baseboard heat

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Hi,
Yesterday, for the first time I saw what was inside a baseboard radiation: 3/4" copper tube with fins. I see how the fins can be efficient at releasing the heat. But the volume of water is minuscule. Over an 8' run, the amount of water in the tubing is
pi*(3/8)^2*8*12*0.0173160173 = 0.734398282 quarts
But how much heat can be contained in less than a quart of water?
Many thank in advance!
Sam
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The water is circulating, the copper removes heat quickly, it works but I like cast iron better.
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How many GPM are you re-circulating?
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On 9/19/2010 1:32 PM, Molly Brown wrote:

I don't know. I've always assumed (incorrectly?) that the pump stays on just long enough to replace cold water in the system with hot water. So I figured in one cycle, the water in the fin tubing get replaced just once.
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Sam Takoy wrote: ...

Of course not, it's a continuous loop and the pump circulates the time the demand is on...
--
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To add to that, it circulates as long as the thermostat(s) calls for heat. The water gives up its heat along the way and goes back to the boiler to be reheated. The boiler burner runs as needed and is controlled by an aquastat in the reservoir. Once the water is heat to its max setting, the burner shuts off until the water temperature drops to the lowest setting and starts running again. Setting run from about 120 min to 160 or 180 max.
It would be a good idea to have someone explain the workings to you. Knowing how it works, you may be able to prevent a service call on a cold winter night by knowing how to get the system up running again.
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Why would you assume that? In fact, the pump continues to run as long as the thermostat is calling for heat.

The obvious absurdity of that conclusion should have told you that your premise was incorrect.
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On 9/19/2010 4:00 PM, Doug Miller wrote:

Yes, I concur with the complete absurdity of my conclusion. However, there is one thing I still can't explain.
If fin tubing that contains less than a quart of water and a humongous surface are can release the heat effectively in the amount of time it takes the water to travel its length, how can a radiator with 20 times as much water and less surface area release the heat effectively?
My calculation is this: If a radiator holds 20 times as much water, it takes 20 times as long to replace the water, so it has 20 times as long to release the heat. That would be just right if it had the same surface area, but its surface area is much less (pretty good, but no fins). So I must conclude that either the radiator or the fin tubing don't release the heat effectively.
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Who says it can (or can't)? As explained (very well, btw) by EdP, the temperature of the water is held between 160F and 180F (his example, your system may be set somewhat differently). If the water drops below the low limit, the circulating pump will shut off, if above 180F the boiler will cycle off.

How would you conclude that? Either is going to heat the room until the thermostat is satisfied. In addition, the boiler can only add so much heat to the water. If the radiators and the boiler aren't matched either the zones or the boiler will cycle to maintain temperature, as long as the thermostat is demanding heat.
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On Sun, 19 Sep 2010 20:00:41 GMT, snipped-for-privacy@milmac.com (Doug Miller) wrote:

calling for heat.
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On Sun, 19 Sep 2010 17:14:49 -0400, snipped-for-privacy@snyder.on.ca wrote:

*AND* the reservoir temperature is above the min-limit.
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On Sun, 19 Sep 2010 17:43:36 -0500, " snipped-for-privacy@att.bizzzzzzzzzzzz"

is called for, even when the temperature is below limit and the boiler is fired. It only makes sense for it to work this way or both the boiler fire and the pump would be constantly cycling - which is BAD for efficiency.
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wrote:

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On Sun, 19 Sep 2010 17:13:24 -0400, snipped-for-privacy@snyder.on.ca wrote:

No.
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On Sep 19, 5:43pm, " snipped-for-privacy@att.bizzzzzzzzzzzz"

The pump runse constantly as long as any thermostat is calling for heat, and the water temperature is above some minimu. This is a very slow/gradual process, but you don't get the blast of cool/hot air like you get with a hot air heating system. Because the fins are copper, you get fairly rapid heat transfer from the water to the fins, and thence into the air. But the ability to raise the temperature is probably less than half that of a hot air system. I prefer the hot water radiators for heat, but then you have to have a separate system for air conditioning, so the air handling system is what I have always had in my primary house. My second condo, in Colorado, has a hot water system. It is great, especially because it does not cause as much dust,
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On Sun, 19 Sep 2010 18:08:05 -0700 (PDT), "hr(bob) snipped-for-privacy@att.net"

That's what I said (though with fewer typos ;).

That certainly depends on the amount of baseboard. The output of the boiler and a hot-air furnace are similar.

I had a hydronic system in my NY and VT homes. It was alright (hated oil). I have a heat pump in this house (AL) and hate it. I call it "forced cold air heat". I have to keep the temperature a good 5F higher than I did in VT and it doesn't recover worth a damn, even though it never gets that cold outside (delta-T is never more than 45F for more than an hour or two).
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On Sun, 19 Sep 2010 17:43:56 -0500, " snipped-for-privacy@att.bizzzzzzzzzzzz"

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wrote:

NO. Wrong.
You have it right in one of your posts, where you wrote "On the one system I maintain, the pump runs constantly when any heat is called for, even when the temperature is below limit and the boiler is fired."
The pump runs constantly *when*any*heat*is*called*for*. When the call for heat ceases, the pump stops running.
That directly contradicts "The pump runs CONSTANTLY". It does nothing of the kind. It runs until there is no longer a call for heat, then it shuts off.
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On Tue, 21 Sep 2010 02:12:39 GMT, snipped-for-privacy@milmac.com (Doug Miller) wrote:

just long enough to replace cold water in the system with hot water"
When it is heating - it runs constantly.
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On Mon, 20 Sep 2010 22:57:12 -0400, snipped-for-privacy@snyder.on.ca wrote:

I certainly said nothing of the kind.

I've never seen one that didn't cut out when (if) the low-limit was reached.
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