Nest Thermostat & CycleGard

Tolik

This is my second heating season with a Nest thermostat.

I noticed yesterday that the when the CycleGard activates the Nest goes into a delay mode after the CycleGard deactivates. In theory the thermostat (any) should constantly be calling for heat even though the CycleGard is active?

In my situation the CycleGard shuts the boiler down for about two-three min and then the Nest adds an additional two-three delay. That doesn't sound right to me.

I'll be emailing Nest support as well but wanted to get input of the heatinghelp community.

Thank you.

P.S. is it really CycleGard or CycleGaurd?

Jamie Hall

It's CycleGard -- the folks who come up with trademarks can't spell.

There have been a number of commentaries on both of these contraptions over the last few years, with a sort of general feeling that neither of them play particularly well with steam heat -- although you would think the CycleGard would, as that's what it's meant for. The Nest -- not so much. It was thought up by folks with forced air, and works well with that by all accounts, and its use on high mass systems of any kind -- steam, gravity hot water, radiant, whatever -- was perhaps not quite as well thought out.

I admit that I'm not too surprised that they don't play well together...

ChrisJ

You need to have the LWCO (Cyclegard) wired in after the thermostat at the boiler so the thermostat never loses power. My boiler was originally wired so when the LWCO tripped it also cut the 24VAC from the thermostat, this is no longer the case.

I don't usually say this, but I would recommend a professional make this modification.

I too, don't like the Nest. I owned one for about an hour before returning it but the above modification should fix your specific complaint.

BigRedSteam

Same setup here on my Dunkirk PSB..nest does give me lots of visual info on cycle times, which help me tune things a bit. BUT the delay feature does prolong cycle times when the CycleGard runs the intermittent test.

ChrisJ, any chance you can elaborate on 'wiring the LWCO after the thermo?

ChrisJ

BigRedSteam said:

Same setup here on my Dunkirk PSB..nest does give me lots of visual info on cycle times, which help me tune things a bit. BUT the delay feature does prolong cycle times when the CycleGard runs the intermittent test.

ChrisJ, any chance you can elaborate on 'wiring the LWCO after the thermo?

Right now your LWCO is in the circuit before the thermostat so when the LWCO switch opens it cuts the 24VAC+ from the thermostat. You need to have a professional come and change the setup so the LWCO cuts power from the circuit after the thermostat, rather than before. This way the Nest never loses power and knows the system is still running.

Right now, your Nest is assuming the power went out or something every time your LWCO goes into it's awful test mode. From the Nest's perspective, this isn't normal.


The downside is after that modification your vent damper won't close during the LWCO test so you'll lose some heat up the flue. The upside is your vent damper will last longer.

Tolik

What you are saying makes sence. Technically the Nest should be more accomidating. Meaning it needs to be programed to allow a certain time of momentary power loss. It's a few lines of code at most.

If the cyclegard is known to turn off every 20 min for 90 seconds then the nest should allowed a power loss of up to 100 seconds (or whatever other cyclegards are set to)

Ohh this only works if the thermostat has a battery, All Nest thermostats do.

Hope someone from Alphabets or Google or Nest or whoever reads this. Calling support would be a waste of time. I still can't get mine to be a clock. The new one does ****... sorry rant.

ChrisJ

Tolik said:

What you are saying makes sence. Technically the Nest should be more accomidating. Meaning it needs to be programed to allow a certain time of momentary power loss. It's a few lines of code at most.



If the cyclegard is known to turn off every 20 min for 90 seconds then the nest should allowed a power loss of up to 100 seconds (or whatever other cyclegards are set to)



Ohh this only works if the thermostat has a battery, All Nest thermostats do.



Hope someone from Alphabets or Google or Nest or whoever reads this. Calling support would be a waste of time. I still can't get mine to be a clock. The new one does ****... sorry rant.

No,
It's already programmed to go into a sort of "hold" mode after a power loss to protect equipment. This is intentional. My Ecosteam is the same way only it goes into hold for whatever amount of time I program it for which is 10 minutes by default.

I would have a professional come in and do the minor modification to how the LWCO is wired to solve the problem. As much as I dislike the Nest, this one isn't it's fault in my opinion.

Tolik

If another thermostat can do it so should the nest.

I should have the option to pick 10 min as in ur case to allow for momentary power loss while the system is still calling for heat. The nest should continue to call for heat while on battery power. If power loss is more then 10 min then it should report a fault in the system.

The nest should be smarter than the LWCO it's advertised as "smart" why should I have to rewire my stuff that works.

You are right it is one of its faults, that can be corrected in two ways.

SWEI

The CPU, display, and WiFi chipset in the Nest need about an order of magnitude more power than a standard programmable thermostat does. If you want to use a Nest, you need to give it enough power to operate.

Tolik

I'm not sure how long the battery in the nest lasts but I would imagine it be more than five min.

Five min can easily accomidate any CycleGard compatibility issues.

Is that really to much to ask from a "smart" thermostat. Simple logic.

ChrisJ

The Nest advertises being able to run without a common. I certainly hope it can run for more than an hour off of it's internal battery.

Tolik

After speaking with senior tech support for Nest I was advised that the only solution is to run a common wire. To my surprise though Nest stated they will reimburse me for the cost of hiring an electrician. I received an email with instructions to submit an invoice.

That's nice of them.