What kind of thermometer and where to put it?

[tucson]

We have a problem with uneven temperatures. I want to check my whole house but I don't know what kind of thermometer is accurate enough to be taken seriously by my HVAC company. I also don't know how to choose the place to put it in each room.

Is there a cheap thermometer that's accurate so I can get one for each room? Maybe at Home Depot, Lowes, Target, Ace Hardware or some other chain store so I can get it quickly? Or is there one that costs a little more but registers very quickly so I can take it from room to room?

I have a couple little inexpensive digital thermometers that I've compared to the thermostat but I can't tell if they're accurate. They're also slow to change when I move them to a different room.

Thanks for your help.

[Big Unit]

A $15 thermometer from any hardware store is accurate enough. Take readings in all rooms but you will need to let the thermometer rest in each room for at least 5 or 10 minutes to settle down.

[ampulman]

A $15 thermometer from any hardware store is accurate enough. Take readings in all rooms but you will need to let the thermometer rest in each room for at least 5 or 10 minutes to settle down.

Agree! Your local supermarket may have a decent one (with hold display) for the same price.

While they will probably be off a degree or three, the error will be insignificant, as you will be measuring the difference (a few degrees) in temperature between rooms.

If you want, you can calibrate the thermometer at 2 points; a glass of ice and water (32*), and boiling water (212).

Amp

[tucson]

Do you mean just get one and move it from room to room?

Or get one for each room, then calibrate them all so they read the same? I don't get how to do that. Won't water ruin a thermometer that has a hold display?

Since it's just a few degrees, doesn't it have to be accurate?

I must be missing something. It's one of those days.

Thanks for your help.

[Big Unit]

As Amp stated it doesn't need to be right on with the temp.. You are not looking for an average temp. at the end but a difference in temp.. Use the same thermometer and set it in one room for 10 min. write down the temp. then move it to another room for ten min., write down the temp. and keep repeating the process until you're done. Then you will be able to look at what you wrote down and see that the kitchen is 3 deg. cooler than the living room or whatever your measurements happen to be. Just be aware when doing this of heat coming through windows from sunlight or from the oven in the kitchen and so on.

[wahoo]

Why are you needing to "get back" with your HVAC company about uneven temperatures?? You may be "suffering" from simple physics, heat rises, cold air falls, and the sun comes up in the east and goes down in the west, and oh yeah, colder air blows out of the North. Have you tried simply running the HVAC unit's fan on continuous?? This usually evens out most temperature differences. I remember one gal we had that kept complaining about un-even temperatures, however once we checked it out, we found the east windows solar gain, and the west windows solar gain accounted for all the un-even temperatures. She even admitted that the home seemed to "even out" during the night! She had only 3 degress of difference, however she also refused to run the fan to compensate. Impossible to "fix".
Now if you are getting 15 to 20 degrees, then that is a horse of a different color. Just a couple is common.

[wahoo]

Oh yeah, forgot the gal who called us out on an emergency call on Thanksgiving when her CO detector went off. She had been cooking the Thanksgiving meal for 6 hours with a gas cookstove! Imagine the CO build up since she had no vent hood to the outside!

[tucson]

We got a whole new system. We told them we had a problem with uneven temperatures. They said they could fix it if we replaced most of our ductwork so we did. We also upgraded to a variable speed unit because they said it would make the system extremely quiet, save electricity and help even out the temperatures.

Now they say our house is old, our windows are old, we have too much glass, there wasn't a good place to put the return, etc, etc. We talked about all this before they did the work and they said it would not be a problem.

The rooms near the thermostat stay around 76 but our family room is very uncomfortable even with the ceiling fan on. Yesterday, it got up to around 93 outside and it was 87 in the family room according to my digital thermometer. In the summer it's much hotter out and doesn't cool off at night so it's a lot worse.

The air is very strong from the registers near the thermostat but not so much in the family room. We tried adjusting the other registers but even with them closed most of the way it only helped a little. Plus the air is so strong there that it got really loud.

I think we kept the fan on in the summer but I can't remember. We have allergies so we like to keep it circulating through the filter. It's not great though since the kitchen register is right over the stove. It blows right on you and makes it hard to use the gas stove.

[beenthere]

Sounds like they put back in the same size duct work as they took out.

Do you know if that is the case.

[wahoo]

Sounds like you have an air balance/flow problem as your variation in Temp. seems too high. Need to have them back and run an air flow check on entire house and give you a list of registers and airflow from each. Usually this will show what the problem is that is causing your variation in temps.

[threadcutter]

It sounds like your system is out of balance. I am assuming you closed floor registers in rooms where the air flow was strong in an attempt to push air to rooms where air flow was weak. This action will most often result in noise issues and does little to relieve your problem. Ask your installer if they put in balancing dampers on the take offs from the main supply trunk. This is where balancing should be done. Have you installers come back and balance the system with instruments. They should be able to give the cfm at each register.
Good Luck

[tucson]

Never heard of an air flow check but it sounds like that's what we need. Is that what I should call it when I ask them? Each time I complained they checked the unit which is on the roof and said it's fine.

The system is part hard duct and part flex. I don't think they ever balanced it. I don't know if we have balancing dampers, never heard of them.

I think they told us to adjust the registers. They replaced our old registers with ones called OBD registers. They also called them registers with butterfly dampers. They're either in the ceiling or on a wall near the ceiling.

They said the old flex duct to the family room was too small and was part of the problem. They said they'd enlarge it but it's in the attic so I'm not sure. I'll try to find out.

Thanks for the suggestions. They're really helpful.

[ampulman]

Or get one for each room, then calibrate them all so they read the same? I don't get how to do that. Won't water ruin a thermometer that has a hold display?

Since it's just a few degrees, doesn't it have to be accurate?

I must be missing something. It's one of those days.



You don't have to calibrate the thermometer. I only mentioned it in case you wanted to see how much of an error it has. Assuming a range of room temperatures of about 10 degrees, any inherent error will be of no consequence.

As water will damage any electronic instrument, only the metal stem is immersed in the hot/cold water.

Amp

[DanW13]

sounds like theres no dampers on any of the supply runs, and the duct work was not sized according to the size equipment that was installed ? Did they run a load cal on your home to show you what your home required as far as size equipment ? I bet the duct work is both undersized and oversized in most areas. Call them back to install dampers on the supply runs after they have showed you that all duct work installed is sized properly. What size equipment was in your home prior to the new equipment being installed ? Did they simply replace what you had ? Make a list of question to ask them before they come back out and do not let them leave until your satisified they have showed you on paper that the duct work and equipment is sized accordingly.

[alstar]

Balancing the system is very important to us in Minnesota; where my wife sits must be warm enough or her fingers really hurt from the cold. [This has also been a hobby for me, since I worked a couple of years installing industrial instrumentation and a few other years in statistical design of experiments.] So here goes with thermometers:

Originally, I tried a number of different thermometers: red-thread in glass, digital, and dial. For me, the best kind was the 4 inch dial thermometer, available in hardware and home stores for about $5 each. [An update on this below.] They are easier to see than red-thread in glass thermometers and cheap enough to spread around the house.

First, I put all the thermometers together on a table for a few hours. Since all areas of the house would read within ten degrees, it was not as important to calibrate them absolutely; they just had to be relatively the same. When they had settled down, I marked each one on masking tape with its deviation from the most common temperature, as "reads 1+" or "reads 3-."

Then I placed these thermometers in the various places where my wife would sit or work. Several times during the next days, I wrote down the location, the indicated temperature and the "corrected" temperature, especially when my wife was in that area. I determined that she was most comfortable at 74 F. [Always protect the raw data 'cause it's most expensive to redo the experiment from the start. BTW, there is a lot in the news this month about corrupted data.]

I had to adjust the baffles in the ducts as well as the registers in the rooms to get sufficient heated air flow in the different rooms. And even though it's just turning cold late in Minnesota this year, she seems to be comfortable for now.

[As an update to this, we have to adjust the humidity in the house as well. My new favorite meter is Springfield "Comfort Monitor" #90113-1, with dials for both temperature and humidity. An Acurite digital meter # 00891 (that is not too easy to see) has both indoor temperature and humidity and a thermocouple for outdoor temperature--or the time.]

Hopefully this has been helpful,
alstar

[tucson]

If I call it that, will they know exactly what test to do?

What instrument should they use to get cfm?

Should all the registers be wide open?

Thanks again for all your help.

[REP]

You don't have to calibrate the thermometer. I only mentioned it in case you wanted to see how much of an error it has. Assuming a range of room temperatures of about 10 degrees, any inherent error will be of no consequence.

As water will damage any electronic instrument, only the metal stem is immersed in the hot/cold water.

Amp
If you waqnted to,its not that hard to calibrate each thermometer to true temp.
You take a glass or bowl ,fill it with ice water and after a few minutes of the sensing elements in the water adjust to 32 degrees.Now all the thermometers should be the same.
very simple very easy.

[skippedover]

Tell you what. Ask them for the room-by-room Manual 'J' load calculation they did on your house. Then you can post it here and we can begin to help. But my suspicion is, they didn't do a load analysis but operated off their 'vast experience' in sizing both the equipment and the duct system. If I'm wrong, let me know but if I'm right, you didn't do your homework (Dept. of Energy and every single equipment manufacturer all state that the ONLY way to size the system is Manual 'J') and they're hacks because they're holding themselves out as pros and they don't take the first step at professionalism. Can't wait for the answer!!

[tucson]

to size the unit. But does that tell them what ductwork is needed?

[alstar]

Update on 4-13-2010:
After two months in South Florida, I find it very hard to recommend a humidity meter to go along with the thermometer. Even our Honeywell 8321 thermostat/ humidistat gives inconsistent readings.
I have two units of Springfield "Comfort Monitor" which differ by 20% RH. When I put my most consistent electronic units outside in about 90% RH [This is Florida.], some of them never recovered to read a lower RH inside.
If someone could recommend a consistent humidity meter, I would appreciate it.
Thanks,
Alstar

[bsharp]

[QUOTE=alstar;6423682]Update on 4-13-2010:
After two months in South Florida, I find it very hard to recommend a humidity meter to go along with the thermometer. Even our Honeywell 8321 thermostat/ humidistat gives inconsistent readings.
I have two units of Springfield "Comfort Monitor" which differ by 20% RH. When I put my most consistent electronic units outside in about 90% RH [This is Florida.], some of them never recovered to read a lower RH inside.
If someone could recommend a consistent humidity meter, I would appreciate it.
Thanks,
Alstar[/QUOTE

Google "sling psychrometer"