Upstairs Colder than Downstairs

wanttolearn

Hi-

I have been reading many posts on these walls and tweaking my steam system, but my problem remains:  My upstairs floors is approx. 4 degrees cooler than downstairs.  Let me give you some background on what I have done so far to improve my steam system:

1.  my steam boiler is brand new, and I have had it confirmed that it has been set up correctly  (i.e. pressure setting, piping, etc. is correct).

2.  I have replaced all the vents on my radiators with Varivalve Quick Vents

2.  I have wrapped insulation around all my pipes in the basement. 

3.  Lastly, I have added two Groton #2 at the end of both my main pipes to make sure that venting is quick.

Based on all the above tweaks, my system works quite well.  Once the boiler fires on, within 10 minutes approx. half my radiators get warm, and after another 10 minutes (i.e. 20 minutes in total) all radiators are nice and warm, and the house heats up quickly and fairly evenly.  Is this response time good?

The problem is this: Let's say I want upstairs to be a comfortable 72 degrees at all times.  To achieve this I initially set the thermostat (that is located downstairs) at say 74 degrees.  The house quickly heats up, and soon the heat shuts off and the desired temperature are met upstairs and downstairs.  However, this is where the problem slowly sets in.  With the downstairs thermostat set at a steady 74, gradually the upstairs temp starts dropping.  Within a day or so, it falls to 70, and I am back to my original 4 degree differential.  I dont want to turn downstairs any higher than 74, but 70 upstairs is a little to cool for comfort.

I have tried to analyze what is going on, and my only possible explanation is that my heating cycle is too short.  on average, my boiler fires up approx. every 90 minutes, and it stays on for 10 to 15 minutes each time.  it seems that this is long enough to heat downstairs, but not long enough to heat upstairs properly.  Is my thermostat at fault?  I have a Honeywell Pro TH4000.

These are all the relevant facts I can think of.  Does anyone have any suggestions?

Mike Kusiak_2

Insulation?

It sounds like upstairs has a higher heat loss than downstairs, so even though both areas are initially heated to the same temperature, upstairs drops in temperature faster, and after some time reaches a lower temperature than downstairs.



How much insulation do you have in the attic? If you increased the insulation, your upstairs heat loss would be reduced and the temperature difference would be reduced.

Dave in QCA

System Balance may be the problem

It sounds like from the conditions that you describe, that when the house is cold, it heats up quickly and evenly. 

Then... the problems start to set in..  Once the house is warm, the cycles are going to be shorter and system balance is critical.

Do you have a thermostat that is set for no more than 1 cycle per hour?  This is usually the best for cast iron steam systems.

As the temps begin to drift off, have you monitored an observed the characteristics of each steam cycle.  What I am going to guess is that your downstairs radiators are getting more steam than the upstairs radiators.   So, you need to do some monitoring.  Check several radiators downstairs when the boiler cycles, and see how much of each of the radiators got hot.  25% - 50%... just how much of the radiator got hot on average of the downstairs radiators.  Then, in the same cycle, see how much of the upstair radiators got hot.  I am going to guess that it is less.

YOu say you got Varivalve vents.  Are these the Heat Timer Varivalves?  Are they all set at the same position?  What is that?  All the way open? half way? 25%? 

While you're at it, a few pictures always helps the people on here who are giving answers, get a better understanding of your system.   Boiler, piping, etc... and the radiators too.

crash2009

Sounds like everything is working pretty good

 because you said the entire house gets up to temp about the same time.  I agree with Mike that the heatloss might be higher on the second floor, and/or the main floor is vented a hair too much. 

I think you might be able to compensate for the and/or by slowing all the vents on the first floor by 2/16ths and slowing the second floor by 1/16th.  This would take a bit longer to heat everything but the second floor would continue to vent a bit longer.

You are real close to perfect balance.  Mark the slider with a sharpie so you can always go back.  

wanttolearn

Updated Post

Hi-

thanks for the posts.  Let me add the following clarifications:

1.  most of the varivalves on the ground floor as switched fully to "close" and upstairs fully to "open".  I did this to try to push the maximum heat upstairs.

2.  Yes, there is a large ed attic above the second floor, but the attic is fully finished with a carpet floor and carper base, etc.  There is also some decent amount of insulation in the attic ceiling and walls.  The temp in the unheated attic is in the mid 50s (when outside is in the 30s).  Does this indicate that the attic is being "heated" by the 2nd floor?

I suspected that the attic might be the source of the problem, but I didnt think too much heat would travel through the finished attic carpet floor.  Also, why does the temp differential between 1st and 2nd floor stop at 4 degrees?  If the attic was the source of the heat loss, wouldnt the 2nd floor keep losing heat until it is the same temp as the attic?

Any further thoughts after reading this?

Mike Kusiak_2

Heat loss

If  the attic is at 50F when its 30F outside and the sun is not heating the roof, then the heat has to be coming from the second floor ceiling. There is no other place for the heat to come from. The fact that the attic temperature is about halfway between outdoors and the second floor shows that you have about the same amount of insulation in the attic floor as you do in the attic ceiling and walls. The 4 degree differential between upstairs and downstairs only shows that you are still not putting enough heat into the second floor to meet the total heat loss.



Either you have to decrease the heat leaving the second floor to the outside and attic, or increase the amount of heat entering until there is a balance, and the second floor temperature remains constant at the thermostat setpoint.