Design Advice - Thermostat w/ Elk Integration

[vancek]

Hey Cocooners;

I'm hoping I can solicit some design advice as it relates to thermostats. I'm in the process of installing an Elk into our new office for security, door control, smokes, etc. I'd also like to seriously investigate installing thermostats. The office is 12,000sf. It has 8 roof top HVAC units, and I believe a couple of those may be zoned. There may be as many as 12 thermostats. Our HVAC contractors are doing a survey on the systems next week to map out exactly how the current system is setup, zoned, etc.

Anyway, we have a few goals with multi-tenanting in mind:

1) I'd like to be able to negotiate the set points with the tenant and control those. Ideally, the tenant could control the temp +/- 5 degrees, for example, but couldn't control outside of that range. Is this controlled by the Elk or the stats themselves?

2) I'd like to be able to automate the setpoint during off-business hours based on a schedule, with overrides based on armed / disarmed status. This should be controlled by zone, and possibly by area within a zone. In our portion of the building, for instance, the lab area will be zoned seperately. If its a weekend, I might enter the lab (through a seperate perimeter door), but would not likely go into the office area. I'd love it if it would only warm up / cool down the lab area that was being used, unless a door was opened to one of the other areas (all badge controlled).

3) What kind of communication exists between Elk and the tstats in this environment? For instance, does the elk periodically poll the temps on the tstats? If so, is that variable accessible in the rules? So, if a particular area increases above a certain temp, I could fire a notification rule? I know I can run seperate temp sensors, but why do that if we can accurately get that from the tstats...

4) We have tremendous flexibility for running cable in this building. Its a 3 year old building and good drop ceiling access, so we'll be pulling tons of cable anyway. Pulling new cable to centralize the 'brains' will not be an issue.


I've done alot of reading on the forum regarding the HEI, RCS, and Aprilaire tstats, but I'm still not sure what would be best in this environment. Most of the examples seem to involve one or two units. I realize some of the decisions will hinge on what kind of HVAC units we have. I believe they are all single stage heat and cool, but I won't know for sure until late next week.

I've also read the serial expander manual and I understand how they are wired up. From a cabling perspective, I really like the RCS units because the control unit could be centralized. This would allow me to centralize all of those units, then home run a cable to each HVAC unit and to each WDU.


Anyway, I appreciate your time and any advice you are willing to provide.

Thanks!
Vance

 

[Chakara]

I've been thinking about a thermostat hooked to the Elk as well - obviously nothing like what you are doing here though!

Anyway, poking at RP, it does appear that you can trigger a rule based on temps - even to the point of "If temp is >X or <Y then set temp to Z. It's a bit odd in that it seems you can trigger off of cooling and heating separately - not sure how that works.

The rules may get complex, but it "looks" possible. Hoping to hear back from someone who has done it - even if on a smaller scale...

 

[AutomatedOutlet]

Since you may have a combination of zoned vs. non--zoned, I think that the RCS tstat may be the way to go.

You could set rules that can have different set points of each of them but I'm not sure if you could give them a "range" for individual control.

You ideas about scheduling or based on armed/disarmed status are all fine. We do that in our building here. You could do want you want to in the lab area. It's just a matter of writing the rules to handle that.

The Elk talks to the tstats over the RS485 bus.

Yes, you could set rules to trigger events based on temperature on any termostat, keypad that has temp sensor (KP1 style), or temperature sensor.

 

[shenandoah75]

Anyway, poking at RP, it does appear that you can trigger a rule based on temps - even to the point of "If temp is >X or <Y then set temp to Z. It's a bit odd in that it seems you can trigger off of cooling and heating separately - not sure how that works.

I do this with the elk and hai tstats (2 zone). I don't want the kids / mrs taking my A/C below a certain temp (esp in cooling) in Florida during Aug-Oct ecause of the cost... So if you try to bring it to 68 for example, Elk immediatelly pulls it back up to my minimum threshold... The downside of this is that if we're planning on having a lot of people over as we are this saturday and you wanted it real cool to start with, you have to edit the elk rules temporarly via ElkRP to allow for it (unless you make that rule a little more complex using some other input/output setting as an override). I have the HAI and i may be wrong, but i don't think it has an override on the unit like the Aprilaire does. But such functionality would seem to be something which people could easily learn to use to defeat your intended purpose for the other 99% of the time pretty easily...


re: the seperate triggering, since your setpoints are generally differnet for cool/heat (i.e. we have heat set in 60s and ac in upper 70s) and the rules / "reset" point would be different - i might have misunderstood your point, but i think splitting the mode is correct...

thx
-brad

 

[vancek]

Anyway, poking at RP, it does appear that you can trigger a rule based on temps - even to the point of "If temp is >X or <Y then set temp to Z. It's a bit odd in that it seems you can trigger off of cooling and heating separately - not sure how that works.

I do this with the elk and hai tstats (2 zone). I don't want the kids / mrs taking my A/C below a certain temp (esp in cooling) in Florida during Aug-Oct ecause of the cost... So if you try to bring it to 68 for example, Elk immediatelly pulls it back up to my minimum threshold... The downside of this is that if we're planning on having a lot of people over as we are this saturday and you wanted it real cool to start with, you have to edit the elk rules temporarly via ElkRP to allow for it (unless you make that rule a little more complex using some other input/output setting as an override). I have the HAI and i may be wrong, but i don't think it has an override on the unit like the Aprilaire does. But such functionality would seem to be something which people could easily learn to use to defeat your intended purpose for the other 99% of the time pretty easily...


re: the seperate triggering, since your setpoints are generally differnet for cool/heat (i.e. we have heat set in 60s and ac in upper 70s) and the rules / "reset" point would be different - i might have misunderstood your point, but i think splitting the mode is correct...

thx
-brad

Awesome, thanks for the info guys! That helps tremendously.

Has anybody played with multiple brands of tstats and have any particular pros / cons for them? It seems like they all function pretty much the same, just curious if there's anything we should be watching out for in particular with one brand over the other.

Thanks again and happy holidays!
Vance