Old steam rads and new hot water boiler???


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Old 07-19-07, 07:18 AM
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Old steam rads and new hot water boiler???

Hi Folks,
Background info:
Bought an old 1870's house that had steam radiators and no insulation. It has since been gutted totally and properly insulated etc. The heating system that came with the place was completely irreparable and has since been removed. The previous owners had gave up on the boiler in the 70's and had been heating the place with a coal stove in the basement through an unlined chimney....

Anyways, I have purchased a new forced hot water system that I have yet to install. I have kept the original radiators and I understand that I can convert them to hot water or at least do an exchange with a local place for the hot water version.

I have been told by a plumber that if I use a modern hot water boiler with the old cast iron radiators I will have a problem because junk from the radiators will clog up the boiler and make it break.

I am wondering if anyone hear was heard such a thing and if so how do you prevent this? I see many people use hot water radiators???????

Thanks a bunch in advance.
Lief
 
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Old 07-19-07, 07:23 PM
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Will they take the pressure? They have to withstand up to 30psi.

We're all assuming that they are 2 pipe right?

And you'll need to really flush them out really well and pressure test them. A wye strainer with a fine filter before the boiler or even keeping the heating side on the other side of a heat exchanger might be a good bet.

This is an area where even experts fear to tread.
 
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Old 07-30-07, 12:08 AM
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I agree that using the steam radiators on a hot water system is not an adventure to be embarked upon lightly. I would take the exchange option. Even then it wouldn't hurt to flush them out before putting them in service.

Something else to consider...determining the amount of radiator needed for each room now that they are all insulated. You can figure you will need about 25 - 30 BTU/sq ft of heat per room. But how do you figure the output of the radiators? I found this site when I was looking to put cast iron radiators back in my (old) house: http://www.colonialsupply.com/resources/radiator.htm. Continue on to pgs 2 and 3 to determine the EDR ratings of the radiators you will be getting.

Sometimes you can find an old manufacturer's book on the radiators if you know who made them. This will tell you the specs for their radiators, and it saves all that math. The place that will exchange the radiators for you might have such a book.

I hope this helps.
 
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Old 08-06-07, 11:35 AM
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Originally Posted by Who View Post
Will they take the pressure? They have to withstand up to 30psi.

We're all assuming that they are 2 pipe right?

And you'll need to really flush them out really well and pressure test them. A wye strainer with a fine filter before the boiler or even keeping the heating side on the other side of a heat exchanger might be a good bet.

This is an area where even experts fear to tread.
Hi there,
The radiators I am looking at for replacement have been tested to 60 psi. They also claim to be flushed. I am not entirely sure what flushed means from this particular place. I have read online that there is some kind of chemical flush that could be done. Does any one know more about the flushing process?

I was trying to avoid the heat exchanged for this project as I understand this losses efficiency. It might be the safest option so I may do so anyways.
So if I do with the heat exchanger I would simply make a small loop from the boiler to the exchange back to the boiler. The other side of the exchanger would be the same as the original plan. Does this sound correct?

If I used this filter suggestion, I could simply place a shutoff valve before and after the filter. I should be able to clean the filter out fairly easily. What type of material would be good to use and does anyone have any specific examples that I can research?

Thanks again for feedback..
 
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Old 08-06-07, 09:00 PM
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Do a heat loss. Size the boiler to the heat loss. Dependant on the boiler of choice you may require boiler protection. I would also use outdoor reset. May as well get the most for your money.
 
 

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