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Old 01-14-2010, 07:26 AM   #1
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Boiler outdoor reset control


I read a brief article about use of an outdoor reset control to limit boiler water temp based on outside temp. Seemed like a pretty good idea and I'm trying to figure out if it's something that would easily adapt to my 10 year old Burnham Series 2 boiler.

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Old 01-14-2010, 12:04 PM   #2
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Boiler outdoor reset control


Most commercial and industrial buildings that use hot water for their air handler hot water coils have what is called a reset schedule with outside thermometers that changes the hot water temperatures according to outside ambient air temperature.

Example: Not true figures just an example .

Outside air Temp Hot water temp

55 & above 130 & lower

45 140

35 150

25 160

15 170

5 180

I have not seen this in residential housing but I am sure someone has it somewhere.

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Old 01-14-2010, 12:50 PM   #3
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Boiler outdoor reset control


Outdoor reset is doable on that boiler but, whether or not it is worth doing depends on many things.

What do you use for domestic hot water?
What type of heat emitters do you have?
What is age of house?
There are many other factors but this will be a start.
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Old 01-14-2010, 01:31 PM   #4
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Boiler outdoor reset control


Outdoor reset is very common on residential systems.

Do you have a tankless coil in your boiler.
If not. You can use outdoor reset.

Savings of 15% or more are possible. Depending on your areas winter conditions.
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Old 01-14-2010, 02:34 PM   #5
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Boiler outdoor reset control


I don't have a tankless coil, my hot water comes from a basic stand alone gas water heater. If I remember correctly, the high limit on my boiler is set manually by a "thumb wheel", would that wind up being replaced? Any good references I should look at to get familiar?
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Old 01-14-2010, 02:37 PM   #6
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Boiler outdoor reset control


No, the limit control stays the same. And set the same. The outdoor reset is wired in series with the aquastat.
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Old 01-14-2010, 02:57 PM   #7
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Boiler outdoor reset control


Quote:
Originally Posted by Joe F View Post
Any good references I should look at to get familiar?
http://lmgtfy.com/?q=outdoor+reset
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Old 01-14-2010, 09:55 PM   #8
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Boiler outdoor reset control


The best way to do outdoor reset on that boiler is system reset not boiler rest. It will reset the system but let the boiler run up to whatever temperature it needs to.
More reset info.
Look down the right column and click on Outdoor reset.
http://www.comfort-calc.net/tech_area_index.htm#HWB
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Old 01-15-2010, 06:49 AM   #9
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Boiler outdoor reset control


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Originally Posted by beenthere View Post
Outdoor reset is very common on residential systems.

Do you have a tankless coil in your boiler.
If not. You can use outdoor reset.

Savings of 15% or more are possible. Depending on your areas winter conditions.
Not Really that common.
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Old 01-15-2010, 07:16 AM   #10
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Boiler outdoor reset control


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Originally Posted by SULTINI View Post
Not Really that common.
Maybe not in philly.

But around here. Very few new boilers go in. That don't have outdoor reset installed with them. Weather as standard with the boiler, or as an add on option.

Weil McLain Ultra, it comes with the boiler as standard(both oil and gas version of the boiler).

Buderus, it comes with the Logamatic control(both oil and gas version of the boiler).
Along with some other brands.

Most residential mod/con boilers now come with outdoor reset as standard. Those that don't recommend it. And its sold as an add on upgrade.

At least half of my boiler sales have outdoor reset.
And my competition is offering it also. So they're seeing the same trend as me. People want to save money. And are willing to pay a little extra up front to do so.

What residential mod/con are you selling that doesn't have it.

And is there a reason you don't offer it as an upgrade to new boiler sales/swap outs of non condensing boilers. Or as an energy saving upgrade/add on to customers for their current boiler.
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Old 01-15-2010, 09:15 AM   #11
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Boiler outdoor reset control


So a reset replaces the controller/aquastat...I see prices of $350 or so....
I have a Honeywell controller, circuit board stamped 8805
I'm going to be replacing the boiler (23 years old - not in great shape)
So I'm thinking its better to just wait & have one installed with the new boiler

I've adjusted my Hi-limit temp down
Once the weather warms up I'll turn it down more for the Spring
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Old 01-15-2010, 11:10 AM   #12
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Boiler outdoor reset control


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Originally Posted by tk03 View Post
The best way to do outdoor reset on that boiler is system reset not boiler rest.
What's the difference?
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Old 01-15-2010, 11:55 AM   #13
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Boiler outdoor reset control


I think many of the older boilers did not like running at a lower water temp. I think they were prone to cracking at lower temps, not sure. If running fuel with high sulfur lower temps can cause the sulfur to react with the moisture and other exhaust gases and condense out as sulfuric acid which would corrode (rust out) the boiler. Not commonly a problem with the more refined fuels used in housing. So for those boilers you would use a mixing valve to temper the water temp down by mixing the boiler water with some return water, that way the boiler runs at its maximum water temp all the time. The disadvantage is that the boiler should have higher efficiency at the lower water temp so you would not gain that efficiency.

Read the manufactures instructions, the should list a minimum operating temp if there is one.
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Old 01-15-2010, 02:32 PM   #14
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Boiler outdoor reset control


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Originally Posted by Scuba_Dave View Post
So a reset replaces the controller/aquastat...I see prices of $350 or so....

NO.

It doesn't replace the controller/aquastat. It is installed in series with the controller/aquastat.

Outdoor resets controls are NOT safety controls like a aquastat is.
So if you had one installed on your current boiler. It would be reused on your new boiler.
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Old 01-15-2010, 04:37 PM   #15
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Boiler outdoor reset control


The only thing a reset controller does is change set points on water circulation temperatures other than that the boiler operates just as it would with thermostat controls and safety controls unchanged.

If it gets real cold outside the water temperature gets hotter if it gets hotter outside the water temperature goes down.

It just gives you control over the water temperature, it's not a constant.

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