Runtal Radiators

Andyck78

How do i size a runtal panel radiator if its sold by 2" increments?
I'm looking at the VLX56/56 B/Board panel radiator. I have the square ft of radiation for the cast iron radiator that the customer wants to replace. 60 sqft. How do I figure the conversion and size?

Thanks for any input

Ironman

60 sq. ft. @ 170* average SWT = 9000 btus. Look at Runtal's rating tables for the rad your considering to see if it can give you 9000 btus. I kinda doubt that you'll find a single one that will.

You also need to consider that water takes the path of least resistance. If you're removing a rad that has 1" or 1 1/4" piping, and you connect a Runtal that has 1/2" connections... Guess what? There will be very little or no flow through the Runtal.

Old CI radiator systems were carefully designed and balanced. They move water at a very low velocity with little head (especially gravity systems with large pipes). If you're gonna try and connect a modern rad with small connections, then you need to add a separate circulator for it.

Andyck78

Right now the current radiator is piped in 1/2 black pipe. The radiator is also located in a enclosed kitchen cabinet that does not have any way to vent into the kitchen. I will be giving an option to add a multipule speed circulator to this line also. the room is also fairly small only 9 x 11. I was told that it was an addition added many years ago. How do you size the btu need for just one room? Do iI need to run a manual J for this room?

Ironman

How about using a toe kick heater? You'd still need a separate circulator for it.

The manual J or equivalent is the most accurate, but unless you have an unusual room with a very high heat loss (excessive glass, no insulation, all sides exposed, etc.), you shouldn't need more than 35 btus per sq. ft.

A toe kick heater would be controlled by a separate stat, pump relay and circulator, so over sizing it some wouldn't matter.

Andyck78

The kick space maybe an option, probably way more cost effective too