Honeywell Heating Thermostats: My Experience With

Hello,
Have received so many really good answers to problems and questions I've posted in the past, thought I would post something positive, for once. So, I'll share my experience on this subject with everyone.
Live in Mass. in a typical 30 year old colonial with gas, forced hot water heating on two zones.
Have always had the Honeywell mechanical thermostats for each zone. The ones with the bi-metallic coiled spring with the Mercury switch vial on the top.
For 30 years, my wife was always complaining about the large temp swings that would occur in most of the rooms.
I tried playing with the heat anticipator, but nothing really changed.
Well, this year I finally broke down and put in two Honeywell digital thermostats.
All I can say is Wow. (no, I don't work for Honeywell)
No matter when you look at them, the set point is exactly the same as the resultant room temp. No more wide fluctuations. Simply terrific.
Probably due to a very tight hysterersis loop characteristic on the new thermostats. (resulting in much tighter control)
Don't like the idea that it requires a battery, but heck, I can probably remember to change it once a year.
A good question is whether I will be paying more for heat now. The old furnace mode was, of course, wide temp swings with the furnace going on and off rarely, but staying on longer.
vs.,
Now, with very frequent on-offs, but shorter actual furnace runs each time.
Have no idea how this relates to actual heating costs, or efficiency ? Comments ?
Anyway, for anyone still using the old Mercury ones, my suggestion is to really consider getting one of these new digital ones.
Bob
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I think it's just easier to maintain a smaller temperature differential with a digital than a mechanical thermostat. I have no problem with Honeywell thermostats, but I have found White Rogers thermostats work equally as well and cost significantly less.

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On Sun, 18 Nov 2007 19:38:55 -0500, "RBM" <rbm2(remove

Our White Rogers thermostat works like a charm; this is what installers put in, and I'm very pleased with ours, now entering its 5th winter.

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wrote:

I replaced my mercury-switches 8 years ago with two Honeywell Programmable thermostats (separate systems for each level). They work great and I use both A/C and heating with these. For winter I lower temperatures to low 40's at night and it's set to rise to 65-degrees when I get up at 6 AM. This temperature difference seems natural and saves a lot of energy. Set it once and forget it.
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Robert11 wrote: ...

...
You should not always trust the temperature display on thermostats:
I have found one thermostat (Carrier) that actually changed the displayed room temperature when you changed the set point without turning on the furnace! This only happened in certain situations when you increased the set point by only one degree. The furnace would not turn on and the display would change about a minute later. But it was consistent and repeatable in its behavior.
That said, almost any digital thermostat is far superior to any mechanical one.
...

It is hard to compare. It is "an apples vs. oranges" comparison: To do your cost comparison, do you compare the heating costs when you set the new thermostat to the minimum of the previous temperature swings? the maximum? or somewhere in between?

And don't forget to properly dispose of the old one. Mercury is hazardous waste and should not be put in landfill.

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The Honeywell pro models have a display adjustment where the installer can add a positive or negative offset to the displayed room temp!
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Short cycling will put more wear on components and reduce efficency a on your unit. It takes time to warm up a unit to full eficiency. How many times it runs an hour and you comfort will determine what is best. If it runs only five minutes or so then it never reaches full efficency. While you had to large a swing before you may have none now which can be adjusted with your new thermostat. Try increasing the temp differential and see what you can live with. I increase mine till im uncomfortable then cut it back a bit
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Rick Blaine wrote:

That's fine. But in this case the offset varied from minute to minute! I would call it measurement fraud.
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[snip]
The short cycling is probably costing you a little extra money. Heat is lost on start-up and shut-down and more heat is radiated from the boiler itself since it's staying at a higher average temperature. If the boiler is in the house then the radiated heat loss isn't so bad since it does help warm the house (maybe too warm in the boiler room). On the other hand, that warm air in the boiler room is getting burned by the boiler (assuming no external air supply) so some of it is lost up the vent.

It's amazing what a little applied technology can do for comfort. There are some other steps that can help with comfort and cost. Maybe you've already addressed them and the following comments won't be helpful. Then again, maybe it's time to think about a few more improvements.
How is the insulation and weather seal on the house? Assuming a normal 2 degree temperature swing, many short cycles indicate the house may be losing heat fairly rapidly. Blown in attic insulation is cheap. Windows are more work but at least inspect the caulking.
The next step is to consider replacement of that 30 year old boiler with a more efficient unit. Look at your heating costs and determine whether or not a 20 to 30% reduction in fuel use would pay for a new boiler in a reasonable period of time. Also see if your utility has rebates for installing a more efficient unit. There are some federal tax incentives for really high efficiency units but the qualifing boiler is darned expensive.
I replaced my 45 year old boiler last spring. So far I'm using about half the gas I used last year. The heat exchanger was shot so I didn't have much choice but the fuel savings weren't enough to justify boiler replacement. Fortunately, gas is still relatively cheap locally. Your situation may be a little different since your gas is more than twice the price.
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Robert11 wrote:

Just last week, we had a new A/C unit installed in our house, which necessitated a new thermostat. The old Honeywell mercury deal was replaced with a Trane electronic deal, which I'm told is just a private-labeled Honeywell unit.
It seems to be able to control the furnace so that there's less than a degree of temperature swing, without causing the furnace to run too often. I agree, it's great.
I don't have any idea if it's saving me any money or not, although I did program the unit with a modified version of the "energy star" default settings it comes with (my idea of a comfortable ambient room temperature is a few degrees cooler than those programmed in by default; I also bumped up the default A/C temps a little to try to save some ducats in the summer.) I guess I'll find out over the next couple months, when I can compare this winter's gas bills to last year's.
nate
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