House a/c issue

[homebuilt burner]

I put central air in the house last summer. It does a great job of cooling the house off. The problem is when we go to bed at night, the master bedroom is upstairs. The downstairs where the tstat is stays cool but the upstairs warms up and we wake up in the middle of the night hot. But the a/c doesn't come on.

 

[James-W]

Whoever installed the system did something wrong. Obviously, cold air falls and warm air rises. But with the proper ductwork this should not be an issue.

 

[zmaxmotorsports]

I'm sure the duct work was pre existing,no sense in blaming the furnace guy for that.
I'd try setting the fan setting to on instead of auto to keep the air moving upstairs since your stat is reading main floor temp.

 

[moserjj]

You could try this https://shop.ecobee.com/products/ecobee3 and use the remote thermostat you put upstairs to run the unit

Sent from my ONEPLUS A3000 using Tapatalk

 

[The Cobbler]

common issue in homes that weren't ducted for AC . close down some vents on the main floor, open the upstairs ones full and leave the circulation fan on continuous .

an old friend had a 2story town home, same issue. we ran a duct straight off the main trunk in the basement, thru a closet on the main floor (and thru a closet directly above) ducted it out high on the hall wall and that helped a huge amound. winter time for heating he closed it off.

 

[homebuilt burner]

So, yes there are issues with the house. Built in the 40's with hot water heat, converted to forced air in the 1990's, but still poorly insulated. The duct work was retrofitted in the chimney chase so good but not great.

I was wondering if there was away to hook a second tstat in to the upstairs? I didn't want to run the circulation fan all night. I tried that once and it seems to continue to cool, but the on switch was set to cool at the time. Would I need to turn the system off and the fan on?

 

[firworks]

I literally just installed an Ecobee 4 to deal with this exact problem. My house was built in 1964 and has central HVAC and actually still has the original York A/C unit outside!

I've been working on this issue for a few weeks now. Constant complaints from the GF about it being too hot in our bedroom. She gets up at 4AM and goes down to sleep on the couch etc. Turns out my girlfriend is a very warm sleeper. Really, she's more furnace than human. I put a temperature sensor in our bedroom and the temperature would eventually raise by almost 10 degrees when she would go in and get in bed, but obviously that doesn't effect the thermostat down in the living room so the A/C stays off.

The Ecobee3/4 comes with a remote sensor, so I have that put in the bedroom. It automagically sets up a "home" and "sleep" comfort profile. All I had to do was say to look at the remote sensor only in the "sleep" profile and the main thermostat sensor only in the "home" profile. It switches profiles at around 10PM and now our bedroom will be cold at night.

Previously we had been dealing with it by setting the Thermostat way high or way low right before bed depending on if it was Summer or Winter. I'm looking forward to nice warm nights later on this year too!

 

[yeldogt]

In some homes continuous fan is the only solution for mismatched loads. You run the risk of increasing humidity as the fan will remove any water from the evaporator each time the unit cycles.

Normally the cool air from the lower level is not enough to cool the upstairs for very long .. on warm day you will need the compressor.

The solution is zoning -- most homes have inadequate, poorly balanced ductwork .. and you are trying to push air to the hottest part of the house -- and it wants to fall to the basement.

 

[Junkman]

Had the same problem for the past 20 years, and when the A/C was originally installed, they tried to solve it with a Honeywell Tstat on the first floor and a remote tstat on the second. That didn't work out, so they reversed the tstats, and the bedroom tstat controlled heat and A/C. Still didn't work out very well, but it was better than any other solution. Finally, this year, we scrapped the whole set up, and installed a separate air handler on the second floor, and another in the basement for the first floor. The house hasn't been cold on either floor all winter. The A/C still hasn't been installed, so I don't know how that is going to work, but I have to believe that it will be better than what we previously had for the past 20 years.

 

[JerryC]

IMHO, there are two problems.
1. Keeping the GF in bed now. Window ac unit, can get it today and have it working today.
2. Fix the HVAC. No suggestions on this from me other then to get a few opinions and estimates. Maybe #1 works well enough to not need #2.

 

[SiGmA_X]

The solution is zoning -- most homes have inadequate, poorly balanced ductwork .. and you are trying to push air to the hottest part of the house -- and it wants to fall to the basement.

Yep. But it is usually a pretty substantial bill to fix it as most older HVAC units are single speed, right?

 

[yeldogt]

Yep. But it is usually a pretty substantial bill to fix it as most older HVAC units are single speed, right?

The OP just put the system in -- I guess whoever --- did not do his homework.

Most homes have oversized equipment and undersized ductwork ... most retrofits are worse as you are trying to find any location to run a duct run.

I grew up in a home with zoning -- it was done in the 50's when my parents rebuilt it. Zoning is not new and will work -- actually, modern equipment make zoning easier .. and can easily fix houses with bad ductwork.

But yes, Zoning adds cost. When I added it to my present house w/ a new system ... i believe it was around $1500.00

 

[6768rogues]

I have a 100+ year old house. Every duct has a damper so I have a winter setting (mainly first floor) and a summer setting (biased to the second floor). I always run the fan continuously when in AC mode. Otherwise rooms with large windows tend to get warm before the system kicks back on. With the fan on, the house stays uniformly comfortable.

 

[M-technik-3]

Another thought would be to install a mini split on second floor and use that as coll air sinks, or a whole house fan

 

[homebuilt burner]

I was looking at it yesterday, I think I can run ductwork from the basement through some closets and just put a small fan in line. Then I would be able to pull the cool air out of the basement at night.

 

[Weslsew]

Do you have a ceiling fan in the bedroom? That can help a lot. I would also consider adding a ductless system for the bedroom if your gf wants to sleep in a refrigerator, they are efficient and you don't have to freeze out the entire house

 

[tyme2par4]

I saw this on "This Old House" a few months back: https://try.ecoventsystems.com/

Looks like it would work for you.

 

[ptgarcia]

My house was built in 1976 and has the same problem as the OP. A combination of poor insulation and what appears to be an undersized AC for SoCal (gets up to and over 100*F routinely in the summer) leads to a typical 8*F delta between the first and second floor with the AC on. So last year I installed an Ecobee 3 smart thermostat to hopefully help with the situation. The Ecobee has two features that I really like: 1. remote sensors you can place anywhere in the house that it can use when determining inside temperature; 2. A programmable option that allows you to run the fan-only for a certain amount of time each hour. So I have mine programmed to run 10 minutes every hour (temps are still mild here, once it heats up I'll make that 15-20 minutes), and it accomplishes that in intervals of approximately 2.5 minutes run time every 15 minutes (don't know the exact frequency and duration). Keeping the air from stagnating really helps with comfort levels inside the house. The remote sensor I mounted in the master bedroom (the hottest room in the house) and have the thermostat use the sensor to calculate inside temps. Combined with a couple other adjustments to the registers I've been able to keep the wife happy enough. A couple weeks ago I added solar tint to the bedroom windows (the only windows that get direct sunlight) to further combat the heat, but eventually I need to get a professional in and be ready to plop down the big bucks to straighten the system out.

 

[firebirdparts]

Honestly, you need to leave the fan on all night. If you run a hot air return down from the top floor, you'd still need to leave the fan on all night. If you run a big cold air duct up from the basement, you'd still need to leave the fan on all night. It should be obvious why that is the case. When it gets hot upstairs, there's no reason the unit would ever come on if the thermostat is on the first floor. No amount of ductwork will help if nothing flows through it.

Now, if you move the thermostat to the 2nd floor, that will also work great, and the first floor will get a lot colder. You can throttle outlets to balance this situation and that may or may not work well for you. You wouldn't need to leave the fan any time you are willing to stay in the same room as the thermostat.

The best solution for a 2 story house is two separate systems, but you can get by.

 

[SiGmA_X]

The OP just put the system in -- I guess whoever --- did not do his homework.

Most homes have oversized equipment and undersized ductwork ... most retrofits are worse as you are trying to find any location to run a duct run.

I grew up in a home with zoning -- it was done in the 50's when my parents rebuilt it. Zoning is not new and will work -- actually, modern equipment make zoning easier .. and can easily fix houses with bad ductwork.

But yes, Zoning adds cost. When I added it to my present house w/ a new system ... i believe it was around $1500.00

Yes, I agree, it probably should have been accounted for in the OP's retrofit work. I guess it kind of depends on what exactly was installed. My 2 story house could use zoning, the upstairs gets warmer than the downstairs in all seasons. They didn't consider it when AC was added in a decade or so ago, because it would have at least doubled the cost. I doubt it would have doubled the cost in the 90s when the furnace was installed though. And doing it now unless I am mistaken would take a full replacement of the handler and AC - or doing a bypass damper but that isn't ideal. I know this isn't my thread, but I would be interested in other options. Maybe they'd work for the OP, too.

I would always consider zoning when replacing a HVAC system, like you said, the cost isn't zero but it isn't *that* much when doing a whole system replacement.

Question for the thread for both the OP and myself: Whats the feeling on zone dampers and a bypass damper for a 2 floor house with separately ducted zones that run as a single zone on an air handler that doesn't have variable speeds?

 

[6768rogues]

I would not use a duct and fan to pull basement air up at night. Unless you have a dehumidifier in your basement, you will be pulling cool but humid air up and if it causes the AC to cycle less frequently you will not get good dehumidification. Also, duct fans tend to be noisy.

 

[LS6 Tommy]

You could try this https://shop.ecobee.com/products/ecobee3 and use the remote thermostat you put upstairs to run the unit

Sent from my ONEPLUS A3000 using Tapatalk

IMO the best smart stat on the market. I wish they made a kit for hydronic zone valves...


Tommy