Forum / THE MAIN WALL / EDR calculations for steam

## EDR calculations for steam (13 Posts)

• ### Not 100%

I'm not 100% sure, of course, but I did my best to find out. I have 4 different types of radiators in the house: 3 column (2.5" columns) 2 column (3" columns) 5 tube(1.5" tubes) 5 tube (1" tube) (this is a newer "slenderized" radiator) You can take a look a my calculations here if you want: http://spreadsheets.google.com/pub?key=p-vF8xroIeHlQJEnrp2RQMw
• ### How to factor in the pipes?

Using an article and EDR table I found on Colonial Supply's website [1], I calculated the EDR of my radiators. Boiler sizing must account for steam in the pipes as well, right? I saw a mention on another form of multiplying the radiator EDR by 1.5 to get the correct sizing for the whole system. Is this accurate, and if not, how does one account for the pipes? Thanks, Jeremy [1] http://www.colonialsupply.com/resources/radiator3.htm
• ### Normally

For most residential steam systems, a piping and pick-up factor of 1.33 is sufficient, especially if the piping is well-insulated. On older systems (where piping is somewhat larger for a given system), a 1.50 factor is commonly suggested. Keep in mind though, that if you are selecting your boiler based on the I=B=R "net SF" or "net EDR", that factor has already be taken into account. You match your connected radiation and select the boiler to meet it as closely as possible. What I do is to calculate the piping as well as the radiation. (I want to take off the piping too so as to get good venting data so none of this work is wasted.) I take my net connected radiation EDR and see what I get for a boiler based on the 1.33 factor. Then I take my piping converted to EDR and add that to the radiation EDR and compare the two totals. More often than not, the 1.33 factor is enough to cover the piping. On older systems, indeed, that 1.50 factor comes pretty close to reality. Do both and then you know, for everyone's piping layout is different.
• ### Hmm

I'm doing this because I suspect my new boiler was oversized, though the contractor did measure everything himself before ordering it. My calculations put the EDR of the radiators at about 280 sq/ft. My boiler is an Burnham IN6PV. The literature I just read at Burnham.com lists an I=B=R NET rating of 454sq feet. That's a pretty big difference (the IN4 puts out 271 sq/ft, and the IN5 puts out 363). I don't quite understand how the pickup factor can be taken into account by Burnham since the piping can differ from house to house. That, and the fact that my house is only 1450 sq/ft and the IN6 is the biggest PV boiler they make lead me to believe that the original calculation was flawed.
• are you sure of the radiators size and style you are using?
Cost is what you spend , value is what you get.

cell # 413-841-6726
• Burnham includes a pickup up factor for "normal" piping. I have always assumed that this meant an average steam system. If you have a larger than normal system or a lot of uninsulated pipes then you have to figure for that also.
• ### My gut says

that your radiation potential (67,200 BTUH) works out to just over 46 BTUH per SF. In a location with a design of zero or single digits, that seems rational for an older, not well insulated house. So there is some basis there. The piping and pickup factor is always a guess, as you say, no one knows what your piping is. But the 1.33 factor does not belong to Burnham but to the industry, set forth years ago based on lots of experience. The IN4 might well have worked if your piping is not extravagant and if it is well insulated. Otherwise an IN5.
• ### House meets those criteria

Boston area, not insulated well at all. The question is, what can I possibly do about it now? I paid \$6500 for this thing.