Swamp cooler recommendations?

[SecondCor521]

No particular reason other than I've been told that's a Bad Thing To Do (tm).

The house is roughly 1700 square feet, so the main floor is ~1500 square feet and the upstairs room is ~200 square feet.

I might try slightly closing all of the downstairs vents. Right now they're all wide open throughout the whole house.

 

[Amethyst]

I figured it was mostly labor and mark-up. If we decide to do it, and I suspect we will, we will shop around. A/C is probably one of Florida's biggest industries.

I realize OP is not in Florida..just figured I'd throw the mini-split out there, since I've just now learned of their existence.

I don't know if $3-5K would be a reasonable total charge, but I can get a decent 9000-BTU/hr mini-split for less than $900, and with a SEER of 22.

In the same capacity, the top-of-the-line Panasonic unit with an astounding SEER of 31 costs $1,500, while a Panasonic with a pedestrian SEER of 16 is only $750.

You need a hole of about 1.5" diameter to run the refrigerant lines through the wall.

 

[Just_Steve]

Just install a zone damper and thermostat upstairs. Create a two zone system.

 

[NW-Bound]

The house is roughly 1700 square feet, so the main floor is ~1500 square feet and the upstairs room is ~200 square feet.

I might try slightly closing all of the downstairs vents. Right now they're all wide open throughout the whole house.

Unlike the modern mini-splits that are of variable speed design, older central ACs run at only one speed. When there's not enough airflow to remove all that "coolness" that is supplied, the evaporator gets too cold and will ice up when the condensation freezes up instead of draining off as water. That effect is reversible and does not cause any permanent damage.

Some installations may have a remote room serviced by a long duct that does not carry enough airflow. In your case, that is likely the case, plus that bonus room is the one that gets the most heat gained from the exterior.

One way to boost the airflow is using an inline duct fan to help move more air to a specific room. Whether such a fan can be easily installed or not depends on the accessibility of the duct that services that room.

 

[SecondCor521]

I'll have to take a look and see. As is typical for houses around here, the bonus room is immediately above the garage. There are four A/C vents into the bonus room via the floor. The blower is in the garage, and the AC unit is just outside the garage on the north side of the house.

 

[NW-Bound]

If the bonus room sits directly above the blower (indoor air handler), then the room already has the shortest path to that blower, compared to rest of the home. With 4 vents, I do not see that the supply path would be inadequate.

Then, the return air has to exit the room, and finds its way back to the blower. Is it via a door or the staircase to a common return, or the room has its own dedicated air return?

 

[SecondCor521]

If the bonus room sits directly above the blower (indoor air handler), then the room already has the shortest path to that blower, compared to rest of the home. With 4 vents, I do not see that the supply path would be inadequate.

Then, the return air has to exit the room, and finds its way back to the blower. Is it via a door or the staircase to a common return, or the room has its own dedicated air return?

The room has it's own dedicated air return. It's a square vent about 14" on a side. In the ceiling, near the door.

 

[SecondCor521]

The other thing that I think may contribute to the heat problem up there is that there is no gable vent for that part of the attic above the bonus room.

The bonus room is aligned East/West and the window and gable without vent face West.

The main house is aligned North/South and there is a gable vent on the North and a gable vent on the South.

(There are roof vents that appear to be adequate on both roof ridge lines.)

 

[NW-Bound]

The room has it's own dedicated air return. It's a square vent about 14" on a side. In the ceiling, near the door.

Then, it should have the best airflow in the house. Can you feel the air movement in/out of these vents, and compare that to the ones inside the house?

Assuming that there's sufficient airflow when the blower is on, then the problem is caused by the bonus room getting heat gain that the main house does not. This causes a temperature imbalance that can only be remedied by having giving the bonus room its own AC.

If the main house is sufficiently cooled so that the thermostat tells the AC to shut down, yet the bonus room keeps getting heated up, all the vents for the bonus room will not help any if the AC does not even turn on.

And if you relocate the thermostat to the bonus room to control its temperature better, then when the AC runs to cool the bonus room, the main house will get too cold because it does not suffer from the same heat gain.

You can close down the vents in the main home in order to equalize the "coolness" supply to match the difference in heat gain.

Or you can put the blower on "Fan" to circulate the air throughout the house to equalize the temperature, but this costs electricity and may not help enough.

The only real solution is to provide the bonus room with its own AC. If you can mount a small window AC, that will be the cheapest and quickest solution.

 

[Just_Steve]

 

[SecondCor521]

Right. This is what I was thinking of earlier with my "Ask This Old House" comment. Thoughts on cost to convert a single zone system to a dual zone system? House was built in 2004 and probably has a standard efficiency air conditioner that seems to be properly sized.

@NW-Steve, right. You've described the problem. Running the blower fan helps, but there is still too much of a temperature differential on some days. The bonus room does get enough air flow I think. I'll check again.

I'm not keen on a window-mounted A/C unit. It'd be right on the front of the house and I have an HOA that would probably frown on it. (There's nothing inherently wrong or bad about them, but around here they're typically viewed as, uh, low-rent type things.) Also, the window opens horizontally so I think I'd have to have a platform. Finally, it would just look ugly on the front of my house.

For now I'm going to try to block the heat gain in through the bonus room window and see how much that helps.

 

[Jerry1]

I would have a heating and cooling company look at installing one of these. We had one and it worked great. We had a three season porch that we wanted to use year round so we ran ductwork out to it. The company added one of these fans in line and it pushed a good deal of extra air into the porch.

The other thing to do is keep the door in the bonus room shut and the window covered. Covering the window reduces heat gain and keeping the door shut keeps the air in the room. Remember, heat rises. That means cold air sinks. Closing the door reduces this convection. You can also see if the walls are insulated. Since they are likely inside the attic they may not have been insulated. Insulating them will reduce the radiant heat from the attic.

 

[NW-Bound]

The zone damper shown by Just_Steve is interesting. It converts a single unit into a dual-zone one. Retrofitting one into an existing system would depend on how the original duct work is laid out, I think.

I understand about the reluctance towards the ungainly window AC. Then, you may also rule out the portable AC, although its vent is not as obtrusive as the window AC. Instead of venting via the front window, perhaps it can be vented through the wall on the side, or towards the rear if possible.

Or you may consider this unit that I recently ran across. It is like a dual-hose portable AC, except that it is mounted externally to the home, and the cool air and return air are piped in via hoses. You will need a platform to mount it.

 

[ERD50]

...

I'm not keen on a window-mounted A/C unit. It'd be right on the front of the house and I have an HOA that would probably frown on it. (There's nothing inherently wrong or bad about them, but around here they're typically viewed as, uh, low-rent type things.) Also, the window opens horizontally so I think I'd have to have a platform. Finally, it would just look ugly on the front of my house.

For now I'm going to try to block the heat gain in through the bonus room window and see how much that helps.

In addition to blocking the heat gain (helps for all cases), have you tried setting the blower fan to run continuously (EDIT- I see you did mention that in # 36 - try with the ducts adjusted as well, shutting off some of the flow to the colder rooms)? Our (very) old A/C with the old Honeywell round, basic thermostat could be set to "ON" instead of "AUTO", and it would run continuously at a low speed, then go to the higher speed when the A/C cycled. We set that overnight, and it helped a lot.

Our new A/C, with fancy thermostat has a mode that can be set to run at low speed XX minutes out of every hour. It accounts for the A/C running, and will only add low speed circulation if it's been off a while.

Both cases helped keep our upstairs more even with the downstairs (where the thermostat was/is). It evens the temperature for the hot room to the colder rooms. I think most modern thermostats have some level of capability for this.

If you try the zone system, you might still run into the frozen coils that NW-Bound warned of. Maybe those systems detect that and adjust the airflow accordingly? I'd ask about that if you go that route.

One more option that might be acceptable in appearance - rather than putting a small window unit in the window, have a hole cut in the wall for it. That might allow you to put it on a less noticeable area of the wall, and it looks better when the window lines aren't messed with. You might even be able to paint it or build a decorative panel around it so it is even less obvious? I've seen this done, and it is a big step up from being in the window. (edit - I see NW-Bound also suggested this for portable A/C venting - a similar option)

-ERD50

 

[NW-Bound]

... Our new A/C, with fancy thermostat has a mode that can be set to run at low speed XX minutes out of every hour. It accounts for the A/C running, and will only add low speed circulation if it's been off a while...

This is something I am looking for myself, in order to equalize the upstairs/downstairs temperatures when I want only the newly installed 1.5-ton minisplit running and not the main central 5-ton AC.

I switched the central blower to "On" to run the circulation continuously, and found out that the motor burns between 400W and 500W. It's a big load to leave on 24 hours.

I could build my own auxiliary control box mounted next to the thermostat with a knob to select different fan duty cycles: 1, 1/2, 1/3, 1/4, 1/5, with an interval unit of 5 minutes. It can be done with a simple microcontroller driving a small relay tied to the fan lines, but I still have other things to take care of.

If I can buy a thermostat with the above function, that would be great.


PS. My niece gave me a Nest thermostat, and I have not even opened it up in 2 years. It may have that function!

 

[ERD50]

...
If I can buy a thermostat with the above function, that would be great.


PS. My niece gave me a Nest thermostat, and I have not even opened it up in 2 years. It may have that function!

Check it out, I'd imagine it does.

Our thermostat is branded as "Trane", but I imagine it is made for them and they slap their name on it? It does many things well, but the UI for the most basic things is stunningly awful.

I'm kicking myself for not complaining to the installer shortly after we got it, I really should have demanded to have a different thermostat installed, this one is just awful. The most common changes, like oh... changing the temperature... take multiply prods and pokes at tiny little targets with tiny little text and not much hinting as to what you need to do. You just have to memorize it. And sometimes long delays between pokes and prods, so you aren't quite sure if you are doing it right, since you don;t get good feedback. My adult daughter couldn't figure it out when she stayed over when we were out.

And why do we need a 'sleep' screen saver on an LCD?And in sleep mode, it only shows the current temperature, not the set temperature. Hey, I already know if I'm hot or cold, I don't need a thermometer to tell me that, I want to know what it is set at to know if I want to change it.

I could go on, but I won't. It's almost amazing how many things they could do wrong, they must have had a contest!

-ERD50

 

[SecondCor521]

@Jerry1, yes, the bonus room walls, floors, and ceilings are insulated. Insulated adequately? Not sure, but from what I can tell (from other things I've looked at) the insulation installer did a reasonably decent mid-priced job of it.

@ERD50, yup, running the fan all the time does even out the temperature difference. Usually my son does a combination of lowering the A/C upper limit temp and turn the fan on. I don't know the electricity cost of just the blower fan. Presumably 0 < fan < A/C.

 

[ERD50]

I don't know the electricity cost of just the blower fan. Presumably 0 < fan < A/C.

By definition it is less than the A/C plus fan, since the fan runs when A/C is on. Also, the "ON"/"circulate" setting runs the fan at a slow (low power) speed, and A/C probably runs it at the high speed, so a further reduction.

But it is also running longer, but I still think it would be a pretty small increase overall. Those A/C compressors are what really suck the power. The fan runs on 120V/15A circuit, the compressor needs 240V hi-amp circuits.

-ERD50

 

[Big_Hitter]

Is there any way to put some sort of diversion flap in the main A/C system so that it preferentially sends conditioned air to a subset of vents? I thought I saw something like that on Ask This Old House one time.

yes, we had something like this in our house in Houston - you could shut off entire ducts

 

[Just_Steve]

I haven't. But my bedroom is on the main floor.

My son living in the bonus room has. (I have given him permission to adjust the thermostat.)

...

Thanks for all the replies and suggestions. Additional question: Is there any way to put some sort of diversion flap in the main A/C system so that it preferentially sends conditioned air to a subset of vents? I thought I saw something like that on Ask This Old House one time.

 

[NW-Bound]

Check it out, I'd imagine it does...

The Nest that I was gifted, T3007ES, does have some function like that, according to the Web.

But I recall my son complaining about it. Because it is a "smart" thermostat, you cannot tell it to absolutely raise the temperature for the peak-demand period. You can only "suggest" that it does so. And you have to play with the setting for its "learning brain" to do what you really want. My son said he had to observe what it did, then guessed what change he had to make so that it would raise the temperature at the right time that he wanted.

Nope. Not for me. I want a deterministic thermostat, that I can set exactly to avoid 3x the rate during peak hours. None of this "dumb-ass smartness" for me.

 

[ERD50]

The Nest that I was gifted, T3007ES, does have some function like that, according to the Web.

But I recall my son complaining about it. Because it is a "smart" thermostat, you cannot tell it to absolutely raise the temperature for the peak-demand period. You can only "suggest" that it does so. And you have to play with the setting for its "learning brain" to do what you really want. My son said he had to observe what it did, then guessed what change he had to make so that it would raise the temperature at the right time that he wanted.

Nope. Not for me. I want a deterministic thermostat, that I can set exactly to avoid 3x the rate during peak hours. None of this "dumb-ass smartness" for me.

Interesting. Though I'm pretty sure that the Nest includes a more 'old fashioned' Time-of-day/Day-of-Week schedule timer that you program manually.

My Son and his wife shut off the 'smart' function of the Nest that was in the house they bought. It kept doing completely screwy things - suddenly, it's super cold every Saturday, why? Oh yeah, two weeks ago last Saturday, the movers were here, it was unseasonably warm, so we blasted the A/C. So now the 'smart' Nest thinks they want to butcher a pig every Saturday

But I'm pretty sure they still have it adjust the temperature for their day/night/work/home schedule.

-ERD50

 

[ERD50]

At about 4:30 they have the solution to the problem that was mentioned that too little air-flow could cause a freeze-up of the coils - a 'bypass damper'. Very simple and cheap.

The bypass goes right from source to return, and will open if the pressure is high on the source side (because too many ducts are blocked). This keeps air flowing through the furnace/A/C.

Though they did it so you would not get too much noise from air rushing into a few ducts, and the cold air might still contribute to freezing, but it should help.

-ERD50

 

[RobbieB]

I got me a "retirement" thermostat.

 

[ERD50]

I got me a "retirement" thermostat.

Don't laugh, I miss mine!

That device has an excellent user interface. At a glance, and with both hands full as you walk by, carrying something, you can see all the settings, and current temperature at a glance. Temperature setting? Set to ON/OFF/COOL? Fan on AUTO or ON? Current temperature?

Any setting is directly accessible, with positive tactile feedback. It just works. No batteries, no re-booting it.

OK, it doesn't do all the other 'smart stuff' that my new thermostat (mostly) does quite a good job at. But the point is, that should all be in addition to what the old round thermostat did. There is no reason to sacrifice the access to the common settings, and the no-touch feedback, everything else should be "in addition to".

-ERD50