I want thermostats that allow the room temp to drop a few degrees before sending


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Old 12-19-18, 03:19 PM
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I want thermostats that allow the room temp to drop a few degrees before sending

I have 1960's thermostats. I want thermostats that will allow the room temperature to drop a few degrees before turning the boiler back on. Can I buy thermostats that will do this? I don't know much about thermostats. I do know that my boiler keeps trying to fire back up too early.
 
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Old 12-19-18, 03:27 PM
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Welcome to the forums.

I do know that my boiler keeps trying to fire back up too early.
That is usually the job of the aquastat.
In a multi zone system the thermostat activates the zone valve.

You want thermostats that allow for fewer cycles per hour.
 
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Old 12-19-18, 04:29 PM
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Thumbs up Welcome to our forums!

You really need to describe in detail exactly what you have as far as boiler type, steam or hot water, whether your thermostat controls a pump or the boiler, what you have for radiators, what type of house you have and roughly where you live.
 
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Old 12-20-18, 08:10 AM
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Most newer thermostats have a "delta-T" adjustment. That is the on-off or differential between call for heat and satisfied. i.e. want room temp at 70F and you call for heat at 65F or whatever. Get thermostat with delta-T

Honeywell and some others have "smart response" Want morning temp to be 70F at 6AM? It will bring start bring up heat earlier so at 6AM it is 70F
 
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Old 12-30-18, 07:00 PM
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My boiler is a Dunkirk Q90. Where is the aquastat or what does it look like? My boiler fires up and immediately shuts back down over and over until it is actually cool enough to run. Sometimes I go and kill power to it for 30 minutes because the water pipes are way too hot to need to fire up. After the 30 minutes, the water pipes are cooler and the boiler fires up and stays lit as it should. I guess I'm trying to overcome a program glitch. Except for that and it sometimes locks out because of all the cycling, its a good system. Thanks for the advise, I will look into the delta-T thermostats unless it turns out I have a bad aquastat.
 
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Old 12-30-18, 08:34 PM
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This may be the manual for your boiler. Scroll down to page 34 and see if this helps.

https://dunkirk.com/sites/default/fi...Q-90%20IOM.pdf
 
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Old 12-31-18, 05:40 AM
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Hi, it sounds like you are concerned with the boiler short cycling, it sounds more like an aquastat problem then a Tstat issue, if you turn the Stats down to 55* do you still have the same issue? Post some pics of the boiler controls, it maybe helpful.
Geo
 
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Old 01-07-19, 12:42 PM
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Hi, thanks for y'all's time! I looked up my system as provided by Dr. Spott. It seems that the only aquastat I have is a high-limit in the casting hot water outlet. It shows that the call for boiler re-start is by thermostat only. My boiler keeps trying to restart when the water pipes are still hotter than July. If I turn down the thermostats (2 ea.), the boiler stays off. The only time I detect the start sequence occurring needlessly is when the water pipes are hot. It would seem like an aquastat problem, but I only have the hi-limit. I think that the control unit "thinks" it needs to re-fire before necessary. I need thermostats that will not send a restart signal this early...I think. I don't know enough about thermostats to know what it needs.
I followed the fault isolation manual. According to it, my boiler system is happy as hell. The problem not addressed in it is that the boiler starts just long enough to get flame, but then the gas valve closes (Clunk!), and it tries again. Eventually, it will cool off enough that the boiler will stay lit. I don't like all the unnecessary cycling because I will go through ignitors and gas valves and they are expensive and the gas valve would be hard to replace.
 
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Old 01-07-19, 01:05 PM
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M.R.
As you now know, you have a cold start system with a high limit only aquastat which only is activated or powered by the t-stat.

Your stat is only a switch, like a toggle or light switch only it works off of temp. You could replace that stat with a light switch if you wanted and just flip it on when you wanted heat and off when done. Sounds silly but that's all a stat is, simply put.

That being said your boiler is only reacting to your stat which is only reacting to how fast your house looses heat.

Some stats have adjustable differential settings to slightly alter run times. Your dif. setting should be matched to the control it is controlling. For ex. if it goes to a zone valve it depends on the brand. A Honeywell may be .4 where a Taco is .9. A wrong setting especially on a Taco will give you erratic behavior of the valve which controls the boiler and sometimes shows up as short cycling for no reason.

Thermostats have evolved like everything else and some are not compatible with all systems. Stats usually come factory setting of a 2 deg. span to prevent short cycling of the boiler and some can be adjusted for longer or shorter spans but all this depends on everything being sized right and installed correctly.
 
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Old 01-10-19, 04:50 PM
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It turns out that my boiler is cracked internally, leaking water. Any recommendations on a boiler for a 3000sq ft house?
 
 

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