So this is my first year and a half in this 1962 house in NJ.
I am not sure if what I will describe makes sense or is actually expected and I don't have good scientific measures to back up my "claims" but in any case I wanted to share with you guys my "observations" and ask if this is something to follow up on.
First the description of my HVAC system and insulation:
The house is Forced air with central air. Compressor / furnace Unit is old (about 12 yrs) but in the winter and in the summer the air pressure is good (blower works well / filters changed regularly and keeping all vents open).
The air temp in winter is quite warm and in the Summer, the compressor still delivers very cold air.
New windows but older doors...attic insulated in two ways: R49 (new, put down by me last year) over the BRs, LR but only R19 (original to previous owner) over kitchen and office room and 1 Bath - as I plan to do some work there.
New siding with 1inch insulation to the outside and the house wrap.
Walls - old R13 insulation....as far I can tell by what I have seen when cutting sheetrock in a few places for new outlets etc...

ANd now for my observation:

What I am feeling is that while in Winter - the house warms up quickly and stays warm for a while...in the summer the house somehow loses the cool air rather quickly and warms up quickly, making the compressor kick in frequently.
The temps in NJ so far haven't reached high 90s but I am already concerned over how quickly the house warms up.....and wonder....if my house retains warmth in the winter rather well...why am I losing cold air in the summer?

This seems to be odd to me how much more efficient the house seems in the cold vs. heat

Any ideas ?

Thank you!

 

IMHO, I think by virtue of it being summer you will loose cooling effect more rapidly just because doors are opened more frequently and interior furnishing don't tend to absorb the cool air as they might absorb warm air. You might want to call the gas company or heating contractor to do an infered scan of your house to see where energy losses might be found.

 

You have a typical furnace system with A/C added on. That's just what I have. It is a poor system for cold air distribution as the upstairs doesn't receive the amount of cold air needed to counteract the heat of the second floor and the registers are too low.

The duct work was designed to deliver the bulk of the heated air downstairs as heat rises. This system design is just opposite of what is ideal for the summer.

One key issue.... make sure the attic is well ventilated. It doesn't matter how well the attic is insulated... the air must be kept moving.

 

Yes, what Pete says. We added a few small utility fans on the upper floor registers to help draw up the cool air. It helps a lot. But beware, if used continuously those fans will drive up you electric bill.

 

Was the attic air sealed before adding the new insulation.
What's the soffit and roof venting situation?
Any insulation in the floor joist?
What type style house is it?
Knee walls on the second floor?

 

should have mentioned: it is a ranch style house with semi-finished basement...i.e. I have insulated and closed the ceiling in the basement but walls are concrete....like the entire foundation.
It's just painted.

As for sealing attic - I admit I did just OK job.....all major gaps sealed like around the lights but didn't bother where electrical wires drop down...this however, I would imagine would be a bigger issue in Winter...since it is the hot air that raises....

 

Hi Paul,
Air sealing is effective for both summer and winter. Where the warm air is pushed up and out in the winter your ac fills your house with heavy cold air in the summer. That heavier air sinks and leaks out the lower portions of the house and is replaced by that very hot air in the attic seeping down through those electrical penetrations and other paths into your walls.

Although your heating and cooling system share the same ducts which as PJ explained, are designed more for heating then cooling, the heating and cooling BTUs are generated by entirely different engines. That is where the manual J heating and cooling calculations come in, to determine the proper size of those units. There is also a Manual (?) S I think for duct sizing as well.

A common technique used in homes with ac and heat is to open and close specific registers seasonally. But, you should have the extra capacity to start with so that closing some brings you back to proper design as opposed to insufficient air flow. Look for places where you can run more or larger supply and return ducts and put those electrical and other air leaks back onto your future to-do list.

Bud

 

Manual D for duct sizing.

Ducts for cooling need to be significantly larger than for heating simply because the temperature differential between the desired room temperature and the supply air during cooling is generally much closer than for heating. That means more air needs to be moved during cooling.

Add in that the furnace is probably twice as large (or larger) than necessary and you can easily see that a heating system may seem just fine in heating mode but inadequate when in cooling mode.

 

now it all makes more sense....very helpful explanations - this is why I keep coming to this forum....

THANK YOU!