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rucy 12-13-2009 10:58 AM

Honeywell minizone compatiability with variable speed furnace
Heat went out Friday night and came back on and off intermittently before repairman got here. Here is what he is telling me: My Honeywell Minizone Emm-3 is not compatiable with my Rheem 5-ton variable speed furnace. It is an RGFD. Both went into service on June 2006. He says the Honeywell is single speed and it is overworking my furnance and that is most likely why they had to replace my furnace motor in August (warranty). They did not put the unit in but I am having difficulty understanding how the wrong zoning board got installed. Is it true that this zoning board can't handle a variable speed furnace?


beenthere 12-13-2009 11:54 AM

It is a single stage control panel.

Does your zone system have a bypass damper?

If it has one. Does it have a weighted arm, or is it a motorized modulating damper?

rucy 12-13-2009 12:15 PM

Each zone has a bypass damper and it is motorized, e.g., hard-wired. I am not sure if this answers the question? I do know one of the dampers is sticking and they said they would need to replace that.

beenthere 12-13-2009 12:24 PM

I believe the dampers you are talking about. Are your zone dampers. Not bypass dampers.
A bypass damper. Would allow air from the supply to return to the return duct/plenum. Instead of going to a zone.

beenthere 12-13-2009 12:25 PM

Take pics of your furnace, and the duct work near it, and post them.

rucy 12-13-2009 01:34 PM

5 Attachment(s)
here are pics. mechanical room is fairly small and cramped but hopefully the pics will help. There is a large standalone dehumidifier hooked into the system so that will explain some of the huge ducts heading downward.


rucy 12-13-2009 01:36 PM

pic # 4 is ductwork heading into dehumidifier and pic #5 is ductwork above.

beenthere 12-13-2009 01:43 PM

I don't see a bypass damper, or duct.
One will help. Generally, a modulating bypass damper is better for VS blowers.

But a barometric is better then nothing.

rucy 12-13-2009 01:51 PM

So do you think I need a different zoning board or a bypass damper or both? They are recommending a different zoning board with no mention of a bypass damper. don't want to change the board if all I need is a modulating bypass damper. What are your thoughts? I know it is not an exact science but want to make sure I am asking the right questions when talking with them.

rucy 12-13-2009 01:53 PM

Oh, one other thing, based on your last post, do I have a barometric type?

beenthere 12-13-2009 02:07 PM

I don't see that you have a bypass. Kinda of hard to tell the way the pipes are ran. You can ask your contractor if it has one.

A panel that can control a 2 stage furnace is the best thing to get. Along with a bypass if both of your zones are less then 60% of the furnaces total capacity.

A good panel to get. Would be the Honeywell Envirozone. It has auto mastering.
What it would do. Is not bring on the heat for the zone that uses it the least, when that zone calls for heat. It would open the dampers for both zones. And run the fan. So that the warm air from the master zone begins to warm the other zone. So that when the furnace runs, it heats both at same time.

Plus, when the master zone is calling. It will open the other zone at times. To prevent that zone from calling for heat 5 minutes later.

Its not cheap, as it uses communicating thermostats. but it is a very good zone system.

Honeywell does make a less expensive model line. Called truezone. And they can control 2 stage furnaces also.

rucy 12-13-2009 02:43 PM

Thank you. You have been very helpful.

rucy 12-16-2009 07:51 AM

I found out I didn't have a bypass damper so the HVAC co is going to install a modulating damper and we will see how that goes. One difficult is it to install a Truezone or Envirozone? My thought is if I need one is to do it myself. I am fairly good at all repairs and do most in my home as long as it is not rocket science.


beenthere 12-16-2009 11:13 AM

Truesone is very easy. And will work with any Thermostat.
Envirozone must use communicating thermostats.

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