Thoughts on Nest thermostat

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stevenz

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#159999 19-Dec-2014 16:14

Bought a house with a DVS-type system in it and an accompanying thermostat, which of course is ripe for gadgetising (which I just decided is a word).

The obvious choice seems to be one of the Nest units, which aren't particularly cheap and don't _appear_ to be sold in NZ, not that that's much of a deterrent (thanks YouShop!)

Has anyone used one of these? Any thoughts\opinions\suggestions?

I still need to investigate compatibility, but they seem like a neat device and if nothing else look a lot swisher than the standard grey boxes.

Cheers.

@KnightNZ

Aredwood

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#1201307 21-Dec-2014 01:27

My understanding is that the Nest thermostats are only intended for use with proper central heating systems. Not a ventilation system that thinks it is a heating system (HRV and DVS systems). If you want to "Mod" it, Just go the Arduino route. That way you could add humidity sensing as well as temp sensing.

As a minimum the nest thermostat will need a temp sensor in the roof to match the DVS system.

And unlike a central heating system, the roof space heat is free, so no need to try and conserve it. But of course it is only available at certain times / weather conditions. While heat from a central heating system is always available. But costs money so you do need to conserve it. Therefore completely different means of control are required.

Short answer - don't bother with trying to use a nest thermostat on a DVS system

stevenz

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#1202089 22-Dec-2014 14:46

It's not a DVS as such, there's a gas heater involved in the unit somewhere. Might have to look into the Arduino idea.

@KnightNZ

Aredwood

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#1203478 24-Dec-2014 23:07

stevenz: It's not a DVS as such, there's a gas heater involved in the unit somewhere. Might have to look into the Arduino idea.

So is your system actually a ducted gas central heating system? If so then it is completely different to a DVS system. As all DVS and HRV systems do is take air from your roof space, run it through a filter, and then discharge it into your house. With typically a temp sensor in the roof and another in the house. With some simple control programming to change the fan speed.

Compared to a ducted gas system that takes air already in your house, heats it, then puts it back into your house.

You will definitely need to figure out which system you have.