Thermostat for Variable-Speed Blower
I'm thinking of installing a digital programmable heat pump thermostat, but need one that can control a multi-stage compressor as well as a variable-speed blower. Besides the Honeywell VisionPro IAQ (YTH9421), are there any other thermostats that can control humidy by adjusting blower speed?
In other threads I saw mentioned that there are some other thermostats that compensate for high humidity by overcooling, but which do not actually control blower speed. As my system has a variable speed blower, I am only interested in thermostats that can actually control blower speed.
Does anyone know if the Carrier Infinity control can be used with non-Carrier systems - like a Lennox?
BTW: I would have thrown this question out to the "Controls" forum, but the people who frequent that forum seem to be mainly interested in controls for commercial systems.
What is a "non-proprietary" connection for controlling blower speed?
Good question. The blower on my unit is definitely variable. It runs at different speeds under different conditions, and does this without the need for manual intervention (e.g. changing jumpers). But, I am unsure whether or not this control is achieved in a non-prorietary way.
Originally Posted by a0128958
What is the usual way for thermostats, such as the aforementioned Honeywell VisionPro IAQ, to control variable-speed blowers? Are there extra wires involved to accomplish this? Is the speed of the blower continuously variable, or are there several specific blower speeds from which the thermostat must choose?
Lennox HP21 H.P. with CB21-51/65-1P Air Handler
The current system is as follows:
Originally Posted by beenthere
Outdoor Unit: Lennox HP21-511-3P
Indoor Unit: Lennox CB21-51/65-1P
Thermostat: Couldn't find a model on it. (Mechanical)
Humidistat: Lennox "EfficiencyPlus" (Mechanical)
It is my understanding that the current humidistat controls blower speed to achieve the desired level of dehumidification. However, it is not infinitely-variable. The "Engineering Data" document (#210055) I have on the air handler explains that the controller on the ECM motor makes available 12 different speeds. From these 12 available speeds, the installer or service technician must field-select three speeds that are actually used:
1 - Heat
2 - High Cool
3 - Low Cool (or continuous fan)
So, is this how current variable-speed blowers are controlled as well, or is their speed infinitely variable?