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42

More than you've ever wanted to know about the C wire: Lets start by explaining what the C wire is, and why it's needed. Ye olde thermostat In the olden days thermostats were simple switch devices, that used Mercury Switches to complete the circuit and turn on the heat/AC. Mercury switches were commonly used in bimetal thermostats. The weight of the ...


13

Actually, you should be able to make them work in the UK. An electrically savvy friend of mine has one up for sale on ebay along with this note: I would suggest that only the technology savvy avid DIYer, or keen professional electrician with enough research install this item. Unfortunately because this thermostat is not intended for direct installation to ...


12

The logic involved is much more complex. Right now the logic is simple: if AC Mode and it's too hot, turn on AC, else turn off AC if Furnace mode and its too cold turn on furnace, else turn off furnace But the determination of when to switch between heating and cooling modes is much more complex - otherwise the ac would kick on, and it would get too ...


8

You are missing something. Either you have not found the correct breaker yet, or the breaker is not inside the breaker panel for your house. Walk through each breaker in the breaker planel for your house. You could have a mislabled breaker. (The breaker you are looking for is likely a two-pole 240V breaker, maybe 30 amps or better.) Since this is a ...


7

I found the manual for the old thermostat on the web. Turns out '4' is an alternative label for Rh on some old models. I guess I needed that.


7

I am assuming you own the building and can make these changes, but depending on the amount of money you want to spend: Turn down the temperature on the thermostat Move the thermostat to one of the apartments, probably in a locked box so the tenants can't actually control it, but it at least reflects the real temperature. You can also get thermostats with ...


6

I've got one that I've been using since late December. I'm not sure yet if it has helped reduce heating costs. I have to examine the bill numbers from the last two months. I also switched operating modes on the furnace when the Nest was installed. I was previously using a single stage thermostat and relying on the furnace (a Bryant furnace) to decide ...


6

One big thing to remember about Nest is that it is a low voltage thermostat. Therefore, it can't be used on a typical heating system in the UK (say) as we tend to have 240V connections to thermostats and timers. Check the voltage of your existing thermostat/timer. If it's a low voltage one then Nest should work.


6

The device you linked to will work. You are essentially converting to a SPST "thermostat" from your current DPST thermostat. Some people feel a SPST thermostat is dangerous because the heating device is always connected to a hot leg of the power mains. Both legs are disconnected with a DPST device. Yet this SPST practice is common and acceptable in many ...


5

You have to check that the thermostat is compatible with your HVAC system. Heat pumps need the emergency heat switch, multi-stage high efficiency HVAC's have multiple fan settings, and electric baseboards may have 120/240v lines instead of the 24v wires. For the lower end models, or for those seen in the far north or south, you may have a thermostat for ...


5

There are programmable thermostats that automatically switch from heat to a/c and to heat again. Some Honeywell thermostats, such as the 8000 Series, have 'auto' setting where you can program the Heat temperature and the cool temperature and the thermostat will automatically switch from heat to cool. I don't know how long they've been on the market though.


5

How did you check the vent? Mine had an open airway, but after years of use, I picked up a cleaning brush and was amazed as how much lint came out of the vent. If your dryer is anywhere other than on an outside wall, I'd pickup a cleaning kit just because they are nice to have and reduce your fire risk. Here's one from Amazon: That reminds me, I should ...


5

I also have a thermostat that requires a C wire hookup for wifi access. The spec calls for a 24 volt DC and I presently have it wired to share a 24 volt termination on my AC air handler. What I discovered was that this termination in the air handler does not provide a constant output of 24 volts. Instead, it cycles as called upon by the air handler and ...


5

Use an Add-a-Wire Device Assuming your thermostat and furnace are compatible and you're just short on conductors between them, you could use one of these add-a-wire devices. This device won't work for C wires. However, it does allow one to combine two of the other relay wires down to 1, freeing up a dedicated wire for C. For example, in a standard 4-wire ...


5

The reason furnaces (as opposed to heat pumps) keep running is to cool them back off since the burner is pretty hot. It may be a safety issue (too much undistributed heat could make the furnace hot to the touch and possibly result in a fire), but I suspect it's also done to extend the life of the furnace from large temperature swings with the side benefit of ...


5

I called a number of Central Heating contractors and also Uponor, the company that makes the controller. I was told that the clicking noise comes from the soft-fuses inside the controller trying to reset. They said box has failed and needs to be replaced by an electrician. Since the controller is the simplest model in their range, there are no diagnostic ...


5

Here are other personal experiences with using this device in The Nederlands. Below a list of problems I encountered with the product due to the fact I’m not living in the US: You can only set time by entering a US zipcode. No time support for timezones outside the US. How difficult can it be to make a basic functionality like a clock work ...


5

What you actually need is a single thermostat that has support for one or more secondary remote thermometers. I believe the Honeywell TB8220U1003 supports this via this part: As a side note, it is often necessary to properly balance your HVAC system depending on the season by adjusting the dampers to increase/reduce the airflow to certain areas based on ...


5

Some programmable thermostats do base their filter reminder on run time. However, the problem is looking at a filter, their change out period is not mentioned in runtime, it just says 'every 6 months' or something like that, so it's a little tricky to convert sometimes. The Radiothermostat 3M-50 (in your link) says: FILTER - AIR FILTER ALERT - The ...


5

Use the numbers. The position of the terminals in the wiring diagram is likely just for ease of drawing, and may not exactly model the actual device.


5

You're looking for a specification called the operating temperature range of the thermostat or router or both. This is the temperature range within which the manufacturer states that the device will function correctly. For consumer electronics like these, it's typically from 0°C (32°F) up to about 60°C (140°F) to 70°C (158°F). So if ...


4

Can you look at the furnace during the time it is blowing cold air and see if the flame is on? The thermostat has the ability to control the fan, but typically the thermostat sends a "turn heat on" signal to the furnace and the furnace controls are setup to turn the flame on for a X amount of time (to warm up the air) and then turn on the fan once the timer ...


4

Looking at your thermostat specs etc, I assume it is a basic bimetallic rotary spring operated mechanism with manual SPST switching. since you can operate it to "on" and you know the contacts close in manual mode, and when physically turned/twisted, I suggest a couple of tests to verify operation of the bi metal spring. Disconnect the electrical power. Use ...


4

Here's a good guide on thermostat wiring: http://wiki.xtronics.com/index.php/Thermostat_signals_and_wiring Most likely, all you should need to do is connect one wire to either W for heating or Y for a cooling system, and the other to R (or Rh for heating or Rc for cooling).


4

Some systems are line-voltage in which case you could get a 120V or even 240V shock from the thermostat wiring. I believe the Nest is designed for 24V systems. It does seem a bit extreme to suggest turning off the power to your entire house. I would probably settle with turning off the power to your furnace and then verifying with a non-contact voltage ...


4

You would need to hook up the nest thermostat where the wires are. This might be right next to your furnace. The nest might not work the best there. You can also buy some thermostat wire and pull it through the walls to a better location as well.


4

You want multiple zones on a single furnace. To achieve this you need more than an additional thermostat - you need electronically controlled baffles in your heating system. The way such systems work is - you have each "zone" blocked off by a baffle, and a thermostat in each zone. Both thermostats can call for heat, triggering the furnace to fire, and ...


4

I'm going to go ahead and say that YES, you can do as you propose, wiring the two thermostats in parallel. While, as others have correctly pointed out, this will not let you achieve temperature control in both the upstairs and downstairs simultaneously, I'm going to take you at your word that you simply do not want it to be uncomfortably cold in the ...


4

Home thermostats typically operate with a "dead band", a range above and below the set point that the furnace operates over. For example, if the setpoint is 68°F the furnace might turn on at 62°F and off at 71°F.


4

It's a bit high but whether it will be a problem depends on your thermostat and how it tolerates the high voltage. Also consider that the furnaces controller board is also receiving this voltage. Before you start anything else, check to see if your thermostat can be calibrated and complete this step first. To rule out the higher voltage as the cause of ...



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