How to calculate EDR for dummies

RTW · February 13

A lot has been posted on knowing EDR to match boiler size and thought this Link would give residential homeowners a better understanding on how to measure EDR on their own

radiatorest.pdf

I read in a post the other day the EDR # should correspond to the Steam Sq. # on the boiler label plate

Im an amateur with steam heat, so don't hold me to this info. and follow professional advice

All the best,

RTW

delcrossv · February 13

The book Every Darn Radiator is more accurate. But this will "ballpark" you.

Not sure about the x1.25 to get boiler size as SqFt of steam on the boiler plate already includes a 33% pickup factor. Adding another 25% would get you well oversized.

Dave in QCA · February 13

One of the problems with the guide at

radiatorest.pdf

is that it only mentions one type of tubular radiator. In fact their are two and they are greatly different. The first version of tubular radiators had thicker section, mearsuring 2.5" on center, the same as most column radiators. Then, the slenderized version came on to the market with a section dimension of 1.75" thick.

Dave in QCA · February 13

Another good EDR guide comes from an old ASHRAE guide book. I have been using this guide since 1982. More exact EDR ratings from the manufacturers is even more accurate and Dan has a ton of those in his publication, EDR - Every Darned Radiator.

radiator sizing information.pdf

Pumpguy · February 13

The EDR is equally needed when sizing vacuum and condensate pumps for 2 pipe systems.

Whenever I'm asked about replacement pumps or system problems, and ask what is the system's EDR, no-one yet, ever, has given me this information based on an actual survey of the radiation.

So that leaves me with having to rely on the steaming capacity of the boiler plant, or the pumping capacity of the old equipment.

And then they wonder why the new equipment doesn't work any better than the old stuff did. Doing the same thing and expecting a different result is………………