Recessed Radiators

PittsburghRowHouse

Hi team,

You all have been a big help on my path to installing hot water heat in the rowhouse my wife and I are renovating in Pittsburgh. One question remains: should we install recessed radiators?

I like the look of this style here: https://us.v-cdn.net/5021738/uploads/editor/a8/i8il5rqgq33o.jpg. We're planning on using Ecostyle radiators throughout the house. The reason I may want to do recessed is that it is a small house and floor space is at a premium.

I see two options:
1. Just install them recessed in the bathrooms
2. Install them recessed throughout the house

From the old posts I've read here, I understand a few things:
a. Recessed radiators are ~30% less efficient
b. To make up for that, make them ~20% bigger
c. Insulate the hell out of the back (particularly if on an exterior wall) and put reflective metal behind the rad
d. Give them enough space to allow the air to circulate

My questions are:
i. Are the things I understand true (a-d)?
ii. How much space around the radiators should be given?
iii. Is there anything else that I am not considering that I should be?

Thank you!

hot_rod

I like the looks of that installation a lot.

Yes you are correct on a-d.

I'm not sure the exact % of output hit you take. That rad transfers both by convection, air movement across the fins, and some radiant from the warm metal surface. You could watch that with an infrared camera.

I think you have enough space around it to get the convective currents into the space.

My biggest concern is insulation, or lack of, behind the rad. It will be a cold spot and a potential freeze? What R-value can you end up with being. Foam board is R-5 per inch.

Good news is the colder temperature due to lack of insulation drives output and operating cost

tim smith

I would not think more than 20-25% loss. Maybe call Runtal and talk to one of the design tech guys about the recessing loss, I would oversize quite a bit more to keep water temps down especially if you have a condensing boiler. I usually size at appx 130 or so water temp to figure radiator output with condensing boiler to keep return temps down to stay in condensing range on boiler. Cost and room is gets to be a factor but I try. Also I would feel curving the top of recess box would help with maybe 6" above radiator or so. maybe 4 below. Just a thought. I attached a sketch of kind of what I would think. No hard science behind it, just some practical thoughts maybe. Good Luck, Tim

tim smith

Just last thought, I usually figure the 25% or so loss with an enclosure or cover. I really don't suspect it will be that much but worth checking with mfr.