Thermostat not satisfying

Even though the Honeywell was had batteries, is it possible C and not G was connected? If its heat only, G for fan only typically isn't used. It can be used, but its not common. (Get it?)

Like Ed, said, R,W,C at the thermostat and zone panel.

Oh yeah... Nest. Is there seperate Rc and Rh? You'd think connect power to Rh for heat only, but some Nest models don't like that. If so you might need to jump Rc and Rh.

Can you post pictures of thermostat wiring and zone board?

If you have full control (On - Off) of the heat at the thermostat's location by touching the wires R & W wires, I would definitely use (connect) the C wire on the thermostat and the HZ311. You may not need the G connections unless you want (need) fan control. Depending on the thermostat the Rh and Rc may need a jumper.

The C wire provides constant 24 VAC power to the NEST.

It is interesting you had the same symptoms with two different thermostats. I'd suspect the wiring or heating equipment.

first thing @briandonahue1800 says: "I have a gas fired furnace system in a customers house"

And I do not see any mention of a boiler or a zone valve. so Where did that come from @Jamie Hall and @109A_5 ?

Ok from what I am reading here Brian, has a customer where you have R W and G connected to the old thermostat. The G wire us used to operate a fan on switch or a fan when the heating or cooling circuit is controlled by the thermostat. (on a gas furnace the furnace operates the ductwork blower fan and the G wire is not needed.) When you decided to use a smart thermostat you need to free up a wire in order to use it as a C or common wire.

The Nest thermostat should be wired R from HZ311 Zone thermostat to the R on the NEST. The W from HZ311 Zone thermostat to the W on the NEST. Finally the C on the HZ311 Zone thermostat to the C on the NEST. This will leave you without a G to operate the fan independently as the old Honeywell used to.

Are you following me so far?

This would be the logical rewire for the NEST thermostat to the heat only zone: See zone 2 below.

This presents a problem if Zone 2 is also to be cooled using the Zone 1 heating and cooling thermostat. I don’t know how that would have worked in the summer with only three wires on the Zone 2 damper, since there is no way to open the Zone 2 damper when Zone 1 is calling for cooling, and there are no cooling wires to the Zone 2 thermostat.

However, I am not sure how the system operated for cooling prior to the Nest thermostat(s) installation. Perhaps that is the way it was designed on purpose.

Sounds like a wiring issue, not the thermostat. For a gas furnace with that HZ311 zone board, you should have:

• R (24V power)
• W (heat call)
• G (fan)
• C (common - if Nest requires it)

The Nest needs a C-wire for power. If you don't have one connected, that could be why it's not satisfied/shutting off properly.

Check at the zone board: Is there a C terminal? If yes, run that wire to the Nest. The constant call for heat sounds like the Nest isn't getting stable power and can't properly control the relay.

Also double-check the zone board itself—if it's stuck calling for heat even with the thermostat wired correctly, the board might be faulty. Try jumping R to W directly at the board to see if it cycles properly.

Hope that helps!

Remove (disconnect) this white wire, what happens ???

As I see it, there may be some unconventional thermostat wiring going on here. When there is no call for heat or cooling, spring-open/power-closed dampers will be in the open position. That could allow the air conditioning to operate because all dampers are open, by wiring the thermostat Y terminal directly to the Y terminal on the furnace in some unconventional “Frankenstein” wiring arrangement that may have worked with a standard 2-wire heat thermostat.

In that scenario, the furnace transformer could have been used for cooling, while the zone panel transformer operated the heating system—somehow avoiding interference between the two transformers, even though they were indirectly tied together through the thermostat wiring by use of the Rc and Rh terminals on the old thermostat for heat and cool function. That is not a proper or recommended configuration, but it can sometimes appear to function.

With the addition of a smart thermostat, the situation changes. A smart thermostat requires a common (C) wire, and that C must be matched to the same transformer as the R (hot) connection. This cannot be done reliably if two different transformers are involved in the control circuit, as described above.

To get this system working properly, you will need to start from scratch and follow the standard wiring configuration. Both zone thermostats should control heating and cooling through the the HZ311 zone panel, and only the zone panel’s equipment terminals should connect to the furnace.

What you have now is not a stable control scheme, and there is no simple fix. The correct approach is to remove all the existing wiring and rewire the system from scratch according to the HZ311 panel manufacturer’s instructions, without deviation.

Well if the heat stops when the W wire is disconnected from the HZ311.

It is the thermostat wiring or the thermostat. Since the problem started with a battery powered thermostat I would suspect the thermostat wiring.

If you reconnect the W wire at the HZ311 and disconnect the W wire at the thermostat and the heat continues it is the thermostat wiring. Maybe a staple rubbed through or rodent damage, which is making an unwanted connection between the R wire and the W wire between the HZ311 and the thermostat location.

What was the result of this experiment ?

If you removed the white wire from W on the thermostat side of the zone panel and it stopped, then the problem is the wiring or the thermostat. You pick.

Well then I got nuthin. Gremlins?