While variable speed would be the best option, you might also consider a 2-stage unit that would be effective and not quite as expensive.

IMPO

SR

I think it‘s a poor idea to have a communicating furnace with a non communicating AC condenser...it‘s a conundrum...if going with a single stage AC condenser like the XR16,then I would look at and price a two stage var speed high eff furnace...

https://www.trane.com/residential/en/products/gas-furnaces/s9v2-vs/

TD

Thank you very much. The guy who gave us the estimate also said a two stage A/C would have hardly any advantage over the one stage, so we didn't even get an estimate for that. He seemed very thorough with options but did not mention a whole house dehumidifier - I didn't know they existed. We run a portable dehumidifier in the basement until we need to turn on the heat, but it's loud and it would be nice to get rid of it. I'll inquire about the whole house option. The one other advantage of the variable speed A/C is that it's quieter and I want to move it to one of our bedroom walls - don't know how to tell if that would be a problem. So many options and we're pretty ignorant about this stuff!

IMO the whole house dehumidifier is a must in humid climates and also reduces heating and cooling costs since often the moist air feels too cool or too hot .

The Trane VX18 is very expensive is would be overkill for your climate. I don't understand why this contractor is saying there would be hardly advantage of a 2-stage over a single stage. My recommendation would be a 2-stage condenser like the XR17 and hold off spending the money and the electricity costs of a whole house dehumidifier.

If the budget allows, I would recommend a variable speed 95%+ efficiency furnace with a thermostat which will cool to dehumidify.

I'll have lots of questions for the contractor! But, mike_home, could you explain what you mean by "furnace with a thermostat which will cool to dehumidify." How can the furnace dehumidify? When the furnace is running we're using the humidifier. And yes, we're planning on the Trane SC95m which is 95%+ efficiency.

Some thermostats measure humidity and can be set to run when the humidity level is too high. Let's say you set the thermostat in the summer to be 75 degrees with a 50% humidity level. If the humidity level goes up to 55%, but the temperature in the room is 75 degrees, the thermostat may turn on the AC in the low stage (if you have a 2-stage AC) and run until the humidity level comes down to 50%. In the process the temperature may drop below 75 degrees. In this case the humidity level is taking precedence over the temperature. This is some times referred to as cool to dehumidify.

The cool to dehumidify works best when you have a communicating variable speed furnace and the communicating thermostat. The thermostat will slow down the blower speed to lower the humidity. The slow blower speed will minimize the drop in temperature. The set up may not be as good as a whole house dehumidifer, but in your climate it should work well. If you have a return and supply in the basement, it may eliminate the need to run your basement dehumidifer, or at least reduce the amount of operating hours.

Thanks for explaining - I think I understand better.

Note: Cool to dehumidify or whatever you want to call it / is mostly a gimmick. If paired to an inverter AC only then would it be better.

I'll tell you why: They use a 3 degree temperature band to allow the AC to run to dehumidify.

Wisconsin is primarily a 'low need' for cooling climate. So the amount of time you would have the stars align to make this function worthy of anything... well it's not likely to be much time.

Example: You set humidity function to cool with a 3 degree temp band. This means that if your set point is 75 and humidity reading is higher than set point, it will cool to 72 (3 degree temp band max on most thermostats). In an attempt to get to your humidity set point. It cools faster than it will dehumidify, because an air conditioner is designed to drop temperature. A by-product of that is *some dehumidification*.

For some 72 maybe too cold. Because an air conditioner's primary focus is to 'drop temperature' this feature is often clouded with 'over cooling' because a 2 stage air conditioner - first stage is 70% of capacity.

If your set point is 70, it would attempt to dehumidify to 67. So you're fighting a battle of over cooled versus what little bit of dehumidification you're going to get from it. If there is no heat load on the structure... which most of the time this is the case *for Wisconsin climate*. Well then all these good intentions get wasted.

I can't say that an inverter AC for Wisconsin area is worth it. But from a dehumidification stand point there is nothing better except for a dedicated whole home dehumidifier, that runs from a humidistat with it's own settings.

I can't tell you how many times I've talked with people who say 'Hey, I have my humidity set point at 50% but the humidity is reading 60% in here... I think something is wrong with this thing.'

I ask them what is the temperature set point... they say it's 74 in the room the set point is 77 and the AC is off.

Well no kidding... 3 degree band. SO the response is --- lower the temp setting.

The rebuttal to that is: That will make it TOO COLD. Well you don't get dehumidification then.

There is no dehumidification if the AC is off.

Inverters work differently. Cooling loads could be as low as 25% --- 25% of capacity of the machine. Which lessens the amount of 'over cooling' while running in dehumidification mode. Loosely referred to as a 3 degree band around temperature set point. Because? It still makes it's decision to run or not to run based off and around temperature.

A dedicated dehumidifier runs based on humidity reading. That is the difference.

Oh gosh - now I think my head is going to explode. But I appreciate all the information.

Oh gosh - now I think my head is going to explode.

LOL. Yeah the first time I had to try explain this issue it didn't go well. Explosion is probably a mild description. I've gotten better at explaining it, but if you're a newbie to these kinds of things it's alot to wrap your head around all at a once.

Realize you have the temperature set point and then a 3 degree band lower beyond that to 'attempt to' dehumidify. Once the thermostat hits a temp 3 degree lower than set point, the AC shuts off and there is no 'cool to dehumidify' beyond that... unless you drop the temperature setting further. It's a much larger challenge here in Katy, Texas because our shoulder seasons and humidity threats are larger and longer lasting. I know the issue well living here.

I think the issue would be mild for Wisconsin you may not notice it. But that only means you're likely not needing the feature to begin with??? That's something for you to decide.

You can pair this 'cool to dehumidify' feature to a single stage AC as well... but this doesn't make it work any better, as over cool is the result. The 3 degree band is adjustable to 1, 2, or 3 degrees.

Some thermostats give a larger band, but this result is still over cooling. Just so you know the trade off to *some humidity relief* is over cooling. This issue of over cooling will be more pronounced for a climate like Wisconsin... because as outside temps drop, the AC (whatever brand) the capacity goes up, marginally in cooler outdoor weather. Why? because heat transfer is easier accomplished in cooler weather. Because of that, there is more over cooling going on.