due to stack effect. Add to this and more outside air gets sucked in as another contributor.

Air systems improperly balanced often exacerbate if not instigate unforeseen conditions.

Jerry Olsen

Heating balance

Thanks for the input. I think the major problem is heat rising. All the heat moves up stairs and stays there.

Brad White

Not to delve into semantics but...

warm air rises. Heat moves in line of sight. That aside, let's use it to your advantage.

Putting a return up there would likely make that worse by giving yet another motive force (besides buoyancy) to cause an imbalance.

So long as there is a pathway back to the return, deliver less air to the warm parts and more air to the cold parts. I do not mean to make it sound so simple, but that is what you must do.

Jeff Hutter

need help with heat balance

Hope this makes sense:
I have a 29 unit multi family. The boiler is a Weil Mclain low pressure 2-pipe steam thats top fed. I believe it was installed about 10 years ago (before my tenure) and contolled by an R&D Controller with 4 sensors.
For the past 3-4 years I have been dealing with an incredible inbalance of heat from the top floor units to the 1st floor units. Temps readings are 74 to 80 degrees from the 2nd floor to the 4th floor.The first floor barely breaks 65. A month ago all the thermostatic traps (radiator)were replaced as well as the line trap (B&J FT54)...nothing changed. I took temp readings on the lines as well as the return lines. With the boiler cooking for and hour the first floor traps read 145 degrees yet the top floors roasted at 190 to 200. This tells me that there is a pressure problem 'cause I'm not getting steam, checking the boiler guage it didn't move from 0.
Are there any suggestions on what my issue is?
Thanks

jp_2

correction brad?

isn't more correct to say, warm "fluid and gases" rises in the presences of sufficient gravity?

Brad White

I would not say that, JP

isn't more correct to say, warm "fluid and gases" rises in the presences of sufficient gravity?

Gases are fluids as are liquids, gravity is more or less constant at a given location. A warmer and/or less dense fluid will rise in the presence of a colder, more dense fluid- that I can live with.

But I mean no insult in defining my terms versus yours, I hope you know.

Brad White

You may

want to post this as a "New Thread" so that it gets the attention you deserve. This is now tagged on to another thread and so has a limited audience. No harm in asking, just want you to get an answer.

jp_2

welll

I thought fluids were gases but couldn't remmember for sure.

I think many people do not realize that the only difference between conduction and convection is in fact gravity!

I think thats a fun fact to share. without gravity, you have radiation and conduction.

Steamhead (in transit)

Jeff

Where are you located?

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Brad White

By supplying less of it

and letting it cool to ambient (equilibrium), it will lose the buoyancy which is it's motive force. If the room is supplied with more hot air than is necessary to heat it, the room will overheat. Similarly, the downstairs should not be overheatd either.

You are discovering why forced hot air systems and comfort tend to pass each other in the night.