simple custom electronics HVAC interface ?

[red-beard]

How do you control the locations? There is only one A/C system and it is either on or off. I guess he could install variable remote controlled registers as well. Or He could install a second A/C unit, which might be cheaper...

[TimT]

How do you control the locations?

In hydronic systems there are zone valves which control where the heat is going. You could have a heat zone for each room in the house, which would require a thermostat in each room..

Most systems here are broken down into two or three zones..

I think forced air systems, which is what Mr. Masraum is asking about can be zoned in a similar fashion.. solenoid controlled dampers would need to be installed etc..

Retrofitting something like this may not be cost effective...

[javadog]

If your system can't accomodate two stats, go ahead and add the second one and run the wire to the unit. Pull the old stat wires off and attach the new wires. Nest xinter, swap the wires again and make the downstairs stat functional. 5 minutes, twice a year and your problem is solved. You still may need to do a little air balancing. with the registers.

JR

[masraum]

Originally Posted by TimT

In hydronic systems there are zone valves which control where the heat is going. You could have a heat zone for each room in the house, which would require a thermostat in each room..

Most systems here are broken down into two or three zones..

I think forced air systems, which is what Mr. Masraum is asking about can be zoned in a similar fashion.. solenoid controlled dampers would need to be installed etc..

Retrofitting something like this may not be cost effective...

I would love to go with a more modern system, but I'm not going to put that much money into this house. This house has also got Aluminum wiring, blech!

It'd be really easy to put a second thermostat in even if it's the only functional thermostat in the house.

Thanks guys.

[911pcars]

I was going to recommend adding a second HVAC thermostat upstairs too, but you said you only wanted to control the fan motor, not AC or heating, so instead I suggested adding a separate fan-controlled thermostat circuit upstairs.

I don't think adding a second thermostat will automatically switch the fan ON without also delivering cool or heated air.

Confirm this action using your primary HVAC thermostat.

Sherwood

[red-beard]

Originally Posted by masraum

. This house has also got Aluminum wiring, blech!

Have you installed the kits in each outlet? Except for the risk of an electrical fire, there isn't anything wrong with Aluminium wiring...

[dad911]

Aluminum to individual outlets? That is where it gets the bad reputation. Aluminum is common in high-current circuits like A/C, etc, and shoul be problem free if installed properly. (conductive grease)

[Porsche_monkey]

Depends on the age of the aluminum wire. The early wire was prone to cracking over time wherever it go 'nicked' during stripping. The later stuff was fine.

If you have had no issues so far then it likely won't ever be a problem. But all joints/connections should be coated in No-Al-Ox.

[masraum]

The entire house, every outlet, switch, box, everything is Al from 1967.

Because we bought the house with an FHA loan, we had to have the proper co/alr outlets put in everyplace including for GFCIs and switches. I've still had a few a couple of "sparky" incidents in the last 14 years. I've gone back through the switches and outlets (originally done by an electrician) and added noalox to all of the connections and tightened them up, and yes, I've had wire break near the end where it gets bent and unbent to wrap around connections etc....

I know that properly done Al should be fine, but in the future, I'll stick with copper since it's more robust and you don't have to worry as much that it's been "properly" done.

[fuelie600]

Ask this old house did a feature on retrofitting forced-air HVAC with zones. Clever system. Found the site by searching the this old house website. Check here:

http://www.homecomfortzones.com/mytemp.htm

[T77911S]

the Tstat should have a switch just for the fan, then when the temp gets too hot, the compressor will kick in, this will run the fan 24/7 though

i dont think you need diodes. the Tstat is just a switch, unless you have a digital one. even then, as long as the 24vac is from the same source it sould not matter. plus, the controls are AC not DC.

the foam is pricey. i paid around $600 to insulate a 400 sq foot room. but if you are going to keep the house, it may be worth it.

[red-beard]

Originally Posted by masraum

The entire house, every outlet, switch, box, everything is Al from 1967.

Because we bought the house with an FHA loan, we had to have the proper co/alr outlets put in everyplace including for GFCIs and switches. I've still had a few a couple of "sparky" incidents in the last 14 years. I've gone back through the switches and outlets (originally done by an electrician) and added noalox to all of the connections and tightened them up, and yes, I've had wire break near the end where it gets bent and unbent to wrap around connections etc....

I know that properly done Al should be fine, but in the future, I'll stick with copper since it's more robust and you don't have to worry as much that it's been "properly" done.

Al was only allowed for a couple of years in the 1960's for house wiring. NEC doesn't allow it now.

[masraum]

Originally Posted by T77911S

the Tstat should have a switch just for the fan, then when the temp gets too hot, the compressor will kick in, this will run the fan 24/7 though

i dont think you need diodes. the Tstat is just a switch, unless you have a digital one. even then, as long as the 24vac is from the same source it sould not matter. plus, the controls are AC not DC.

the foam is pricey. i paid around $600 to insulate a 400 sq foot room. but if you are going to keep the house, it may be worth it.

Right, I'd like to not have the fan running 24/7. Right now that's what I do, or I turn it on when I leave for the day and then turn it off in the evenings. It'd be nice to have something that could automatically do the trick. Moving the thermo upstairs, I think would be an improvement, but even then, I couldn't set the fan to come on based on the thermostat, it'd be the AC.

I was thinking diodes would be necessary if I had 2 sets of switches/thermostats in case one was on and then the other came on, but maybe not.

Sounds like the foam would be pricey to do our roof. I'd love to vacuum all of the old crap out of the attic and put some new insulation in. Hell, I'd think that even some foam panels between the rafters would have to help.

[masraum]

Originally Posted by red-beard

Al was only allowed for a couple of years in the 1960's for house wiring. NEC doesn't allow it now.

I guess we just got lucky!

[911pcars]

Another suggestion. Install a whole house fan or even a ceiling fan with it's own thermostat/timer. Energy usage might also be less than the HVAC fan.

Sherwood

[Dennis Kalma]

I have had the same problem, solution was to put in a Honeywell Perfect Climate system. It allows two thermostats and averages the temperature, plus it offers a bunch of other options such as running the fan 20 minutes out of every hour, all the set back stuff, humidity and ventilator controls etc.

I think they still sell them at:
http://customer.honeywell.com/techlit/PDF/50-0000s/50-8151.pdf

Easy wiring....a unit goes next to your furnace, it uses the existing 4 low voltage wires to run the head unit, I think it is just two wires to the remote temperature sensor.

It has a neat outdoor temperature feature that varies the humidity based on outside air temperature so you don't get frost on the windows, plus it monitors the run time on the fan and reminds you to replace the filter when needed.

Good system...I have two...

Dennis