# Estimating old radiator water volume?

### Estimating old radiator water volume?

I'm trying to estimate the total volume of my heating system to make sure I have the proper size expansion tank. Neither the book I bought nor the software that came with it covers estimating water volume of radiators. Does anyone know the approximate volume that my radiators would have per section? I've attached a couple pictures of them. They are mostly 38" tall X 10 1/2" deep. They vary in width from 1 1/2' to over 4'. If someone had an idea of what each section would contain I could estimate it pretty close.
Thank you. BG
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biggreen1
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### Re: Estimating old radiator water volume?

Take a look at this link:

There are pdf files of old radiator catalogs. One of them should have the info you need. Post your findings here, to help the next guy.

Yanche
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### Re: Estimating old radiator water volume?

thank you for the link. So far I know my radiators are made by American Radiator Co. The style is Rococo and they were made at least as far back as 1897. They have 5 square feet per section if they are 38" high. So far no volume info.
biggreen1
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### Re: Estimating old radiator water volume?

figure this out in radiation to the load by compiling the radiators

based on 12 psi operating and 30psi relief

If less than 1,000 square feet of radiation - multiply the total by .03 for a steel tank
If between 1,000 and 2,000 use .025
if greater use .02

to convert this to use a diaphragm tank

tank your result and multiply times .55 if the building is two stories tall - or by .44 if three stories

The answer will give you the volume of the diaphragm expansion tank -- Manufacturers list volume in their literature.

This is likely over sized but it doesn't fail.

Sting
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### Re: Estimating old radiator water volume?

Those are some fine looking radiators.

coalkirk
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### Re: Estimating old radiator water volume?

X-trol 30= to old 30 gal tank.Better to big than to small!
DON
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### Re: Estimating old radiator water volume?

NOW is also the time to renew - or refurbish - or replace those green leaky - most likely not working balancing valves on the radiators.

Here is a link to a non electric thermal reacting valve that will control a hot spot in a multi radiator zone.
http://www.statesupply.com/displayItem.do?sku=DC1060

or you can simply get a new valve.

This one is fun to look at

Sting
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### Re: Estimating old radiator water volume?

Your radiators are very similar to mine. I have 54 sections. When the contractor replaced my boiler three years ago, he installed an Amtrol Extrol Model 60 expansion tank, listed as 7.6 gallons. (Originally he put in a smaller one, found it was inadequate, and replaced it with the Model 60. One symptom of "too small" was that the boiler relief valve was releasing a couple cups of water per day.)

As someone said in an earlier posting, better too big than too small.

Incidentally, I think the contractor said my total radiator capacity was 55,000 BTU. I just realized when counting the sections, that works out to about 1000 BTU per section.
rberq
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### Re: Estimating old radiator water volume?

Yanche,
I checked all the pdf files on that web site, lots of good, interesting info but no volumes that I could find. I'm going to look some more.
Coalkirk,
Thanks, I sure couldn't afford to replace them.
rberg,
Thats great info. I ran my info through Stings formula below.
Sting,
Here is what I come up with using your formula:
147 sections X 5 sq. ft. per section= 735 sq. ft. X .03= 22.05 X .55 for my 2 story house= 12.1275gal.
According to that, a extrol 60 with a capacity of 7.6 gal. is not enough. I really should have a extrol 90 with a 14 gal. capacity. The "expert" at the local plumbing store is confident that a 60 is enough. It's been working OK with the 60, probably because we usually only use 7 of the 12 radiators. He said hardly anyone uses a 90 and it's a special order. He quoted a price of about \$125 which seemed good compared to what I've seen at a couple on-line places. As Big Beam said, better to big than two small so I'm going with a 90.

If I can find water capacities I'll post them. Thank you all
biggreen1
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### Re: Estimating old radiator water volume?

and please note again -- this formula will likely oversize the expansion tank - but when shooting semi blindly with volume - its the final result that counts.

if you have been getting by with the 60 -- let it be so!

should you have drama in the future -- well maybe just plumb a vertical port some place before the circ pump - that you can isolate (normally you have an isolation already on the pump and an isolation valve on the boilers) and install another 60 in the future -- if needed...

Sting
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### Re: Estimating old radiator water volume?

Take a look at one of my posts on expansion tanks:

installation questions

Send me the information the various fields are asking for an I'll run it through the calculator and post the results

This is the software calculator you get with John Siegenthaler's book.

Yanche
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### Re: Estimating old radiator water volume?

Yanche,
That's one of the books I've been reading and that is the software I was trying to use. Without a estimate of radiator volume how can you use it?
biggreen1
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### Re: Estimating old radiator water volume?

And that's the problem. The volume of these was lost with the manufacturer. You can guess - but we did a better guess with the radiation. and measuring the pipe runs - good luck - I might consult a palm reader!

I was monkey wrench on a job recently and the customer had a newer Hi end water softener that metered gals used. We set it the night before to recharge and filled the system noting the before and after registration of the meter.

Sort of a rear view mirror approach to system sizing -- but any port in a storm ah captain?

Sting
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### Re: Estimating old radiator water volume?

Don't even think about replacing those radiators.

wsherrick
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### Re: Estimating old radiator water volume?

wsherrick wrote:Don't even think about replacing those radiators.

Agreed. I have fought that battle twice now with my wife. We have a 28 X 14 living room where the cast iron radiators cover about 7 linear feet of wall, and give a nice even heat. The contractor estimated we would have to cover almost every inch of wall available to get equivalent heat from hot water base board. And then what becomes of the ten feet of bookcases, the table in the corner, the stereo cabinet, the antique desk, the grandfather clock, etc. etc.? They just don't look the same when forced to sit six inches out from the walls.
rberq
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