Saturday, 17 April 2021

ComfortBridge and Variable speed Heat Pump AVZC20

Hello all, long time lurker, new member. I previously worked on the commercial side designing controllers for a large HVAC company for about a decade.

Equipment:
  • Amana AVC20 Variable Speed Heat Pump
  • Goodman GMVC96 - Two stage heat, variable speed fan furnace
  • Honeywell HZ432 Zone controller with 4 zones
  • 15-20x Honeywell dampers
  • 3x Honeywell TH8320 wireless Redlink t-stats
  • 1x Honeywell TH8321 hardwired stat
  • Misc Redlink comm gear.

Setup:
  • All of the stats connect to the zone controller and only and single of each W (heating), Y (cooling), and G (fan) signals are sent to the furnace.
  • The furnace is connected to the heat pump via a 2-wire (ComfortNET, it seems) interface.
  • In heating mode, the furnace is configured to ramp up slowly to 100% (over 60 min) before eventually kicking on the gas stage(s) (60 additional min). This is done via ComfortBridge, if I am not mistaken.

I bought a variable speed unit because I want a constant temperature and humidity in my home. I expect the system to run at a constant operating point throughout the day as/when needed.
Instead, when there is a heat/cool call in any of the zones, the system ramps from a starting point and shuts off immediately when the calls are removed. It has never remained on when a call is removed, it cycles like 40 times a day. Aside from the ramping during prolonged calls, it behaves like a single stage unit.
As expected, the behavior is the same whether one or all four zones are calling.

Unfortunately, my contractor does not understand the system.

Questions:
1. How should this system behave with ComfortBridge? Should it integrate the calls over time and pick a percentage to run full time? Is there a way to get my desired operation with ComfortBridge /this system.
2. The zone controller has three W (heat) outputs and two Y (cool) outputs and the furnace has two Y and two W inputs. Would connecting two of these help with the modulation of the unit? For example, if the furnace sees one call for cool it will start at 30%, but if it sees two, it will start at 60% or whatever?
3. What is the best setup I can have with this hardware? Is there a piece to upgrade that will improve this?


source https://hvac-talk.com/vbb/threads/2228274-ComfortBridge-and-Variable-speed-Heat-Pump-AVZC20?goto=newpost

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