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The Venstar Colortouch T7900 has the ability to cool past the cool setpoint to reach a humidity setpoint.

Taking it to a basic electric/electronic level, I'd think that these two terminals are either a signal, or a contact (or equivalent) closure. With nothing connected to them, can you read an AC or DC...

Given that the connections are called HUM+ and HUM-, maybe its putting out 24 VDC for a DC relay. Have you tried measuring a DC voltage across those connections when there is a call to dehumidify?

I'd bet on it having a centrifugal switch that's not closing (not engaging the start winding) when stopped, if it's buzzing when turned on but spins up to speed when spun manually. Other possibility...

Another reason for suggesting the relay is that it would provide isolation between the two control voltage systems (one seems to be 24vdc and the other 24vac) in the case that your problem could be...

I'd test this in steps. I would start by just connecting a 24vac control relay coil across the aux heat output and see if it activates (and doesn't blow the fuse) when aux heat is called for. If that...

Venstar Colortouch thermostats have a delayed fan off setting, up to 120 seconds.

Ultimately, it's company B's mistake and their problem. It's laudable that you're trying to patch things up to eliminate any loss, but they can't hold it against you if things don't work out due to...

I'll routinely take pictures of wiring and mounting details of anything I will be taking apart. A smartphone is handy for that.

The original question does end with "Other than the heat released from the fan and the compressor motors I mean", so that should be left out of the explanation. It's a theoretical question: where...

One question comes to mind: what is the temperature of the condensed water? Wouldn't it be warm, so it's storing some of the heat? Emptying the dehumidifier bucket (or draining the water away) would...

You could add a simple 24 vac relay (SPDT) with one set of both normally open and normally closed contacts (relays with just normally closed contacts are rare). This relay's coil would be across the...

Getting back to wire nuts, last summer I was surprised to see ceramic wire nuts, in an old brass lighting fixture. Solid ceramic, threads and all.

Oh yes, for sure. You have the full power conducting capacity of the pole transformer and lead-in until the first overcurrent protection device (usually the main breaker) kicks in, or the weakest...

Yes, routing two cables (one from the furnace and one from the thermostat) is a good idea. Keep the same wire colors for the thermostat to furnace and heat pump signals. Allows for easily separating...

Well there are smart stats, and Wifi stats. Some are Wifi without necessarily being "smart", in the sense of making adjustments on their own based on occupancy sensing and things like that. I have a...

Yes, and the ground is a poor conductor, with resistance varying widely depending on how wet (and where) it is. It only takes as few as 10 milliamps to cause muscle contraction.

Actually you need to hop away, like a rabbit, keeping both feet together. It's the voltage gradient between your two feet that's the problem.

Assuming you can move any muscles at all, the first thing would be to put your two feet together. Otherwise, there is little you can "do".

The main return duct (16" x 8") is along the center of the house. I have added an 8" round duct, about 15 feet long, from that to the area where the stove is. A long time ago the guy cleaning my oil...

Well the primary purpose of the wood stove wasn't to serve as central heating, but more as a nice pleasant thing to use during the cold winter months in the basement. It's in a corner of the...

Thanks, that's the kind of technical answer I was looking for. The return I'd be adding would represent about 25% of the return air volume, so it wouldn't be overwhelming. I'm also looking to add...

I think that hackers have more interesting targets than thermostat servers! For the little personal information that they'd find there, I'm not worried. A bigger concern is the reliable availability...

A few notes and observations.

My own degree was in electrotechnology, instrumentation and control, hence my familiarity with relay logic, ladder logic diagrams, AND/OR logic, etc. I like to view...

Thanks for the responses so far.

I didn't really mean physical damage to the evaporator coil. The coil is right above the oil furnace heat exchanger so I know it can put up with a lot of hot air...

A quick question: what would be a ballpark figure for the maximum air temperature that can be safely passed through a heatpump evaporator (in heating mode) without running the risk damaging anything?...

What you're trying to so is similar to something we have here in Quebec, called "bi-energie", whereas the electric utility gives us a lower electricity rate year round, except when the outside...

Yes. My Whirlpool Duet front loading washer has the same type of motor (3 phase with VFD) which allows the washer to go a various speeds (for wash and spin) and reverse rotation by controlling the...

The thing with varistors is that triggering their overvoltage clamping mode degrades them over time, and they'll eventually fail, and usually short out. This is why the motor appears to fail...

In that regard, an ECM motor is much like a stepper motor, but on a larger scale.

One thing that's been popular in the woodworking hobby world is to convert wood turning lathes to variable speed. Drill presses are also the object of such conversions. One way had been to use VFDs...

Interesting responses. Thanks!

Yes, the points that come up in the various videos I've seen on the subject is that ECM motors are very expensive to replace, fail more easily, and (from an...

Hello. It's been a while since I've participated in a discussion. I do various things, electronics related, and enjoy learning the theory of operation of all kinds of stuff. One thing that's come up...

A computer is a high speed idiot. It has no intelligence, imagination, conscience, creativity, etc. It can emulate intelligence, up to the degree that you program it to do so, but it's always making...

This is what I have used to make rectangular holes and straight cuts in already installed ducts, along with a very portable 3 gal compressor. The compressor quickly runs out of air after cutting 12...

We don't have any oil fired power plants. Almost all power in Quebec is hydroelectric, the rest being some wind power. Some older places like hospitals, schools, etc that still have oil heat are...

So no indication of it being outlawed as such in your part of the world. Yes, disallowing replacements is one thing, repair is another. In reading the FAQ (in French) about repairs, minor repairs and...

Here in Quebec oil heat is being phased out, with the end of any oil furnace replacements at the end of next year. You also won't be able to repair any furnace that's more than 20 years old. Needless...

Well that's it, I'm aiming for comfort, which is more often related to RH than absolute temperature. I don't like it too cold either. I usually set the AC to cool to 25 degrees (that would be roughly...

Interesting. 5 kW is what I had in mind, since it's the minimal value I could pretty well do by running just one heat strip. I don't think I really have to aim for 50% RH. Maybe it's because I'm...

Thing is, could a heat pump that has the thermostat using it's "cool to dehumidify" function get the humidity down to 45% or 50% do that without excessively cooling the air?

One thing I forgot to...

Hello all.

It's been a while since I posted here. I have a Venstar T7900 thermostat, which is a great model. Has nice features and is very configurable. One feature it has which I had always...

Hey I'm also from the past, back in the days of (names that come to mind) Diceman, James(followed by 4 digits), Bamacracker, Benncool, Alltemp, Robo(something), etc. I sort of let my participation...

Well that's mainly it I chose this model, among other things, because it was quiet. I even looked up the condenser fan rpms in the specs as part of the process. My question was mainly about how...

Hello everyone. It's been a while since I've posted. I just had a new Carrier 25hpb6 installed, replacing my 38YXA that served me for 19 years. I notice that the new heat pump has no sound blanket...

Interesting suggestion regarding the damping material. Thanks! I'll need to push my investigation a bit farther to see if it's coming from a solid panel, like the service access. If it's the grille...

Hi All!

It's been a while since I've logged on, although I do look at the various subjects every once in a while. I was a lot more active a number of years ago, when some members with names like...

This is the document that I found which correlates the TXV part number and unit capacity:

ftp://mrpb.mingledorffs.com/techserv/mgl/2010_Spring_Service_Update_Meeting/TXVs/TXV_Whitepaper_2003.pdf
...

Thanks crymtide. Well he went and got it out of his truck stock when he came to examine the unit. They are a well known Carrier dealer in the Montreal area. Since posting, I checked that the...

Hi to all.

I have a Carrier 38YXA030 (2.5 ton) heat pump that has been running well until last week, when there was a problem with the compressor stopping due to thermal overload. The compressor...