Warm Air Vs Boiler

 
Tryingitout
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Post by Tryingitout » Tue. Feb. 17, 2015 7:59 pm

$125.00 is way less than I would have expected to Michigan. I am remodeling a 6 story building that has a lot of steam radiators in it, can they be used for hot water?

 
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StokerDon
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Post by StokerDon » Tue. Feb. 17, 2015 8:22 pm

If they are 1 pipe steam radiators and have a threaded plug on the opposite side. I would think you just remove the plug and then you have 2 pipe hot water radiators!

I would love to have radiators in my system.

-Don

 
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coaledsweat
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Post by coaledsweat » Tue. Feb. 17, 2015 10:00 pm

Tryingitout wrote:$125.00 is way less than I would have expected to Michigan. I am remodeling a 6 story building that has a lot of steam radiators in it, can they be used for hot water?
You can use them but typically hot water requires more radiation then steam due to the difference in temperatures between the two. If it is piped for steam, put steam in. The boilers are the same, but in a steam boiler there is a headspace above the water level and the controls are slightly different.

 
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Post by Pacowy » Wed. Feb. 18, 2015 8:50 am

coaledsweat wrote:You can use them but typically hot water requires more radiation then steam due to the difference in temperatures between the two. If it is piped for steam, put steam in.
x2. All else equal, the same radiator will yield about 1/3 less heat with hot water than with steam, so you'd be putting in a lot of effort to downgrade the usable capacity of the system. Most of the difference in output stems from the capture by the steam radiator of the "latent heat of vaporization" - the large chunk of energy required to convert water at 212 deg to steam - and not just from the temperature differential.

If you were starting from scratch, a properly-designed hot water system almost certainly would be somewhat more efficient than a steam system, but that doesn't mean running hot water through existing steam radiation would produce satisfactory performance.

Mike


 
Pacowy
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Post by Pacowy » Wed. Feb. 18, 2015 8:59 am

Tryingitout wrote:I suppose there is no way to know if I would burn more coal with a warm air or boiler. I can assume these will burn more than my Hitzer.
All else equal boilers tend to be more efficient than furnaces because water is better than air as a medium for transferring and storing btu's. Obviously, the actual performance of individual units depends on such factors as the size and design of their heat exchangers.

A boiler or furnace conceivably could burn less coal than the Hitzer if you give it the same job (i.e., radiating space heat from a single point). It is reasonable to expect it to burn more if you use it to power a central system that provides controlled heat over a larger area, makes DHW, etc.

Mike
Last edited by Pacowy on Wed. Feb. 18, 2015 4:15 pm, edited 1 time in total.

 
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coalkirk
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Post by coalkirk » Wed. Feb. 18, 2015 3:14 pm

I understand your concerns but take it from the experts here. Boiler with hot water coil in your ductwork and never look back. It's a no brainer. Just do the homework to size the boiler for your anticipated demand.

 
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Post by McGiever » Wed. Feb. 18, 2015 6:53 pm

And give equal attention to the sizing of the true output of the air coil.
Sizing a air coil too small will make even the biggest of boiler seem too small.

 
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Post by Tryingitout » Wed. Feb. 18, 2015 9:09 pm

I would then assume that oversizing is a problem also. I will do my home work before any purchases. I am glad that there is a place like this for us to get information, thanks.


 
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Rob R.
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Post by Rob R. » Thu. Feb. 19, 2015 6:28 am

Hot water has the benefit of simple zoning, and compact pipes to carry the heat.

 
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windyhill4.2
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Post by windyhill4.2 » Thu. Feb. 19, 2015 7:01 am

I've never seen any issues with the over-sized heat exchangers I installed in our buildings. One is not required to use all the BTU's available in the water going thru the exchanger.

 
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coaledsweat
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Post by coaledsweat » Thu. Feb. 19, 2015 7:39 am

windyhill4.2 wrote:I've never seen any issues with the over-sized heat exchangers I installed in our buildings. One is not required to use all the BTU's available in the water going thru the exchanger.
Exactly, there would be no losses and a big reserve. Sounds better than being on the edge to me.

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