Help determining EDR (heat output) of convectors

frogpond

Hi all. I’m new to all of this and need some help. I have a gas boiler and convectors recessed into the wall (pictures are attached). I want to get rid of the gas and go with an electric option that still uses the convectors, possibly geothermal. But that would mean going from water temperatures of 180 F down to 150 or 160. I am hoping you all can help me figure out if I can do that and still adequately heat my house.

From my research and reading posts on this forum, it looks like the way to do that is determine the EDR of my convectors at the different temperatures and determine whether that will meet my house’s heatload needs.

The house was built in 1957 and the convectors are presumably original. They have no model number or anything (that I can see) and say only that they are Tuttle and Bailey Inc., New Britain, Connecticut. Googling that has not proven fruitful. They use hot water, not steam.

Each convector has 3 horizontal pipes of 1/2" diameter. They are 2.5" tall and 5.5" deep (and of varying length, from room to room). The feed pipes are 3/4" diameter and are 7" long from the floor to the convector.

I understand that there is a book out there with EDRs for various systems – any chance any of you know what I have and what the EDR is? Pictures are attached. Thank you!

Alan (California Radiant) Forbes

Dunham was a brand that didn’t put their name on their convectors. Do any of these enclosures look like yours?

frogpond

Hi Alan. They look similar to the first picture you shared. But as I noted in my initial post, they have Tuttle and Bailey Inc., New Britain, Connecticut stamped on them, which I assume means they are not Dunham?

Alan (California Radiant) Forbes

Oh, sorry. Here you go. 

frogpond

Thank you! I really appreciate your assistance.

Do you mind a few newbie follow up questions?

1) The first page of the document says that if I have recessed convectors (which is what I have), I subtract 4". Is that measurement made from the edges of the cover? Or the convector itself (after the cover is removed)?

2) What water temperature does that EDR measure in the table assume? 180F or something different?

3) How do I convert the EDR to BTU/h? I found online that it is multiplied times 240, but does that assume a specific temperature?

4) How do I use this information if I want to calculate the BTU/h with a different temperature, say 160F (right now the water is heated to 180F)?

Alan (California Radiant) Forbes

1) The first page of the document says that if I have recessed convectors (which is what I have), I subtract 4". Is that measurement made from the edges of the cover? Or the convector itself (after the cover is removed)? 

 

I’d guess the former. 

For your BTU conversions:

frogpond

Wow, that's super helpful. So just to make sure I'm doing it right:

If I have, say (on the bottom table of the pictures you posted earlier) a radiator that has 42.5 EDR, then that is 7,225 BTU/h at 180F and 4,675 BTU/h at 150F.

Thanks for all of this. Which book is this from?

Alan (California Radiant) Forbes

https://heatinghelp.com/store/detail/e-d-r-ratings-for-every-darn-radiator-and-convector-youll-probably-ever-see