Thermostat Options for Multistage Heat Pump with Dampers

[wdconnors]

I am in the process of purchasing a new house and doing a full replacement of the original HVAC system from 1997.  We've settled on a multistage heat pump system that is being engineered to allow damper control without adverse effects (heat/pressure buildup when closed, etc.).

 

I mainly want to be able to turn down a wireless thermostat in a separate room (let's say my office), close dampers where desired, and cool the single room without drastically changing the temperature in the rest of the house.

 

I am now struggling to find the best option to integrate this system.  I can control the dampers via Insteon On/Off modules with ease, but deciding on the thermostat has been a pain point.  The Insteon thermostat does not support heat pumps in addition to its reliability issues.  The Venstar + Insteon adapter seems like a decent option for main thermostat, but I'm not sure how the wireless options work, if at all.  I also see there are some abilities to integrate other wireless thermostats on the market via the network module.

 

Can anyone suggest a good way to do this and what thermostat/wireless options I should look at?

 

From a programming angle, do I need to write it out so that the main thermostat actually adjusts its set point to turn the HVAC on?  For example, main thermostat is set to 76 and I turn down a wireless thermostat to 73, I assume I then need to change the main thermostat set point to 73 so the unit comes on and the dampers close per my design.  If that's the case, should I then have it change the main thermostat set point back to 76 once the wireless set point hits 73?

[stusviews]

No matter which thermostat(s) you use, if you want the temperature in one area to be different from the temperature in another area, then you need a zoned HVAC system with a sensor, usually a thermostat, in each distinct area. BTW, zoned systems adjust dampers for each zone independently.

[wdconnors]

I'm looking to create a pseduo zoned system using programming and dampers that I can control.  In theory I could just buy a zone controller and hook the dampers and stats up to that, but I'd rather not.

[stusviews]

The wireless thermostat would need to be completely independent of the wired thermostat to be able to control the dampers AND head pump separately unless both zones are always "on." Otherwise, how could it control heat pump?

[wdconnors]

Yeah, I guess that's mainly what I am asking/trying to figure out.  In theory, I could program something like the following:

 

-Main thermostat is set to 76

-If wireless thermostat is changed to a set point lower than main thermostat, reduce main thermostat to match wireless set point (thus turning on the system) and close the dampers in the other rooms

-Once wireless thermostat hits set point, change main thermostat back to original set point and open all dampers

-If during operation the main thermostat increases 1 degree, open all dampers

 

Ultimately, I am assuming that with dampers cut off to the area where the main thermostat is mounted, it is not going to drastically change temperature which should let me control it with the above scenario/programming.

 

There's also the ability to just scrap this idea as a whole.  The dampers are a phase two installation after the new HVAC so if I change my mind on doing this, no big deal.

[larryllix]

I am not sure why you would want to change the setpoint of the main because a remote zone wants heat? Perhaps during A/C this could apply?

 

I would tend to think to set up your "serious" and hardwired thermostat to do as it pleases and just control dampers with other remote zone stats to open close the dampers for each area.

This is provided the main area stat has the highest temp demand and/or the naturally warmest area of the house . I haven't thought about A/C in this thing and completely different rules may apply. I have no zones for my A/C but the air handler runs full out to move the BTUs away from the coil and distributes well. Mind you in the last few years I have learned to keep the hydronic basement floors running with a  touch of heat while the A/C is on. My well water running through the basement floor makes it too cold and the heat is recovered to warming up the cold water before hitting the HW heater for usage anyway. Not wasted energy.

 

Two stages can be effected by wing zones opening their dampers and running the circ fan for 5-15 minutes before demanding some central heat A/C. The light heat and A/C days are the hardest to handle. Full on heat or A/C runs the fan lots and the house is usually fairly even when that happens.

[wdconnors]

Yes, this is really not going to be used in a heating scenario in any capacity (I live in Florida).  From an A/C perspective, I like to keep my office colder than the rest of the house.  Basically I'm just trying to figure out a way, again, if it at all, to keep a single room multiple degrees cooler than the rest of the house.

[larryllix]

OK. In my heating scheme each thermostat looks after it's own zone. Thermostats open the valve or damper (I have none of those), delay a bit to accommodate full open and turn on the main control for heat. As a delayed second stage now they turn on the heat/cold source. They don't interact with other zones. This can apply if you have dampers that don't fully close to accommodate A/C freeze up. Make sure the installer installs a freeze detector that cuts off the compressor. Lack of air movement could be a problem for freeze up and hurt your compressor. No matter what you do the compressor should be OK then. If the compressor cycles too much the house will just not cool enough and you will make amends.

[stusviews]

We have the front half, the rear half of our home and the media room each zoned separately. One zone panel, three thermostats. Voila!

 

Each zone is also controlled by the ISY.

 

Edit: The separate zoning for the media room was added later, no additional dampers needed, only a change in wiring. I had already installed a 4-zone panel.

[flores]

Sorry to cross post, but I did a similar thing wiring a Raspberry Pi, high voltage relay (I used the Sainsoft prewired stuff), and wiring directly to my thermostat.  I had to use a multimeter as the thermostat went to different stages to kind of reverse engineer it. 

 

Here is a script as an example that runs to my project dashboard.  https://github.com/flores/lotomation/blob/master/bin/ghetto-nest.rb

Starting on line 22 you can see how I had to wire it for my particular thermostat.  It took quite a bit of time to fiure out which pins fired and when.

 

It ended up looking like the pictures here: https://github.com/flores/lotomation#hvac-control

 

This post here talks about the temperature sensing part and has a video demo.  Maybe you can rework some of that stuff for your project?  http://forum.universal-devices.com/topic/13525-pi-1wire-interface-methods/?do=findComment&comment=120749

 

Some things I learned that I did not realize until doing it:

* It's really high voltage and potentially I am afraid about my HVAC running all day because of a bug in my code (both because of cost but more importantly fire risk!)

* the program above has some built-in safties because of the above:

** If the HVAC has been running for an hour straight, it turns off automatically and sends me a text (with a link to turn it back on if I want). 

** If the power goes out and turns back on, the relays default to off mode.  This way if I have a power outtage or the Raspberry-Pi crashes while the HVAC is on, it will kill itself and stay off.  I had to wire the relays in reverse (default off) but this is easy with the Sainsoft stuff.

 

Just ideas/sharing!

[wdconnors]

We have the front half, the rear half of our home and the media room each zoned separately. One zone panel, three thermostats. Voila!

 

Each zone is also controlled by the ISY.

 

Edit: The separate zoning for the media room was added later, no additional dampers needed, only a change in wiring. I had already installed a 4-zone panel.

 

Can you send me the thermostats, dampers, and the zone panel you installed?

[stusviews]

Can you send me the thermostats, dampers, and the zone panel you installed?

No, but I can tell you about them

 

The thermostats are INSTEON which are not heat pump compatible. But they replaced Venstar thermostats which are. The dampers are standard dampers, opened or closed. The zone panel is a Honewell Totalzone. But, there's nothing special about the system other that that it's under ISY control.

[wdconnors]

The only thing you control via the ISY is your thermostats and the subsequent programs for it to behave how you want?

 

Obviously your system is how a normal zoned system would be designed, but I feel like there are scenarios where I would want individual control of dampers without having to adjust said thermostat to have that area's damper close/open.  Are you able to do this in your current system?  I'm assuming no since the dampers and thermostats are wired to the zone controller and it makes changes based on set point.

[stusviews]

Opening a damper is useless if cooling (or heating) is not called for because nothing is flowing through the ducts. I'm not sure why you would want to shut off air to a zone while keeping the cooled (or heated) air blowing, but damper actuators can be individually controlled using an I/O Linc (or INSTEON relay if it's a line voltage actuator).

[johnnyt]

I use ISY to close dampers to my basement during ac calls and to close a damper to a room that doesn't need heat during a heat call. I use IOLincs plus a device that's not longer sold by Smarthome (forget what they called it) to sense when the stat is calling for heat or ac because my stat is not hooked into ISY. I did have one that homeseer controlled but the comms died over a year ago and I haven't pulled the trigger on a new one because I can't decide (leaning to venstar and venlink but still waiting). Don't forget to think of making things fail safe. You don't want to start your ac with fan on high and all (or too many) dampers closed because something didn't work as planned. I used normally open dampers and a killawatt power meter to make sure I wasn't causing my furnace motor to work too hard to push the air under the worse case - I put a 120v plug on my furnace line so I can run it off a UPS, and it's the kind of furnace fan (variable speed DC motor) that maintains the CFM so I can see the wattage go up when the static pressure goes up.

 

 

Sent from my iPad using Tapatalk

[stusviews]

That's a great retrofit remedy. But I'm guessing that the OP would prefer to have all contingencies in place. For example, we originally installed a 4-zone panel, but used only two zones. Then we needed a third for only one room.

[xgfreon]

I am using an Arzel hpp4 zone panel.

you install the dampers in each of your 6" runs. this works well in a home that is not already ducted separate for zoning ahead of time.

you run pneumatic tubing to each run and its controlled by the zone panel using pumps. These dampers have rubber sleaves around the whole closing mechanism to make them really close tight, no air bypass.  you can change your zones easliy by just moving one tube to another branch right at the board.

 

You can also install what is called a slave board. This can operate dampers without a call for heat or cool. you could then control a simple 2 wire thermostat to change what is happening in that one area dependent on what the rest of the system is doing. The board is very customizable. look it up.

I am an hvac contractor i can tell you that these boards alone cost me about 650.00 plus about 50.00 per damper. I have 20 dampers.