Would it be beneficial if one did a conventional night setback and were to use a second thermostat mounted by the boiler who's only task was to make the boiler to run at 180 via the hot water connection (connecting terminals 3 and 4 on a Burnham board, I don't know if or how that would work with other manufacturers) only between the hours of 6AM and 7AM.

That would allow the boiler not to run at all during the night hours, and the 180 circulating temperature would quickly satisfy the room thermostat.

Then during the day the ODR can take over and maintain the temperature as it sees fit.

I find the thermostat is calling for heat 4-6 hours overnight to maintain the room temperature 24/7 -- and no one's there to enjoy it. This idea would make it work hard for one hour vs running for 4-6.

Is there a way to tell how long the boiler is actually firing vs just idling with the circulator on?

 

Let me see if I understand what you are asking.

You want to use a programmable thermostat to 'make' the connection to 3 and 4 only between 6 and 7 AM ?

I presume that you would use this el cheapo thermostat as follows:

Program the 'home' time to begin at 6 AM and set an ungodly high temp so that it remains calling the entire hour. Then program the 'away' time to begin at 7 AM at an ungodly low temp so that it never calls for heat. In effect, using it as a cheap programmable timer?

Yes, that will work. I'm not really familiar with your boiler though... won't closing 3 and 4 simulate a domestic water heater call and the boiler will fire to high limit the whole hour even after the home has reached the thermostat setpoint and the pump shuts down? Will it be beneficial? Dunno... I guess it's easier than getting up early to warm the home up so the Missus can make you breakfast!

I still don't understand why you can't program the control to provide the 'boost' you need to do a quick recovery. Isn't there a setting for that?

 

Boost is either on or off and may not be used just when wanted.
What about a two stage thermostat and stage two when it turns up connects to 3 & 4.
I assume there is no indirect water heater. It will also depend on the piping.

 

Going with the 2 stage idea...

What if one were to mount TWO thermostats in the area, have the second one operate the 3/4 terminals. Set it to the same temp as the first thermostat using the same home @6 AM /away @7 AM idea. This would work more or less the same as a 2 stage I think? And if the zone came up to temp faster than the hour, it would open the 3/4 terminals and automatically revert to the ODR settings.

 

NJ that would work but personally I would not two thermostats on my wall. Secondly the two stage idea would also work any time it is needed and not work if not needed. Turn intel recovery off.

 

How does a two stage thermostat work? At what point does the second stage kick in?

 

There are a few degrees of 'differential' between the two stages.

If the temp drops below say 3 or 4 degrees below this differential, the 2nd stage kicks in.

Say you're set for 70 ... if the 1st stage can handle the load, and the temp never drops below say 67, the 2nd stage will never kick in. If it drops below that, reinforcements are called.

 

Oh cool. I wish I could find the spec for my thermostat as to how much differential Honeywell uses.

I need to get some heat added to my basement shop. Because it has been so mild this year, it hasn't gotten too cold down there. It's actually just right for doing work. So that had me thinking about how often the heat would need to come on. I didn't want a micro zone on the boiler. After seeing rbecks idea about the second stage, I was thinking that I would hook up my basement thermostat to just the zone valve. So whenever another zone called for heat, the basement would get hot water until satisfied. If this wasn't an adequate setup, I could run the second stage to TT on the boiler so it would turn on and run the circ without the need for the other zones.

 

Hello Droo',
If you have a programmable Honeywell, the "6 cycles per hour" setting is a 1 degree differential.
At least the ones i have are.
Otherwise the anticipator setting effects the differential of the old stand by Honeywells.

I have half the zones in my house setup without the end switches. They almost always work good enough to heat just by gravity. Of course they get a boost when the pump comes on. It certainly helps extend the boiler cycle.

Poor man's constant circulation.
On my 1st floor which is the biggest load. I have two almost matched thermostats. (sorry RBeck) they are both set for 1 degree differential and they are set one degree apart.
at 75 they are both off
at 74 T'stat-A just opens the zone valve, the other - B turns off
at 73 the other thermostat B, turns on and closes the end switch for max heat.
Works pretty good. Almost.
I wish there were half degree differntials and staging.
When it drops to 73 mom gets a chill.


Peter

 

Most two stage stats will call stage one and drop 2 before stage two comes on. But most are adjustable. The whole idea of two stage stats is 40 years old.

2 Stage Thermostat Opertion

 

My Robertshaw thermostat has totally adjustable differentials on both the first and second stages, maybe even on the third stage that I don't use. I have my second stage set at 3 degrees below the first stage so the only time the second stage cuts in is if I manually change the setpoint more than 3 degrees higher than the ambient temperature.

 

I would have to bypass my IQ control in order to bring the circ on without the burners. I suppose it would just need the right kind of relay.

 

You have to watch some of the newer thermostats, they use PID logic and we find they tend to bring second stage in sooner than one would like. Especially true for the strip heaters in the Geo systems we do...

 

How can I tell, and what is PID logic? I use Honeywell rth2310b.

 

Hello Droo',
PID=proportional–integral–derivative
If you want to blow your brains out,
read here:
PID controller - Wikipedia, the free encyclopedia

Typically if PID is involved, they usualy brag about it in the marketing for the thermostat.

Peter