Looking for a more sensitive thermostat

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Yes, I realize what I'm asking for will mean that my furnace/AC will be running less efficiently, but I'm willing to give this up for comfort. I've had two thermostats in two different homes over the last 15 years. One was a Robert Shaw and now I have a Honeywell, both were electronic and when they were set to their most sensitive settings which caused the furnace/AC to cycle more neither cycled as much as I wished they had. Is there a brand or maybe a particular thermostat out there that is known to be more sensitive than others?
Thanks in advance. Craig T
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CraigT wrote:

(...)
Look. Here's what's going on. I'm going to focus primarily on the furnace side for now, not the A/C side.
You have a furnace in your house that probably puts out more BTU's of heat than it should. In other words, your furnace is over-sized for your house.
What this means is that it can over-heat your house and make you uncomfortable just at the point when the thermostat tells it to shut off. Then as your house cools down, you are again uncomfortable by the coolness just at the point when the thermostat tells the furnace to turn on.
To deal with this, you have 3 options - which can be employed either individually or in any combination:
A) have the furnace put out less heat when it's on. I personally dial down the gas input to my furnace so as to modulate the intensity of the flames (exactly what you do with your barbeque) so that my furnace runs longer and this leads to a more even heat for the house. This works well for older furnaces that ARE NOT computer or electronically-controlled (these are typically 30 to 35 years old) and it can also work well for furnaces that have electronic ignition but are otherwise NOT REALLY computer-controlled (25 to 30 years old) and are likely to NOT be condensing (ie - high efficiency) type.
B) the "hysteresis" or the "span" of the thermostat can be changed (in your case - reduced). Some thermostats have the ability to set the temperature spam between when the furnace shuts off and when it comes back on. This is typically either 1, 2 or 3 degrees F. Sometimes this setting is a small switch on the back of the thermostat (ie - not typically or frequently-accessible user adjustable). When you set it to 1, the furnace cycles more frequently, but theoretically will give you a more even temperature over time. If your current thermostat does not allow you to set the SPAN, or if the span setting is fixed at either 2 or 3 degrees F, then you want to look for a thermostat that has an adjustable SPAN, or one that has a fixed span of 1 degree F.
c) run your fan continuously. If your furnace fan is always running, this will lead to a more evenly heated house and can overcome any tendency to over-shoot or under-shoot the desired temperature. The benefits of running your fan continuously in the summer are even greater, and is the preferred way to deal with keeping or maintaining the desired temperature during A/C use.
One final thought: Where you thermostat is located in your house may be the sole reason for your temperature discomfort, or at least play a major role. This has to do with air currents and circulation and there might be a better location for it in the house. An extension of this idea is that the thermal coupling of the thermostat to the wall itself may be influencing how the thermostat is sensing temperature, and placing an insulating layer between the wall and the thermostat may provide the solution you are seeking.
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My furnace or AC is not oversized, every contractor that has seen my setup has said that I'm close to being undersized. When my units run one of my complaints is that they run for so long, they do not easily overcome the sizing of my house. My house is only 10 years old and as I stated already I have the thermostat already set to its most sensitive setting. I didn't say it but it is on an interior wall. Like I said I want the heating and cooling units to cycle more often for shorter times, I do not want to listen to a fan running 24/7.
What I want to know is if there is a thermostat out there that is more sensitive than the rest or can be set to be so? Like rather than settings of 1,2,or 3 for sensitivity settings it allows for a more sensitive setting like .5?

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wrote:

A new thermostat is not going to solve the problem. If the heater is sized that it needs to run a long period to put enough heat into the house, shutting it off sooner will only make it cooler and have it work longer for the next cycle.
Why not tackle the real problem, the noise? That seems to be what is really bothering you. Perhaps you can put in a variable speed blower or otherwise change the speed of what you have. Or change a duct of vent that is making the noise. Or box in and insulate the unit.
Regardless of the thermostat, the burner has to run a given amount of time to produce the heat needed to warm your house. A more sensitive thermostat may break it into smaller periods, but it still has to run the same total time. If, in an hour it now runs 10 on, five off, you may be able to get it to run five on, but it will still have to run the same 40 minutes total.
You may want to consider putting in some supplementary heat in the room you occupy so the furnace runs less keeping the rest of the house warm. A small electric space heater will help and can be noiseless.
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Surely the change he talks about wouldn't make the furnace turn off sooner. I think it would make it turn back on sooner.

My old furnace came with a three speed blower, changed by chainging which wire was connected. Unfortunately, it was already set to the slowest speed.

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CraigT used improper usenet message composition style not only by top-poasting, but also by full-quoting:

For one thing, a 10 year-old house should be super-efficient in terms of insulation, heat loss and being sealed for air leaks and outside air infiltration. This should make it LESS likely that you'd have comfort problems caused by the cycling of your HVAC system.
Second, I'm not exactly sure what you mean when you say that your thermostat is set to it most "sensitive" setting. I'm not aware of a thermostat that has a sensitivity setting, unless this is the SPAN setting I was talking about in my previous post. Please either confirm that, or explain how this sensitivity setting works. If your current thermostat has a SPAN setting, tell us what those settings are, and which of them you've tried.

Not knowing where on earth you are, you could either be using your A/C or your furnace right now. So it would help to know which of those you'd like to fix for the moment.
As well, what type of furnace do you have? Is it forced-air natural gas? Is it a heat pump? Is it electric?

That's fine, but it could still be in a poor location. For example, is it right over or near an air supply duct or vent? Can the sun shine directly on it? Is it in a secluded corner where it can't get a good sense of ambient air temperature?

If your house is only 10 years old, then almost certainly your HVAC fan is multi-speed - or at least it's capable of multi-speed operation if it's connected to an appropriate wall-mounted control switch.
And I have news for you. If you think that you'd be more satisfied with a furnace that goes on and off every few minutes vs having a constant (and possibly quieter low-speed) fan running all the time, then you'd probably be wrong.

I would think it would be ridiculous to have a span of 0.5 degrees F.
Also -> note this:
If your thermostat has a Celcius/Farenheight setting, then it might be that if it's set to Celcius, your SPAN option of 1 would be 1 degree celcius, which is almost 2 degrees farenheight. So set your thermostat to Farenheight so that your "sensitivity" setting of 1 becomes 1 degree farenheight.
If your furnace really is undersized, then it should basically be on all the time (and not be able to bring the house up to the temperature you want). I doubt that's whats really happening, because your system appears to be cycling.
Unless you have a monster house, or your house was improperly built, insulated or ducted, then it's hard to imagine what an undersized furnace looks like for a 10 year-old house. Some ducting jobs can be horrible - wrong size ducts, poor sealing between joints, garbage left in the ductwork while the house was being built. Maybe that's your problem (assuming you have forced-air natural gas furnace that is).
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Home Guy wrote:

Of course - you asked a bunch of contractors and they all say it's undersized. That's because they all want to sell you a new furnace.
This is the standard answer for an HVAC contractor -> "You need a new system".
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That depends on how cold it is outside. The above problem would only present itself when it's really cold outside.

It used to be that HVAC guys chose to err on the side of possibly making the system too large, since that is less likely to result in bitching. But here in NJ I've seen a trend to err on the other side now with systems that are too small. One house I know of in particular is Energy Star certified, about 7 years old. Not sure exactly what role that plays in it
>Some ducting jobs can be

Yes, I've seen all that too. House I was talking about above has one register in a hallway that you can see is not connected to a duct. And two registers that are virtually right above the furnace put out almost no air. Which is hard to diagnose because the idiot former owner had the basement drywalled. Never saw anything like it. Get this. They drywalled around the furnace, hot water heaters, etc. The guy must have been paid by the hour or something with all the cuts, dips, etc. You or I would just put up a utility room around the that area because it's useless anyhow.
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" snipped-for-privacy@optonline.net" used improper usenet message composition style by unnecessarily full-quoting:

The way the OP is describing the situation, it seems that the contractors are telling him that the reason for his environmental discomfort is because is furnace is undersized (which would be a bull-shit reason for such a problem).
You will note that the OP is not posting this question in the middle of winter - and he's not complaining that his home is generally colder than he wants it to be.

And would you expect comfort problems in November with an undersized furnace?
Or in January?
We don't even know where this guy is, or that he has a nat-gas furnace.
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Christopher Young top-poasted:

It's meant to infer a klownish posting style.
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There is a secondary menu you can bring up by holding down two buttons at the same time where you can choose H1, H2, or H3, C1, C2, or C3. H1 C1 gives the shortest cyles, both running and non-running, for Heating and Cooling and coversely H3 C3 gives the longest cycles. Both elctronic thermostats I've owned had these sub menus.

What difference would it make what kind of heating and cooling I have. The system is functioning properly, just not the way I want it to. My heating and cooling bills are relatively low for the size of the house and temps are pretty consistant in every room. I am not going to spend $10,000 to replace my HVAC when all I want is a $100 thermostat. They built varying amounts of sesitivaty into thermostats so as to suit different people's comfort levels, I just want a little more cycling than the average person.

No.
No.
Is it in a secluded corner where it can't get a good

No
It is not multi-speed.

I am not looking for something wild and crazy. I'm just asking for a little more of an adjustment than the amount that the average thermostat provides.

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wrote:

Know what you mean. I don't like short cycling either. Especially noticeable when temps are very low. The Honeywell I have has a 3 degree swing range, but even set at 3 degrees it acts at about 1-to 1.5 degrees. Seems the thermostat manufacturers go for comfort to avoid complaints. Ran across this that somebody mentioned in a forum. http://www.luxproducts.com/support/TX9000TS_ENG_LARGE-SIZE.pdf
Supposedly can be set with up to 8 degree swing, but make sure.
--Vic
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On 11/25/2011 1:55 PM, Vic Smith wrote:

...
...
You read him wardsback...he does want very short cycling.
--
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Then I take it it back I said whatever. (-:
--Vic
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CraigT wrote:

Well, if you gave the make/model numbers of these thermostats, we could obtain the documentation for them on the web and figure out what the H1/C1 settings correspond to in terms of actual degrees (C or F).

Different systems (particularly heating systems) have different time-constants and different abilities to inject heat into your living space. We are talking about a feedback loop between the thermostat and the furnace (or heat-source) and you seem to have a problem about the responsiveness or over-shoot/under-shoot of this feedback loop.

So, you have a pretty basic furnace (a "builder's furnace") which is what the contractor was able to pull off the back of someone's truck and throw into the basement.
I'm going to guess that you're not the original owner of the house, and now that you've been living in it for 6 months you don't like how the HVAC system is working compared to your last house.

Go to home despot or Lowes or some other hardware store and browse through the thermostats and look for one that specifically lets you set the span or hysteresis IN TERMS OF DEGREES C or F and not some unknown parameter or value.
You might also want to do this:
Go and buy a $10 indoor digital thermometer that can track the MIN and MAX temperature and display it to you at the push of a button. Set this thermometer on the coffee table next to your favorite arm chair, wait a few hours and hit the RESET button, and leave it alone for a few days. After that, check what it recorded for the Min and Max temperature and come back here and post those numbers.
If those numbers are Min: 66 / Max: 74, then yes, you have a problem. If the numbers are 69/71, then I'd say what are you complaining about.
One final question: Have you programmed your current thermostat to turn down the temperature during the night (say, from midnight to 6 am) to something like 65 or 66, and then raise the temp up to 68 or 70 during the day?
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I asked the same thing many posts ago too. It's remarkable that we don't have the most basic info, which is exactly how big the objectionable swings are. If it's 69/70, I doubt any thermostat is going to fix the problem. If it's 69/72, then any digital thermostat will likely do much better or there is a problem other than the thermostat. And that is assuming the temp fluctuations are at the thermostat. If they are in a room remote from the thermostat, then it's very likely not a problem that any thermostat is going to fix. Essentially he's asking for a thermostat capable of holding temp range X, without telling us what X is.
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On 11/25/2011 08:17 AM, Home Guy wrote: <snip>

<snip>
Is the wall behind it sealed? If not, cold air can travel through the wall space and dramatically affect thermostat operation.
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CraigT wrote:

Hmmm, Easiest is getting the blower run on low sped all the time kicking into higher speed when heating or cooling. What style house, where is the location? Jow big? My unit in summer or winter runs 2-3 times an hour.We are comfy. Having a wireless 'stat I can move it where I want for better comfort.
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wrote:

You remind me. I wanted to get a wireless stat, but didn't want to spend the money. I think now I'm just going to get an X-10 that will only turn the furnace house-current on and off. I'd replace the "Emergency" toggle siwtch in the basement with an X-10 on-off switch, which works remotely and locally.
At the very least that will turn the furnace off when I open the window upstairs.
Any real downside to this plan?
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micky wrote:

Generally BAD idea. RISK If you have an electric furnace, you're probably ok. If you have gas, I'd worry about it. Makes me nervous to pull the plug on the control system of something that's on fire. If it's a heat pump, I'd worry about short-cycling the system and burning up the compressor. The safety systems expect to have the power on. Yes, a well-designed system will take care of that on power up...a well-designed system... But you can bet the designers/evaluators did not contemplate someone pulling the plug as a routine control input. Their bean counters were much more concerned with taking out that last penny of cost.
X10 There have been many variants of X10. My experience is with the older stuff. It's not secure. Depending on how far between the button and the switch, Whether it's on the same side of the line, noise, etc. it may or may not switch reliably. And it can switch when you least expect it. So if it's 99 reliable, you can expect that it will screw up only once in a hundred times...like once a week??? It's not the things you plan for that hurt you. It's the unexpected that causes the problems. You need to be DARNED sure that nothing bad can happen while you're not home. If you're not there to dial 911, your house will burn further down.
Compare the cost of a proper thermostat with the cost of damage to the system and/or your house.
The local control function works by supplying current when off and sensing whether anything is there. Works well for a lamp. For an electronic control, not so much. What happens when the controller gets just enough juice to fsck things up?
Try this: Hook a CFL lamp up to an appliance module and let it warm up. When you switch off the relay, the local control current charges up the cap in the CFL until the inverter turns on and flashes the lamp. There are online instructions on how to pull a component to disable this function, but you no longer have local control.
If I were gonna cobble together something with X10, I'd use an isolation relay in the control path from the existing thermostat, but before the safety mechanisms in the controller.
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