Hvac control

[seem]

here is my situation

i currently have a heat pump hvac with a non-electronic thermostats. i would like to gain control of the temperature by zone in the house (4-6 zone). i would use normally opened damper to split the zone. i'm on a limited budget ( 500- 800$)

so here is my question

-what system/controller should i use? ( a thermostat with multiple sensor would be nice)( i have acces to a computer that could be used as a "server" to control everything)
- what are the easiest temp sensor to work with using that system?

i would like to have only one thermostat ( or only computer controlled with one in the hvac room that could bypass the system in case of it failing)
i would like to be able to acces the system for future home automation upgrade( web acces/phone acces, data logging of the temperature ...)
the system has to be able to control the heat pump and the electric furnace for heating and cooling, and control the damper


thanks for your help

 

[icellama21]

When you say 4-6 zones, but only one thermostat, what is your goal? Do you want to have a different temp in each zone? To turn on/off zones based on occupancy? Etc?

One thermostat will turn the heat/AC on or off based on the temperature at a single point(or an average of multiple points), and cannot control multiple zones. It will just turn the heat on/off.

You will need something else to control the zone dampers, possibly relays connected to a computer or automation system. Most VAC dampers work on 24VAC, so closing a NO damper is as simple as switching 24VAC from a transformer to the damper. With your budget it will be very hard to implement many dampers. Most duct dampers are 50-100 USD each. You may want to consider using register-dampers and improvising a control solution, there are some threads here about that.

You also need to do some research on HVAC design. Zoning a system involves more than adding dampers. You have to make sure that adequate airflow is present at your coil. Otherwise you will have freezing/overheating problems that can damage your heat pump. If you can budget it, get a zone control panel that monitors the plenum temp and will shut everything down if the temp is too extreme. In general make sure that your smallest zone is large enough to ensure adequate airflow. If not, then you need a bypass damer.

 

[SteveQ]

seem

If your goal is to reduce your energy consumption, then you might be able to close off certain rooms during the day or night by using a simple timer connected to a transformer that controls a damper. However, you must be careful not to restrict the airflow to the point of causing the heatpump to overheat or freeze up. You should be OK if you close off 1 or 2 rooms but more than that will probably cause airflow problems. Start with 1 or 2 zones and see how it works.

Steve Q

 

[seem]

i would like different heat in each zone but it was more to control occupancy based on the time of the day and days of the week
i tought about a bypass( pressure activated) to control pressure to make sure i wouldn't burn the fan but completly forgot about the coil temperature
for the zone i might turn it into 3 zone one for each level ( bedroom, family room/kitchen, basement)

 

[seem]

ok i have another question

is there a cheap controller( x10 compatible) that can recieve input from temperature sensor or any sensor(rain, humidity, light)( it can be plugged to a computer 24/7 )

if so i've found a way to make it with my tight budgetusing relay-8 and an x10 compatible thermostat and hvac controller

 

[SteveQ]

I use Homeseer software, a TI103 x10 interface, and the TEMP08. My HVAC system if fully automated. Search the Homeseer.com bulletin board. There are lots of posts about automating/ zoning an HVAC system.

Steve Q

 

[seem]

thanks a lot

 

[dpilati]

thanks a lot

Just so everyone knows - adding a zoning system "on the cheap" - can lead to premature failure of your HVAC equipment and unbelievably can lead to higher energy bills. I know - the last part is hard to believe but by closing off dampers - you can raise the pressure in the ducts and lead to increased leakage of the ducts into unconditioned space.

I've been manually closing dampers for a while and it is okay to a point. But closing off rooms completely will most likely lead to excess pressure in the other ducts. This obviously can harm the HVAC equipment and it can cause short cycling which also wastes energy.

It sucks - but the only way to probably control temps in rooms is to spend some real coin. I am building and just plunked a fair amount of extra money into a system designed to be zoned. It measures pressure and can cut the fan speed in response.

 

[broconne]

thanks a lot

Just so everyone knows - adding a zoning system "on the cheap" - can lead to premature failure of your HVAC equipment and unbelievably can lead to higher energy bills. I know - the last part is hard to believe but by closing off dampers - you can raise the pressure in the ducts and lead to increased leakage of the ducts into unconditioned space.

I've been manually closing dampers for a while and it is okay to a point. But closing off rooms completely will most likely lead to excess pressure in the other ducts. This obviously can harm the HVAC equipment and it can cause short cycling which also wastes energy.

It sucks - but the only way to probably control temps in rooms is to spend some real coin. I am building and just plunked a fair amount of extra money into a system designed to be zoned. It measures pressure and can cut the fan speed in response.

Do all variable speed systems measure the pressure and cut back in response? Or are additional systems needed?

 

[Rupp]

It's funny but it' almost like we need to go back to widow air conditioning units. They are "zoned" and can be controlled very inexpensively. Odd how the old stuff was so much more simple isn't it?

 

[drozwood90]

Well, you just need to know your limits.

I agree, if you "goof" up the system, you can mess up and break / waste $$.

However, if your system is pretty well balanced, then shutting off 40% of the ducts shouldn't cause an issue (for a properly sized system).

The issue becomes, when you do that, what happens to the pressure in the REST of the system? If this messes up your balance, then it will cause as much harm as it would good.

That's why I'm going to get a pressure sensor, ensure I am not getting too close to the trip point, make sure the manafold's temperature is not getting too high (my system will short cycle if it gets too high), then have two settings. When the zones are both on, everything is as I have it now in the house. When the other "zone" is shut down (during the night I'll be turning down / off most of the downstairs) I'll have to have the system re-tune the dampers to ensure that I do not have the "new" zone configuration out of balance.

--Dan

 

[SteveQ]

thanks a lot

Just so everyone knows - adding a zoning system "on the cheap" - can lead to premature failure of your HVAC equipment and unbelievably can lead to higher energy bills. I know - the last part is hard to believe but by closing off dampers - you can raise the pressure in the ducts and lead to increased leakage of the ducts into unconditioned space.

I agree with you, but the reality is people have been closing off registers to unused rooms for years. I see very little difference between this and using a motorized damper to achieve the same thing. I think it is important for people to "try and see" before they make a major investment. I agree with Dan. "Know your limits"! Anyone creating a do-it-yourself zoning system needs to do the homework to make sure they don't do something dangerous or stupid!

Steve Q

 

[seem]

from what i've seen since i can'T control fan speed i will have a bypass damper( to control pressure ) and i will have a place to dump the air if thing get too hot or cold damper will open in the basement and fan will start ( i have a big duct in the basement the register is 16X16) so it shoudl be enough to save the system.