Ways to convert 5 thermostat wires into 7?

[paulbates]

I have an existing 5 conductor thermostat wire running through a crawl space that there is no real way to service.

 

The existing run has five wires, and I am putting in new heater that will require these 7:

• W1 Heat Stage 1
• W2 Heat Stage 2
• W3 Humidification (configured in the stat)
• Y Cooling Stage 1 (existing)
• G Fan
• R Return
• C Common (Power the stat)

Here is what I have found:

 

1) Venstar Add a wire gets me to 6 wires: http://www.venstar.com/Thermostats/ACC0410/

This kind of does it, by only getting me to 6 wires. To get it to work I will need to locally power 'C' at the stat to open up a wire, which is doable.

 

2) Fast-Stat, runs everything over 4 wires:  http://www.fast-stat.net/

Their model 5000 seems to be able to do it. Its more expensive than 1) above

 

3) EZIO4s ... 2 of these in concert with the existing wire should do it,  but its the most expensive option. I have no need for the left over contacts that I wouldn't use when installing it. Some day I will sell this house, and would not want to leave core HVAC on Insteon, no HVAC company will know how to service it, replace and program broken ezios.

 

4) Use the existing wire as a stringer to pull an 8 conductor wire through.  Cheapest & Tempting. Extra wire leaves the door open for 2 stage cooling some day.  But if it gets stuck on the way through I am hosed. Its pretty much a horizontal pull across an inaccessible for ~35' across joists at right angles. What has been people's success with this method, any regrets?

 

Are their other options, or what has worked for you?

[stusviews]

4) If the thermostat cable was installed before to wall were in place, then it's likely that it was stapled in place at least at each end. If it's free, then it's best to have a person at each end of the pull. My experience is that more difficult pulls require--well, experience.

 

2) I agree, the model 5000 appears appropriate.

[paulbates]

I was thinking about trying the wire pull. I also told each company that I was keeping my new stats and I needed help with the wiring. We'll see what each method costs and go from there

 

Thanks for your thoughts Stu

 

Paul

[larryllix]

Check the existing cable for free movement by two people see-sawing it back and forth to determine the possibility of pulling a larger cable through. Make sure the joint will NOT let go and the joint is no larger than the cable. This can be done by stripping each cable and leaving conductors at different lengths so that single wire joins are all staggered.

 

I would attempt to get another cable pulled in on it's own. This sometimes takes a coin size hole in drywall at turn points inside a closet or other not-so-visible spots. A stiff steel wire or electrician's fish tape can help.

 

Another thought but it only gets you one more conductor and depends on the receiving end equipment. Use two diodes, one in each W wire turned back to back so that W1 transmits positive half cycles and W2 transmits negative half cycles and then the same thing at the equipment end to split them back into two wires. My furnace has a DC motor in it and it turned out to have some inputs that are polarity sensitive, on a 24vac system, to get more logic signals into the GE motor.

[paulbates]

I think the diode solution is really all I'm getting for my money with add-a-wire and fast start. You are way ahead of me in the electronics department though. To that point on the DC motor, does that mean the diode solution possibly won't work for a DC motor?

 

The small drywall hole will work for the first part, at the stat, a drop of about 5 feet to the floor over the crawlspace. A new wire should be able to follow the existing wire that way and follow through the existing hole. The good news is that is has quite a bit of play there. It might be possible to see a new wire hanging down from the stat location in the crawls space, and find a way to reach it bring it through the access point where I can see it. hmmmm

 

I can't see the current wire once it enters the craws space from above, until it appears about 20' wire feet and 2 right angles later in a joist between the house and crawspace

 

Thank you Larry

[larryllix]

I think the diode solution is really all I'm getting for my money with add-a-wire and fast start. You are way ahead of me in the electronics department though. To that point on the DC motor, does that mean the diode solution possibly won't work for a DC motor?

 

The small drywall hole will work for the first part, at the stat, a drop of about 5 feet to the floor over the crawlspace. A new wire should be able to follow the existing wire that way and follow through the existing hole. The good news is that is has quite a bit of play there. It might be possible to see a new wire hanging down from the stat location in the crawls space, and find a way to reach it bring it through the access point where I can see it. hmmmm

 

I can't see the current wire once it enters the craws space from above, until it appears about 20' wire feet and 2 right angles later in a joist between the house and crawspace

 

Thank you Larry

My air-handler has a programmable electronic motor with 24vac "logic" inputs for multiple speeds and one is actually polarity sensitive in order to get more speeds out of less connections. It does ramping speeds and things like that right inside the motor. If your furnace has contactors that receive the thermostat signals the diodes may not work. AC relays do not have the same construction and one polarity may cause them to become pole-struck where the laminations become magnetised and one day do not let go causing the circuit to stay on. It's been a long time for me but one type has a soft metal (usually copper) barrier between the laminations in the armature (moving part) so that ferrous metal never touches ferrous metal for a good magnetic "stick" after the power is removed.

 

 

From the thermostat hole I know two ways to get there through a wall and floor plate.

- from the bottom with a stiff wire and somebody grabbing it through the thermostat hole in the  drywall. This may work from the top also.

- from the thermostat hole using a string with a small nut on it you just "dance" the weight, hitting the floor plate, until you feel it drop further and then extend it further down through the hole in the 2x? and sheeting. Always tie off each end of the string for each of your "success" sections. Make sure the weight is smaller than the hole in the floor. This may be too small to accommodate another cable anyway. You may need to drill a new and larger hole from the bottom. Flashlights and mirrors may be required to be sure you don't drill into any existing wiring. Goggles and eating wood chips on you back is fun but it can be done. Don't drop the flashlight down inside the wall! Tape and string on it if needed!

 

I would be working at each pull span until I have strings though each section. Then when all the sections of pull are tamed pull in better and stronger pull lines (nylon or steel cable?).

 

 

Edit: Correction. The input is not polarity sensitive in terms of DC polarity but rather "phase" sensitive in terms of AC voltage polarity. I had to move my main panel breaker to the other 120v leg, aligning  it's phase to make one input work.

[Teken]

If you even have any doubt in your mind about completing this task. Hire it out and pay what ever it costs to run a new cable run. The money spent will be long forgotten in a few months once the core system is in place.

 

Breaking a wire pull half way through and having to tare open 35 feet of drywall will give you 30 years of nightmares and six months in the dog house with the wife when it's 40 below.

 

 

Encrypted By: Phoenix Security Solutions

[paulbates]

Yeh, I think I will tell the HVAC company of choice to figure it in to there quote. Its 3 year same as cash financing anyway, so I can ignore the cost for a while 

[larryllix]

Yeh, I think I will tell the HVAC company of choice to figure it in to there quote. Its 3 year same as cash financing anyway, so I can ignore the cost for a while 

I always find it easier to patch my small holes in the drywall than the contractors huge holes in the drywall but that is just me and the patching (if any) can be contracted into the job. RePaint is usually "your" job either way.  I built my own home so I have a different outlook and we both have the tendinitis in our shoulders from holding nail guns over our heads.

 

A good tactician will usually find a way to fish the cable through without holes or at least small ones where they are easily manageable. eg. Who cares if a drywall patch is a little bumpy in the back of your closet behind the clothes?  Depends what you have the most of... money or time and experience. 

[paulbates]

This wall is behind a couch. The stat is mounted on the side of kitchen cabinet and the wire goes through there at 5' and then down. 

 

I tend to be around when the work is going on and volunteer for things like drywall holes. The contractor with the highest rating in my spreadsheet was also the most flexible on homeowner needs, like keeping my thermostats and wiring humidity contacts there. 

 

I travel during the week, so I don't want to start something I can't finish. And I will pay someone to go into the crawlspace to get a hold of the wire if that's what it takes. I am too tall, and probably getting too old, to be messing with that  

[larryllix]

 

I travel during the week, so I don't want to start something I can't finish. And I will pay someone to go into the crawlspace to get a hold of the wire if that's what it takes. I am too tall, and probably getting too old, to be messing with that  

I hear ya'... well most of the time.

[robocam]

You can actually use two Venstar add-a-wire units to turn 5 wires into 7. I stumbled upon your post when searching for how to wire the second add-a-wire. Does anyone have a theory on how to do it? I'm awaiting a reply from Venstar.

 

http://files.venstar.com/accessories/Acc2_SS_HR.pdf

 

In the manual, they have you combining the signals from G and Y (fan and cool from my understanding).

 

http://cache-m2.smarthome.com/manuals/304aaw.pdf

 

If I wanted to, could I use the second add-a-wire on any two other signal contacts? The manual states not to use it on the R or C terminals. For example, in addition to combining G and Y, could I combine Y2 & W2, Y2 & W, or  W2 & W? I wonder if you can add a third to convert 5 wires into 8 (leaving out the common and power but combining 2 signals on each of the remaining 3 wires).

 

 

 

I have an existing 5 conductor thermostat wire running through a crawl space that there is no real way to service.

 

The existing run has five wires, and I am putting in new heater that will require these 7:

• W1 Heat Stage 1
• W2 Heat Stage 2
• W3 Humidification (configured in the stat)
• Y Cooling Stage 1 (existing)
• G Fan
• R Return
• C Common (Power the stat)

Here is what I have found:

 

1) Venstar Add a wire gets me to 6 wires: http://www.venstar.com/Thermostats/ACC0410/

This kind of does it, by only getting me to 6 wires. To get it to work I will need to locally power 'C' at the stat to open up a wire, which is doable.

 

2) Fast-Stat, runs everything over 4 wires:  http://www.fast-stat.net/

Their model 5000 seems to be able to do it. Its more expensive than 1) above

 

3) EZIO4s ... 2 of these in concert with the existing wire should do it,  but its the most expensive option. I have no need for the left over contacts that I wouldn't use when installing it. Some day I will sell this house, and would not want to leave core HVAC on Insteon, no HVAC company will know how to service it, replace and program broken ezios.

 

4) Use the existing wire as a stringer to pull an 8 conductor wire through.  Cheapest & Tempting. Extra wire leaves the door open for 2 stage cooling some day.  But if it gets stuck on the way through I am hosed. Its pretty much a horizontal pull across an inaccessible for ~35' across joists at right angles. What has been people's success with this method, any regrets?

 

Are their other options, or what has worked for you?

[paulbates]

I had an email exchange with Venstar about add-a-wire, trying to figure that out. I was told to "just repeat the process like for G&Y".

 

However, I could not get specific directions or wires. As I was putting in new furnaces at the time, I had them pull new wire with enough conductors to do the job for both. My contractor was not promoting the add-a-wire concept and I feel better knowing that its one less thing to break.

[stusviews]

Paul,

 

After a more careful reading, I noticed that you listed both Return and Common wire. Those terms have the same meaning. Which specific thermostat are you installing?

[paulbates]

Hi Stu-

 

I may have labeled them wrong in the write up. R & C are the 24vac leads needed to power the stat. R is power and one of the leads I didn't have before. C is how the individual thermostat calls make it back... fan, heat , cool, etc.

 

I had new wire run and installed the stats a year ago.. the thread was revived today to ask about having 2 add a wires.

 

Paul

[stusviews]

Colors and code letters can be confusing. C is an abbreviation for common. The common wire is the return for power. It's the equivalent of the neutral wire. OTOH, in powerline wiring, the return is the switch leg or load wire. R is the abbreviation for red. Red is the standard color for power. Unlike powerline wiring, thermostats wiring doesn't always follow convention.

 

In any case, I'm glad you got everything wired correctly.