Another NEST thread: High velocity systems?


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Old 01-04-13, 10:35 AM
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Another NEST thread: High velocity systems?

Hi, first post here, saw a bunch of helpful NEST related answers here before so thought I'd signup and ask a question of my own!

Just recently installed a NEST myself to replace my old thermostat and for the most part I think it's working well. However, I'm finding it seems to have trouble warming the house past 19-20C. The NEST is displaying the correct current temperature, it matches with the old thermostat so I know it's not a calibration issue, but it seems to have to keep the heat running all day or for hours at night just to try bring the temperature up 0.5 degrees. We don't have a big house (around 1500 sq.ft) so I'm not sure why that is.

I called one of the local HVAC contractors and while he didn't have time to come by to look just yet, he suggested that it may have something to do with the fact that my house uses a high velocity system, with the water boiler as the heat source. He thinks that the old thermostat may have been configured differently as a result, and I should look to see if the NEST has something similar.

I've called NEST support, but they don't seem very good with anything except basic troubleshooting for NEST wifi or power connection issues and such, which I'm not having.

Relevant info:
Old Thermostat: Honeywell TH6110D1013
Wires: G W Y R
HRV: VanEE 60H
Furnace? Fan?: Temp-Mizer HV-52H

So question is, what am I looking for? The air coming out of the vents is lukewarm, so I know it's not just running the fan and not activating the heat, just not nearly as warm as I'd expect. I honestly don't know if this was the case before as I've not paid nearly as much attention to it until after I got the NEST. Is it possible it's not compatible with high-velocity systems?

Much thanks in advance!
 
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Old 01-04-13, 07:07 PM
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What your boiler temp set to?

What is your air flow temp?

Honeywell to me honestly is a better t-stat and they been around for years and is proven products, Nest is just a new kids on the block.

What was wrong with the Honeywell? If you want one to control form your phone, they make it as well.
 
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Old 01-04-13, 11:06 PM
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Boiler temp: Honestly no idea. There's a little control with buttons on the water boiler to set it from "cooler" to "hotter", but none of the lights come on. The boiler works as I'm getting hot water just fine, but I don't seem to be able to adjust or see the temp.

Air flow temp: How do I check?

I'll be honest and admit I got the NEST for the geek gadget value primarily. My friend got me a different wifi thermostat for Christmas and I traded it in for the NEST because the other one required a C wire and the NEST didn't. All the Honeywell wifi thermostats I could find at the hardware store all required a C wire, I didn't want to have to run the extra wire. Having a zigbee chip built in even though it's currently not used is also nice as I intend to explore more house automation stuff in the future. Having now read the manual for the old thermostat and discovering its early-heat/cool abilities as well as some other tricks makes me much more comfortable with returning the NEST and putting the old one back on if I have to, but I do like it for its aesthetic value as well. I'm even ok admitting to the wife she was right to tell me not to get the NEST, if I have to

Checking the various ducts and hoses, I can feel that hot water is piping to what I assume is a heat transfer sink or something in the HV-52, and the duct that's directly on top of that that leads to all the other ducts in the house definitely feels hot, but even opening one of my basement vents (shortest path from the main duct) the air coming out of it doesn't feel particularly warm. The wife doesn't think air coming out of the vents was ever particularly warm, even before I installed the NEST, so perhaps it's something with the heating system period, and not some kind of weird incompatibility?
 
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Old 01-05-13, 07:08 AM
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Honeywell are smart stats, and it does the math to figure everything out for comfort, where Nest is just a "dumb" stat..

Do you do a lot of traveling that you need the wifi to control it remotly?

I would get someone in to check your water temp, sounds like it's not working right for you, and lucky Honeywell is able to keep you comfort.
 
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Old 01-05-13, 07:28 AM
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Interesting you consider the NEST a dumb thermostat and the Honeywell a smart one, looking through the manuals I'm not sure what would make the Honeywell "smarter", it sounds like the main smart thing is the early-on heating that they both can do (honeywell not by default, nest by default). What else would there be? They do seem to be relatively simple devices with the NEST having the advantage of a much more polished interface.

We frequently travel to the city for 2-3 days at a time, so both the auto-away and the remote controllable away features are very nice for us.
 
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Old 01-05-13, 07:39 PM
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Here is something for ya on the HOneywell..

 
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Old 01-05-13, 07:50 PM
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The smart thermostats use a learning algorithm that works i'm fractions of a degree and typically take 2-4 Weeks to learn about your house. Expect them to have your epuipment running much different than what you wetter use to with a conventional thermostat. If you are worried about how your equipment is preforming then calling a technician to come take measurements would be the best course of action. If you set a program with the nest thermostat it will take it a little time to accurately balance itself while it calculates the rate your house losses and gains heat.
 
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Old 01-05-13, 07:55 PM
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Jay: Very cool thermal governer with that VisionPro thermostat! I don't think my old model has anything that sophisticated, though it does have early-on. Does that require a C wire to work? Is it much cheaper than the NEST?

jrozie: Yeah I think my concern right now is with the equipment's performance....I wonder if the local techs might balk at seeing the NEST though and blame that rather than seeing the actual problem.
 
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Old 01-05-13, 08:06 PM
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Honeywell Digital t-stat does that, and the ones you had does the feture.
 
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Old 01-05-13, 08:15 PM
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Call the technician for a system checkup instead of a problem call, have him do a temp rise to make sure it's in range and ask him to show you how to adjust the water temp.

Honeywell makes nice thermostats and the 8000 is a great one but the cost is comparible, the install is about the same, the system program can get a little complicated for people not familiar with it the 8000 especially since it Wii accommodate nearly any piece of equipment installed in a HVAC system.
 
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Old 01-09-13, 09:58 AM
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Thanks guys, I'm having someone come in this week to take a look, hopefully they won't get too bothered by all the other questions I have now that I'm looking into this stuff more closely! =)
 
 

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