Imbalance in forced air system

mrspeeder

We have a split level house with the Master bedroom on the third floor and the remaining bedrooms on the second floor. The Master is pretty well insulated while the bedrooms below are on top of the garage and not properly insulated. The thermostat is in the master bedroom. The registers are 11"X11" for all bedrooms. The registers in the main bedroom are near the bed and similar for the other bedrooms since those rooms aren't that big.

I tried to balance the system by closing 2 dampers in the master bedroom, but that left the room cold and continuously pumping heat to the other room since the room does not heat up and then then thermostat turns off.

The heat is extremely strong and blows well but to well! if I close the dampers and then close the registers a good amount of air still comes out.

It gets very uncomfortable as it's too hot.

Any ideas would be great!

Thank you in advance.

Jamie Hall

Two things. First, where are your returns? Remember that you can't get good circulation, never mind balance, without having adequate returns.

Second, I guess I'm a little confused. You say you close two registers in the master bedroom, and then it gets too cold -- and then the thermostat in the master bedroom turns off. Eh? And it's continuously pumping heat into the other room... but the registers are turned off?

Kindly unconfuse me...

mrspeeder

Sorry for the confusion.

After closing the registers the master bedroom gets cold, but the other rooms are getting heat continuously. This is because the set temperature in the thermostat is higher than the room temperature in the master bedroom. There is basically no heat coming into the master bedroom so the thermostat wont turn off. I was thinking of maybe installing sensors in the other rooms for the thermostat.

The return is in the ceiling above the staircase between the 2 floors.

STEVEusaPA

You really can’t close registers and think air (or enough air) will be 'forced' into a different part of the house. Balancing requires much more than that.
In your situation (I also have a 4 level split) you need two systems-2 for the top 2 levels, 2 for the lower. Anything else just isn’t going to provide even, consistent comfort.
That’s 2 properly designed, installed, commissioned systems.

bburd

Have you tried partially reopening the master bedroom registers, or leaving one closed and the other open? 

pedmec

Closing a register to try and balance a system is not the proper way of accomplishing balancing. Shutting down the dampers at the registers creates velocity noise's at the registers. You need to find the dampers in the takeoff at the trunk provided they installed the dampers and the dampers are accessible. You balance the system by adjusting the position of the damper at the takeoff.

mrspeeder

STEVEusaPA said:

You really can’t close registers and think air (or enough air) will be 'forced' into a different part of the house. Balancing requires much more than that. In your situation (I also have a 4 level split) you need two systems-2 for the top 2 levels, 2 for the lower. Anything else just isn’t going to provide even, consistent comfort. That’s 2 properly designed, installed, commissioned systems.

yes, I have 2 systems. The top system runs the top 2 floors. 

bburd said:

Have you tried partially reopening the master bedroom registers, or leaving one closed and the other open? 

Yes, this worked a little better. But the heat and air force is very strong. If we compare it to a cars heater fan, the heater fan blows on high all the time. 

Peakedtoosoon said:

If some rooms are colder or hotter than others, then either the system has not been properly balanced and/or you need a zoned system. That said, i'd suggest you go back to the first important step, and get a Manual J completed for each room in the house. You can't balance a system, if you don't know what your room CFM should be........any other approach is just a wet finger in the air IMO.

ok, i'll research this. 

pedmec said:

Closing a register to try and balance a system is not the proper way of accomplishing balancing. Shutting down the dampers at the registers creates velocity noise's at the registers. You need to find the dampers in the takeoff at the trunk provided they installed the dampers and the dampers are accessible. You balance the system by adjusting the position of the damper at the takeoff.

Im assuming this is the box where all the hoses come out of and then goes to each room? This is where I shut the dampers off, basically turned it 45 degrees. 


I guess the best way to describe the heating system is its very very strong maybe over engineered for the top floors. 

pecmsg

I guess the best way to describe the heating system is its very very strong maybe over engineered for the top floors.

NOT Engineered!
You need a room-by-room Manual "J" to determine the heat load loss then a Manual "D" for the duct design too get the CFM's required for each room.

bburd

It’s possible the fan speed was set too high, most are adjustable. Generally, a lower speed is used for heating and a higher one for cooling, when condensation on the coil increases resistance to airflow.

mrspeeder

bburd said:

It’s possible the fan speed was set too high, most are adjustable. Generally, a lower speed is used for heating and a higher one for cooling, when condensation on the coil increases resistance to airflow.

My units are Rheem, I'll check the manual to see if there are settings.

bburd

Most fans use multi speed motors; speeds are changed by connecting different windings.

Older units had single speed motors; speeds were changed by adjusting pulleys.

mrspeeder

my model number for Rheem is: R92TA0701317MSA.

looks to be a single stage based on the specs.
It says do not use low speed for heating? But I want low speed. 

bburd

It’s a five speed motor. The wiring diagram indicates the motor as “IBM”. Below this the five speed wires which run to the board are shown. The “motor speed wiring” chart is just to the left of this at the top of the diagram.

Depending on which furnace you have, the factory default has the HEAT blower terminal on the board connected to speed two (yellow) or three (purple). Low is speed one (red), and should not be used for heating. Unused speed wires should be connected to M1 or M2 on the board per Note 2 at bottom left.

The nameplate should specify the maximum and minimum temperature rise through the furnace, which determines the permissible range of blower speed.

mrspeeder

Ok, seems like I can't lower the speed? The red one is the lowest?

EdTheHeaterMan

I read all the comments that @mrspeeder made and I did not get this answer form any of the comments so ?I will ask the question and give multiple choice answers to choose from

When you close the master bedroom dampers and the master bedroom gets too cold, the blower keeps running. What happens to the rooms that used to get insufficient heat?

A. They still get insufficient heat.
B. They get just enough heat.
C. They get too hot.

Based on the answer to this question, there is a different solution for each.

If your answer is C the rooms get too hot. then you need to slowly and gradually open the damper to the master bedroom to allow a small percentage of heat in so the thermostat will be able to be satisfied. after your first small adjustment wait 24 hours to see if the other floor is still too hot. then open the damper a little more and wait 24 hours. Eventually you will get the proper mix for the home.

If your answer is B then you need to get a different duct design and possibly some zoning dampers to allow for individual thermostat control for each floor

If your answer is A then you have the wrong size heater. it is too small.

pecmsg

Blindly opening a closing dampers is not good. 

Most units are oversized on undersized ducts. This causes less air flow and higher temperature differential on the heat exchanger.