Circulator Question

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  #1  
Old 01-19-05, 06:39 PM
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Circulator Question

How can I lengthen the time a pump stays on on my boiler. It seems to shut off to early and I think it may be better if it were to circulate the water around longer after the boiler shuts down....or would it???
 
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Old 01-20-05, 06:13 AM
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The circulator will run until the thermostat is satisfied for heat and then shut off. The boiler will turn on and off within the on/off limits of the aquastat setting you selected.
 
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Old 01-20-05, 06:21 AM
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hi, your circulator will begin to run when the thermostat calls for the heat. it will also continue to run after the burner shuts off according to the low/hi settings. when the thermostat is satisfied, then the circ pump will shut off. the newer pumps are pretty silent, maybe that is why you are asking this question. hope it helped.
 
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Old 01-20-05, 06:29 AM
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Ahhh yes.... The Taco 007 pumps seem pretty reliable, maintainance free and cheaper than the B&G 100... The only thing is that perhaps they are too quiet and harder to verify when they are actually running
 
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Old 01-20-05, 07:03 PM
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Thanks guys, guess I should have stated that I have an Armstrong Astro 30 circulator and a Honeywell Aquastat. I have opened the aquastat panel and hi side is set to 180. low side is set to 120. I guess I can't do any more since 120 is the lowest setting.

I have noticed that the pump cycles on and off for a while then stays on. All seems well with it. What I am thinking is that in the early stages when the pump starts the water temp drops and then shuts the pump off again. Can this happen? What would setting the stat at 160 or 140 for hi side. would that start the pump earlier. Also I have monitored the water temp and it seems that the temp guage never goes past 150, but when I touch the pipes they feel very very hot to me. (never mind will get a second guage to verify first one... lol)

So to understand an Aquastat ei. lo side 120 turn pump off at this temp
hi side 180 turn pump on at this temp

is this correct?

Thanks
 
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Old 01-21-05, 07:30 AM
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Hi, I believe your "low" setting is way to low. It should be a 160low and 180high. I'm sure others will concur with this. Please post back.
-Bob
 
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Old 01-21-05, 07:35 AM
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Hi again Exile....your pump is turned on by the calling of heat from your thermostat in your living area. Your burner is turned on by the water temperature settings. Your "on" setting is the low # while it will shut off when it achieves the high # on your settings. Again, I would recommend the 160 for the low and 180 for the high. Good Luck...post back.
-Bob
 
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Old 01-21-05, 09:51 AM
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Wink

Exile :I dont see how that boiler can heat the home if it turned on at 120o like said most boiler are set for 160o for the burner to turn on and 180o to turn off.

ED
 
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Old 01-21-05, 03:23 PM
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Hmmm. I have asked many questions over the years to our contractor who cleans our boiler about not having good heat. And now all of you have answered it It all makes sense now. this is why my back bedrooms are always cold while the front rooms are ok. I will change the low side to 160 and see what happens.

Oh by the way Bob I am almost certain that when thermastat calls for heat that the circulator does not come on. I will confirm this tonight.


Many thanks!!!!
 
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Old 01-21-05, 04:28 PM
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Ok I changed the low side to 160 Set thermostat call for heat.
Boiler turns on but circulator does not.

Monitored Boiler temp, it climbed to 165 aprox and circulator turns on. As water is pumped through the temp gauge begins to drop...at 140 pump shuts off. Water temp climbs again to 165 aprox and cycles through as stated above. Water temp does not reach 180

Is this correct?
 
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Old 01-21-05, 05:18 PM
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Consider this...

It sounds like what you are adjusting is the safety limits not the operating controller (if there isn't one - there should be). The safety limit controller is just that - for safety - it prevents the boiler from operating above its operating capacity and it prevents the boiler from operating below its flue gas condensation temperature ( 140 deg F for non condensing boilers). Thus the reason the pump shuts off at 140 deg f...without flow the boiler temp will rise above the low limit setting and power on the pump.

This should not be used to control the boiler...some jurisdictions allow it but most do not.

A proper boiler controller would be weather activated and have a purge cycle on it.

Essentially it raises the boiler temperature as it gets colder outside and vice versa. The circulator can be controlled to run for a few minutes after the burner has shut off to purge any heat from the boiler.

There are so many makes, models with features and benefits that would be useful to your system. Not sure what the policy is here on this site regarding links ...but there are many good sites to get help on these types of boiler controls.

What you would be looking for is an indoor/outdoor boiler control and a professional to install it.

Be careful with playing with boiler temperatures (particularly safety switches) ...too low and the flue gases can condense plugging up the exchanger leading to carbon monoxide poising and possible death....too high and you may damage some components and cause the relief valve to blow...also leading to potential for personal injury or death.

Good Luck.
 
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Old 01-21-05, 08:21 PM
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Hello Rbean, The control says dual aquastat by Honeywell. I am thinking that that controls the circulator.
 
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Old 01-22-05, 12:40 AM
eaugie
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I also have a honeywell control (R8182D), and it functions as you say. Circ will turn off at lo limit, so if you are getting back to lo limit after startup it will quit till temp gets back up. Circ will not turn on righgt away after burner starts though. Mine has to almost get to high temp before it starts up (seems strange to me, but it's brand new). My limits are 190/160.

Hi limit is to shut burner down only so you don't make steam. Lo limit turns on boiler (and turns off circ so you don't cycle "cold" water). Now, the Diff, that's a good one. I have gotten about 3 diff answers on what it does from "professionals". But it "seems" to work that after lo limit, circ will not come on till you pass the diff above lo limit, or else it's just a coincidence on mine. Hope this helps.

BTW, go to the Honeywell site and download manual for control. It has a cycle explanation there. Good luck
 
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Old 01-22-05, 11:37 AM
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The Dual Aquastat

is typically a safety device...a boiler should never be controlled on high or low limits – but in-between.

If it is a non condensing boiler then the minimum return temperature should limited to 140 deg f that’s true...it's also true that at maximum load you may need 180 deg F...but what temperature should the boiler be, when its spring or fall...the lower the operating temperature the less fuel is consumed and the greater the stability of the system. If your boiler is running at 180 deg F when it's relatively warm outside then it will cycle like crazy - very inefficient and very uncomfortable.

Also what would happen to your boiler and your safety if this "control" were to fail? …and all electromechanical devices fail sooner or later - is there a back up control?

That’s why in the CSA B214 Code they require an operating control and a safety control wired in series - as in two separate devices - not two temperature control points.

If you email me the brand of your boiler and your location, I’ll put you in touch with the local representative who can provide you with their specific recommendations.
 
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Old 01-22-05, 10:01 PM
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Exile

Please provide us with the make & model number of the aquastat. From your description of it, I believe you have the proper control if your boiler does not have a domestic coil.
 
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Old 01-23-05, 09:21 AM
RBean
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For your files...Round or otherwise

Sounds like you guys have it under control (pun unintended) - here's the text from CSA B214...file in the appropriate spot...cheers.

3.9 Controls

3.9.1 Safety Limit Controls
After installation of the boiler, safety limit controls shall be tested in accordance with the manufacturer’s installation instructions before the boilers are turned over to the owner. Care shall be taken to ensure that no system components are exposed to high water temperatures that will be detrimental to the system components.

3.9.2 Temperature-Actuated Control
Every boiler or system of commonly connected boilers shall have at least one temperature-actuated control to shut off the fuel supply when the system water reaches a preset operating temperature. In addition to the temperature operating control required, each boiler shall have a high temperature limit control that will prevent the water temperature from exceeding the maximum allowable temperature. This control shall cause safety shutdown of the boilers. All boilers rated at 117 kW (400 000 Btu/h) or greater shall include a manual reset device on the high temperature limit control.

Have a great weekend.
 
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Old 01-23-05, 02:27 PM
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Boiler stats

Hello!

Ok Here are the boiler stats

Boiler: Slantfin Model: GG100HXPED Installed 1997

Watts Boiler & Liquid Level Controler Model OEM/170

Honeywell Dual Aquastat Model: L4081B

Mizer Auto Damper

I believe the GG on the boiler stands for non condensing 100,000 btu from what I have read.
The liquid level senser is in series with the aquastat

I have now noticed since the cold spell we have been having here...I placed the thermostat at 71 degrees. After a few hours the circulator is now running for a long time or the way it should to my knowledge. I am now thinking since the water in the system is at temperature throughout the system, the water temp now does not fall below the 140 degree mark and the circulator then runs longer.

Prior to this temp increases at boiler pump turns on temp falls in boiler below 140 pump shuts off....a sea/saw motion so to speak beacause of the cold water coming back to the boiler. Which now brings me to another question...thermal shock

Anyway seems to like the hotter temps at the termostat.

Hope most are staying warm with this latest cold snap and storm
 
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