Wiring a Lennox AM30 with a Newmac wood add on

[muskie]

I have a lennox am 30 and a newmac add on wood furnace. I currently have 2 thermostats hooked up. I am using the wood furnace as a main source of heat and the am 30 as a back up. My question is how do I wire the thermostats up so that when the wood furnace calls for heat only the fan on the am 30 comes on? As it is now, the circulator pump also comes on. Both thermostats are 1 heat and 1 cool. They both have a auto or manual fan option also. The am 30 has w,r,y,c,g and the wood add on has r,w,g,t,t. Any help you could provide would be greatly appreciated.

 

[stihly dan]

How does a forced air furnace have a pump? G is for fan only.

 

[superwd6]

The control on the Newmac is standard for wood furnaces but is used to open 24 volt damper motor when calling for heat.Wiring diagram is usually inside the cover of that control and set up so that when your secondary heat kicks in (AM30) the damper or inducer motor for fire shuts off the wood side. Any I've seen use an insertion type Fan/Limit control that powers the fan on temp rise above the wood heat exchanger. If you live in Ontario you should have a WETT certified HVAC company do the work. That way when your house burns down you still get insurance:msp_wink: For those that don't know, AM30 is an Air handler with hot water coil and internal circ pump. While were on that , check that yours isn't leaking water on the coil before it starts running across the floor:msp_biggrin:

 

[Whitespider]

How does a forced air furnace have a pump? G is for fan only.

That's because the AM30 isn't a forced air furnace. The AM30 is an air handler/heat exchanger unit, it contains the blower motor, heat exchanger and circulating pump. Normally the AM30 is connected to a HM30 water heating unit. The HM30 heats water and stores it for use at both the sink/tub/shower faucets and the AM30 heat exchanger. When the thermostat call for heat it tells the AM30 to start pumping hot water into its heat exchanger from the HM30 water heater/storage unit.


muskie,
A lot more information is needed... starting with, did you do the existing wiring and how is it wired now? Are the 2 thermostats wired separately, in series, or in parallel? Are the 2 furnaces wired to each use their own 120v/24v transformers, or are they wired to use a common transformer. If you don't know what I'm talking about... hire somebody that does.

 

[stihly dan]

Thats good to know. Although 3 pieces of equipment for heat seems a little odd and expensive. Maybe a combo wood furnace? really, that is alot of things that could fail.

 

[muskie]

Thanks for the help so far. I will answer the questions as best I can. The units were indeed installed by a WETT installer and inspected. This was our preference as was our insurance company. The thermostat for the am30 is wired direct to that unit. The add on is wired to that unit. He then ran 2 wires from the hi-lo on the add on to the R and G of the am30. Does this make sense? And as for alot of things to break, well its really only 2 units. Would be the same for any combo, its just my 2 units are not built into 1 housing. I did find that not all WETT techs are created equal. While the installer was bang on in clearances and such, he did wire it that way. And the inspector had no solution as he was only an inspector not an installer. I am not really interested in calling the installer back until I have a firm understanding of how it should be hooked up. There is a 24v transformer on the add on that has 1 leg going to the G on the add on with the other wire being hooked to the thermostat. I will check it again when I get home just to ensure I am giving you accurate info. And again, I really do appreciate the help so far.

 

[stihly dan]

The r and g wires to t-stat sound right. What is the w of the t-stat hooked to? You may need an isolation relay on the g at the funace from the hi lo to the pump. When the furnace calls for hot water powering the pump, it has to turn the fan on. so if you power only the fan, power back feeds to the pump turning it on. the isolation relay will stop this. They are about 10 bucks.

 

[superwd6]

Put your exact model of the wood add on so we can see what they want for fan control. As I said before , every one I ever seen uses a fan/limit control (insertion typ 5,88 or 11" in length) to turn on the fan while the thermostat controls firing rate (air supply).Put on a picture or two:msp_smile: