how low can my aquastat settings be?

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Old 11-01-08, 07:57 PM
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how low can my aquastat settings be?

finally got the solar hw system installed on my house today. works good even though it is cold out. i tied it in line after the boiler so i could pick up some preheated water from that while its running. the storage tank is essentially an indirect tank with an electric heating element in it if needed. with all my wood burning and general energy saving things im doing it seems my boiler is never needed for heat. hasnt really been an issue since i needed hw but now i barely need it for that. its an old utica starfire 3 with a afg burner its been set at 180h-160L and was fine for me. now that its barely used id like to tone it down abit. id like to see how low in the setting i can go and still be able to heat the house to say 65 at most and avoid condensation build up. im not sure if their are any standard settings that people know of that can share or should i just start playing with it and figuring it through trial and error. id like to be around 130-140 or lower for the winter and possibly shut it off during the summer. i am mildly concerned about cold starting it but i can deal with that later. this will be an extended temporary thing till i can save up for a whole new boiler since im not sure how much this one left in it.
 
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Old 11-02-08, 12:15 AM
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kit, if yer gonna be cold-starting that boiler, then the aquastat on the boiler will have to be changed. The LOW setting is what keeps the boiler warm ... which by the way, that LOW setting at the very least should be turned to something like 140 ... and if the solar is going to supply ALL of the domestic hot water, you might as well turn it all the way down.

As for the high setting, I wouldn't try that either... but if you had to experiment, one 'rule' to keep in mind is that the RETURN water should probably not be allowed to run too much below ohhh, say 125 or so ... I'd be concerned if it spent much time below that temp, and even that may be a bit cool.

So, when you figure the delta T (difference in temp between Supply and Return) on the system is going to be at LEAST 20 (and probably higher), then you shouldn't go much below about 145 ... and honestly, I'd be a bit uncomfortable with that... personally, I'd be nervous about setting the HIGH any less than 160 ... Some boilers are designed to tolerate lower return temps ... but I doubt that yours is one of them.

If the boiler barely runs these days, why not just let it be ?
 
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Old 11-02-08, 07:35 AM
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i suppose i could just let it be which is fine but i am trying to work it out of the system. at this point i dont even need it except for back up to the wood furnace which i am new too. i used it last year and didnt have any real issues with the wood furnace but i did keep my boiler going in case and for hw. now im not expecting any issues this year with the wood furnace or solar system so i dont think i need it it all but wouldnt mind keeping it in standby. at its present settings it can run the house 100% at a moments notice but i dont really need that. most i would need is to keep the house above freezing in an emergency. i was just wondering if thats even posible or economical. my main goal is to get a new boiler that will only heat the house not the water and even then only on a backup basis. the more money i save now the sooner that will happen. after rebates the solar was free, i just had to have the money up front so i gotta wait till tax time to get the money back and reinvest in the new boiler. im guessing you would leave it alone if you were in my situation so thats what ill probably do. got any good new boiler recommendations?
 
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Old 11-02-08, 08:15 AM
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got any good new boiler recommendations?
I like the Burnham MPO ... but there's tons and tons of good boilers out there.

I'd probably leave it alone, but if it's not leaking when it's cold, I might consider changing the aquastat out. If it's a 'backup' only, as long as it's running, there's probably not even a need to spend the bucks to change it out.
 
 

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