Replacing gas valve and sizing boiler based on radiator size

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Old 01-07-08, 10:24 AM
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Replacing gas valve and sizing boiler based on radiator size

This may have gotten lost when placed in an older posting - so I thought I would try again.

I am thinking about replacing my 40 year old Peerless gas boiler - if not entirely at least the pilot gas valve with an electonic ignition.

I would consider replacing the whole boiler if I could acheive better efficiency with a new one. FWIW, in Denver during cold winter months I am using about 330 cu feet of natural gas for an 1800 sf fairly well insulated and efficient windowed house.

From what I have read, sizing a boiler is done by first sizing the room for the right radiator size, then sizing the boiler based on the radiator size.

Since I am keeping my radiators - I have listed their sizes at
http://vfwTech.com/Liquid/BoilerInfo.htm, and I was hoping that if someone (HVAC-EMT or anyone else) could tell me the right size boiler based on radiator size.

I was also hoping that I could get a suggestion as to a good replacement electronic ignition gas valve for my current Peerless - from the face plate I got the following info on it
boiler no - G-360-W-S
rated 500 SF
160,000 BTU / hr max 200,000
120,000 BTU Steam
160,000 BTU Water

Thanks
 
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Old 01-07-08, 11:35 AM
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DP:
Here's a radiator sizing chart that will come in handy for you to estimate the square-feet of EDR installed throughout your house. Taken from an old book I have.


Once you have the grand total, compare to the Net I=B=R figure on the sizing chart of the boiler of your choice...and presto.

The upgrade (if you decide to go that road), is called "Intermittent Pilot Ignition retrofit kit". Honeywell makes them. It consists of an IPI-gas valve, an ignitor/pilot assembly, an IPI-module and wire harness
 
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Old 01-10-08, 11:11 AM
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Apprciate the chart. Thanks.

On the Intermittent Pilot Ignition retrofit kt, I noticed some posts indicated that the pilot was worth keeping because it kept the undersurface "condensation" free.

We are not in a humid area - but I am wondering if that should be of concern in replacing the gas value with the pilot ignition system.

And I am still wondering if a new steam boiler would be that much more efficient than my current one.
 
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Old 01-13-08, 06:10 PM
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Originally Posted by dpdenver View Post
And I am still wondering if a new steam boiler would be that much more efficient than my current one.
and still wondering
 
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Old 01-13-08, 06:40 PM
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That would depend on the size of the old boiler, near boiler piping and the efficiency of the old boiler
 
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Old 01-13-08, 08:08 PM
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If this is a "steam" system and not a hot-water system the increased efficiency of a newer boiler probably would not be as great as if it were a hot-water system. Still, you should see some increase.

I personally do not like standing pilots and I think that the "benefits" of a standing pilot in keeping a boiler rust-free (on the fire side) may be exaggerated.

HOWEVER, I have very little experience with small boilers. The smallest boilers I worked with were 1.2 million BTUs per hour. They had modulating power burners. I also tended to a 1.5 million BTU unit that had standing pilots and atmospheric burners with on / off control. All of these boilers were in use year-round.
 
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Old 01-13-08, 09:23 PM
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Originally Posted by rbeck View Post
That would depend on the size of the old boiler, near boiler piping and the efficiency of the old boiler
Thanks - I posted the size on the original post - G-360-W-S
rated 500 SF
160,000 BTU / hr max 200,000
120,000 BTU Steam
160,000 BTU Water

I don't know how to measure it's efficieny - could you shed somoe light on that ?

And it is a low pressure steam - I have heard they have not improved their efficiency that much - but didn't really know. It is a 1970 model.
 
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Old 01-14-08, 07:03 AM
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The efficiency went up some from 1970 but not a whole lot. The bigger savings will be proper sizing and piping if not correct now. The fact that the new boilers have less water and make steam faster is another fuel savings.
 
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Old 01-14-08, 09:45 AM
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Based on my radiator sizes and the chart provided in the first response, my boiler should be sized about 450 sq ft.

My Boiler is rated at 500 SF.

So my boiler is sized 10% larger than my radiators require.

My system seems to be venting properly - I do get a slight banging of poples (not at the boiler - but from the pipes in the system - not the radiators) when the system initially fires up every day (I have it set back during the day when we are not home) - so it comes on late afternoon after having cooled down from the morning.

Does that sound out of line ?
 
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Old 01-16-08, 11:34 AM
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maybe not well asked.

If my radiators size out at 450sf, would a 500 sf system be considered oversized or adequately sized?

If you were to replace the system, would you SF size would you replace it with ?
 
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Old 01-16-08, 11:53 AM
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I dunno. rbeck would be the person for this, but he's not been here for a while.
 
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