How do convector element ratings work?

josieT

I'm trying to understand how convector elements work. In this spec http://www.ocsind.com/steel-convector-elements.php
for example, a 36 inch long and 8 inch deep convector at 180 degrees has a rating of 6.3. How is that converted to BTUs?

The spec is very confusing. On the first table, it doesn't give the length of the convectors for the prices given.

Any comments on convectors vs radiators for hot water in terms of well one performs vs the other. I need to replace my undersized sunrads and looking for options both for heat and aesthetics and safety (i.e. little kids).

Robert O'Brien

EDR to BTU= multiply x 240

josieT

Like i mentioned, 180 degrees which is the lowest temp they provided.

Rich_49

AWT and AFUE of the boiler now become a huge factor . The radiators are sized and designed for an average water temp of 160* , 40* Delta . Boiler making 180* at design and returning 140* , not quite condensing but much higher efficiency than returning 170* . though outdoor reset will be employed regardless of the posters final decision this cannot be ignored . We are nearing the point of no return (on investment) .

At some point in this process Smiths fan convectors were specified , these were in fact fan convectors that would have heated the space with water south of 140* at design . Would have taken an electrician a day to pull wire and do necessary work for such a huge gain in boiler / system efficiency . Would anyone care to elaborate on this suggestion ? Even though it may cost a bit more now at install the benefits are forever .

http://www.smithsenvironmental.com/PSU_Brochure.pdf

Gordy

Rich said:

AWT and AFUE of the boiler now become a huge factor . The radiators are sized and designed for an average water temp of 160* , 40* Delta . Boiler making 180* at design and returning 140* , not quite condensing but much higher efficiency than returning 170* . though outdoor reset will be employed regardless of the posters final decision this cannot be ignored . We are nearing the point of no return (on investment) .

At some point in this process Smiths fan convectors were specified , these were in fact fan convectors that would have heated the space with water south of 140* at design . Would have taken an electrician a day to pull wire and do necessary work for such a huge gain in boiler / system efficiency . Would anyone care to elaborate on this suggestion ? Even though it may cost a bit more now at install the benefits are forever .

http://www.smithsenvironmental.com/PSU_Brochure.pdf

Like insulation the gift that keeps on giving, and that is sustained system efficiency. You get one shot, at getting the most out of it. Unless you wanna do it twice.

Rich_49

Unfortunately , at 2.7 ACH w/o storms and a predicted 2 ACH with panel rads were never a good fit for the second floor . Room sizes also would lead one to install more than 1 per room and ceiling and wall work become an issue . A slight noise is much easier to tolerate than a cold room .

Bob Bona_4

On high speed they are very annoying. If I HAVE to use one I size for low speed.

Great dust and hair catchers.

Rich_49

They were sized for low speed and 140* AWT . Hatteras , although I get where you are going with this it would be piss poor planning on my part to design a system that was originally purchased with a high efficiency in mind to use water temps that high and throw any chance of the unit condensing out the window .
Can someone who would use high temps with a condensing boiler even begin to think they have a clue ? This job is a nightmare created by someone who did not have one . When the OP stated she may want cast iron radiators I sized them for 160* AWT with a 40* Delta trying to wring out all I could for her . Quite the balancing act and lotsa recommendations on this one . It has been an experience .

Rich_49

Hat , I already gave up some efficiency and condensing with the 160* AWT on the coldest days . Doing the best job possible while still staying ahead or the dopes is what makes me me . If I had to design to a less efficient standard than I have predetermined I pass on the job . Strive for perfection , you'll never acheive it but on the way you'll find excellence . Since hardly anyone will ever spend the money to do it right I must perform in this manner to stay alive and receive the word of mouth and recommendations .
The other issue is on record cold times which have happened for longer than the 99% bins over the last 2 winters I cannot guarantee them the setpoint they desire . COMFORT at all conditions is my goal . I lowered the setpoint and gave up some condensing time , I am not willing to lower it from there . If the customer would like to I will send my specs and they can fond someone to screw it up . At the end of the day I will not be liable . Matters not to me that the house could strain spaghetti .

josieT

Thanks for the help. Looks like even a 10 inch element even at 180 wouldn't get me to the BTUs in Rich's spec. Just wanted to be sure before sealing up the old recessions for good.

Smith output is unreal. Haven't seen a radiator come even close in output esp at the lower water temps. In the pic, they look huge. But looking at the dimensions the PSU-30 is 20 inches tall, 30 inches wide and 6 inches deep. That's not too bad. Wonder why more people don't use them. You can't beat that heat.