A look inside a Herpstat

[The Serpent Merchant]

Today I had one of my Herpstat 4's open so I could clean out dust build up. I do this every 6 months to keep everything running like new. I decided to take a picture and explain how these things work for those who are interested.



Color code:

Red: The 4 Triacs. These are what do the hard work of reducing the power going to each output. Each Triac has a heat sink as they can generate a fair amount of heat.

Orange: The Internal Temperature sensor. This tells the herpstat if it needs to run the internal case fan or not to keep the herpstat from overheating (I've never had mine need to turn on)

Gray: Mechanical relay. This physically cuts power to the thermostat in the case of a thermostat failure (prevents the thermostat from failing in the "on" position)

Blue: This is the speaker for the alarm and beeping while navigating the various menus.

Purple: These 2 chips are the "Brain" of the thermostat

Magenta: Battery (either to keep settings in the case of power failure or for the real time clock. I'm not 100% sure but if I had to guess I would say that it is for the clock)

Yellow: Clock (for night drop functionality)

The build quality on these units is really top notch. Besides a few pins that were slightly overheated during the soldering process this board is spotless. Practically military grade.

[Mike41793]

Informative. Thanks aaron!

[Flikky]

Awesome! Great to know how things work

[John1982]

I was wondering what you use when cleaning.

[The Serpent Merchant]

I was wondering what you use when cleaning.

I use compressed nitrogen gas which passes through an Ionizer (eliminates any risk of ESD (static electricity) which is super overkill... But I already have the equipment set up for my job anyway. Good old canned air will work just fine.

[satomi325]

Great informative and interesting write up!

Sent from my DROID RAZR using Tapatalk 2

[Gio]

Really nice, informative post Aaron.

Thanks to you we have the Herp II. It's probably the most important part of out setup and certainly makes going on vacations worry free! I will probably begin a cleaning regime now because of this post.

[dav4]

Cool stuff. My relatively short term plan is to get a herpstat 4 to regulate the heat for two AP T8s that haven't been purchased yet(just don't tell my wife, please). Thanks for the write up.

[1nstinct]

this is a great post, now i will be also starting a cleaning process!

[The Serpent Merchant]

I feel I should make a few things clear so nobody kills a $300 thermostat...

1. Always unplug the unit first

2. Never touch any of the internals.

• Some of the components stay charged even after power has been disconnected. (which can give you a nasty shock)
• Your body has a static electric field that can short out sensitive components (thereby potentially killing the thermostat)

3. Never get any of the internals wet (common sense)

Dust cleaning helps to keep airflow throughout the thermostat. If dust builds up inside the components will run hotter which will decrease the lifespan of some components. (most components in a herpstat aren't really effected by this)

How often you need to dust clean will depend on a few things:

1. Air quality in your house (more dust in the air = more frequent cleanings)
2. How often the fan on the herpstat runs (When the fan runs it draws more dust in than when the fan isn't running)

Most people won't see any dust build up in the first year or so. I dust clean all of my electronics every 6 months (computer/game consoles/audio equipment/workbench equipment) If I wasn't in this practice already I would probably only check my herpstats once a year maybe even every other year. (things like computers etc. build up dust exponentially faster than something like a herpstat will)