Thermostat question

A couple of years ago the furnace was replaced and a new thermostat installed. The new thermostat is identical to the old one. The temperature never reaches the setpoint. Currently the temperature reaches about 70 degrees with the setting at 73. Also the new furnace seems to cycle on and off more frequently than the old one. The new one is a much higher efficiency. Should I try a new thermostat or reinstall the old one? Or just accept the bias? The old one had a wider "span" setting.

Reply to
Ronald'
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If you're getting the room temperature reading off of the thermostat, and not a remote thermometer, I'd say you have a bad unit. I'd try the old one

Reply to
RBM

Depending on the thermostat, you may be able to adjust those factors. Do you have the manual that came with the thermostat? If not try the manufacturer's web site and see if they have a downloadable manual.

Reply to
Joseph Meehan

If you have a Honeywell mercury thermostat, Make sure it is level. A slight "tilt" will change the settings.

---MIKE---

Reply to
---MIKE---

Ronald,

You say that the temp never reaches the setpoint but you also say that the furnace is "cycling". What is causing the furnace to shut off before it reaches the setpoint? Remove the thermostat and jumper the heating wires. Does the furnace cycle or does it keep running. If the furnace shuts off call a furnace guy. If the furnace doesn't cycle then the problem is with the thermostat.

Dave M.

Reply to
David Martel

Ever see a mercury thermostat with adaptive recovery?

Reply to
trader4

Ooops, wrong thread, my bad! But still, he said it was a new thermostat. They stopped selling mercury thermostats a long time ago.

Reply to
trader4

This is a mercury thermostat and was "new" with the installation of the furnace 2 years ago.

Reply to
Ronald'

I assume you spend more than fifty bucks for the new furnace? Why not spend another thirty bucks and get a thermostat using technology from this century? Why the eight dollar thermostat?

Reply to
AZ Nomad

It's the basic Honeywell round thermostat.

Reply to
Ronald'

I think I would opt for a more modern thermostat. However it is still possible to be a furnace problem. They will shut down if they sense an overheat situation in the furnance.

Reply to
Joseph Meehan

Well, you learn something new everyday. I thought mercury thermostats had been totally phased out. But it looks like only some states have passed laws banning them and they can still be sold in other states. It amazes me that there isn't a FED ban on them by now, as mercury is a hazardous waste and this is an application where it can easily be replaced. Also kind of amazing that with a new furnace install, they wouldn't give you at least a cheap programmable.

So, I agree with Mike and would check that it's level, because if it is not, this is the problem that results.

Reply to
trader4

It is also possible it is reaching the "set point" but not the indicated point. Some cheap thermostats never read quite right. What is the actual temperature from a real thermometer? Maybe it should be swapped out for a good programmable model.

Reply to
Edwin Pawlowski

The height of seventeenth century technology.

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Reply to
AZ Nomad

The actual temperature is exactly the same as indicated on the thermostat - measured with 2 different thermometers. The last I looked, this thermostat was commonly sold in stores. I called the outfit that installed the furnace. They now supply a different brand and type of thermostat. It seems that I will be crawling out of the dark ages.

Reply to
Ronald'

Yeah, but the OP might as well replace the existing thermostat with a programmable electronic one. Sensibly programmed, it will pay for itself in very short order. They're available at very low cost at many outlets including Walmart and Target. Just be sure to buy a unit suitable for your furnace/system.

This may solve all of his problems. If it doesn't, there may be a seperate issue causing the furnace to cycle and that will have to be investigated.

But there's a good chance a new thermostat will fix the problem and save money.

Reply to
Malcolm Hoar

Ooops, wrong thread, my bad! But still, he said it was a new thermostat. They stopped selling mercury thermostats a long time ago.

Reply to
TH

In that case, the indicator dial is probably off. Set it to 76 to reach 73. Problem solved.

Best bet is still a programmable if you want to save some heating money. In my house, they go up to 70 degrees first thing in the morning, then drop back to 68 for the rest of the day, then to 64 at night for comfortable sleeping. The heat comes on 15 minutes before I get out of bed. Works well.

Reply to
Edwin Pawlowski

Programmable is the way to go. We had an old mercury t-stat when we bought our place and had problems getting the temperature set. It would usually get hotter than the preset temperature. The programmable we have now is dead nuts on. Very consistent. It's set for 68 when we're home and that's the reading we get on the t-stat unit in the hallway and on the thermometer in the living room. I love it. It pretty much paid for itself last year when natural gas prices were so high. Now we're looking at getting a new furnace this spring. Our current one is old (at least 20yrs.), but is very reliable. It's just not very efficient and I worry about the condition of the heat exchanger.

-Felder

Reply to
Felder

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