Aquastat Question

[McKraut]

I am thinking of using this aquastat in the new boiler setup. I want it to stop the circulator (from boiler to house) if the temperature goes below 140* or above 195*. I want it to stop if the temp goes below 140* to save residual heat in the boiler. I have 100' of PEX to protect so I want it to cut off above 195*. I will set my overheat/dump zone circulator set to start at 190*. Is this aquastat what I am looking for?

 

[maple1]

I don't think that one will do what you want. Maybe some else will have a suggestion, I've forgotten the models of stats on my system and no time to dig into it right now.

 

[McKraut]

Can anybody help me with this?

 

[maple1]

I'm only half knowing what I'm talking about here. And I havent looked around any more since my last reply

Sounds like you are essentially looking for a stat with a 55° differential. And all or most are 30° max. A Johnson temp controller might work. An A419 maybe in Celcius. Manual says differential of 30, in F or C. I think those were replaced by A421. Not familiar with those at all (I do have a 419 on my DHW circ) but I just quickly read a manual and sounds like they might have replaced the diff setting, with temp on and off setting. So that might work too. Big maybes there. I'll try to look at all my stats later here and see if I can figure anything further out.

 

[McKraut]

Thank you. I really appreciate your help.

Bob

 

[Tonty]

I don’t know about which type of aquastat to use, but I wonder how much heat you’ll actually loose between your dump zone temp of 190 and aquastat shutoff at 195. It would depend what kind of dump zone it is. At this point, mine is set to dump in a hydronic floor heat situation, and I don’t get rid of much heat with 600 gallons of water. If I’d set it to dump into my coil in my forced air unit, AND that unit was running, I’d get rid of quit a bit more. That is largely because my floor heat is tempered to 100, and the coil isn’t tempered at all.

 

[McKraut]

The dump zone is composed of 5 cast iron radiators and would quickly drop the temperature of the boiler if was called for. I would think that it would be large enough to help with the 1050 gallons but I do not know for sure.
Bob

 

[Tonty]

Yes, that sounds like you could get rid of quit a bit of heat there.

 

[maple1]

The dump zone is composed of 5 cast iron radiators and would quickly drop the temperature of the boiler if was called for. I would think that it would be large enough to help with the 1050 gallons but I do not know for sure.
Bob

Will it dump in a power outage?

 

[salecker]

With my storage system i don't have a dump zone.
I guess your storage is tiny,just the boiler jacket?
I had an extended power outage shortly after filling the boiler with wood.
It was out for about 6 hours.It was the first outage after building my system so i was watching it like a hawk.The law of thermodynamics took over and my storage kept charging although there was no power the fire went to idle mode and didn't produce much.

 

[McKraut]

Can someone answer this question for me about the circulator?
I am still looking for a way to turn off the circulator below 140* and off above 190*. I can't use the differential because as far as I can see, the largest differential (mechanically set) is 30*. Can I put two aquastats in series? I would put in a L4006B that makes at 140* and then L4406A that breaks at 190*.
Any thoughts are appreciated!
Bob

 

[maple1]

Can someone answer this question for me about the circulator?
I am still looking for a way to turn off the circulator below 140* and off above 190*. I can't use the differential because as far as I can see, the largest differential (mechanically set) is 30*. Can I put two aquastats in series? I would put in a L4006B that makes at 140* and then L4406A that breaks at 190*.
Any thoughts are appreciated!
Bob

Did you check out the controllers mentioned in post 4? Thought you would get more feedback on this.

 

[maple1]

Also I dont think the series would work as the one that makes at 140 would break when it hits the upper differential, I think? So 170? Before the other one gets to break at 190?

 

[McKraut]

Also I dont think the series would work as the one that makes at 140 would break when it hits the upper differential, I think? So 170? Before the other one gets to break at 190?

I was trying to go the cheap way. I already have the L4406A and was hoping to save money. If my idea won't work, I will look more closely at your suggestion in post 4. Interestingly, I just checked out the A421 and it is cheaper than a new Honeywell. I will let you know what I find out.

Thank you,
Bob

 

[McKraut]

I did reach out to Johnson Controls and they did not provide any help. I can't get a straight answer from them.

Bob